Section

[Code of Federal Regulations]
[Title 40, Volume 7]
[Revised as of July 1, 2005]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR60.A4]

[Page 241]

Appendix A-4 to Part 60--Test Methods 6 through 10B

Method 6--Determination of sulfur dioxide emissions from stationary
sources
Method 6A--Determination of sulfur dioxide, moisture, and carbon dioxide
emissions from fossil fuel combustion sources
Method 6B--Determination of sulfur dioxide and carbon dioxide daily
average emissions from fossil fuel combustion sources
Method 6C--Determination of Sulfur Dioxide Emissions From Stationary
Sources (Instrumental Analyzer Procedure)
Method 7--Determination of nitrogen oxide emissions from stationary
sources
Method 7A--Determination of nitrogen oxide emissions from stationary
sources--Ion chromatographic method
Method 7B--Determination of nitrogen oxide emissions from stationary
sources (Ultraviolet spectrophotometry)
Method 7C--Determination of nitrogen oxide emissions from stationary
sources--Alkaline-permanganate/colorimetric method
Method 7D--Determination of nitrogen oxide emissions from stationary
sources--Alkaline-permanganate/ion chromatographic method
Method 7E--Determination of Nitrogen Oxides Emissions From Stationary
Sources (Instrumental Analyzer Procedure)
Method 8--Determination of sulfuric acid mist and sulfur dioxide
emissions from stationary sources
Method 9--Visual determination of the opacity of emissions from
stationary sources
Alternate method 1--Determination of the opacity of emissions from
stationary sources remotely by lidar
Method 10--Determination of carbon monoxide emissions from stationary
sources
Method 10A--Determination of carbon monoxide emissions in certifying
continuous emission monitoring systems at petroleum refineries
Method 10B--Determination of carbon monoxide emissions from stationary
sources
The test methods in this appendix are referred to in Sec. 60.8
(Performance Tests) and Sec. 60.11 (Compliance With Standards and
Maintenance Requirements) of 40 CFR part 60, subpart A (General
Provisions). Specific uses of these test methods are described in the
standards of performance contained in the subparts, beginning with
Subpart D.
Within each standard of performance, a section title ``Test Methods
and Procedures'' is provided to: (1) Identify the test methods to be
used as reference methods to the facility subject to the respective
standard and (2) identify any special instructions or conditions to be
followed when applying a method to the respective facility. Such
instructions (for example, establish sampling rates, volumes, or
temperatures) are to be used either in addition to, or as a substitute
for procedures in a test method. Similarly, for sources subject to
emission monitoring requirements, specific instructions pertaining to
any use of a test method as a reference method are provided in the
subpart or in Appendix B.
Inclusion of methods in this appendix is not intended as an
endorsement or denial of their applicability to sources that are not
subject to standards of performance. The methods are potentially
applicable to other sources; however, applicability should be confirmed
by careful and appropriate evaluation of the conditions prevalent at
such sources.
The approach followed in the formulation of the test methods
involves specifications for equipment, procedures, and performance. In
concept, a performance specification approach would be preferable in all
methods because this allows the greatest flexibility to the user. In
practice, however, this approach is impractical in most cases because
performance specifications cannot be established. Most of the methods
described herein, therefore, involve specific equipment specifications
and procedures, and only a few methods in this appendix rely on
performance criteria.
Minor changes in the test methods should not necessarily affect the
validity of the results and it is recognized that alternative and
equivalent methods exist. Section 60.8 provides authority for the
Administrator to specify or approve (1) equivalent methods, (2)
alternative methods, and (3) minor changes in the methodology of the
test methods. It should be clearly understood that unless otherwise
identified all such methods and changes must have prior approval of the
Administrator. An owner employing such methods or deviations from the
test methods without obtaining prior approval does so at the risk of
subsequent disapproval and retesting with approved methods.
Within the test methods, certain specific equipment or procedures
are recognized as being acceptable or potentially acceptable and are
specifically identified in the methods. The items identified as
acceptable options may be used without approval but must be identified
in the test report. The potentially approvable options are cited as
``subject to the approval of the Administrator'' or as ``or
equivalent.'' Such potentially approvable techniques or alternatives may
be used at the discretion of the owner without prior approval. However,
detailed descriptions for applying these potentially approvable
techniques or alternatives are not provided in the test methods. Also,
the potentially approvable options are not necessarily acceptable in all
applications. Therefore, an owner electing to use such potentially
approvable techniques or alternatives is responsible for: (1) assuring
that

the techniques or alternatives are in fact applicable and are properly
executed; (2) including a written description of the alternative method
in the test report (the written method must be clear and must be capable
of being performed without additional instruction, and the degree of
detail should be similar to the detail contained in the test methods);
and (3) providing any rationale or supporting data necessary to show the
validity of the alternative in the particular application. Failure to
meet these requirements can result in the Administrator's disapproval of
the alternative.

Method 6--Determination of Sulfur Dioxide Emissions From Stationary
Sources

Note: This method does not include all of the specifications (e.g.,
equipment and supplies) and procedures (e.g., sampling and analytical)
essential to its performance. Some material is incorporated by reference
from other methods in this part. Therefore, to obtain reliable results,
persons using this method should have a thorough knowledge of at least
the following additional test methods: Method 1, Method 2, Method 3,
Method 5, and Method 8.

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
SO2............................... 7449-09-5 3.4 mg SO2/m3
(2.12 x 10)-7 lb/ft3
------------------------------------------------------------------------

1.2 Applicability. This method applies to the measurement of sulfur
dioxide (SO²) emissions from stationary sources.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A gas sample is extracted from the sampling point in the stack.
The SO² and the sulfur trioxide, including those fractions in
any sulfur acid mist, are separated. The SO² fraction is
measured by the barium-thorin titration method.

3.0 Definitions [Reserved]

4.0 Interferences

4.1 Free Ammonia. Free ammonia interferes with this method by
reacting with SO² to form particulate sulfite and by reacting
with the indicator. If free ammonia is present (this can be determined
by knowledge of the process and/or noticing white particulate matter in
the probe and isopropanol bubbler), alternative methods, subject to the
approval of the Administrator are required. One approved alternative is
listed in Reference 13 of Section 17.0.
4.2 Water-Soluble Cations and Fluorides. The cations and fluorides
are removed by a glass wool filter and an isopropanol bubbler;
therefore, they do not affect the SO2 analysis. When samples
are collected from a gas stream with high concentrations of metallic
fumes (i.e., very fine cation aerosols) a high-efficiency glass fiber
filter must be used in place of the glass wool plug (i.e., the one in
the probe) to remove the cation interferent.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of the
user to establish appropriate safety and health practices and determine
the applicability of regulatory limitations before performing this test
method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water for at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating to
eyes, skin, nose, and lungs. 30% H2O2 is a strong
oxidizing agent. Avoid contact with skin, eyes, and combustible
material. Wear gloves when handling.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eyes and
skin. Inhalation causes irritation to nose, throat, and lungs. Reacts
exothermically with limited amounts of water.
5.2.3 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 1 mg/m³ for 8 hours will cause lung damage or, in
higher concentrations, death. Provide ventilation to limit inhalation.
Reacts violently with metals and organics.

6.0 Equipment and Supplies

6.1 Sample Collection. The following items are required for sample
collection:
6.1.1 Sampling Train. A schematic of the sampling train is shown in
Figure 6-1. The sampling equipment described in Method 8 may be
substituted in place of the midget impinger equipment of Method 6.
However, the Method 8 train must be modified to include a heated filter
between the probe and isopropanol impinger, and the operation of the
sampling train and sample analysis must be at the flow rates and
solution volumes defined in Method 8. Alternatively, SO2 may
be determined simultaneously with particulate

[[Page 242]]

matter and moisture determinations by either (1) replacing the water in
a Method 5 impinger system with a 3 percent H2O2
solution, or (2) replacing the Method 5 water impinger system with a
Method 8 isopropanol-filter-H2O2 system. The
analysis for SO2 must be consistent with the procedure of
Method 8. The Method 6 sampling train consists of the following
components:
6.1.1.1 Probe. Borosilicate glass or stainless steel (other
materials of construction may be used, subject to the approval of the
Administrator), approximately 6 mm (0.25 in.) inside diameter, with a
heating system to prevent water condensation and a filter (either in-
stack or heated out-of-stack) to remove particulate matter, including
sulfuric acid mist. A plug of glass wool is a satisfactory filter.
6.1.1.2 Bubbler and Impingers. One midget bubbler with medium-coarse
glass frit and borosilicate or quartz glass wool packed in top (see
Figure 6-1) to prevent sulfuric acid mist carryover, and three 30-ml
midget impingers. The midget bubbler and midget impingers must be
connected in series with leak-free glass connectors. Silicone grease may
be used, if necessary, to prevent leakage. A midget impinger may be used
in place of the midget bubbler.

Note: Other collection absorbers and flow rates may be used, subject
to the approval of the Administrator, but the collection efficiency must
be shown to be at least 99 percent for each test run and must be
documented in the report. If the efficiency is found to be acceptable
after a series of three tests, further documentation is not required. To
conduct the efficiency test, an extra absorber must be added and
analyzed separately. This extra absorber must not contain more than 1
percent of the total SO2.

6.1.1.3 Glass Wool. Borosilicate or quartz.
6.1.1.4 Stopcock Grease. Acetone-insoluble, heat-stable silicone
grease may be used, if necessary.
6.1.1.5 Temperature Sensor. Dial thermometer, or equivalent, to
measure temperature of gas leaving impinger train to within 1 [deg]C (2
[deg]F).
6.1.1.6 Drying Tube. Tube packed with 6- to 16- mesh indicating-type
silica gel, or equivalent, to dry the gas sample and to protect the
meter and pump. If silica gel is previously used, dry at 177 [deg]C (350
[deg]F) for 2 hours. New silica gel may be used as received.
Alternatively, other types of desiccants (equivalent or better) may be
used, subject to the approval of the Administrator.
6.1.1.7 Valve. Needle valve, to regulate sample gas flow rate.
6.1.1.8 Pump. Leak-free diaphragm pump, or equivalent, to pull gas
through the train. Install a small surge tank between the pump and rate
meter to negate the pulsation effect of the diaphragm pump on the rate
meter.
6.1.1.9 Rate Meter. Rotameter, or equivalent, capable of measuring
flow rate to within 2 percent of the selected flow rate of about 1
liter/min (0.035 cfm).
6.1.1.10 Volume Meter. Dry gas meter (DGM), sufficiently accurate to
measure the sample volume to within 2 percent, calibrated at the
selected flow rate and conditions actually encountered during sampling,
and equipped with a temperature sensor (dial thermometer, or equivalent)
capable of measuring temperature accurately to within 3 [deg]C (5.4
[deg]F). A critical orifice may be used in place of the DGM specified in
this section provided that it is selected, calibrated, and used as
specified in Section 16.0.
6.1.2 Barometer. Mercury, aneroid, or other barometer capable of
measuring atmospheric pressure to within 2.5 mm Hg (0.1 in. Hg). See the
Note in Method 5, Section 6.1.2.
6.1.3 Vacuum Gauge and Rotameter. At least 760-mm Hg (30-in. Hg)
gauge and 0- to 40-ml/min rotameter, to be used for leak-check of the
sampling train.
6.2 Sample Recovery. The following items are needed for sample
recovery:
6.2.1 Wash Bottles. Two polyethylene or glass bottles, 500-ml.
6.2.2 Storage Bottles. Polyethylene bottles, 100-ml, to store
impinger samples (one per sample).
6.3 Sample Analysis. The following equipment is needed for sample
analysis:
6.3.1 Pipettes. Volumetric type, 5-ml, 20-ml (one needed per
sample), and 25-ml sizes.
6.3.2 Volumetric Flasks. 100-ml size (one per sample) and 1000-ml
size.
6.3.3 Burettes. 5- and 50-ml sizes.
6.3.4 Erlenmeyer Flasks. 250-ml size (one for each sample, blank,
and standard).
6.3.5 Dropping Bottle. 125-ml size, to add indicator.
6.3.6 Graduated Cylinder. 100-ml size.
6.3.7 Spectrophotometer. To measure absorbance at 352 nm.

7.0 Reagents and Standards

Note: Unless otherwise indicated, all reagents must conform to the
specifications established by the Committee on Analytical Reagents of
the American Chemical Society. Where such specifications are not
available, use the best available grade.

7.1 Sample Collection. The following reagents are required for
sample collection:
7.1.1 Water. Deionized distilled to conform to ASTM Specification D
1193-77 or 91 Type 3 (incorporated by reference--see Sec. 60.17). The
KMnO4 test for oxidizable organic matter may be omitted when
high concentrations of organic matter are not expected to be present.

[[Page 243]]

7.1.2 Isopropanol, 80 Percent by Volume. Mix 80 ml of isopropanol
with 20 ml of water.
7.1.2.1 Check each lot of isopropanol for peroxide impurities as
follows: Shake 10 ml of isopropanol with 10 ml of freshly prepared 10
percent potassium iodide solution. Prepare a blank by similarly treating
10 ml of water. After 1 minute, read the absorbance at 352 nm on a
spectrophotometer using a 1-cm path length. If absorbance exceeds 0.1,
reject alcohol for use.
7.1.2.2 Peroxides may be removed from isopropanol by redistilling or
by passage through a column of activated alumina; however, reagent grade
isopropanol with suitably low peroxide levels may be obtained from
commercial sources. Rejection of contaminated lots may, therefore, be a
more efficient procedure.
7.1.3 Hydrogen Peroxide (H2O2), 3 Percent by
Volume. Add 10 ml of 30 percent H2O2 to 90 ml of
water. Prepare fresh daily.
7.1.4 Potassium Iodide Solution, 10 Percent Weight by Volume (w/v).
Dissolve 10.0 g of KI in water, and dilute to 100 ml. Prepare when
needed.
7.2 Sample Recovery. The following reagents are required for sample
recovery:
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 Isopropanol, 80 Percent by Volume. Same as in Section 7.1.2.
7.3 Sample Analysis. The following reagents and standards are
required for sample analysis:
7.3.1 Water. Same as in Section 7.1.1.
7.3.2 Isopropanol, 100 Percent.
7.3.3 Thorin Indicator. 1-(o-arsonophenylazo)-2-naphthol-3,6-
disulfonic acid, disodium salt, or equivalent. Dissolve 0.20 g in 100 ml
of water.
7.3.4 Barium Standard Solution, 0.0100 N. Dissolve 1.95 g of barium
perchlorate trihydrate [Ba(ClO4)2 3H2O]
in 200 ml water, and dilute to 1 liter with isopropanol. Alternatively,
1.22 g of barium chloride dihydrate [BaCl2 2H2O]
may be used instead of the barium perchlorate trihydrate. Standardize as
in Section 10.5.
7.3.5 Sulfuric Acid Standard, 0.0100 N. Purchase or standardize to
0.0002 N against 0.0100 N NaOH which has
previously been standardized against potassium acid phthalate (primary
standard grade).
7.3.6 Quality Assurance Audit Samples. When making compliance
determinations, audit samples, if available must be obtained from the
appropriate EPA Regional Office or from the responsible enforcement
authority and analyzed in conjunction with the field samples.

Note: The responsible enforcement authority should be notified at
least 30 days prior to the test date to allow sufficient time for sample
delivery.

8.0 Sample Collection, Preservation, Storage and Transport

8.1 Preparation of Sampling Train. Measure 15 ml of 80 percent
isopropanol into the midget bubbler and 15 ml of 3 percent
H2O2 into each of the first two midget impingers.
Leave the final midget impinger dry. Assemble the train as shown in
Figure 6-1. Adjust the probe heater to a temperature sufficient to
prevent water condensation. Place crushed ice and water around the
impingers.
8.2 Sampling Train Leak-Check Procedure. A leak-check prior to the
sampling run is recommended, but not required. A leak-check after the
sampling run is mandatory. The leak-check procedure is as follows:
8.2.1 Temporarily attach a suitable (e.g., 0- to 40- ml/min)
rotameter to the outlet of the DGM, and place a vacuum gauge at or near
the probe inlet. Plug the probe inlet, pull a vacuum of at least 250 mm
Hg (10 in. Hg), and note the flow rate as indicated by the rotameter. A
leakage rate in excess of 2 percent of the average sampling rate is not
acceptable.

Note: Carefully (i.e., slowly) release the probe inlet plug before
turning off the pump.

8.2.2 It is suggested (not mandatory) that the pump be leak-checked
separately, either prior to or after the sampling run. To leak-check the
pump, proceed as follows: Disconnect the drying tube from the probe-
impinger assembly. Place a vacuum gauge at the inlet to either the
drying tube or the pump, pull a vacuum of 250 mm Hg (10 in. Hg), plug or
pinch off the outlet of the flow meter, and then turn off the pump. The
vacuum should remain stable for at least 30 seconds.
If performed prior to the sampling run, the pump leak-check shall
precede the leak-check of the sampling train described immediately
above; if performed after the sampling run, the pump leak-check shall
follow the sampling train leak-check.
8.2.3 Other leak-check procedures may be used, subject to the
approval of the Administrator.
8.3 Sample Collection.
8.3.1 Record the initial DGM reading and barometric pressure. To
begin sampling, position the tip of the probe at the sampling point,
connect the probe to the bubbler, and start the pump. Adjust the sample
flow to a constant rate of approximately 1.0 liter/min as indicated by
the rate meter. Maintain this constant rate ( 10
percent) during the entire sampling run.
8.3.2 Take readings (DGM volume, temperatures at DGM and at impinger
outlet, and rate meter flow rate) at least every 5 minutes. Add more ice
during the run to keep the temperature of the gases leaving the last
impinger at 20 [deg]C (68 [deg]F) or less.
8.3.3 At the conclusion of each run, turn off the pump, remove the
probe from the

[[Page 244]]

stack, and record the final readings. Conduct a leak-check as described
in Section 8.2. (This leak-check is mandatory.) If a leak is detected,
void the test run or use procedures acceptable to the Administrator to
adjust the sample volume for the leakage.
8.3.4 Drain the ice bath, and purge the remaining part of the train
by drawing clean ambient air through the system for 15 minutes at the
sampling rate. Clean ambient air can be provided by passing air through
a charcoal filter or through an extra midget impinger containing 15 ml
of 3 percent H2O2. Alternatively, ambient air
without purification may be used.
8.4 Sample Recovery. Disconnect the impingers after purging. Discard
the contents of the midget bubbler. Pour the contents of the midget
impingers into a leak-free polyethylene bottle for shipment. Rinse the
three midget impingers and the connecting tubes with water, and add the
rinse to the same storage container. Mark the fluid level. Seal and
identify the sample container.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
7.1.2.................... Isopropanol check.. Ensure acceptable level
of peroxide impurities
in isopropanol.
8.2, 10.1-10.4........... Sampling equipment Ensure accurate
leak-check and measurement of stack
calibration. gas flow rate, sample
volume.
10.5..................... Barium standard Ensure precision of
solution normality
standardization. determination.
11.2.3................... Replicate Ensure precision of
titrations. titration
determinations
11.3..................... Audit sample Evaluate analyst's
analysis. technique and standards
preparation.
------------------------------------------------------------------------

10.0 Calibration and Standardization

10.1 Volume Metering System.
10.1.1 Initial Calibration.
10.1.1.1 Before its initial use in the field, leak-check the
metering system (drying tube, needle valve, pump, rate meter, and DGM)
as follows: Place a vacuum gauge at the inlet to the drying tube and
pull a vacuum of 250 mm Hg (10 in. Hg). Plug or pinch off the outlet of
the flow meter, and then turn off the pump. The vacuum must remain
stable for at least 30 seconds. Carefully release the vacuum gauge
before releasing the flow meter end.
10.1.1.2 Remove the drying tube, and calibrate the metering system
(at the sampling flow rate specified by the method) as follows: Connect
an appropriately sized wet-test meter (e.g., 1 liter per revolution) to
the inlet of the needle valve. Make three independent calibration runs,
using at least five revolutions of the DGM per run. Calculate the
calibration factor Y (wet-test meter calibration volume divided by the
DGM volume, both volumes adjusted to the same reference temperature and
pressure) for each run, and average the results (Yi). If any
Y-value deviates by more than 2 percent from (Yi), the
metering system is unacceptable for use. If the metering system is
acceptable, use (Yi) as the calibration factor for subsequent
test runs.
10.1.2 Post-Test Calibration Check. After each field test series,
conduct a calibration check using the procedures outlined in Section
10.1.1.2, except that three or more revolutions of the DGM may be used,
and only two independent runs need be made. If the average of the two
post-test calibration factors does not deviate by more than 5 percent
from Yi, then Yi is accepted as the DGM
calibration factor (Y), which is used in Equation 6-1 to calculate
collected sample volume (see Section 12.2). If the deviation is more
than 5 percent, recalibrate the metering system as in Section 10.1.1,
and determine a post-test calibration factor (Yf). Compare
Yi and Yf; the smaller of the two factors is
accepted as the DGM calibration factor. If recalibration indicates that
the metering system is unacceptable for use, either void the test run or
use methods, subject to the approval of the Administrator, to determine
an acceptable value for the collected sample volume.
10.1.3 DGM as a Calibration Standard. A DGM may be used as a
calibration standard for volume measurements in place of the wet-test
meter specified in Section 10.1.1.2, provided that it is calibrated
initially and recalibrated periodically according to the same procedures
outlined in Method 5, Section 10.3 with the following exceptions: (a)
the DGM is calibrated against a wet-test meter having a capacity of 1
liter/rev (0.035 ft³/rev) or 3 liters/rev (0.1
ft³/rev) and having the capability of measuring volume to
within 1 percent; (b) the DGM is calibrated at 1 liter/min (0.035 cfm);
and (c) the meter box of the Method 6 sampling train is calibrated at
the same flow rate.
10.2 Temperature Sensors. Calibrate against mercury-in-glass
thermometers.
10.3 Rate Meter. The rate meter need not be calibrated, but should
be cleaned and maintained according to the manufacturer's instructions.
10.4 Barometer. Calibrate against a mercury barometer.
10.5 Barium Standard Solution. Standardize the barium perchlorate or
chloride solution against 25 ml of standard sulfuric acid to which 100
ml of 100 percent isopropanol

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has been added. Run duplicate analyses. Calculate the normality using
the average of duplicate analyses where the titrations agree within 1
percent or 0.2 ml, whichever is larger.

11.0 Analytical Procedure

11.1 Sample Loss Check. Note level of liquid in container and
confirm whether any sample was lost during shipment; note this finding
on the analytical data sheet. If a noticeable amount of leakage has
occurred, either void the sample or use methods, subject to the approval
of the Administrator, to correct the final results.
11.2 Sample Analysis.
11.2.1 Transfer the contents of the storage container to a 100-ml
volumetric flask, dilute to exactly 100 ml with water, and mix the
diluted sample.
11.2.2 Pipette a 20-ml aliquot of the diluted sample into a 250-ml
Erlenmeyer flask and add 80 ml of 100 percent isopropanol plus two to
four drops of thorin indicator. While stirring the solution, titrate to
a pink endpoint using 0.0100 N barium standard solution.
11.2.3 Repeat the procedures in Section 11.2.2, and average the
titration volumes. Run a blank with each series of samples. Replicate
titrations must agree within 1 percent or 0.2 ml, whichever is larger.

Note: Protect the 0.0100 N barium standard solution from evaporation
at all times.

11.3 Audit Sample Analysis.
11.3.1 When the method is used to analyze samples to demonstrate
compliance with a source emission regulation, an audit sample, if
available, must be analyzed.
11.3.2 Concurrently analyze the audit sample and the compliance
samples in the same manner to evaluate the technique of the analyst and
the standards preparation.
11.3.3 The same analyst, analytical reagents, and analytical system
must be used for the compliance samples and the audit sample. If this
condition is met, duplicate auditing of subsequent compliance analyses
for the same enforcement agency within a 30-day period is waived. An
audit sample set may not be used to validate different sets of
compliance samples under the jurisdiction of separate enforcement
agencies, unless prior arrangements have been made with both enforcement
agencies.
11.4 Audit Sample Results.
11.4.1 Calculate the audit sample concentrations and submit results
using the instructions provided with the audit samples.
11.4.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
11.4.3 The concentrations of the audit samples obtained by the
analyst must agree within 5 percent of the actual concentration. If the
5 percent specification is not met, reanalyze the compliance and audit
samples, and include initial and reanalysis values in the test report.
11.4.4 Failure to meet the 5-percent specification may require
retests until the audit problems are resolved. However, if the audit
results do not affect the compliance or noncompliance status of the
affected facility, the Administrator may waive the reanalysis
requirement, further audits, or retests and accept the results of the
compliance test. While steps are being taken to resolve audit analysis
problems, the Administrator may also choose to use the data to determine
the compliance or noncompliance status of the affected facility.

12.0 Data Analysis and Calculations

Carry out calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature.

Ca=Actual concentration of SO2 in audit sample,
mg/dscm.
Cd=Determined concentration of SO2 in audit
sample, mg/dscm.
CSO2=Concentration of SO2, dry basis, corrected to
standard conditions, mg/dscm (lb/dscf).
N=Normality of barium standard titrant, meq/ml.
Pbar=Barometric pressure, mm Hg (in. Hg).
Pstd=Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
RE=Relative error of QA audit sample analysis, percent
Tm=Average DGM absolute temperature, [deg]K ([deg]R).
Tstd=Standard absolute temperature, 293 [deg]K (528 [deg]R).
Va=Volume of sample aliquot titrated, ml.
Vm=Dry gas volume as measured by the DGM, dcm (dcf).
Vm(std)=Dry gas volume measured by the DGM, corrected to
standard conditions, dscm (dscf).
Vsoln=Total volume of solution in which the SO2 sample is
contained, 100 ml.
Vt=Volume of barium standard titrant used for the sample
(average of replicate titration), ml.
Vtb=Volume of barium standard titrant used for the blank, ml.
Y=DGM calibration factor.

12.2 Dry Sample Gas Volume, Corrected to Standard Conditions.

[[Page 246]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.181

Where:

K1=0.3855 [deg]K/mm Hg for metric units,
K1=17.65 [deg]R/in. Hg for English units.

12.3 SO2 Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.182

Where:

K2=32.03 mg SO2/meq for metric units,
K2=7.061 x 10^-5 lb SO2/meq for English
units.

12.4 Relative Error for QA Audit Samples.
[GRAPHIC] [TIFF OMITTED] TR17OC00.183

13.0 Method Performance

13.1 Range. The minimum detectable limit of the method has been
determined to be 3.4 mg SO2/m³ (2.12 x
10^-7 lb/ft³). Although no upper limit has been
established, tests have shown that concentrations as high as 80,000 mg/
m³ (0.005 lb/ft³) of SO2 can be
collected efficiently at a rate of 1.0 liter/min (0.035 cfm) for 20
minutes in two midget impingers, each containing 15 ml of 3 percent
H2O2. Based on theoretical calculations, the upper
concentration limit in a 20 liter (0.7 ft³) sample is about
93,300 mg/m³ (0.00583 lb/ft³).

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 Alternative Procedures

16.1 Nomenclature. Same as Section 12.1, with the following
additions:

Bwa=Water vapor in ambient air, proportion by volume.
Ma=Molecular weight of the ambient air saturated at impinger
temperature, g/g-mole (lb/lb-mole).
Ms=Molecular weight of the sample gas saturated at impinger
temperature, g/g-mole (lb/lb-mole).
Pc=Inlet vacuum reading obtained during the calibration run,
mm Hg (in. Hg).
Psr=Inlet vacuum reading obtained during the sampling run, mm
Hg (in. Hg).
Qstd=Volumetric flow rate through critical orifice, scm/min
(scf/min).
Qstd=Average flow rate of pre-test and post-test calibration
runs, scm/min (scf/min).
Tamb=Ambient absolute temperature of air, [deg]K ([deg]R).
Vsb=Volume of gas as measured by the soap bubble meter, m\3\
(ft\3\).
Vsb(std)=Volume of gas as measured by the soap bubble
meter, corrected to standard conditions, scm (scf).
[thetas]=Soap bubble travel time, min.
[thetas]s=Time, min.

16.2 Critical Orifices for Volume and Rate Measurements. A critical
orifice may be used in place of the DGM specified in Section 6.1.1.10,
provided that it is selected, calibrated, and used as follows:
16.2.1 Preparation of Sampling Train. Assemble the sampling train as
shown in Figure 6-2. The rate meter and surge tank are optional but are
recommended in order to detect changes in the flow rate.

Note: The critical orifices can be adapted to a Method 6 type
sampling train as follows: Insert sleeve type, serum bottle stoppers
into two reducing unions. Insert the needle into the stoppers as shown
in Figure 6-3.

16.2.2 Selection of Critical Orifices.
16.2.2.1 The procedure that follows describes the use of hypodermic
needles and stainless steel needle tubings, which have been found
suitable for use as critical orifices. Other materials and critical
orifice designs may be used provided the orifices act as true critical
orifices, (i.e., a critical vacuum can be obtained) as described in this
section. Select a critical orifice that is sized to operate at the
desired flow rate. The needle sizes and tubing lengths shown in Table 6-
1 give the following approximate flow rates.
16.2.2.2 Determine the suitability and the appropriate operating
vacuum of the critical orifice as follows: If applicable, temporarily
attach a rate meter and surge tank to the outlet of the sampling train,
if said equipment is not present (see Section 16.2.1). Turn on the pump
and adjust the valve to give an outlet vacuum reading corresponding to
about half of the atmospheric pressure. Observe the rate meter reading.
Slowly increase the vacuum until a stable reading is

[[Page 247]]

obtained on the rate meter. Record the critical vacuum, which is the
outlet vacuum when the rate meter first reaches a stable value. Orifices
that do not reach a critical value must not be used.
16.2.3 Field Procedures.
16.2.3.1 Leak-Check Procedure. A leak-check before the sampling run
is recommended, but not required. The leak-check procedure is as
follows: Temporarily attach a suitable (e.g., 0-40 ml/min) rotameter and
surge tank, or a soap bubble meter and surge tank to the outlet of the
pump. Plug the probe inlet, pull an outlet vacuum of at least 250 mm Hg
(10 in. Hg), and note the flow rate as indicated by the rotameter or
bubble meter. A leakage rate in excess of 2 percent of the average
sampling rate (Qstd) is not acceptable. Carefully release the
probe inlet plug before turning off the pump.
16.2.3.2 Moisture Determination. At the sampling location, prior to
testing, determine the percent moisture of the ambient air using the wet
and dry bulb temperatures or, if appropriate, a relative humidity meter.
16.2.3.3 Critical Orifice Calibration. At the sampling location,
prior to testing, calibrate the entire sampling train (i.e., determine
the flow rate of the sampling train when operated at critical
conditions). Attach a 500-ml soap bubble meter to the inlet of the
probe, and operate the sampling train at an outlet vacuum of 25 to 50 mm
Hg (1 to 2 in. Hg) above the critical vacuum. Record the information
listed in Figure 6-4. Calculate the standard volume of air measured by
the soap bubble meter and the volumetric flow rate using the equations
below:
[GRAPHIC] [TIFF OMITTED] TR17OC00.184

[GRAPHIC] [TIFF OMITTED] TR17OC00.185

16.2.3.4 Sampling.
16.2.3.4.1 Operate the sampling train for sample collection at the
same vacuum used during the calibration run. Start the watch and pump
simultaneously. Take readings (temperature, rate meter, inlet vacuum,
and outlet vacuum) at least every 5 minutes. At the end of the sampling
run, stop the watch and pump simultaneously.
16.2.3.4.2 Conduct a post-test calibration run using the calibration
procedure outlined in Section 16.2.3.3. If the Qstd obtained
before and after the test differ by more than 5 percent, void the test
run; if not, calculate the volume of the gas measured with the critical
orifice using Equation 6-6 as follows:
[GRAPHIC] [TIFF OMITTED] TR17OC00.186

16.2.3.4.3 If the percent difference between the molecular weight of
the ambient air at saturated conditions and the sample gas is more that
3 percent, then the molecular weight of the gas
sample must be considered in the calculations using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.187

Note: A post-test leak-check is not necessary because the post-test
calibration run results will indicate whether there is any leakage.

16.2.3.4.4 Drain the ice bath, and purge the sampling train using
the procedure described in Section 8.3.4.

[[Page 248]]

16.3 Elimination of Ammonia Interference. The following alternative
procedures must be used in addition to those specified in the method
when sampling at sources having ammonia emissions.
16.3.1 Sampling. The probe shall be maintained at 275 [deg]C (527
[deg]F) and equipped with a high-efficiency in-stack filter (glass
fiber) to remove particulate matter. The filter material shall be
unreactive to SO2. Whatman 934AH (formerly Reeve Angel 934AH)
filters treated as described in Reference 10 in Section 17.0 of Method 5
is an example of a filter that has been shown to work. Where alkaline
particulate matter and condensed moisture are present in the gas stream,
the filter shall be heated above the moisture dew point but below 225
[deg]C (437 [deg]F).
16.3.2 Sample Recovery. Recover the sample according to Section 8.4
except for discarding the contents of the midget bubbler. Add the
bubbler contents, including the rinsings of the bubbler with water, to a
separate polyethylene bottle from the rest of the sample. Under normal
testing conditions where sulfur trioxide will not be present
significantly, the tester may opt to delete the midget bubbler from the
sampling train. If an approximation of the sulfur trioxide concentration
is desired, transfer the contents of the midget bubbler to a separate
polyethylene bottle.
16.3.3 Sample Analysis. Follow the procedures in Sections 11.1 and
11.2, except add 0.5 ml of 0.1 N HCl to the Erlenmeyer flask and mix
before adding the indicator. The following analysis procedure may be
used for an approximation of the sulfur trioxide concentration. The
accuracy of the calculated concentration will depend upon the ammonia to
SO2 ratio and the level of oxygen present in the gas stream.
A fraction of the SO2 will be counted as sulfur trioxide as
the ammonia to SO2 ratio and the sample oxygen content
increases. Generally, when this ratio is 1 or less and the oxygen
content is in the range of 5 percent, less than 10 percent of the
SO2 will be counted as sulfur trioxide. Analyze the peroxide
and isopropanol sample portions separately. Analyze the peroxide portion
as described above. Sulfur trioxide is determined by difference using
sequential titration of the isopropanol portion of the sample. Transfer
the contents of the isopropanol storage container to a 100-ml volumetric
flask, and dilute to exactly 100 ml with water. Pipette a 20-ml aliquot
of this solution into a 250-ml Erlenmeyer flask, add 0.5 ml of 0.1 N
HCl, 80 ml of 100 percent isopropanol, and two to four drops of thorin
indicator. Titrate to a pink endpoint using 0.0100 N barium perchlorate.
Repeat and average the titration volumes that agree within 1 percent or
0.2 ml, whichever is larger. Use this volume in Equation 6-2 to
determine the sulfur trioxide concentration. From the flask containing
the remainder of the isopropanol sample, determine the fraction of
SO2 collected in the bubbler by pipetting 20-ml aliquots into
250-ml Erlenmeyer flasks. Add 5 ml of 3 percent
H2O2, 100 ml of 100 percent isopropanol, and two
to four drips of thorin indicator, and titrate as before. From this
titration volume, subtract the titrant volume determined for sulfur
trioxide, and add the titrant volume determined for the peroxide
portion. This final volume constitutes Vt, the volume of
barium perchlorate used for the SO2 sample.

17.0 References

1. Atmospheric Emissions from Sulfuric Acid Manufacturing Processes.
U.S. DHEW, PHS, Division of Air Pollution. Public Health Service
Publication No. 999-AP-13. Cincinnati, OH. 1965.
2. Corbett, P.F. The Determination of SO2 and
SO3 in Flue Gases. Journal of the Institute of Fuel. 24:237-
243. 1961.
3. Matty, R.E., and E.K. Diehl. Measuring Flue-Gas SO2
and SO3. Power. 101:94-97. November 1957.
4. Patton, W.F., and J.A. Brink, Jr. New Equipment and Techniques
for Sampling Chemical Process Gases. J. Air Pollution Control
Association. 13:162. 1963.
5. Rom, J.J. Maintenance, Calibration, and Operation of Isokinetic
Source Sampling Equipment. Office of Air Programs, U.S. Environmental
Protection Agency. Research Triangle Park, NC. APTD-0576. March 1972.
6. Hamil, H.F., and D.E. Camann. Collaborative Study of Method for
the Determination of Sulfur Dioxide Emissions from Stationary Sources
(Fossil-Fuel Fired Steam Generators). U.S. Environmental Protection
Agency, Research Triangle Park, NC. EPA-650/4-74-024. December 1973.
7. Annual Book of ASTM Standards. Part 31; Water, Atmospheric
Analysis. American Society for Testing and Materials. Philadelphia, PA.
1974. pp. 40-42.
8. Knoll, J.E., and M.R. Midgett. The Application of EPA Method 6 to
High Sulfur Dioxide Concentrations. U.S. Environmental Protection
Agency. Research Triangle Park, NC. EPA-600/4-76-038. July 1976.
9. Westlin, P.R., and R.T. Shigehara. Procedure for Calibrating and
Using Dry Gas Volume Meters as Calibration Standards. Source Evaluation
Society Newsletter. 3(1):17-30. February 1978.
10. Yu, K.K. Evaluation of Moisture Effect on Dry Gas Meter
Calibration. Source Evaluation Society Newsletter. 5(1):24-28. February
1980.
11. Lodge, J.P., Jr., et al. The Use of Hypodermic Needles as
Critical Orifices in Air Sampling. J. Air Pollution Control Association.
16:197-200. 1966.
12. Shigehara, R.T., and C.B. Sorrell. Using Critical Orifices as
Method 5 CalibrationStandards. Source Evaluation Society Newsletter.
10:4-15. August 1985.

[[Page 249]]

13. Curtis, F., Analysis of Method 6 Samples in the Presence of
Ammonia. Source Evaluation Society Newsletter. 13(1):9-15 February 1988.

18.0 Tables, Diagrams, Flowcharts and Validation Data

Table 6-1--Approximate Flow Rates for Various Needle Sizes
------------------------------------------------------------------------
Needle
Needle size (gauge) length Flow rate
(cm) (ml/min)
------------------------------------------------------------------------
21............................................ 7.6 1,100
22............................................ 2.9 1,000
22............................................ 3.8 900
23............................................ 3.8 500
23............................................ 5.1 450
24............................................ 3.2 400
------------------------------------------------------------------------

[[Page 250]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.188

[[Page 251]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.189

[[Page 252]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.190

[[Page 253]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.191

Method 6A--Determination of Sulfur Dioxide, Moisture, and Carbon Dioxide
From Fossil Fuel Combustion Sources

1.0 Scope and Application

1.1 Analytes.

[[Page 254]]

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
SO2............................... 7449-09-05 3.4 mg SO2/m3
(2.12 x 10-7 lb/ft3)
CO2............................... 124-38-9 N/A
H2O............................... 7732-18-5 N/A
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of sulfur dioxide (SO2) emissions from fossil fuel combustion
sources in terms of concentration (mg/dscm or lb/dscf) and in terms of
emission rate (ng/J or lb/10⁶ Btu) and for the determination
of carbon dioxide (CO2) concentration (percent). Moisture
content (percent), if desired, may also be determined by this method.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A gas sample is extracted from a sampling point in the stack.
The SO2 and the sulfur trioxide, including those fractions in
any sulfur acid mist, are separated. The SO2 fraction is
measured by the barium-thorin titration method. Moisture and
CO2 fractions are collected in the same sampling train, and
are determined gravimetrically.

3.0 Definitions [Reserved]

4.0 Interferences

Same as Method 6, Section 4.0.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. Same as Method 6, Section 6.1, with the
exception of the following:
6.1.1 Sampling Train. A schematic of the sampling train used in this
method is shown in Figure 6A-1.
6.1.1.1 Impingers and Bubblers. Two 30=ml midget impingers with a
1=mm restricted tip and two 30=ml midget bubblers with unrestricted
tips. Other types of impingers and bubblers (e.g., Mae West for
SO2 collection and rigid cylinders containing Drierite for
moisture absorbers), may be used with proper attention to reagent
volumes and levels, subject to the approval of the Administrator.
6.1.1.2 CO2 Absorber. A sealable rigid cylinder or bottle
with an inside diameter between 30 and 90 mm , a length between 125 and
250 mm, and appropriate connections at both ends. The filter may be a
separate heated unit or may be within the heated portion of the probe.
If the filter is within the sampling probe, the filter should not be
within 15 cm of the probe inlet or any unheated section of the probe,
such as the connection to the first bubbler. The probe and filter should
be heated to at least 20 [deg]C (68 [deg]F) above the source
temperature, but not greater than 120 [deg]C (248 [deg]F). The filter
temperature (i.e., the sample gas temperature) should be monitored to
assure the desired temperature is maintained. A heated Teflon connector
may be used to connect the filter holder or probe to the first impinger.

Note: For applications downstream of wet scrubbers, a heated out-of-
stack filter (either borosilicate glass wool or glass fiber mat) is
necessary.

6.2 Sample Recovery. Same as Method 6, Section 6.2.
6.3 Sample Analysis. Same as Method 6, Section 6.3, with the
addition of a balance to measure within 0.05 g.

7.0 Reagents and Standards

7.1 Sample Collection. Same as Method 6, Section 7.1, with the
addition of the following:
7.1.1 Drierite. Anhydrous calcium sulfate (CaSO4)
desiccant, 8 mesh, indicating type is recommended.

Note: Do not use silica gel or similar desiccant in this
application.

7.1.2 CO2 Absorbing Material. Ascarite II. Sodium
hydroxide-coated silica, 8- to 20-mesh.
7.2 Sample Recovery and Analysis. Same as Method 6, Sections 7.2 and
7.3, respectively.

8.0 Sample Collection, Preservation, Transport, and Storage

8.1 Preparation of Sampling Train.
8.1.1 Measure 15 ml of 80 percent isopropanol into the first midget
bubbler and 15 ml of 3 percent hydrogen peroxide into

[[Page 255]]

each of the two midget impingers (the second and third vessels in the
train) as described in Method 6, Section 8.1. Insert the glass wool into
the top of the isopropanol bubbler as shown in Figure 6A-1. Place about
25 g of Drierite into the second midget bubbler (the fourth vessel in
the train). Clean the outside of the bubblers and impingers and allow
the vessels to reach room temperature. Weigh the four vessels
simultaneously to the nearest 0.1 g, and record this initial weight
(mwi).
8.1.2 With one end of the CO2 absorber sealed, place
glass wool into the cylinder to a depth of about 1 cm (0.5 in.). Place
about 150 g of CO2 absorbing material in the cylinder on top
of the glass wool, and fill the remaining space in the cylinder with
glass wool. Assemble the cylinder as shown in Figure 6A-2. With the
cylinder in a horizontal position, rotate it around the horizontal axis.
The CO2 absorbing material should remain in position during
the rotation, and no open spaces or channels should be formed. If
necessary, pack more glass wool into the cylinder to make the
CO2 absorbing material stable. Clean the outside of the
cylinder of loose dirt and moisture and allow the cylinder to reach room
temperature. Weigh the cylinder to the nearest 0.1 g, and record this
initial weight (mai).
8.1.3 Assemble the train as shown in Figure 6A-1. Adjust the probe
heater to a temperature sufficient to prevent condensation (see Note in
Section 6.1). Place crushed ice and water around the impingers and
bubblers. Mount the CO2 absorber outside the water bath in a
vertical flow position with the sample gas inlet at the bottom. Flexible
tubing (e.g., Tygon) may be used to connect the last SO2
absorbing impinger to the moisture absorber and to connect the moisture
absorber to the CO2 absorber. A second, smaller
CO2 absorber containing Ascarite II may be added in-line
downstream of the primary CO2 absorber as a breakthrough
indicator. Ascarite II turns white when CO2 is absorbed.
8.2 Sampling Train Leak-Check Procedure and Sample Collection. Same
as Method 6, Sections 8.2 and 8.3, respectively.
8.3 Sample Recovery.
8.3.1 Moisture Measurement. Disconnect the isopropanol bubbler, the
SO2 impingers, and the moisture absorber from the sample
train. Allow about 10 minutes for them to reach room temperature, clean
the outside of loose dirt and moisture, and weigh them simultaneously in
the same manner as in Section 8.1. Record this final weight
(mwf).
8.3.2 Peroxide Solution. Discard the contents of the isopropanol
bubbler and pour the contents of the midget impingers into a leak-free
polyethylene bottle for shipping. Rinse the two midget impingers and
connecting tubes with water, and add the washing to the same storage
container.
8.3.3 CO2 Absorber. Allow the CO2 absorber to
warm to room temperature (about 10 minutes), clean the outside of loose
dirt and moisture, and weigh to the nearest 0.1 g in the same manner as
in Section 8.1. Record this final weight (maf). Discard used
Ascarite II material.

9.0 Quality Control

Same as Method 6, Section 9.0.

10.0 Calibration and Standardization

Same as Method 6, Section 10.0.

11.0 Analytical Procedure

11.1 Sample Analysis. The sample analysis procedure for
SO2 is the same as that specified in Method 6, Section 11.0.
11.2 Quality Assurance (QA) Audit Samples. Analysis of QA audit
samples is required only when this method is used for compliance
determinations. Obtain an audit sample set as directed in Section 7.3.6
of Method 6. Analyze the audit samples, and report the results as
directed in Section 11.3 of Method 6. Acceptance criteria for the audit
results are the same as those in Method 6.

12.0 Data Analysis and Calculations

Same as Method 6, Section 12.0, with the addition of the following:
12.1 Nomenclature.

Cw=Concentration of moisture, percent.
CCO2=Concentration of CO2, dry basis, percent.
ESO2=Emission rate of SO2, ng/J (lb/10⁶
Btu).
FC=Carbon F-factor from Method 19 for the fuel burned, dscm/J
(dscf/10⁶ Btu).
mwi=Initial weight of impingers, bubblers, and moisture
absorber, g.
mwf=Final weight of impingers, bubblers, and moisture
absorber, g.
mai=Initial weight of CO2 absorber, g.
maf=Final weight of CO2 absorber, g.
mSO2=Mass of SO2 collected, mg.
VCO2(std)=Equivalent volume of CO2 collected at
standard conditions, dscm (dscf).
Vw(std)=Equivalent volume of moisture collected at standard
conditions, scm (scf).

12.2 CO2 Volume Collected, Corrected to Standard
Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.192

Where:

K3=Equivalent volume of gaseous CO2 at standard
conditions, 5.467 x 10^-4 dscm/g (1.930 x 10^-2
dscf/g).

12.3 Moisture Volume Collected, Corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.193

Where:

[[Page 256]]

K4=Equivalent volume of water vapor at standard conditions,
1.336 x 10^-3 scm/g (4.717 x 10^-2 scf/g).

12.4 SO2 Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.194

Where:

K2=32.03 mg SO2/meq. SO2 (7.061 x
10^-5 lb SO2/meq. SO2)

12.5 CO2 Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.195

12.6 Moisture Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.196

13.0 Method Performance

13.1 Range and Precision. The minimum detectable limit and the upper
limit for the measurement of SO2 are the same as for Method
6. For a 20-liter sample, this method has a precision of 0.5 percent CO2 for concentrations between
2.5 and 25 percent CO2 and 1.0 percent
moisture for moisture concentrations greater than 5 percent.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 Alternative Methods

If the only emission measurement desired is in terms of emission
rate of SO2 (ng/J or lb/10\6\ Btu), an abbreviated procedure
may be used. The differences between the above procedure and the
abbreviated procedure are described below.
16.1 Sampling Train. The sampling train is the same as that shown in
Figure 6A-1 and as described in Section 6.1, except that the dry gas
meter is not needed.
16.2 Preparation of the Sampling Train. Follow the same procedure as
in Section 8.1, except do not weigh the isopropanol bubbler, the
SO2 absorbing impingers, or the moisture absorber.
16.3 Sampling Train Leak-Check Procedure and Sample Collection.
Leak-check and operate the sampling train as described in Section 8.2,
except that dry gas meter readings, barometric pressure, and dry gas
meter temperatures need not be recorded during sampling.
16.4 Sample Recovery. Follow the procedure in Section 8.3, except do
not weigh the isopropanol bubbler, the SO2 absorbing
impingers, or the moisture absorber.
16.5 Sample Analysis. Analysis of the peroxide solution and QA audit
samples is the same as that described in Sections 11.1 and 11.2,
respectively.
16.6 Calculations.
16.6.1 SO2 Collected.
[GRAPHIC] [TIFF OMITTED] TR17OC00.197

[[Page 257]]

Where:

K2=32.03 mg SO2/meq. SO2
K2=7.061 x 10^-5 lb SO2/meq.
SO2

16.6.2 Sulfur Dioxide Emission Rate.
[GRAPHIC] [TIFF OMITTED] TR17OC00.198

Where:

K5=1.829 x 10\9\ mg/dscm
K2=0.1142 lb/dscf

17.0 References

Same as Method 6, Section 17.0, References 1 through 8, with the
addition of the following:

1. Stanley, Jon and P.R. Westlin. An Alternate Method for Stack Gas
Moisture Determination. Source Evaluation Society Newsletter. 3(4).
November 1978.
2. Whittle, Richard N. and P.R. Westlin. Air Pollution Test Report:
Development and Evaluation of an Intermittent Integrated SO2/
CO2 Emission Sampling Procedure. Environmental Protection
Agency, Emission Standard and Engineering Division, Emission Measurement
Branch. Research Triangle Park, NC. December 1979. 14 pp.

18.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 258]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.199

[[Page 259]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.410

Method 6B--Determination of Sulfur Dioxide and Carbon Dioxide Daily
Average Emissions From Fossil Fuel Combustion Sources

1.0 Scope and Application

1.1 Analytes.

[[Page 260]]

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Sulfur dioxide (SO2).............. 7449-09-05 3.4 mg SO2/m\3\
(2.12 x 10-7 lb/
ft\3\)
Carbon dioxide (CO2).............. 124-38-9 N/A
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of SO2 emissions from combustion sources in terms of
concentration (ng/dscm or lb/dscf) and emission rate (ng/J or lb/10\6\
Btu), and for the determination of CO2 concentration
(percent) on a daily (24 hours) basis.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A gas sample is extracted from the sampling point in the stack
intermittently over a 24-hour or other specified time period. The
SO2 fraction is measured by the barium-thorin titration
method. Moisture and CO2 fractions are collected in the same
sampling train, and are determined gravimetrically.

3.0 Definitions [Reserved]

4.0 Interferences

Same as Method 6, Section 4.0.

5.0 Safety

6.0 Equipment and Supplies

Same as Method 6A, Section 6.0, with the following exceptions and
additions:
6.1 The isopropanol bubbler is not used. An empty bubbler for the
collection of liquid droplets, that does not allow direct contact
between the collected liquid and the gas sample, may be included in the
sampling train.
6.2 For intermittent operation, include an industrial timer-switch
designed to operate in the ``on'' position at least 2 minutes
continuously and ``off'' the remaining period over a repeating cycle.
The cycle of operation is designated in the applicable regulation. At a
minimum, the sampling operation should include at least 12, equal,
evenly-spaced periods per 24 hours.
6.3 Stainless steel sampling probes, type 316, are not recommended
for use with Method 6B because of potential sample contamination due to
corrosion. Glass probes or other types of stainless steel, e.g.,
Hasteloy or Carpenter 20, are recommended for long-term use.

Note: For applications downstream of wet scrubbers, a heated out-of-
stack filter (either borosilicate glass wool or glass fiber mat) is
necessary. Probe and filter heating systems capable of maintaining a
sample gas temperature of between 20 and 120 [deg]C (68 and 248 [deg]F)
at the filter are also required in these cases. The electric supply for
these heating systems should be continuous and separate from the timed
operation of the sample pump.

7.0 Reagents and Standards

Same as Method 6A, Section 7.0, with the following exceptions:
7.1 Isopropanol is not used for sampling.
7.2 The hydrogen peroxide absorbing solution shall be diluted to no
less than 6 percent by volume, instead of 3 percent as specified in
Methods 6 and 6A.
7.3 If the Method 6B sampling train is to be operated in a low
sample flow condition (less than 100 ml/min or 0.21 ft\3\/hr), molecular
sieve material may be substituted for Ascarite II as the CO2
absorbing material. The recommended molecular sieve material is Union
Carbide \1/16\ inch pellets, 5 A[deg], or equivalent. Molecular sieve
material need not be discarded following the sampling run, provided that
it is regenerated as per the manufacturer's instruction. Use of
molecular sieve material at flow rates higher than 100 ml/min (0.21
ft\3\/hr) may cause erroneous CO2 results.

8.0 Sample Collection, Preservation, Transport, and Storage

8.1 Preparation of Sampling Train. Same as Method 6A, Section 8.1,
with the addition of the following:
8.1.1 The sampling train is assembled as shown in Figure 6A-1 of
Method 6A, except that the isopropanol bubbler is not included.
8.1.2 Adjust the timer-switch to operate in the ``on'' position from
2 to 4 minutes on a 2-hour repeating cycle or other cycle specified in
the applicable regulation. Other timer sequences may be used with the
restriction that the total sample volume collected is between 25 and 60
liters (0.9 and 2.1 ft ³) for the amounts of sampling
reagents prescribed in this method.
8.1.3 Add cold water to the tank until the impingers and bubblers
are covered at least two-thirds of their length. The impingers and
bubbler tank must be covered and protected from intense heat and direct
sunlight. If freezing conditions exist, the impinger solution and the
water bath must be protected.

Note: Sampling may be conducted continuously if a low flow-rate
sample pump [20

[[Page 261]]

to 40 ml/min (0.04 to 0.08 ft³/hr) for the reagent volumes
described in this method] is used. If sampling is continuous, the timer-
switch is not necessary. In addition, if the sample pump is designed for
constant rate sampling, the rate meter may be deleted. The total gas
volume collected should be between 25 and 60 liters (0.9 and 2.1
ft³) for the amounts of sampling reagents prescribed in this
method.

8.2 Sampling Train Leak-Check Procedure. Same as Method 6, Section
8.2.
8.3 Sample Collection.
8.3.1 The probe and filter (either in-stack, out-of-stack, or both)
must be heated to a temperature sufficient to prevent water
condensation.
8.3.2 Record the initial dry gas meter reading. To begin sampling,
position the tip of the probe at the sampling point, connect the probe
to the first impinger (or filter), and start the timer and the sample
pump. Adjust the sample flow to a constant rate of approximately 1.0
liter/min (0.035 cfm) as indicated by the rotameter. Observe the
operation of the timer, and determine that it is operating as intended
(i.e., the timer is in the ``on'' position for the desired period, and
the cycle repeats as required).
8.3.3 One time between 9 a.m. and 11 a.m. during the 24-hour
sampling period, record the dry gas meter temperature (Tm)
and the barometric pressure (P(bar)).
8.3.4 At the conclusion of the run, turn off the timer and the
sample pump, remove the probe from the stack, and record the final gas
meter volume reading. Conduct a leak-check as described in Section 8.2.
If a leak is found, void the test run or use procedures acceptable to
the Administrator to adjust the sample volume for leakage. Repeat the
steps in Sections 8.3.1 to 8.3.4 for successive runs.
8.4 Sample Recovery. The procedures for sample recovery (moisture
measurement, peroxide solution, and CO2 absorber) are the
same as those in Method 6A, Section 8.3.

9.0 Quality Control

Same as Method 6, Section 9.0., with the exception of the
isopropanol-check.

10.0 Calibration and Standardization

Same as Method 6, Section 10.0, with the addition of the following:
10.1 Periodic Calibration Check. After 30 days of operation of the
test train, conduct a calibration check according to the same procedures
as the post-test calibration check (Method 6, Section 10.1.2). If the
deviation between initial and periodic calibration factors exceeds 5
percent, use the smaller of the two factors in calculations for the
preceding 30 days of data, but use the most recent calibration factor
for succeeding test runs.

11.0 Analytical Procedures

11.1 Sample Loss Check and Analysis. Same as Method 6, Sections 11.1
and 11.2, respectively.
11.2 Quality Assurance (QA) Audit Samples. Analysis of QA audit
samples is required only when this method is used for compliance
determinations. Obtain an audit sample set as directed in Section 7.3.6
of Method 6. Analyze the audit samples at least once for every 30 days
of sample collection, and report the results as directed in Section 11.3
of Method 6. The analyst performing the sample analyses shall perform
the audit analyses. If more than one analyst performs the sample
analyses during the 30-day sampling period, each analyst shall perform
the audit analyses and all audit results shall be reported. Acceptance
criteria for the audit results are the same as those in Method 6.

12.0 Data Analysis and Calculations

Same as Method 6A, Section 12.0, except that Pbar and
Tm correspond to the values recorded in Section 8.3.3 of this
method. The values are as follows:

Pbar=Initial barometric pressure for the test period, mm Hg.
Tm=Absolute meter temperature for the test period, [deg]K.

13.0 Method Performance

13.1 Range.
13.1.1 Sulfur Dioxide. Same as Method 6.
13.1.2 Carbon Dioxide. Not determined.
13.2 Repeatability and Reproducibility. EPA-sponsored collaborative
studies were undertaken to determine the magnitude of repeatability and
reproducibility achievable by qualified testers following the procedures
in this method. The results of the studies evolve from 145 field tests
including comparisons with Methods 3 and 6. For measurements of emission
rates from wet, flue gas desulfurization units in (ng/J), the
repeatability (intra-laboratory precision) is 8.0 percent and the
reproducibility (inter-laboratory precision) is 11.1 percent.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 Alternative Methods

Same as Method 6A, Section 16.0, except that the timer is needed and
is operated as outlined in this method.

17.0 References

Same as Method 6A, Section 17.0, with the addition of the following:

1. Butler, Frank E., et. al. The Collaborative Test of Method 6B:
Twenty-Four-Hour Analysis of SO2 and CO2. JAPCA.
Vol. 33, No. 10. October 1983.

[[Page 262]]

18.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]

Method 6C--Determination of Sulfur Dioxide Emissions From Stationary
Sources (Instrumental Analyzer Procedure)

1. Applicability and Principle

1.1 Applicability. This method is applicable to the determination of
sulfur dioxide (SO2) concentrations in controlled and
uncontrolled emissions from stationary sources only when specified
within the regulations.
1.2 Principle. A gas sample is continuously extracted from a stack,
and a portion of the sample is conveyed to an instrumental analyzer for
determination of SO2 gas concentration using an ultraviolet
(UV), nondispersive infrared (NDIR), or fluorescence analyzer.
Performance specifications and test procedures are provided to ensure
reliable data.

2. Range and Sensitivity

2.1 Analytical Range. The analytical range is determined by the
instrumental design. For this method, a portion of the analytical range
is selected by choosing the span of the monitoring system. The span of
the monitoring system shall be selected such that the pollutant gas
concentration equivalent to the emission standard is not less than 30
percent of the span. If at any time during a run the measured gas
concentration exceeds the span, the run shall be considered invalid.
2.2 Sensitivity. The minimum detectable limit depends on the
analytical range, span, and signal-to-noise ratio of the measurement
system. For a well designed system, the minimum detectable limit should
be less than 2 percent of the span.

3. Definitions

3.1 Measurement System. The total equipment required for the
determination of gas concentration. The measurement system consists of
the following major subsystems:
3.1.1 Sample Interface. That portion of a system used for one or
more of the following: sample acquisition, sample transport, sample
conditioning, or protection of the analyzers from the effects of the
stack effluent.
3.1.2 Gas Analyzer. That portion of the system that senses the gas
to be measured and generates an output proportional to its
concentration.
3.1.3 Data Recorder. A strip chart recorder, analog computer, or
digital recorder for recording measurement data from the analyzer
output.
3.2 Span. The upper limit of the gas concentration measurement range
displayed on the data recorder.
3.3 Calibration Gas. A known concentration of a gas in an
appropriate diluent gas.
3.4 Analyzer Calibration Error. The difference between the gas
concentration exhibited by the gas analyzer and the known concentration
of the calibration gas when the calibration gas is introduced directly
to the analyzer.
3.5 Sampling System Bias. The difference between the gas
concentrations exhibited by the measurement system when a known
concentration gas is introduced at the outlet of the sampling probe and
when the same gas is introduced directly to the analyzer.
3.6 Zero Drift. The difference in the measurement system output
reading from the initial calibration response at the zero concentration
level after a stated period of operation during which no unscheduled
maintenance, repair, or adjustment took place.
3.7 Calibration Drift. The difference in the measurement system
output reading from the initial calibration response at a mid-range
calibration value after a stated period of operation during which no
unscheduled maintenance, repair, or adjustment took place.
3.8 Response Time. The amount of time required for the measurement
system to display 95 percent of a step change in gas concentration on
the data recorder.
3.9 Interference Check. A method for detecting analytical
interferences and excessive biases through direct comparison of gas
concentrations provided by the measurement system and by a modified
Method 6 procedure. For this check, the modified Method 6 samples are
acquired at the sample by-pass discharge vent.
3.10 Calibration Curve. A graph or other systematic method of
establishing the relationship between the analyzer response and the
actual gas concentration introduced to the analyzer.

4. Measurement System Performance Specifications

4.1 Analyzer Calibration Error. Less than 2
percent of the span for the zero, mid-range, and high-range calibration
gases.
4.2 Sampling System Bias. Less than 5 percent
of the span for the zero, and mid- or high-range calibration gases.
4.3 Zero Drift. Less than 3 percent of the
span over the period of each run.
4.4 Calibration Drift. Less than 3 percent of
the span over the period of each run.
4.5 Interference Check. Less than 7 percent of
the modified Method 6 result for each run.

5. Apparatus and Reagents

5.1 Measurement System. Any measurement system for SO2
that meets the specifications of this method. A schematic of an
acceptable measurement system is shown in Figure 6C-1. The essential
components of the measurement system are described below:

[[Page 263]]

5.1.1 Sample Probe. Glass, stainless steel, or equivalent, of
sufficient length to traverse the sample points. The sampling probe
shall be heated to prevent condensation.
5.1.2 Sample Line. Heated (sufficient to prevent condensation)
stainless steel or Teflon tubing, to transport the sample gas to the
moisture removal system.
5.1.3 Sample Transport Lines. Stainless steel or Teflon tubing, to
transport the sample from the moisture removal system to the sample
pump, sample flow rate control, and sample gas manifold.
5.1.4 Calibration Valve Assembly. A three-way valve assembly, or
equivalent, for blocking the sample gas flow and introducing calibration
gases to the measurement system at the outlet of the sampling probe when
in the calibration mode.
5.1.5 Moisture Removal System. A refrigerator-type condenser or
similar device (e.g., permeation dryer), to remove condensate
continuously from the sample gas while maintaining minimal contact
between the condensate and the sample gas. The moisture removal system
is not necessary for analyzers that can measure gas concentrations on a
wet basis; for these analyzers, (1) heat the sample line and all
interface components up to the inlet of the analyzer sufficiently to
prevent condensation, and (2) determine the moisture content and correct
the measured gas concentrations to a dry basis using appropriate
methods, subject to the approval of the Administrator. The determination
of sample moisture content is not necessary for pollutant analyzers that
measure concentrations on a wet basis when (1) a wet basis
CO2 analyzer operated according to Method 3A is used to
obtain simultaneous measurements, and (2) the pollutant/CO2
measurements are used to determine emissions in units of the standard.
5.1.6 Particulate Filter. An in-stack or heated (sufficient to
prevent water condensation) out-of-stack filter. The filter shall be
borosilicate or quartz glass wool, or glass fiber mat. Additional
filters at the inlet or outlet of the moisture removal system and inlet
of the analyzer may be used to prevent accumulation of particulate
material in the measurement system and extend the useful life of the
components. All filters shall be fabricated of materials that are
nonreactive to the gas being sampled.
5.1.7 Sample Pump. A leak-free pump, to pull the sample gas through
the system at a flow rate sufficient to minimize the response time of
the measurement system. The pump may be constructed of any material that
is nonreactive to the gas being sampled.
5.1.8 Sample Flow Rate Control. A sample flow rate control valve and
rotameter, or equivalent, to maintain a constant sampling rate within 10
percent.

(Note: The tester may elect to install a back-pressure regulator to
maintain the sample gas manifold at a constant pressure in order to
protect the analyzer(s) from overpressurization, and to minimize the
need for flow rate adjustments.)

5.1.9 Sample Gas Manifold. A sample gas manifold, to divert a
portion of the sample gas stream to the analyzer, and the remainder to
the by-pass discharge vent. The sample gas manifold should also include
provisions for introducing calibration gases directly to the analyzer.
The manifold may be constructed of any material that is nonreactive to
the gas being sampled.
5.1.10 Gas Analyzer. A UV or NDIR absorption or fluorescence
analyzer, to determine continuously the SO2 concentration in
the sample gas stream. The analyzer shall meet the applicable
performance specifications of Section 4. A means of controlling the
analyzer flow rate and a device for determining proper sample flow rate
(e.g., precision rotameter, pressure gauge downstream of all flow
controls, etc.) shall be provided at the analyzer.

(Note: Housing the analyzer(s) in a clean, thermally-stable,
vibration-free environment will minimize drift in the analyzer
calibration.)

5.1.11 Data Recorder. A strip chart recorder, analog computer, or
digital recorder, for recording measurement data. The data recorder
resolution (i.e., readability) shall be 0.5 percent of span.
Alternatively, a digital or analog meter having a resolution of 0.5
percent of span may be used to obtain the analyzer responses and the
readings may be recorded manually. If this alternative is used, the
readings shall be obtained at equally spaced intervals over the duration
of the sampling run. For sampling run durations of less than 1 hour,
measurements at 1-minute intervals or a minimum of 30 measurements,
whichever is less restrictive, shall be obtained. For sampling run
durations greater than 1 hour, measurements at 2-minute intervals or a
minimum of 96 measurements, whichever is less restrictive, shall be
obtained.
5.2 Method 6 Apparatus and Reagents. The apparatus and reagents
described in Method 6, and shown by the schematic of the sampling train
in Figure 6C-2, to conduct the interference check.
5.3 SO2 Calibration Gases. The calibration gases for the
gas analyzer shall be SO2 in N2 or SO2
in air. Alternatively, SO2/CO2, SO2/
O2, or SO2/CO2/O2 gas
mixtures in N2 may be used. For fluorescence-based analyzers,
the O2 and CO2 concentrations of the calibration
gases as introduced to the analyzer shall be within 1 percent (absolute)
O2 and 1 percent (absolute) CO2 of the
O2 and Co2 concentrations of the effluent samples
as introduced to the analyzer. Alternatively, for fluorescence-based
analyzers, use calibration blends of SO2 in air and the
nomographs provided by

[[Page 264]]

the vendor to determine the quenching correction factor (the effluent
O2 and CO2 concentrations must be known). Use
three calibration gases as specified below:
5.3.1 High-Range Gas. Concentration equivalent to 80 to 100 percent
of the span.
5.3.2 Mid-Range Gas. Concentration equivalent to 40 to 60 percent of
the span.
5.3.3 Zero Gas. Concentration of less than 0.25 percent of the span.
Purified ambient air may be used for the zero gas by passing air through
a charcoal filter, or through one or more impingers containing a
solution of 3 percent H2O2.

6. Measurement System Performance Test Procedures

Perform the following procedures before measurement of emissions
(Section 7).
6.1 Calibration Gas Concentration Verification. There are two
alternatives for establishing the concentrations of calibration gases.
Alternative Number 1 is preferred.
6.1.1 Alternative Number 1--Use of calibration gases that are
analyzed following the Environmental Protection Agency Traceability
Protocol Number 1 (see Citation 1 in the Bibliography). Obtain a
certification from the gas manufacturer that Protocol Number 1 was
followed.
6.1.2 Alternative Number 2--Use of calibration gases not prepared
according to Protocol Number 1. If this alternative is chosen, obtain
gas mixtures with a manufacturer's tolerance not to exceed 2 percent of the tag value. Within 6 months before the
emission test, analyze each of the calibration gases in triplicate using
Method 6. Citation 2 in the Bibliography describes procedures and
techniques that may be used for this analysis. Record the results on a
data sheet (example is shown in Figure 6C-3). Each of the individual
SO2 analytical results for each calibration gas shall be
within 5 percent (or 5 ppm, whichever is greater) of the triplicate set
average; otherwise, discard the entire set, and repeat the triplicate
analyses. If the average of the triplicate analyses is within 5 percent
of the calibration gas manufacturer's cylinder tag value, use the tag
value; otherwise, conduct at least three additional analyses until the
results of six consecutive runs agree with 5 percent (or 5 ppm,
whichever is greater) of their average. Then use this average for the
cylinder value.
6.2 Measurement System Preparation. Assemble the measurement system
by following the manufacturer's written instructions for preparing and
preconditioning the gas analyzer and, as applicable, the other system
components. Introduce the calibration gases in any sequence, and make
all necessary adjustments to calibrate the analyzer and the data
recorder. Adjust system components to achieve correct sampling rates.
6.3 Analyzer Calibration Error. Conduct the analyzer calibration
error check by introducing calibration gases to the measurement system
at any point upstream of the gas analyzer as follows:
6.3.1 After the measurement system has been prepared for use,
introduce the zero, mid-range, and high-range gases to the analyzer.
During this check, make no adjustments to the system except those
necessary to achieve the correct calibration gas flow rate at the
analyzer. Record the analyzer responses to each calibration gas on a
form similar to Figure 6C-4.

Note: A calibration curve established prior to the analyzer
calibration error check may be used to convert the analyzer response to
the equivalent gas concentration introduced to the analyzer. However,
the same correction procedure shall be used for all effluent and
calibration measurements obtained during the test.

6.3.2 The analyzer calibration error check shall be considered
invalid if the gas concentration displayed by the analyzer exceeds
2 percent of the span for any of the calibration
gases. If an invalid calibration is exhibited, take corrective action,
and repeat the analyzer calibration error check until acceptable
performance is achieved.
6.4 Sampling System Bias Check. Perform the sampling system bias
check by introducing calibration gases at the calibration valve
installed at the outlet of the sampling probe. A zero gas and either the
mid-range or high-range gas, whichever most closely approximates the
effluent concentrations, shall be used for this check as follows:
6.4.1 Introduce the upscale calibration gas, and record the gas
concentration displayed by the analyzer on a form similar to Figure 6C-
5. Then introduce zero gas, and record the gas concentration displayed
by the analyzer. During the sampling system bias check, operate the
system at the normal sampling rate, and make no adjustments to the
measurement system other than those necessary to achieve proper
calibration gas flow rates at the analyzer. Alternately introduce the
zero and upscale gases until a stable response is achieved. The tester
shall determine the measurement system response time by observing the
times required to achieve a stable response for both the zero and
upscale gases. Note the longer of the two times as the response time.
6.4.2 The sampling system bias check shall be considered invalid if
the difference between the gas concentrations displayed by the
measurement system for the analyzer calibration error check and for the
sampling system bias check exceeds 5 percent of
the span for either the zero or upscale calibration gas. If an invalid
calibration is exhibited, take corrective action, and repeat the
sampling system bias check until acceptable

[[Page 265]]

performance is achieved. If adjustment to the analyzer is required,
first repeat the analyzer calibration error check, then repeat the
sampling system bias check.

7. Emission Test Procedure

7.1 Selection of Sampling Site and Sampling Points. Select a
measurement site and sampling points using the same criteria that are
applicable to Method 6.
7.2 Interference Check Preparation. For each individual analyzer,
conduct an interference check for at least three runs during the initial
field test on a particular source category. Retain the results, and
report them with each test performed on that source category.
If an interference check is being performed, assemble the modified
Method 6 train (flow control valve, two midget impingers containing 3
percent H2O2, and dry gas meter) as shown in
Figure 6C-2. Install the sampling train to obtain a sample at the
measurement system sample by-pass discharge vent. Record the initial dry
gas meter reading.
7.3 Sample Collection. Position the sampling probe at the first
measurement point, and begin sampling at the same rate as used during
the sampling system bias check. Maintain constant rate sampling (i.e.,
10 percent) during the entire run. The sampling
time per run shall be the same as for Method 6 plus twice the system
response time. For each run, use only those measurements obtained after
twice response time of the measurement system has elapsed, to determine
the average effluent concentration. If an interference check is being
performed, open the flow control valve on the modified Method 6 train
concurrent with the initiation of the sampling period, and adjust the
flow to 1 liter per minute (10 percent).

(Note: If a pump is not used in the modified Method 6 train, caution
should be exercised in adjusting the flow rate since overpressurization
of the impingers may cause leakage in the impinger train, resulting in
positively biased results).

7.4 Zero and Calibration Drift Tests. Immediately preceding and
following each run, or if adjustments are necessary for the measurement
system during the run, repeat the sampling system bias check procedure
described in Section 6.4 (Make no adjustments to the measurement system
until after the drift checks are completed.) Record and analyzer's
responses on a form similar to Figure 6C-5.
7.4.1 If either the zero or upscale calibration value exceeds the
sampling system bias specification, then the run is considered invalid.
Repeat both the analyzer calibration error check procedure (Section 6.3)
and the sampling system bias check procedure (Section 6.4) before
repeating the run.
7.4.2 If both the zero and upscale calibration values are within the
sampling system bias specification, then use the average of the initial
and final bias check values to calculate the gas concentration for the
run. If the zero or upscale calibration drift value exceeds the drift
limits, based on the difference between the sampling system bias check
responses immediately before and after the run, repeat both the analyzer
calibration error check procedure (Section 6.3) and the sampling system
bias check procedure (Section 6.4) before conducting additional runs.
7.5 Interference Check (if performed). After completing the run,
record the final dry gas meter reading, meter temperature, and
barometric pressure. Recover and analyze the contents of the midget
impingers, and determine the SO2 gas concentration using the
procedures of Method 6. (It is not necessary to analyze EPA performance
audit samples for Method 6.) Determine the average gas concentration
exhibited by the analyzer for the run. If the gas concentrations
provided by the analyzer and the modified Method 6 differ by more than 7
percent of the modified Method 6 result, the run is invalidated.

8. Emission Calculation

The average gas effluent concentration is determined from the
average gas concentration displayed by the gas analyzer, and is adjusted
for the zero and upscale sampling system bias checks, as determined in
accordance with Section 7.4. The average gas concentration displayed by
the analyzer may be determined by integration of the area under the
curve for chart recorders, or by averaging all of the effluent
measurements. Alternatively, the average may be calculated from
measurements recorded at equally spaced intervals over the entire
duration of the run. For sampling run durations of less than 1 hour,
measurements at 1-minute intervals or a minimum of 30 measurements,
whichever is less restrictive, shall be used. For sampling run durations
greater than 1 hour, measurements at 2-minute intervals or a minimum of
96 measurements, whichever is less restrictive, shall be used. Calculate
the effluent gas concentration using Equation 6C-1.
[GRAPHIC] [TIFF OMITTED] TC16NO91.150

Where:

Cgas=Effluent gas concentration, dry basis, ppm.
C=Average gas concentration indicated by gas analyzer, dry basis, ppm.
Co=Average of initial and final system calibration bias check
responses for the zero gas, ppm.

[[Page 266]]

Cm=Average of initial and final system calibration bias check
responses for the upscale calibration gas, ppm.
Cma=Actual concentration of the upscale calibration gas, ppm.

9. Bibliography

1. Traceability Protocol for Establishing True Concentrations of
Gases Used for Calibrations and Audits of Continuous Source Emission
Monitors: Protocol Number 1. U.S. Environmental Protection Agency,
Quality Assurance Division. Research Triangle Park, NC. June 1978.
2. Westlin, Peter R. and J. W. Brown. Methods for Collecting and
Analyzing Gas Cylinder Samples. Source Evaluation Society Newsletter.
3(3):5-15. September 1978.
[GRAPHIC] [TIFF OMITTED] TC01JN92.141

Figure 6C-3--Analysis of Calibration Gases

Date____________________________________________________________________
Analytic method used

[[Page 267]]

________________________________________________________________________

------------------------------------------------------------------------
Gas concentration (indicate units)
--------------------------------------
High-range
Zero a Mid-range b c
------------------------------------------------------------------------
Sample run:
1.............................. ........... ........... ...........
2.............................. ........... ........... ...........
3.............................. ........... ........... ...........
Average...................... ........... ........... ...........
Maximum percent deviation........ ........... ........... ...........
------------------------------------------------------------------------
a Average must be less than 0.25 percent of span.
b Average must be 50 to 60 percent of span.
c Average must be 80 to 90 percent of span.

Figure 6C-4--Analyzer calibration data

Source identification:__________________________________________________
Test personnel:_________________________________________________________
Date:___________________________________________________________________
Analyzer calibration data for sampling
runs:__________________________________________________________________
Span:___________________________________________________________________

----------------------------------------------------------------------------------------------------------------
Analyzer
Cylinder calibration Absolute Difference
value response difference (percent of
(indicate (indicate (indicate span)
units) units) units)
----------------------------------------------------------------------------------------------------------------
Zero gas.................................................... ........... ........... ........... ...........
Mid-range gas............................................... ........... ........... ........... ...........
High-range gas.............................................. ........... ........... ........... ...........
----------------------------------------------------------------------------------------------------------------

Figure 6C-5--System calibration bias and drift data

Source identification:__________________________________________________
Test personnel:_________________________________________________________
Date:___________________________________________________________________
Run number:_____________________________________________________________
Span:___________________________________________________________________

----------------------------------------------------------------------------------------------------------------
Initial values Final values
----------------------------------------------------
Analyzer System cal. System cal. Drift
calibration System bias System bias (percent of
response calibration (percent of calibration (percent of span)
response span) response span)
----------------------------------------------------------------------------------------------------------------
Zero gas..........................
Upscale gas.......................
----------------------------------------------------------------------------------------------------------------

[GRAPHIC] [TIFF OMITTED] TC16NO91.151

Method 7--Determination of Nitrogen Oxide Emissions From Stationary
Sources

1.0 Scope and Application

1.1 Analytes.

[[Page 268]]

Nitrogen dioxide (NO2)........ 10102-44-0 2-400 mg/dscm
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the measurement of
nitrogen oxides (NOX) emitted from stationary sources.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sample methods.

2.0 Summary of Method

A grab sample is collected in an evacuated flask containing a dilute
sulfuric acid-hydrogen peroxide absorbing solution, and the nitrogen
oxides, except nitrous oxide, are measured colorimetrically using the
phenoldisulfonic acid (PDS) procedure.

3.0 Definitions [Reserved]

4.0 Interferences

Biased results have been observed when sampling under conditions of
high sulfur dioxide concentrations (above 2000 ppm).

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of the
user to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to
performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water for at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating to
eyes, skin, nose, and lungs.
5.2.2 Phenoldisulfonic Acid. Irritating to eyes and skin.
5.2.3 Sodium Hydroxide (NaOH). Causes severe damage to eyes and
skin. Inhalation causes irritation to nose, throat, and lungs. Reacts
exothermically with limited amounts of water.
5.2.4 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 1 mg/m ³ for 8 hours will cause lung damage or, in
higher concentrations, death. Provide ventilation to limit inhalation.
Reacts violently with metals and organics.
5.2.5 Phenol. Poisonous and caustic. Do not handle with bare hands
as it is absorbed through the skin.

6.0 Equipment and Supplies

6.1 Sample Collection. A schematic of the sampling train used in
performing this method is shown in Figure 7-1. Other grab sampling
systems or equipment, capable of measuring sample volume to within 2.0
percent and collecting a sufficient sample volume to allow analytical
reproducibility to within 5 percent, will be considered acceptable
alternatives, subject to the approval of the Administrator. The
following items are required for sample collection:
6.1.1 Probe. Borosilicate glass tubing, sufficiently heated to
prevent water condensation and equipped with an in-stack or heated out-
of-stack filter to remove particulate matter (a plug of glass wool is
satisfactory for this purpose). Stainless steel or Teflon tubing may
also be used for the probe. Heating is not necessary if the probe
remains dry during the purging period.
6.1.2 Collection Flask. Two-liter borosilicate, round bottom flask,
with short neck and 24/40 standard taper opening, protected against
implosion or breakage.
6.1.3 Flask Valve. T-bore stopcock connected to a 24/40 standard
taper joint.
6.1.4 Temperature Gauge. Dial-type thermometer, or other temperature
gauge, capable of measuring 1 [deg]C (2 [deg]F) intervals from -5 to 50
[deg]C (23 to 122 [deg]F).
6.1.5 Vacuum Line. Tubing capable of withstanding a vacuum of 75 mm
(3 in.) Hg absolute pressure, with ``T'' connection and T-bore stopcock.
6.1.6 Vacuum Gauge. U-tube manometer, 1 meter (39 in.), with 1 mm
(0.04 in.) divisions, or other gauge capable of measuring pressure to
within 2.5 mm (0.10 in.) Hg.
6.1.7 Pump. Capable of evacuating the collection flask to a pressure
equal to or less than 75 mm (3 in.) Hg absolute.
6.1.8 Squeeze Bulb. One-way.
6.1.9 Volumetric Pipette. 25-ml.
6.1.10 Stopcock and Ground Joint Grease. A high-vacuum, high-
temperature chlorofluorocarbon grease is required. Halocarbon 25-5S has
been found to be effective.
6.1.11 Barometer. Mercury, aneroid, or other barometer capable of
measuring atmospheric pressure to within 2.5 mm (0.1 in.) Hg. See NOTE
in Method 5, Section 6.1.2.
6.2 Sample Recovery. The following items are required for sample
recovery:
6.2.1 Graduated Cylinder. 50-ml with 1 ml divisions.

[[Page 269]]

6.2.2 Storage Containers. Leak-free polyethylene bottles.
6.2.3 Wash Bottle. Polyethylene or glass.
6.2.4 Glass Stirring Rod.
6.2.5 Test Paper for Indicating pH. To cover the pH range of 7 to
14.
6.3 Analysis. The following items are required for analysis:
6.3.1 Volumetric Pipettes. Two 1-ml, two 2-ml, one 3-ml, one 4-ml,
two 10-ml, and one 25-ml for each sample and standard.
6.3.2 Porcelain Evaporating Dishes. 175- to 250-ml capacity with lip
for pouring, one for each sample and each standard. The Coors No. 45006
(shallowform, 195-ml) has been found to be satisfactory. Alternatively,
polymethyl pentene beakers (Nalge No. 1203, 150-ml), or glass beakers
(150-ml) may be used. When glass beakers are used, etching of the
beakers may cause solid matter to be present in the analytical step; the
solids should be removed by filtration.
6.3.3 Steam Bath. Low-temperature ovens or thermostatically
controlled hot plates kept below 70 [deg]C (160 [deg]F) are acceptable
alternatives.
6.3.4 Dropping Pipette or Dropper. Three required.
6.3.5 Polyethylene Policeman. One for each sample and each standard.
6.3.6 Graduated Cylinder. 100-ml with 1-ml divisions.
6.3.7 Volumetric Flasks. 50-ml (one for each sample and each
standard), 100-ml (one for each sample and each standard, and one for
the working standard KNO3 solution), and 1000-ml (one).
6.3.8 Spectrophotometer. To measure at 410 nm.
6.3.9 Graduated Pipette. 10-ml with 0.1-ml divisions.
6.3.10 Test Paper for Indicating pH. To cover the pH range of 7 to
14.
6.3.11 Analytical Balance. To measure to within 0.1 mg.

7.0 Reagents and Standards

Unless otherwise indicated, it is intended that all reagents conform
to the specifications established by the Committee on Analytical
Reagents of the American Chemical Society, where such specifications are
available; otherwise, use the best available grade.
7.1 Sample Collection. The following reagents are required for
sampling:
7.1.1 Water. Deionized distilled to conform to ASTM D 1193-77 or 91
Type 3 (incorporated by reference--see Sec. 60.17). The
KMnO4 test for oxidizable organic matter may be omitted when
high concentrations of organic matter are not expected to be present.
7.1.2 Absorbing Solution. Cautiously add 2.8 ml concentrated
H2SO4 to a 1-liter flask partially filled with
water. Mix well, and add 6 ml of 3 percent hydrogen peroxide, freshly
prepared from 30 percent hydrogen peroxide solution. Dilute to 1 liter
of water and mix well. The absorbing solution should be used within 1
week of its preparation. Do not expose to extreme heat or direct
sunlight.
7.2 Sample Recovery. The following reagents are required for sample
recovery:
7.2.1 Water. Same as in 7.1.1.
7.2.2 Sodium Hydroxide, 1 N. Dissolve 40 g NaOH in water, and dilute
to 1 liter.
7.3 Analysis. The following reagents and standards are required for
analysis:
7.3.1 Water. Same as in 7.1.1.
7.3.2 Fuming Sulfuric Acid. 15 to 18 percent by weight free sulfur
trioxide. HANDLE WITH CAUTION.
7.3.3 Phenol. White solid.
7.3.4 Sulfuric Acid. Concentrated, 95 percent minimum assay.
7.3.5 Potassium Nitrate (KNO3). Dried at 105 to 110
[deg]C (221 to 230 [deg]F) for a minimum of 2 hours just prior to
preparation of standard solution.
7.3.6 Standard KNO3 Solution. Dissolve exactly 2.198 g of
dried KNO3 in water, and dilute to 1 liter with water in a
1000-ml volumetric flask.
7.3.7 Working Standard KNO3 Solution. Dilute 10 ml of the
standard solution to 100 ml with water. One ml of the working standard
solution is equivalent to 100 [micro]g nitrogen dioxide
(NO2).
7.3.8 Phenoldisulfonic Acid Solution. Dissolve 25 g of pure white
phenol solid in 150 ml concentrated sulfuric acid on a steam bath. Cool,
add 75 ml fuming sulfuric acid (15 to 18 percent by weight free sulfur
trioxide--HANDLE WITH CAUTION), and heat at 100 [deg]C (212 [deg]F) for
2 hours. Store in a dark, stoppered bottle.
7.3.9 Concentrated Ammonium Hydroxide.
7.3.10 Quality Assurance Audit Samples. When making compliance
determinations, and upon availability, audit samples may be obtained
from the appropriate EPA Regional Office or from the responsible
enforcement authority.

Note: The responsible enforcement authority should be notified at
least 30 days prior to the test date to allow sufficient time for sample
delivery.

8.0 Sample Collection, Preservation, Storage and Transport

8.1 Sample Collection.
8.1.1 Flask Volume. The volume of the collection flask and flask
valve combination must be known prior to sampling. Assemble the flask
and flask valve, and fill with water to the stopcock. Measure the volume
of water to 10 ml. Record this volume on the
flask.
8.1.2 Pipette 25 ml of absorbing solution into a sample flask,
retaining a sufficient quantity for use in preparing the calibration
standards. Insert the flask valve stopper into the flask with the valve
in the ``purge'' position. Assemble the sampling train as shown

[[Page 270]]

in Figure 7-1, and place the probe at the sampling point. Make sure that
all fittings are tight and leak-free, and that all ground glass joints
have been greased properly with a high-vacuum, high temperature
chlorofluorocarbon-based stopcock grease. Turn the flask valve and the
pump valve to their ``evacuate'' positions. Evacuate the flask to 75 mm
(3 in.) Hg absolute pressure, or less. Evacuation to a pressure
approaching the vapor pressure of water at the existing temperature is
desirable. Turn the pump valve to its ``vent'' position, and turn off
the pump. Check for leakage by observing the manometer for any pressure
fluctuation. (Any variation greater than 10 mm (0.4 in.) Hg over a
period of 1 minute is not acceptable, and the flask is not to be used
until the leakage problem is corrected. Pressure in the flask is not to
exceed 75 mm (3 in.) Hg absolute at the time sampling is commenced.)
Record the volume of the flask and valve (Vf), the flask
temperature (Ti), and the barometric pressure. Turn the flask
valve counterclockwise to its ``purge'' position, and do the same with
the pump valve. Purge the probe and the vacuum tube using the squeeze
bulb. If condensation occurs in the probe and the flask valve area, heat
the probe, and purge until the condensation disappears. Next, turn the
pump valve to its ``vent'' position. Turn the flask valve clockwise to
its ``evacuate'' position, and record the difference in the mercury
levels in the manometer. The absolute internal pressure in the flask
(Pi) is equal to the barometric pressure less the manometer
reading. Immediately turn the flask valve to the ``sample'' position,
and permit the gas to enter the flask until pressures in the flask and
sample line (i.e., duct, stack) are equal. This will usually require
about 15 seconds; a longer period indicates a plug in the probe, which
must be corrected before sampling is continued. After collecting the
sample, turn the flask valve to its ``purge'' position, and disconnect
the flask from the sampling train.
8.1.3 Shake the flask for at least 5 minutes.
8.1.4 If the gas being sampled contains insufficient oxygen for the
conversion of NO to NO2 (e.g., an applicable subpart of the
standards may require taking a sample of a calibration gas mixture of NO
in N2), then introduce oxygen into the flask to permit this
conversion. Oxygen may be introduced into the flask by one of three
methods: (1) Before evacuating the sampling flask, flush with pure
cylinder oxygen, then evacuate flask to 75 mm (3 in.) Hg absolute
pressure or less; or (2) inject oxygen into the flask after sampling; or
(3) terminate sampling with a minimum of 50 mm (2 in.) Hg vacuum
remaining in the flask, record this final pressure, and then vent the
flask to the atmosphere until the flask pressure is almost equal to
atmospheric pressure.
8.2 Sample Recovery. Let the flask sit for a minimum of 16 hours,
and then shake the contents for 2 minutes.
8.2.1 Connect the flask to a mercury filled U-tube manometer. Open
the valve from the flask to the manometer, and record the flask
temperature (Tf), the barometric pressure, and the difference
between the mercury levels in the manometer. The absolute internal
pressure in the flask (Pf) is the barometric pressure less
the manometer reading. Transfer the contents of the flask to a leak-free
polyethylene bottle. Rinse the flask twice with 5 ml portions of water,
and add the rinse water to the bottle. Adjust the pH to between 9 and 12
by adding 1 N NaOH, dropwise (about 25 to 35 drops). Check the pH by
dipping a stirring rod into the solution and then touching the rod to
the pH test paper. Remove as little material as possible during this
step. Mark the height of the liquid level so that the container can be
checked for leakage after transport. Label the container to identify
clearly its contents. Seal the container for shipping.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
10.1.......................... Spectrophotometer Ensure linearity of
calibration. spectrophotometer
response to
standards.
11.4.......................... Audit sample Evaluate analytical
analysis. technique,
preparation of
standards.
------------------------------------------------------------------------

10.0 Calibration and Standardization

10.1 Spectrophotometer.
10.1.1 Optimum Wavelength Determination.
10.1.1.1 Calibrate the wavelength scale of the spectrophotometer
every 6 months. The calibration may be accomplished by using an energy
source with an intense line emission such as a mercury lamp, or by using
a series of glass filters spanning the measuring range of the
spectrophotometer. Calibration materials are available commercially and
from the National Institute of Standards and Technology. Specific
details on the use of such materials should be supplied by the vendor;
general information about calibration techniques can be obtained from
general reference books on analytical chemistry. The wavelength scale of
the spectrophotometer must read correctly within 5 nm at all calibration
points; otherwise, repair and recalibrate the spectrophotometer. Once
the wavelength scale of the spectrophotometer is

[[Page 271]]

in proper calibration, use 410 nm as the optimum wavelength for the
measurement of the absorbance of the standards and samples.
10.1.1.2 Alternatively, a scanning procedure may be employed to
determine the proper measuring wavelength. If the instrument is a
double-beam spectrophotometer, scan the spectrum between 400 and 415 nm
using a 200 [micro]g NO2 standard solution in the sample cell
and a blank solution in the reference cell. If a peak does not occur,
the spectrophotometer is probably malfunctioning and should be repaired.
When a peak is obtained within the 400 to 415 nm range, the wavelength
at which this peak occurs shall be the optimum wavelength for the
measurement of absorbance of both the standards and the samples. For a
single-beam spectrophotometer, follow the scanning procedure described
above, except scan separately the blank and standard solutions. The
optimum wavelength shall be the wavelength at which the maximum
difference in absorbance between the standard and the blank occurs.
10.1.2 Determination of Spectrophotometer Calibration Factor
Kc. Add 0 ml, 2.0 ml, 4.0 ml, 6.0 ml, and 8.0 ml of the
KNO3 working standard solution (1 ml=100 [micro]g
NO2) to a series of five 50-ml volumetric flasks. To each
flask, add 25 ml of absorbing solution and 10 ml water. Add 1 N NaOH to
each flask until the pH is between 9 and 12 (about 25 to 35 drops).
Dilute to the mark with water. Mix thoroughly, and pipette a 25-ml
aliquot of each solution into a separate porcelain evaporating dish.
Beginning with the evaporation step, follow the analysis procedure of
Section 11.2 until the solution has been transferred to the 100-ml
volumetric flask and diluted to the mark. Measure the absorbance of each
solution at the optimum wavelength as determined in Section 10.2.1. This
calibration procedure must be repeated on each day that samples are
analyzed. Calculate the spectrophotometer calibration factor as shown in
Section 12.2.
10.1.3 Spectrophotometer Calibration Quality Control. Multiply the
absorbance value obtained for each standard by the Kc factor
(reciprocal of the least squares slope) to determine the distance each
calibration point lies from the theoretical calibration line. The
difference between the calculated concentration values and the actual
concentrations (i.e., 100, 200, 300, and 400 [micro]g NO2)
should be less than 7 percent for all standards.
10.2 Barometer. Calibrate against a mercury barometer.
10.3 Temperature Gauge. Calibrate dial thermometers against mercury-
in-glass thermometers.
10.4 Vacuum Gauge. Calibrate mechanical gauges, if used, against a
mercury manometer such as that specified in Section 6.1.6.
10.5 Analytical Balance. Calibrate against standard weights.

11.0 Analytical Procedures

11.1 Sample Loss Check. Note the level of the liquid in the
container, and confirm whether any sample was lost during shipment. Note
this on the analytical data sheet. If a noticeable amount of leakage has
occurred, either void the sample or use methods, subject to the approval
of the Administrator, to correct the final results.
11.2 Sample Preparation. Immediately prior to analysis, transfer the
contents of the shipping container to a 50 ml volumetric flask, and
rinse the container twice with 5 ml portions of water. Add the rinse
water to the flask, and dilute to mark with water; mix thoroughly.
Pipette a 25-ml aliquot into the porcelain evaporating dish. Return any
unused portion of the sample to the polyethylene storage bottle.
Evaporate the 25-ml aliquot to dryness on a steam bath, and allow to
cool. Add 2 ml phenoldisulfonic acid solution to the dried residue, and
triturate thoroughly with a polyethylene policeman. Make sure the
solution contacts all the residue. Add 1 ml water and 4 drops of
concentrated sulfuric acid. Heat the solution on a steam bath for 3
minutes with occasional stirring. Allow the solution to cool, add 20 ml
water, mix well by stirring, and add concentrated ammonium hydroxide,
dropwise, with constant stirring, until the pH is 10 (as determined by
pH paper). If the sample contains solids, these must be removed by
filtration (centrifugation is an acceptable alternative, subject to the
approval of the Administrator) as follows: Filter through Whatman No. 41
filter paper into a 100-ml volumetric flask. Rinse the evaporating dish
with three 5-ml portions of water. Filter these three rinses. Wash the
filter with at least three 15-ml portions of water. Add the filter
washings to the contents of the volumetric flask, and dilute to the mark
with water. If solids are absent, the solution can be transferred
directly to the 100-ml volumetric flask and diluted to the mark with
water.
11.3 Sample Analysis. Mix the contents of the flask thoroughly, and
measure the absorbance at the optimum wavelength used for the standards
(Section 10.2.1), using the blank solution as a zero reference. Dilute
the sample and the blank with equal volumes of water if the absorbance
exceeds A4, the absorbance of the 400-[micro]g NO2
standard (see Section 10.2.2).
11.4 Audit Sample Analysis.
11.4.1 When the method is used to analyze samples to demonstrate
compliance with a source emission regulation, an audit sample must be
analyzed, subject to availability.
11.4.2 Concurrently analyze the audit sample and the compliance
samples in the same manner to evaluate the technique of the analyst and
the standards preparation.

[[Page 272]]

11.4.3 The same analyst, analytical reagents, and analytical system
must be used for the compliance samples and the audit sample. If this
condition is met, duplicate auditing of subsequent compliance analyses
for the same enforcement agency within a 30-day period is waived. An
audit sample set may not be used to validate different sets of
compliance samples under the jurisdiction of separate enforcement
agencies, unless prior arrangements have been made with both enforcement
agencies.
11.5 Audit Sample Results.
11.5.1 Calculate the audit sample concentrations and submit results
using the instructions provided with the audit samples.
11.5.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
11.5.3 The concentrations of the audit samples obtained by the
analyst must agree within 5 percent of the actual concentration. If the
5 percent specification is not met, reanalyze the compliance and audit
samples, and include initial and reanalysis values in the test report.
11.5.4 Failure to meet the 5-percent specification may require
retests until the audit problems are resolved. However, if the audit
results do not affect the compliance or noncompliance status of the
affected facility, the Administrator may waive the reanalysis
requirement, further audits, or retests and accept the results of the
compliance test. While steps are being taken to resolve audit analysis
problems, the Administrator may also choose to use the data to determine
the compliance or noncompliance status of the affected facility.

12.0 Data Analysis and Calculations

Carry out the calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculations.
12.1 Nomenclature.

A=Absorbance of sample.
A1=Absorbance of the 100-[micro]g NO2 standard.
A2=Absorbance of the 200-[micro]g NO2 standard.
A3=Absorbance of the 300-[micro]g NO2 standard.
A4=Absorbance of the 400-[micro]g NO2 standard.
C=Concentration of NOX as NO2, dry basis,
corrected to standard conditions, mg/dsm\3\ (lb/dscf).
Cd=Determined audit sample concentration, mg/dscm.
Ca=Actual audit sample concentration, mg/dscm.
F=Dilution factor (i.e., 25/5, 25/10, etc., required only if sample
dilution was needed to reduce the absorbance into the range of the
calibration).
Kc=Spectrophotometer calibration factor.
m=Mass of NOX as NO2 in gas sample, [micro]g.
Pf=Final absolute pressure of flask, mm Hg (in. Hg).
Pi=Initial absolute pressure of flask, mm Hg (in. Hg).
Pstd=Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
RE=Relative error for QA audit samples, percent.
Tf=Final absolute temperature of flask, [deg]K ([deg]R).
Ti=Initial absolute temperature of flask, [deg]K ([deg]R).
Tstd=Standard absolute temperature, 293 [deg]K (528 [deg]R).
Vsc=Sample volume at standard conditions (dry basis), ml.
Vf=Volume of flask and valve, ml.
Va=Volume of absorbing solution, 25 ml.
12.2 Spectrophotometer Calibration Factor.
[GRAPHIC] [TIFF OMITTED] TR17OC00.200

12.3 Sample Volume, Dry Basis, Corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.201

[[Page 273]]

Where:

K1=0.3858 [deg]K/mm Hg for metric units,
K1=17.65 [deg]R/in. Hg for English units.

12.4 Total [micro]g NO2 per sample.
[GRAPHIC] [TIFF OMITTED] TR17OC00.202

Where:
2=50/25, the aliquot factor.

Note: If other than a 25-ml aliquot is used for analysis, the factor
2 must be replaced by a corresponding factor.

12.5 Sample Concentration, Dry Basis, Corrected to Standard
Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.203

Where:

K2=10\3\ (mg/m\3\)/([micro]g/ml) for metric units,
K2=6.242 x 10^-5 (lb/scf)/([micro]g/ml) for English
units.
12.6 Relative Error for QA Audit Samples.
[GRAPHIC] [TIFF OMITTED] TR17OC00.204

13.0 Method Performance

13.1 Range. The analytical range of the method has been determined
to be 2 to 400 milligrams NOX (as NO2) per dry
standard cubic meter, without having to dilute the sample.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

1. Standard Methods of Chemical Analysis. 6th ed. New York, D. Van
Nostrand Co., Inc. 1962. Vol. 1, pp. 329-330.
2. Standard Method of Test for Oxides of Nitrogen in Gaseous
Combustion Products (Phenoldisulfonic Acid Procedure). In: 1968 Book of
ASTM Standards, Part 26. Philadelphia, PA. 1968. ASTM Designation D
1608-60, pp. 725-729.
3. Jacob, M.B. The Chemical Analysis of Air Pollutants. New York.
Interscience Publishers, Inc. 1960. Vol. 10, pp. 351-356.
4. Beatty, R.L., L.B. Berger, and H.H. Schrenk. Determination of
Oxides of Nitrogen by the Phenoldisulfonic Acid Method. Bureau of Mines,
U.S. Dept. of Interior. R.I. 3687. February 1943.
5. Hamil, H.F. and D.E. Camann. Collaborative Study of Method for
the Determination of Nitrogen Oxide Emissions from Stationary Sources
(Fossil Fuel-Fired Steam Generators). Southwest Research Institute
Report for Environmental Protection Agency. Research Triangle Park, NC.
October 5, 1973.
6. Hamil, H.F. and R.E. Thomas. Collaborative Study of Method for
the Determination of Nitrogen Oxide Emissions from Stationary Sources
(Nitric Acid Plants). Southwest Research Institute Report for
Environmental Protection Agency. Research Triangle Park, NC. May 8,
1974.
7. Stack Sampling Safety Manual (Draft). U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC. September 1978.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 274]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.205

Method 7A--Determination of Nitrogen Oxide Emissions From Stationary
Sources (Ion Chromatographic Method)

1.0 Scope and Application

1.1 Analytes.

[[Page 275]]

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Nitrogen oxides (NOX), as NO2,
including:
Nitric oxide (NO)............. 10102-43-9 ....................
Nitrogen dioxide (NO2)........ 10102-44-0 65-655 ppmv
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of NOX emissions from stationary sources.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

A grab sample is collected in an evacuated flask containing a dilute
sulfuric acid-hydrogen peroxide absorbing solution. The nitrogen oxides,
excluding nitrous oxide (N2O), are oxidized to nitrate and
measured by ion chromatography.

3.0 Definitions [Reserved]

4.0 Interferences

Biased results have been observed when sampling under conditions of
high sulfur dioxide concentrations (above 2000 ppm).

5.0 Safety

5.1 This method may involve hazardous materials, operations, and
equipment. This test method may not address all of the safety problems
associated with its use. It is the responsibility of the user of this
test method to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to
performing this test method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating to
eyes, skin, nose, and lungs.
5.2.2 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 3 mg/m³ will cause lung damage in uninitiated. 1 mg/
m³ for 8 hours will cause lung damage or, in higher
concentrations, death. Provide ventilation to limit inhalation. Reacts
violently with metals and organics.

6.0 Equipment and Supplies

6.1 Sample Collection. Same as in Method 7, Section 6.1.
6.2 Sample Recovery. Same as in Method 7, Section 6.2, except the
stirring rod and pH paper are not needed.
6.3 Analysis. For the analysis, the following equipment and supplies
are required. Alternative instrumentation and procedures will be allowed
provided the calibration precision requirement in Section 10.1.2 and
audit accuracy requirement in Section 11.3 can be met.
6.3.1 Volumetric Pipets. Class A;1-, 2-, 4-, 5-ml (two for the set
of standards and one per sample), 6-, 10-, and graduated 5-ml sizes.
6.3.2 Volumetric Flasks. 50-ml (two per sample and one per
standard), 200-ml, and 1-liter sizes.
6.3.3 Analytical Balance. To measure to within 0.1 mg.
6.3.4 Ion Chromatograph. The ion chromatograph should have at least
the following components:
6.3.4.1 Columns. An anion separation or other column capable of
resolving the nitrate ion from sulfate and other species present and a
standard anion suppressor column (optional). Suppressor columns are
produced as proprietary items; however, one can be produced in the
laboratory using the resin available from BioRad Company, 32nd and
Griffin Streets, Richmond, California. Peak resolution can be optimized
by varying the eluent strength or column flow rate, or by experimenting
with alternative columns that may offer more efficient separation. When
using guard columns with the stronger reagent to protect the separation
column, the analyst should allow rest periods between injection
intervals to purge possible sulfate buildup in the guard column.
6.3.4.2 Pump. Capable of maintaining a steady flow as required by
the system.
6.3.4.3 Flow Gauges. Capable of measuring the specified system flow
rate.
6.3.4.4 Conductivity Detector.
6.3.4.5 Recorder. Compatible with the output voltage range of the
detector.

7.0 Reagents and Standards

[[Page 276]]

7.3 Analysis. The following reagents and standards are required for
analysis:
7.3.1 Water. Same as Method 7, Section 7.1.1.
7.3.2 Stock Standard Solution, 1 mg NO2/ml. Dry an
adequate amount of sodium nitrate (NaNO3) at 105 to 110
[deg]C (221 to 230 [deg]F) for a minimum of 2 hours just before
preparing the standard solution. Then dissolve exactly 1.847 g of dried
NaNO3 in water, and dilute to l liter in a volumetric flask.
Mix well. This solution is stable for 1 month and should not be used
beyond this time.
7.3.3 Working Standard Solution, 25 [micro]g/ml. Dilute 5 ml of the
standard solution to 200 ml with water in a volumetric flask, and mix
well.
7.3.4 Eluent Solution. Weigh 1.018 g of sodium carbonate
(Na2CO3) and 1.008 g of sodium bicarbonate
(NaHCO3), and dissolve in 4 liters of water. This solution is
0.0024 M Na2CO3/0.003 M NaHCO3. Other
eluents appropriate to the column type and capable of resolving nitrate
ion from sulfate and other species present may be used.
7.3.5 Quality Assurance Audit Samples. Same as Method 7, Section
7.3.8.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Sampling. Same as in Method 7, Section 8.1.
8.2 Sample Recovery. Same as in Method 7, Section 8.2, except delete
the steps on adjusting and checking the pH of the sample. Do not store
the samples more than 4 days between collection and analysis.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
10.1.......................... Ion chromatograph Ensure linearity of
calibration. ion chromatograph
response to
standards.
11.3.......................... Audit sample Evaluate analytical
analysis. technique,
preparation of
standards.
------------------------------------------------------------------------

10.0 Calibration and Standardizations

10.1 Ion Chromatograph.
10.1.1 Determination of Ion Chromatograph Calibration Factor S.
Prepare a series of five standards by adding 1.0, 2.0, 4.0, 6.0, and
10.0 ml of working standard solution (25 [micro]g/ml) to a series of
five 50-ml volumetric flasks. (The standard masses will equal 25, 50,
100, 150, and 250 [micro]g.) Dilute each flask to the mark with water,
and mix well. Analyze with the samples as described in Section 11.2, and
subtract the blank from each value. Prepare or calculate a linear
regression plot of the standard masses in [micro]g (x-axis) versus their
peak height responses in millimeters (y-axis). (Take peak height
measurements with symmetrical peaks; in all other cases, calculate peak
areas.) From this curve, or equation, determine the slope, and calculate
its reciprocal to denote as the calibration factor, S.
10.1.2 Ion Chromatograph Calibration Quality Control. If any point
on the calibration curve deviates from the line by more than 7 percent
of the concentration at that point, remake and reanalyze that standard.
This deviation can be determined by multiplying S times the peak height
response for each standard. The resultant concentrations must not differ
by more than 7 percent from each known standard mass (i.e., 25, 50, 100,
150, and 250 [micro]g).
10.2 Conductivity Detector. Calibrate according to manufacturer's
specifications prior to initial use.
10.3 Barometer. Calibrate against a mercury barometer.
10.4 Temperature Gauge. Calibrate dial thermometers against mercury-
in-glass thermometers.
10.5 Vacuum Gauge. Calibrate mechanical gauges, if used, against a
mercury manometer such as that specified in Section 6.1.6 of Method 7.
10.6 Analytical Balance. Calibrate against standard weights.

11.0 Analytical Procedures

11.1 Sample Preparation.
11.1.1 Note on the analytical data sheet, the level of the liquid in
the container, and whether any sample was lost during shipment. If a
noticeable amount of leakage has occurred, either void the sample or use
methods, subject to the approval of the Administrator, to correct the
final results. Immediately before analysis, transfer the contents of the
shipping container to a 50-ml volumetric flask, and rinse the container
twice with 5 ml portions of water. Add the rinse water to the flask, and
dilute to the mark with water. Mix thoroughly.
11.1.2 Pipet a 5-ml aliquot of the sample into a 50-ml volumetric
flask, and dilute to the mark with water. Mix thoroughly. For each set
of determinations, prepare a reagent blank by diluting 5 ml of absorbing
solution to 50 ml with water. (Alternatively, eluent solution may be
used instead of water in all sample, standard, and blank dilutions.)
11.2 Analysis.
11.2.1 Prepare a standard calibration curve according to Section
10.1.1. Analyze the set of standards followed by the set of samples
using the same injection volume for

[[Page 277]]

both standards and samples. Repeat this analysis sequence followed by a
final analysis of the standard set. Average the results. The two sample
values must agree within 5 percent of their mean for the analysis to be
valid. Perform this duplicate analysis sequence on the same day. Dilute
any sample and the blank with equal volumes of water if the
concentration exceeds that of the highest standard.
11.2.2 Document each sample chromatogram by listing the following
analytical parameters: injection point, injection volume, nitrate and
sulfate retention times, flow rate, detector sensitivity setting, and
recorder chart speed.
11.3 Audit Sample Analysis. Same as Method 7, Section 11.4.

12.0 Data Analysis and Calculations

Carry out the calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculations.
12.1 Sample Volume. Calculate the sample volume Vsc (in ml), on a
dry basis, corrected to standard conditions, using Equation 7-2 of
Method 7.
12.2 Sample Concentration of NOX as NO2.
12.2.1 Calculate the sample concentration C (in mg/dscm) as follows:
[GRAPHIC] [TIFF OMITTED] TR17OC00.206

Where:

H=Sample peak height, mm.
S=Calibration factor, [micro]g/mm.
F=Dilution factor (required only if sample dilution was needed to reduce
the concentration into the range of calibration), dimensionless.
10⁴=1:10 dilution times conversion factor of: (mg/10\3\
[micro]g)(10\6\ ml/m\3\).

12.2.2 If desired, the concentration of NO2 may be
calculated as ppm NO2 at standard conditions as follows:
[GRAPHIC] [TIFF OMITTED] TR17OC00.207

Where:

0.5228=ml/mg NO2.

13.0 Method Performance

13.1 Range. The analytical range of the method is from 125 to 1250
mg NOX/m³ as NO2 (65 to 655 ppmv), and
higher concentrations may be analyzed by diluting the sample. The lower
detection limit is approximately 19 mg/m\3\ (10 ppmv), but may vary
among instruments.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

1. Mulik, J.D., and E. Sawicki. Ion Chromatographic Analysis of
Environmental Pollutants. Ann Arbor, Ann Arbor Science Publishers, Inc.
Vol. 2, 1979.
2. Sawicki, E., J.D. Mulik, and E. Wittgenstein. Ion Chromatographic
Analysis of Environmental Pollutants. Ann Arbor, Ann Arbor Science
Publishers, Inc. Vol. 1. 1978.
3. Siemer, D.D. Separation of Chloride and Bromide from Complex
Matrices Prior to Ion Chromatographic Determination. Anal. Chem.
52(12):1874-1877. October 1980.
4. Small, H., T.S. Stevens, and W.C. Bauman. Novel Ion Exchange
Chromatographic Method Using Conductimetric Determination. Anal. Chem.
47(11):1801. 1975.
5. Yu, K.K., and P.R. Westlin. Evaluation of Reference Method 7
Flask Reaction Time. Source Evaluation Society Newsletter. 4(4).
November 1979. 10 pp.
6. Stack Sampling Safety Manual (Draft). U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standard, Research
Triangle Park, NC. September 1978.

17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]

Method 7B--Determination of Nitrogen Oxide Emissions From Stationary
Sources (Ultraviolet Spectrophotometric Method)

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Nitrogen oxides (NOX), as NO2,
including:
Nitric oxide (NO)............. 10102-43-9
Nitrogen dioxide (NO2)........ 10102-44-0 30-786 ppmv
------------------------------------------------------------------------

[[Page 278]]

1.2 Applicability. This method is applicable for the determination
of NOX emissions from nitric acid plants.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A grab sample is collected in an evacuated flask containing a
dilute sulfuric acid-hydrogen peroxide absorbing solution; the
NOX, excluding nitrous oxide (N2O), are measured
by ultraviolet spectrophotometry.

3.0 Definition [Reserved]

4.0 Interferences [Reserved]

5.0 Safety

5.1 This method may involve hazardous materials, operations, and
equipment. This test method may not address all of the safety problems
associated with its use. It is the responsibility of the user of this
test method to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to
performing this test method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burn as thermal burn.
5.2.1 Hydrogen Peroxide (H2O2). Irritating to
eyes, skin, nose, and lungs.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eyes and
skin. Inhalation causes irritation to nose, throat, and lungs. Reacts
exothermically with limited amounts of water.
5.2.3 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 3 mg/m \3\ will cause lung damage in uninitiated. 1 mg/m \3\ for
8 hours will cause lung damage or, in higher concentrations, death.
Provide ventilation to limit inhalation. Reacts violently with metals
and organics.

6.0 Equipment and Supplies

6.1 Sample Collection. Same as Method 7, Section 6.1.
6.2 Sample Recovery. The following items are required for sample
recovery:
6.2.1 Wash Bottle. Polyethylene or glass.
6.2.2 Volumetric Flasks. 100-ml (one for each sample).
6.3 Analysis. The following items are required for analysis:
6.3.1 Volumetric Pipettes. 5-, 10-, 15-, and 20-ml to make standards
and sample dilutions.
6.3.2 Volumetric Flasks. 1000- and 100-ml for preparing standards
and dilution of samples.
6.3.3 Spectrophotometer. To measure ultraviolet absorbance at 210
nm.
6.3.4 Analytical Balance. To measure to within 0.1 mg.

7.0 Reagents and Standards

Note: Unless otherwise indicated, all reagents are to conform to the
specifications established by the Committee on Analytical Reagents of
the American Chemical Society, where such specifications are available.
Otherwise, use the best available grade.

7.1 Sample Collection. Same as Method 7, Section 7.1. It is
important that the amount of hydrogen peroxide in the absorbing solution
not be increased. Higher concentrations of peroxide may interfere with
sample analysis.
7.2 Sample Recovery. Same as Method 7, Section 7.2.
7.3 Analysis. Same as Method 7, Sections 7.3.1, 7.3.3, and 7.3.4,
with the addition of the following:
7.3.1 Working Standard KNO3 Solution. Dilute 10 ml of the
standard solution to 1000 ml with water. One milliliter of the working
standard is equivalent to 10 [micro]g NO2.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Sample Collection. Same as Method 7, Section 8.1.
8.2 Sample Recovery.
8.2.1 Let the flask sit for a minimum of 16 hours, and then shake
the contents for 2 minutes.
8.2.2 Connect the flask to a mercury filled U-tube manometer. Open
the valve from the flask to the manometer, and record the flask
temperature (Tf), the barometric pressure, and the difference
between the mercury levels in the manometer. The absolute internal
pressure in the flask (Pf) is the barometric pressure less
the manometer reading.
8.2.3 Transfer the contents of the flask to a leak-free wash bottle.
Rinse the flask three times with 10-ml portions of water, and add to the
bottle. Mark the height of the liquid level so that the container can be
checked for leakage after transport. Label the container to identify
clearly its contents. Seal the container for shipping.

9.0 Quality Control

[[Page 279]]

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
10.1.......................... Spectrophometer Ensures linearity of
calibration. spectrophotometer
response to
standards.
11.4.......................... Audit sample Evaluates analytical
analysis. technique and
preparation of
standards.
------------------------------------------------------------------------

10.0 Calibration and Standardizations

Same as Method 7, Sections 10.2 through 10.5, with the addition of
the following:
10.1 Determination of Spectrophotometer Standard Curve. Add 0 ml, 5
ml, 10 ml, 15 ml, and 20 ml of the KNO3 working standard
solution (1 ml=10 [micro]g NO2) to a series of five 100-ml
volumetric flasks. To each flask, add 5 ml of absorbing solution. Dilute
to the mark with water. The resulting solutions contain 0.0, 50, 100,
150, and 200 [micro]g NO2, respectively. Measure the
absorbance by ultraviolet spectrophotometry at 210 nm, using the blank
as a zero reference. Prepare a standard curve plotting absorbance vs.
[micro]g NO2.

Note: If other than a 20-ml aliquot of sample is used for analysis,
then the amount of absorbing solution in the blank and standards must be
adjusted such that the same amount of absorbing solution is in the blank
and standards as is in the aliquot of sample used.

10.1.1 Calculate the spectrophotometer calibration factor as
follows:
[GRAPHIC] [TIFF OMITTED] TR17OC00.208

Where:

Mi=Mass of NO2 in standard i, [micro]g.
Ai=Absorbance of NO2 standard i.
n=Total number of calibration standards.

10.1.2 For the set of calibration standards specified here, Equation
7B-1 simplifies to the following:
[GRAPHIC] [TIFF OMITTED] TR17OC00.209

10.2 Spectrophotometer Calibration Quality Control. Multiply the
absorbance value obtained for each standard by the Kc factor
(reciprocal of the least squares slope) to determine the distance each
calibration point lies from the theoretical calibration line. The
difference between the calculated concentration values and the actual
concentrations (i.e., 50, 100, 150, and 200 [micro]g NO2)
should be less than 7 percent for all standards.

11.0 Analytical Procedures

12.0 Data Analysis and Calculations

Same as Method 7, Section 12.0, except replace Section 12.3 with the
following:
12.1 Total [micro]g NO2 Per Sample.
[GRAPHIC] [TIFF OMITTED] TR17OC00.211

Where:

5=100/20, the aliquot factor.

Note: If other than a 20-ml aliquot is used for analysis, the factor
5 must be replaced by a corresponding factor.

13.0 Method Performance

13.1 Range. The analytical range of the method as outlined has been
determined to be 57 to 1500 milligrams NOX (as
NO2) per dry

[[Page 280]]

standard cubic meter, or 30 to 786 parts per million by volume (ppmv)
NOX.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

1. National Institute for Occupational Safety and Health.
Recommendations for Occupational Exposure to Nitric Acid. In:
Occupational Safety and Health Reporter. Washington, D.C. Bureau of
National Affairs, Inc. 1976. p. 149.
2. Rennie, P.J., A.M. Sumner, and F.B. Basketter. Determination of
Nitrate in Raw, Potable, and Waste Waters by Ultraviolet
Spectrophotometry. Analyst. 104:837. September 1979.

17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]

Method 7C--Determination of Nitrogen Oxide Emissions From Stationary
Sources (Alkaline Permanganate/Colorimetric Method)

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS no. Sensitivity
------------------------------------------------------------------------
Nitrogen oxides (NOX), as NO2,
including:
Nitric oxide (NO)............. 10102-43-9 ....................
Nitrogen dioxide (NO2)........ 10102-44-07 ppmv
------------------------------------------------------------------------

1.2 Applicability. This method applies to the measurement of
NOX emissions from fossil-fuel fired steam generators,
electric utility plants, nitric acid plants, or other sources as
specified in the regulations.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

An integrated gas sample is extracted from the stack and passed
through impingers containing an alkaline potassium permanganate
solution; NOX (NO + NO2) emissions are oxidized to
NO2 and NO3. Then NO3^-is
reduced to NO2^-with cadmium, and the
NO2^-is analyzed colorimetrically.

3.0 Definitions [Reserved]

4.0 Interferences

Possible interferents are sulfur dioxides (SO2) and
ammonia (NH3).
4.1 High concentrations of SO2 could interfere because
SO2 consumes MnO4 (as does NOX) and,
therefore, could reduce the NOX collection efficiency.
However, when sampling emissions from a coal-fired electric utility
plant burning 2.1 percent sulfur coal with no control of SO2
emissions, collection efficiency was not reduced. In fact, calculations
show that sampling 3000 ppm SO2 will reduce the
MnO4 concentration by only 5 percent if all the
SO2 is consumed in the first impinger.
4.2 Ammonia (NH3) is slowly oxidized to
NO3^- by the absorbing solution. At 100 ppm
NH3 in the gas stream, an interference of 6 ppm
NOX (11 mg NO2/m\3\) was observed when the sample
was analyzed 10 days after collection. Therefore, the method may not be
applicable to plants using NH3 injection to control
NOX emissions unless means are taken to correct the results.
An equation has been developed to allow quantification of the
interference and is discussed in Reference 5 of Section 16.0.

5.0 Safety

[[Page 281]]

edema of lungs. Exposure to vapor concentrations of 0.13 to 0.2 percent
can be lethal in minutes. Will react with metals, producing hydrogen.
5.2.2 Oxalic Acid (COOH)2. Poisonous. Irritating to eyes,
skin, nose, and throat.
5.2.3 Sodium Hydroxide (NaOH). Causes severe damage to eye tissues
and to skin. Inhalation causes irritation to nose, throat, and lungs.
Reacts exothermically with small amounts of water.
5.2.4 Potassium Permanganate (KMnO4). Caustic, strong
oxidizer. Avoid bodily contact with.

6.0 Equipment and Supplies

6.1 Sample Collection and Sample Recovery. A schematic of the Method
7C sampling train is shown in Figure 7C-1, and component parts are
discussed below. Alternative apparatus and procedures are allowed
provided acceptable accuracy and precision can be demonstrated to the
satisfaction of the Administrator.
6.1.1 Probe. Borosilicate glass tubing, sufficiently heated to
prevent water condensation and equipped with an in-stack or heated out-
of-stack filter to remove particulate matter (a plug of glass wool is
satisfactory for this purpose). Stainless steel or Teflon tubing may
also be used for the probe.
6.1.2 Impingers. Three restricted-orifice glass impingers, having
the specifications given in Figure 7C-2, are required for each sampling
train. The impingers must be connected in series with leak-free glass
connectors. Stopcock grease may be used, if necessary, to prevent
leakage. (The impingers can be fabricated by a glass blower if not
available commercially.)
6.1.3 Glass Wool, Stopcock Grease, Drying Tube, Valve, Pump,
Barometer, and Vacuum Gauge and Rotameter. Same as in Method 6, Sections
6.1.1.3, 6.1.1.4, 6.1.1.6, 6.1.1.7, 6.1.1.8, 6.1.2, and 6.1.3,
respectively.
6.1.4 Rate Meter. Rotameter, or equivalent, accurate to within 2
percent at the selected flow rate of between 400 and 500 ml/min (0.014
to 0.018 cfm). For rotameters, a range of 0 to 1 liter/min (0 to 0.035
cfm) is recommended.
6.1.5 Volume Meter. Dry gas meter (DGM) capable of measuring the
sample volume under the sampling conditions of 400 to 500 ml/min (0.014
to 0.018 cfm) for 60 minutes within an accuracy of 2 percent.
6.1.6 Filter. To remove NOX from ambient air, prepared by
adding 20 g of 5-angstrom molecular sieve to a cylindrical tube (e.g., a
polyethylene drying tube).
6.1.7 Polyethylene Bottles. 1-liter, for sample recovery.
6.1.8 Funnel and Stirring Rods. For sample recovery.
6.2 Sample Preparation and Analysis.
6.2.1 Hot Plate. Stirring type with 50- by 10-mm Teflon-coated
stirring bars.
6.2.2 Beakers. 400-, 600-, and 1000-ml capacities.
6.2.3 Filtering Flask. 500-ml capacity with side arm.
6.2.4 Buchner Funnel. 75-mm ID, with spout equipped with a 13-mm ID
by 90-mm long piece of Teflon tubing to minimize possibility of
aspirating sample solution during filtration.
6.2.5 Filter Paper. Whatman GF/C, 7.0-cm diameter.
6.2.6 Stirring Rods.
6.2.7 Volumetric Flasks. 100-, 200- or 250-, 500-, and 1000-ml
capacity.
6.2.8 Watch Glasses. To cover 600- and 1000-ml beakers.
6.2.9 Graduated Cylinders. 50- and 250-ml capacities.
6.2.10 Pipettes. Class A.
6.2.11 pH Meter. To measure pH from 0.5 to 12.0.
6.2.12 Burette. 50-ml with a micrometer type stopcock. (The stopcock
is Catalog No. 8225-t-05, Ace Glass, Inc., Post Office Box 996,
Louisville, Kentucky 50201.) Place a glass wool plug in bottom of
burette. Cut off burette at a height of 43 cm (17 in.) from the top of
plug, and have a blower attach a glass funnel to top of burette such
that the diameter of the burette remains essentially unchanged. Other
means of attaching the funnel are acceptable.
6.2.13 Glass Funnel. 75-mm ID at the top.
6.2.14 Spectrophotometer. Capable of measuring absorbance at 540 nm;
1-cm cells are adequate.
6.2.15 Metal Thermometers. Bimetallic thermometers, range 0 to 150
[deg]C (32 to 300 [deg]F).
6.2.16 Culture Tubes. 20-by 150-mm, Kimax No. 45048.
6.2.17 Parafilm ``M.'' Obtained from American Can Company,
Greenwich, Connecticut 06830.
6.2.18 CO2 Measurement Equipment. Same as in Method 3,
Section 6.0.

7.0 Reagents and Standards

[[Page 282]]

7.2.3 Sodium Hydroxide, 0.5 N. Dissolve 20 g of NaOH in water, and
dilute to 1 liter.
7.2.4 Sodium Hydroxide, 10 N. Dissolve 40 g of NaOH in water, and
dilute to 100 ml.
7.2.5 Ethylenediamine Tetraacetic Acid (EDTA) Solution, 6.5 percent
(w/v). Dissolve 6.5 g of EDTA (disodium salt) in water, and dilute to
100 ml. Dissolution is best accomplished by using a magnetic stirrer.
7.2.6 Column Rinse Solution. Add 20 ml of 6.5 percent EDTA solution
to 960 ml of water, and adjust the pH to between 11.7 and 12.0 with 0.5
N NaOH.
7.2.7 Hydrochloric Acid (HCl), 2 N. Add 86 ml of concentrated HCl to
a 500 ml-volumetric flask containing water, dilute to volume, and mix
well. Store in a glass-stoppered bottle.
7.2.8 Sulfanilamide Solution. Add 20 g of sulfanilamide (melting
point 165 to 167 [deg]C (329 to 333 [deg]F)) to 700 ml of water. Add,
with mixing, 50 ml concentrated phosphoric acid (85 percent), and dilute
to 1000 ml. This solution is stable for at least 1 month, if
refrigerated.
7.2.9 N-(1-Naphthyl)-Ethylenediamine Dihydrochloride (NEDA)
Solution. Dissolve 0.5 g of NEDA in 500 ml of water. An aqueous solution
should have one absorption peak at 320 nm over the range of 260 to 400
nm. NEDA that shows more than one absorption peak over this range is
impure and should not be used. This solution is stable for at least 1
month if protected from light and refrigerated.
7.2.10 Cadmium. Obtained from Matheson Coleman and Bell, 2909
Highland Avenue, Norwood, Ohio 45212, as EM Laboratories Catalog No.
2001. Prepare by rinsing in 2 N HCl for 5 minutes until the color is
silver-grey. Then rinse the cadmium with water until the rinsings are
neutral when tested with pH paper. CAUTION: H2 is liberated
during preparation. Prepare in an exhaust hood away from any flame or
combustion source.
7.2.11 Sodium Sulfite (NaNO2) Standard Solution, Nominal
Concentration, 1000 [micro]g NO2^-/ml. Desiccate
NaNO2 overnight. Accurately weigh 1.4 to 1.6 g of NaNO2
(assay of 97 percent NaNO2 or greater), dissolve in water,
and dilute to 1 liter. Calculate the exact NO2-concentration
using Equation 7C-1 in Section 12.2. This solution is stable for at
least 6 months under laboratory conditions.
7.2.12 Potassium Nitrate (KNO3) Standard Solution. Dry
KNO3 at 110 [deg]C (230 [deg]F) for 2 hours, and cool in a
desiccator. Accurately weigh 9 to 10 g of KNO3 to within 0.1
mg, dissolve in water, and dilute to 1 liter. Calculate the exact
NO3^- concentration using Equation 7C-2 in Section
12.3. This solution is stable for 2 months without preservative under
laboratory conditions.
7.2.13 Spiking Solution. Pipette 7 ml of the KNO3
standard into a 100-ml volumetric flask, and dilute to volume.
7.2.14 Blank Solution. Dissolve 2.4 g of KMnO4 and 1.2 g
of NaOH in 96 ml of water. Alternatively, dilute 60 ml of
KMnO4/NaOH solution to 100 ml.
7.2.15 Quality Assurance Audit Samples. Same as in Method 7, Section
7.3.10. When requesting audit samples, specify that they be in the
appropriate concentration range for Method 7C.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Preparation of Sampling Train. Add 200 ml of KMnO4/
NaOH solution (Section 7.1.2) to each of three impingers, and assemble
the train as shown in Figure 7C-1. Adjust the probe heater to a
temperature sufficient to prevent water condensation.
8.2 Leak-Checks. Same as in Method 6, Section 8.2.
8.3 Sample Collection.
8.3.1 Record the initial DGM reading and barometric pressure.
Determine the sampling point or points according to the appropriate
regulations (e.g., Sec. 60.46(b)(5) of 40 CFR Part 60). Position the
tip of the probe at the sampling point, connect the probe to the first
impinger, and start the pump. Adjust the sample flow to a value between
400 and 500 ml/min (0.014 and 0.018 cfm). CAUTION: DO NOT EXCEED THESE
FLOW RATES. Once adjusted, maintain a constant flow rate during the
entire sampling run. Sample for 60 minutes. For relative accuracy (RA)
testing of continuous emission monitors, the minimum sampling time is 1
hour, sampling 20 minutes at each traverse point.

Note: When the SO2 concentration is greater than 1200
ppm, the sampling time may have to be reduced to 30 minutes to eliminate
plugging of the impinger orifice with MnO2. For RA tests with
SO2 greater than 1200 ppm, sample for 30 minutes (10 minutes
at each point).

8.3.2 Record the DGM temperature, and check the flow rate at least
every 5 minutes. At the conclusion of each run, turn off the pump,
remove the probe from the stack, and record the final readings. Divide
the sample volume by the sampling time to determine the average flow
rate. Conduct the mandatory post-test leak-check. If a leak is found,
void the test run, or use procedures acceptable to the Administrator to
adjust the sample volume for the leakage.
8.4 CO2 Measurement. During sampling, measure the
CO2 content of the stack gas near the sampling point using
Method 3. The single-point grab sampling procedure is adequate, provided
the measurements are made at least three times (near the start, midway,
and before the end of a run), and the average CO2
concentration is computed. The Orsat or Fyrite analyzer may be used for
this analysis.

[[Page 283]]

8.5 Sample Recovery. Disconnect the impingers. Pour the contents of
the impingers into a 1-liter polyethylene bottle using a funnel and a
stirring rod (or other means) to prevent spillage. Complete the
quantitative transfer by rinsing the impingers and connecting tubes with
water until the rinsings are clear to light pink, and add the rinsings
to the bottle. Mix the sample, and mark the solution level. Seal and
identify the sample container.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.2, 10.1-10.3................ Sampling Ensure accurate
equipment leak- measurement of
check and sample volume.
calibration.
10.4.......................... Spectrophotometer Ensure linearity of
calibration. spectrophotometer
response to
standards.
11.3.......................... Spiked sample Ensure reduction
analysis. efficiency of
column.
11.6.......................... Audit sample Evaluate analytical
analysis. technique,
preparation of
standards.
------------------------------------------------------------------------

10.0 Calibration and Standardizations

10.1 Volume Metering System. Same as Method 6, Section 10.1. For
detailed instructions on carrying out these calibrations, it is
suggested that Section 3.5.2 of Reference 4 of Section 16.0 be
consulted.
10.2 Temperature Sensors and Barometer. Same as in Method 6,
Sections 10.2 and 10.4, respectively.
10.3 Check of Rate Meter Calibration Accuracy (Optional). Disconnect
the probe from the first impinger, and connect the filter. Start the
pump, and adjust the rate meter to read between 400 and 500 ml/min
(0.014 and 0.018 cfm). After the flow rate has stabilized, start
measuring the volume sampled, as recorded by the dry gas meter and the
sampling time. Collect enough volume to measure accurately the flow
rate. Then calculate the flow rate. This average flow rate must be less
than 500 ml/min (0.018 cfm) for the sample to be valid; therefore, it is
recommended that the flow rate be checked as above prior to each test.
10.4 Spectrophotometer.
10.4.1 Dilute 5.0 ml of the NaNO2 standard solution to
200 ml with water. This solution nominally contains 25 [micro]g
NO2^-/ml. Use this solution to prepare calibration
standards to cover the range of 0.25 to 3.00 [micro]g
NO2^-/ml. Prepare a minimum of three standards each
for the linear and slightly nonlinear (described below) range of the
curve. Use pipettes for all additions.
10.4.2 Measure the absorbance of the standards and a water blank as
instructed in Section 11.5. Plot the net absorbance vs. [micro]g
NO2^-/ml. Draw a smooth curve through the points.
The curve should be linear up to an absorbance of approximately 1.2 with
a slope of approximately 0.53 absorbance units/[micro]g
NO2^-/ml. The curve should pass through the origin.
The curve is slightly nonlinear from an absorbance of 1.2 to 1.6.

11.0 Analytical Procedures

11.1 Sample Stability. Collected samples are stable for at least
four weeks; thus, analysis must occur within 4 weeks of collection.
11.2 Sample Preparation.
11.2.1 Prepare a cadmium reduction column as follows: Fill the
burette with water. Add freshly prepared cadmium slowly, with tapping,
until no further settling occurs. The height of the cadmium column
should be 39 cm (15 in). When not in use, store the column under rinse
solution.

Note: The column should not contain any bands of cadmium fines. This
may occur if regenerated cadmium is used and will greatly reduce the
column lifetime.

11.2.2 Note the level of liquid in the sample container, and
determine whether any sample was lost during shipment. If a noticeable
amount of leakage has occurred, the volume lost can be determined from
the difference between initial and final solution levels, and this value
can then be used to correct the analytical result. Quantitatively
transfer the contents to a 1-liter volumetric flask, and dilute to
volume.
11.2.3 Take a 100-ml aliquot of the sample and blank (unexposed
KMnO4/NaOH) solutions, and transfer to 400-ml beakers
containing magnetic stirring bars. Using a pH meter, add concentrated
H2SO4 with stirring until a pH of 0.7 is obtained.
Allow the solutions to stand for 15 minutes. Cover the beakers with
watch glasses, and bring the temperature of the solutions to 50 [deg]C
(122 [deg]F). Keep the temperature below 60 [deg]C (140 [deg]F).
Dissolve 4.8 g of oxalic acid in a minimum volume of water,
approximately 50 ml, at room temperature. Do not heat the solution. Add
this solution slowly, in increments, until the KMnO4 solution
becomes colorless. If the color is not completely removed, prepare some
more of the above oxalic acid solution, and add until a colorless
solution is obtained. Add an excess of oxalic acid by dissolving 1.6 g
of oxalic acid in 50 ml of water, and add 6 ml of this solution to the
colorless

[[Page 284]]

solution. If suspended matter is present, add concentrated
H2SO4 until a clear solution is obtained.
11.2.4 Allow the samples to cool to near room temperature, being
sure that the samples are still clear. Adjust the pH to between 11.7 and
12.0 with 10 N NaOH. Quantitatively transfer the mixture to a Buchner
funnel containing GF/C filter paper, and filter the precipitate. Filter
the mixture into a 500-ml filtering flask. Wash the solid material four
times with water. When filtration is complete, wash the Teflon tubing,
quantitatively transfer the filtrate to a 500-ml volumetric flask, and
dilute to volume. The samples are now ready for cadmium reduction.
Pipette a 50-ml aliquot of the sample into a 150-ml beaker, and add a
magnetic stirring bar. Pipette in 1.0 ml of 6.5 percent EDTA solution,
and mix.
11.3 Determine the correct stopcock setting to establish a flow rate
of 7 to 9 ml/min of column rinse solution through the cadmium reduction
column. Use a 50-ml graduated cylinder to collect and measure the
solution volume. After the last of the rinse solution has passed from
the funnel into the burette, but before air entrapment can occur, start
adding the sample, and collect it in a 250-ml graduated cylinder.
Complete the quantitative transfer of the sample to the column as the
sample passes through the column. After the last of the sample has
passed from the funnel into the burette, start adding 60 ml of column
rinse solution, and collect the rinse solution until the solution just
disappears from the funnel. Quantitatively transfer the sample to a 200-
ml volumetric flask (a 250-ml flask may be required), and dilute to
volume. The samples are now ready for NO2-analysis.

Note: Two spiked samples should be run with every group of samples
passed through the column. To do this, prepare two additional 50-ml
aliquots of the sample suspected to have the highest NO2-
concentration, and add 1 ml of the spiking solution to these aliquots.
If the spike recovery or column efficiency (see Section 12.2) is below
95 percent, prepare a new column, and repeat the cadmium reduction.

11.4 Repeat the procedures outlined in Sections 11.2 and 11.3 for
each sample and each blank.
11.5 Sample Analysis. Pipette 10 ml of sample into a culture tube.
Pipette in 10 ml of sulfanilamide solution and 1.4 ml of NEDA solution.
Cover the culture tube with parafilm, and mix the solution. Prepare a
blank in the same manner using the sample from treatment of the
unexposed KMnO4/NaOH solution. Also, prepare a calibration
standard to check the slope of the calibration curve. After a 10-minute
color development interval, measure the absorbance at 540 nm against
water. Read [micro]g NO2^-/ml from the calibration
curve. If the absorbance is greater than that of the highest calibration
standard, use less than 10 ml of sample, and repeat the analysis.
Determine the NO2^-concentration using the
calibration curve obtained in Section 10.4.

Note: Some test tubes give a high blank NO2^-
value but culture tubes do not.

11.6 Audit Sample Analysis. Same as in Method 7, Section 11.4.

12.0 Data Analysis and Calculations

Carry out calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature.
B=Analysis of blank, [micro]g NO2^-/ml.
C=Concentration of NOX as NO2, dry basis, mg/
dsm³.
E=Column efficiency, dimensionless
K2=10^-3 mg/[micro]g.
m=Mass of NOX, as NO2, in sample, [micro]g.
Pbar=Barometric pressure, mm Hg (in. Hg).
Pstd=Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
s=Concentration of spiking solution, [micro]g NO3/ml.
S=Analysis of sample, [micro]g NO2^-/ml.
Tm=Average dry gas meter absolute temperature, [deg]K.
Tstd=Standard absolute temperature, 293 [deg]K (528 [deg]R).
Vm(std)=Dry gas volume measured by the dry gas meter,
corrected to standard conditions, dscm (dscf).
Vm=Dry gas volume as measured by the dry gas meter, scm
(scf).
x=Analysis of spiked sample, [micro]g NO2^-/ml.
X=Correction factor for CO2 collection=100/(100 -
%CO2(V/V)).
y=Analysis of unspiked sample, [micro]g NO2^-/ml.
Y=Dry gas meter calibration factor.
1.0 ppm NO=1.247 mg NO/m³ at STP.
1.0 ppm NO2=1.912 mg NO2/m³ at STP.
1 ft³=2.832 x 10^-2 m³.

12.2 NO2 Concentration. Calculate the NO2
concentration of the solution (see Section 7.2.11) using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.212

[[Page 285]]

12.3 NO3 Concentration. Calculate the NO3
concentration of the KNO3 solution (see Section 7.2.12) using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.213

12.4 Sample Volume, Dry Basis, Corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.214

Where:

K1=0.3855 [deg]K/mm Hg for metric units.
K1=17.65 [deg]R/in. Hg for English units.

12.5 Efficiency of Cadmium Reduction Column. Calculate this value as
follows:
[GRAPHIC] [TIFF OMITTED] TR17OC00.215

Where:

200=Final volume of sample and blank after passing through the column,
ml.
1.0=Volume of spiking solution added, ml.
46.01=[micro]g NO2^-/[micro]mole.
62.01=[micro]g NO3^-/[micro]mole.

12.6 Total [micro]g NO2.
[GRAPHIC] [TIFF OMITTED] TR17OC00.216

Where:

500=Total volume of prepared sample, ml.
50=Aliquot of prepared sample processed through cadmium column, ml.
100=Aliquot of KMnO4/NaOH solution, ml.
1000=Total volume of KMnO4/NaOH solution, ml.

12.7 Sample Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.217

13.0 Method Performance

13.1 Precision. The intra-laboratory relative standard deviation for
a single measurement is 2.8 and 2.9 percent at 201 and 268 ppm
NOX, respectively.
13.2 Bias. The method does not exhibit any bias relative to Method
7.
13.3 Range. The lower detectable limit is 13 mg NOX/
m³, as NO2 (7 ppm NOX) when sampling at
500 ml/min for 1 hour. No upper limit has been established; however,
when using the recommended sampling conditions, the method has been
found to collect NOX emissions quantitatively up to 1782 mg
NOX/m³, as NO2 (932 ppm
NOX).

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

1. Margeson, J.H., W.J. Mitchell, J.C. Suggs, and M.R. Midgett.
Integrated Sampling and Analysis Methods for Determining NOX
Emissions at Electric Utility Plants. U.S. Environmental Protection
Agency, Research Triangle Park, NC. Journal of the Air Pollution Control
Association. 32:1210-1215. 1982.

[[Page 286]]

2. Memorandum and attachment from J.H. Margeson, Source Branch,
Quality Assurance Division, Environmental Monitoring Systems Laboratory,
to The Record, EPA. March 30, 1983. NH3 Interference in
Methods 7C and 7D.
3. Margeson, J.H., J.C. Suggs, and M.R. Midgett. Reduction of
Nitrate to Nitrite with Cadmium. Anal. Chem. 52:1955-57. 1980.
4. Quality Assurance Handbook for Air Pollution Measurement Systems.
Volume III--Stationary Source Specific Methods. U.S. Environmental
Protection Agency. Research Triangle Park, NC. Publication No. EPA-600/
4-77-027b. August 1977.
5. Margeson, J.H., et al. An Integrated Method for Determining
NOX Emissions at Nitric Acid Plants. Analytical Chemistry. 47
(11):1801. 1975.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 287]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.218

[[Page 288]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.219

Method 7D--Determination of Nitrogen Oxide Emissions From Stationary
Sources (Alkaline-Permanganate/Ion Chromatographic Method)

Note: This method is not inclusive with respect to specifications
(e.g., equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Some material is incorporated
by reference from other methods in this part. Therefore, to obtain
reliable results, persons using this method should have a thorough
knowledge of at least the following additional test methods: Method 1,
Method 3, Method 6, Method 7, and Method 7C.

1.0 Scope and Application

1.1 Analytes.

[[Page 289]]

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Nitrogen oxides (NOX), as NO2,
including:
Nitric oxide (NO)............. 10102-43-9
Nitrogen dioxide (NO2)........ 10102-44-0 7 ppmv
------------------------------------------------------------------------

2.0 Summary of Method

An integrated gas sample is extracted from the stack and passed
through impingers containing an alkaline-potassium permanganate
solution; NOX (NO + NO2) emissions are oxidized to
NO3^-. Then NO3^- is analyzed
by ion chromatography.

3.0 Definitions [Reserved]

4.0 Interferences

Same as in Method 7C, Section 4.0.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of the
user of this test method to establish appropriate safety and health
practices and to determine the applicability of regulatory limitations
prior to performing this test method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water for at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating to
eyes, skin, nose, and lungs. 30% H2O2 is a strong
oxidizing agent; avoid contact with skin, eyes, and combustible
material. Wear gloves when handling.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eye tissues
and to skin. Inhalation causes irritation to nose, throat, and lungs.
Reacts exothermically with limited amounts of water.
5.2.3 Potassium Permanganate (KMnO4). Caustic, strong
oxidizer. Avoid bodily contact with.

6.0 Equipment and Supplies

6.1 Sample Collection and Sample Recovery. Same as Method 7C,
Section 6.1. A schematic of the sampling train used in performing this
method is shown in Figure 7C-1 of Method 7C.
6.2 Sample Preparation and Analysis.
6.2.1 Magnetic Stirrer. With 25- by 10-mm Teflon-coated stirring
bars.
6.2.2 Filtering Flask. 500-ml capacity with sidearm.
6.2.3 Buchner Funnel. 75-mm ID, with spout equipped with a 13-mm ID
by 90-mm long piece of Teflon tubing to minimize possibility of
aspirating sample solution during filtration.
6.2.4 Filter Paper. Whatman GF/C, 7.0-cm diameter.
6.2.5 Stirring Rods.
6.2.6 Volumetric Flask. 250-ml.
6.2.7 Pipettes. Class A.
6.2.8 Erlenmeyer Flasks. 250-ml.
6.2.9 Ion Chromatograph. Equipped with an anion separator column to
separate NO3^-, H3⁺
suppressor, and necessary auxiliary equipment. Nonsuppressed and other
forms of ion chromatography may also be used provided that adequate
resolution of NO3^- is obtained. The system must
also be able to resolve and detect NO2^-.

7.0 Reagents and Standards

Note: Unless otherwise indicated, it is intended that all reagents
conform to the specifications established by the Committee on Analytical
Reagents of the American Chemical Society, where such specifications are
available; otherwise, use the best available grade.

7.1 Sample Collection.
7.1.1 Water. Deionized distilled to conform to ASTM specification D
1193-77 or 91 Type 3 (incorporated by reference--see Sec. 60.17).
7.1.2 Potassium Permanganate, 4.0 Percent (w/w), Sodium Hydroxide,
2.0 Percent (w/w). Dissolve 40.0 g of KMnO4 and 20.0 g of
NaOH in 940 ml of water.
7.2 Sample Preparation and Analysis.
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 Hydrogen Peroxide (H2O2), 5 Percent.
Dilute 30 percent H2O2 1:5 (v/v) with water.
7.2.3 Blank Solution. Dissolve 2.4 g of KMnO4 and 1.2 g
of NaOH in 96 ml of water. Alternatively, dilute 60 ml of
KMnO4/NaOH solution to 100 ml.
7.2.4 KNO3 Standard Solution. Dry KNO3 at 110
[deg]C for 2 hours, and cool in a desiccator. Accurately weigh 9 to 10 g
of KNO3 to within 0.1 mg, dissolve in water, and dilute to 1
liter. Calculate the exact NO3^- concentration
using Equation 7D-1 in Section 12.2.

[[Page 290]]

This solution is stable for 2 months without preservative under
laboratory conditions.
7.2.5 Eluent, 0.003 M NaHCO3/0.0024 M
Na2CO3. Dissolve 1.008 g NaHCO3 and
1.018 g Na2CO3 in water, and dilute to 4 liters.
Other eluents capable of resolving nitrate ion from sulfate and other
species present may be used.
7.2.6 Quality Assurance Audit Samples. Same as Method 7, Section
7.3.10. When requesting audit samples, specify that they be in the
appropriate concentration range for Method 7D.

8.0 Sample Collection, Preservation, Transport, and Storage.

8.1 Sampling. Same as in Method 7C, Section 8.1.
8.2 Sample Recovery. Same as in Method 7C, Section 8.2.
8.3 Sample Preparation for Analysis.

Note: Samples must be analyzed within 28 days of collection.

8.3.1 Note the level of liquid in the sample container, and
determine whether any sample was lost during shipment. If a noticeable
amount of leakage has occurred, the volume lost can be determined from
the difference between initial and final solution levels, and this value
can then be used to correct the analytical result. Quantitatively
transfer the contents to a 1-liter volumetric flask, and dilute to
volume.
8.3.2 Sample preparation can be started 36 hours after collection.
This time is necessary to ensure that all NO2^- is
converted to NO3^- in the collection solution. Take
a 50-ml aliquot of the sample and blank, and transfer to 250-ml
Erlenmeyer flasks. Add a magnetic stirring bar. Adjust the stirring rate
to as fast a rate as possible without loss of solution. Add 5 percent
H2O2 in increments of approximately 5 ml using a
5-ml pipette. When the KMnO4 color appears to have been
removed, allow the precipitate to settle, and examine the supernatant
liquid. If the liquid is clear, the H2O2 addition
is complete. If the KMnO4 color persists, add more
H2O2, with stirring, until the supernatant liquid
is clear.

Note: The faster the stirring rate, the less volume of
H2O2 that will be required to remove the
KMnO4.) Quantitatively transfer the mixture to a Buchner
funnel containing GF/C filter paper, and filter the precipitate. The
spout of the Buchner funnel should be equipped with a 13-mm ID by 90-mm
long piece of Teflon tubing. This modification minimizes the possibility
of aspirating sample solution during filtration. Filter the mixture into
a 500-ml filtering flask. Wash the solid material four times with water.
When filtration is complete, wash the Teflon tubing, quantitatively
transfer the filtrate to a 250-ml volumetric flask, and dilute to
volume. The sample and blank are now ready for
NO3^-analysis.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.2, 10.1-10.3................ Sampling Ensure accurate
equipment leak- measurement of
check and sample volume.
calibration.
10.4.......................... Spectrophotometer Ensure linearity of
calibration. spectrophotometer
response to
standards.
11.3.......................... Spiked sample Ensure reduction
analysis. efficiency of
column.
11.6.......................... Audit sample Evaluate analytical
analysis. technique,
preparation of
standards.
------------------------------------------------------------------------

10.0 Calibration and Standardizations

10.1 Dry Gas Meter (DGM) System.
10.1.1 Initial Calibration. Same as in Method 6, Section 10.1.1. For
detailed instructions on carrying out this calibration, it is suggested
that Section 3.5.2 of Citation 4 in Section 16.0 of Method 7C be
consulted.
10.1.2 Post-Test Calibration Check. Same as in Method 6, Section
10.1.2.
10.2 Thermometers for DGM and Barometer. Same as in Method 6,
Sections 10.2 and 10.4, respectively.
10.3 Ion Chromatograph.
10.3.1 Dilute a given volume (1.0 ml or greater) of the
KNO3 standard solution to a convenient volume with water, and
use this solution to prepare calibration standards. Prepare at least
four standards to cover the range of the samples being analyzed. Use
pipettes for all additions. Run standards as instructed in Section 11.2.
Determine peak height or area, and plot the individual values versus
concentration in [micro]g NO3^-/ml.
10.3.2 Do not force the curve through zero. Draw a smooth curve
through the points. The curve should be linear. With the linear curve,
use linear regression to determine the calibration equation.

11.0 Analytical Procedures

11.1 The following chromatographic conditions are recommended: 0.003
M NaHCO3/0.0024 Na2CO3 eluent solution
(Section 7.2.5), full scale range, 3 [micro]MHO; sample loop, 0.5 ml;
flow rate, 2.5 ml/min. These conditions should give a
NO3^- retention time of approximately 15 minutes
(Figure 7D-1).

[[Page 291]]

11.2 Establish a stable baseline. Inject a sample of water, and
determine whether any NO3^- appears in the
chromatogram. If NO3^- is present, repeat the water
load/injection procedure approximately five times; then re-inject a
water sample and observe the chromatogram. When no
NO3^- is present, the instrument is ready for use.
Inject calibration standards. Then inject samples and a blank. Repeat
the injection of the calibration standards (to compensate for any drift
in response of the instrument). Measure the NO3^-
peak height or peak area, and determine the sample concentration from
the calibration curve.
11.3 Audit Analysis. Same as in Method 7, Section 11.4

12.0 Data Analysis and Calculations

Carry out calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature. Same as in Method 7C, Section 12.1.
12.2 NO3^- concentration. Calculate the
NO3^- concentration in the KNO3 standard
solution (see Section 7.2.4) using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.220

12.3 Sample Volume, Dry Basis, Corrected to Standard Conditions.
Same as in Method 7C, Section 12.4.
12.4 Total [micro]g NO2 Per Sample.
[GRAPHIC] [TIFF OMITTED] TR17OC00.221

Where:

250=Volume of prepared sample, ml.
1000=Total volume of KMnO4 solution, ml.
50=Aliquot of KMnO4/NaOH solution, ml.
46.01=Molecular weight of NO3^-.
62.01=Molecular weight of NO3^-.

12.5 Sample Concentration. Same as in Method 7C, Section 12.7.

13.0 Method Performance

13.1 Precision. The intra-laboratory relative standard deviation for
a single measurement is approximately 6 percent at 200 to 270 ppm
NOX.
13.2 Bias. The method does not exhibit any bias relative to Method
7.
13.3 Range. The lower detectable limit is similar to that of Method
7C. No upper limit has been established; however, when using the
recommended sampling conditions, the method has been found to collect
NOX emissions quantitatively up to 1782 mg NOX/
m\3\, as NO2 (932 ppm NOX).

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

Same as Method 7C, Section 16.0, References 1, 2, 4, and 5.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 292]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.222

Method 7E--Determination of Nitrogen Oxides Emissions From Stationary
Sources (Instrumental Analyzer Procedure)

1. Applicability and Principle

1.1 Applicability. This method is applicable to the determination of
nitrogen oxides (NOX) concentrations in emissions from
stationary sources only when specified within the regulations.
1.2 Principle. A gas simple is continuously extracted from a stack,
and a portion of the sample is conveyed to an instrumental
chemiluminescent analyzer for determination of NOX
concentration. Performance specifications and test procedures are
provided to ensure reliable data.

2. Range and Sensitivity

Same as Method 6C, Sections 2.1 and 2.2.

3. Definitions

3.1 Measurement System. The total equipment required for the
determination of NOX concentration. The measurement system
consists of the following major subsystems:
3.1.1 Sample Interface, Gas Analyzer, and Data Recorder. Same as
Method 6C, Sections 3.1.1, 3.1.2, and 3.1.3.
3.1.2 NO2 to NO Converter. A device that converts the
nitrogen dioxide (NO2) in the sample gas to nitrogen oxide
(NO).
3.2 Span, Calibration Gas, Analyzer Calibration Error, Sampling
System Bias, Zero Drift, Calibration Drift, and Response Time. Same as
Method 6C, Sections 3.2 through 3.8.
3.3 Interference Response. The output response of the measurement
system to a component in the sample gas, other than the gas component
being measured.

4. Measurement System Performance Specifications

Same as Method 6C, Sections 4.1 through 4.4.

5. Apparatus and Reagents

5.1 Measurement System. Any measurement system for NOX
that meets the specifications of this method. A schematic of an
acceptable measurement system is shown in Figure 6C-1 of Method 6C. The
essential components of the measurement system are described below:

[[Page 293]]

5.1.1 Sample Probe, Sample Line, Calibration Valve Assembly,
Moisture Removal System, Particulate Filter, Sample Pump, Sample Flow
Rate Control, Sample Gas Manifold, and Data Recorder. Same as Method 6C,
Sections 5.1.1 through 5.1.9, and 5.1.11.
5.1.2 NO2 to NO Converter. That portion of the system
that converts the nitrogen dioxide (NO2) in the sample gas to
nitrogen oxide (NO). An NO2 to NO converter is not necessary
if data are presented to demonstrate that the NO2 portion of
the exhaust gas is less than 5 percent of the total NOX
concentration.
5.1.3 NOX Analyzer. An analyzer based on the principles
of chemiluminescence, to determine continuously the NOX
concentration in the sample gas stream. The analyzer shall meet the
applicable performance specifications of Section 4. A means of
controlling the analyzer flow rate and a device for determining proper
sample flow rate (e.g., precision rotameter, pressure gauge downstream
of all flow controls, etc.) shall be provided at the analyzer.
5.2 NOX Calibration Gases. The calibration gases for the
NOX analyzer shall be NO in N2. Three calibration
gases, as specified in Sections 5.3.1 through 5.3.3. of Method 6C, shall
be used. Ambient air may be used for the zero gas.

6. Measurement System Performance Test Procedures

Perform the following procedures before measurement of emissions
(Section 7).
6.1 Calibration Gas Concentration Verification. Follow Section 6.1
of Method 6C, except if calibration gas analysis is required, use Method
7, and change all 5 percent performance values to 10 percent (or 10 ppm,
whichever is greater).
6.2 Interference Response. Conduct an interference response test of
the analyzer prior to its initial use in the field. Thereafter, recheck
the measurement system if changes are made in the instrumentation that
could alter the interference response (e.g., changes in the gas
detector). Conduct the interference response in accordance with Section
5.4 of Method 20.
6.3 Measurement System Preparation, Analyzer Calibration Error, and
Sample System Bias Check. Follow Sections 6.2 through 6.4 of Method 6C.
6.4 NO2 to NO Conversion Efficiency. Unless data are
presented to demonstrate that the NO2 concentration within
the sample stream is not greater than 5 percent of the NOX
concentration, conduct an NO2 to NO conversion efficiency
test in accordance with Section 5.6 of Method 20.

7. Emission Test Procedure

7.1 Selection of Sampling Site and Sampling Points. Select a
measurement site and sampling points using the same criteria that are
applicable to tests performed using Method 7.
7.2 Sample Collection. Position the sampling probe at the first
measurement point, and begin sampling at the same rate as used during
the system calibration drift test. Maintain constant rate sampling
(i.e., 10 percent) during the entire run. The
sampling time per run shall be the same as the total time required to
perform a run using Method 7, plus twice the system response time. For
each run, use only those measurements obtained after twice the response
time of the measurement system has elapsed, to determine the average
effluent concentration.
7.3 Zero and Calibration Drift Test. Follow Section 7.4 of Method
6C.

8. Emission Calculation

Follow Section 8 of Method 6C.

9. Bibliography

Same as bibliography of Method 6C.

Method 8--Determination of Sulfuric Acid and Sulfur Dioxide Emissions
From Stationary Sources

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Sulfuric acid, including: 7664-93-9, 7449- 0.05 mg/m3 (0.03 x 10-
Sulfuric acid (H2SO4) mist, 11-9. 7 lb/ft3).
Sulfur trioxide (SO3).
Sulfur dioxide (SO2).......... 7449-09-5........ 1.2 mg/m3 (3 x 10-9
lb/ft3).
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of H2SO4 (including H2SO4
mist and SO3) and gaseous SO2 emissions from
stationary sources.

[[Page 294]]

Note: Filterable particulate matter may be determined along with
H2SO4 and SO2 (subject to the approval
of the Administrator) by inserting a heated glass fiber filter between
the probe and isopropanol impinger (see Section 6.1.1 of Method 6). If
this option is chosen, particulate analysis is gravimetric only;
sulfuric acid is not determined separately.

1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

A gas sample is extracted isokinetically from the stack. The
H2SO4 and the SO2 are separated, and
both fractions are measured separately by the barium-thorin titration
method.

3.0 Definitions [Reserved]

4.0 Interferences

4.1 Possible interfering agents of this method are fluorides, free
ammonia, and dimethyl aniline. If any of these interfering agents is
present (this can be determined by knowledge of the process),
alternative methods, subject to the approval of the Administrator, are
required.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. Same as Method 5, Section 6.1, with the
following additions and exceptions:
6.1.1 Sampling Train. A schematic of the sampling train used in this
method is shown in Figure 8-1; it is similar to the Method 5 sampling
train, except that the filter position is different, and the filter
holder does not have to be heated. See Method 5, Section 6.1.1, for
details and guidelines on operation and maintenance.
6.1.1.1 Probe Liner. Borosilicate or quartz glass, with a heating
system to prevent visible condensation during sampling. Do not use metal
probe liners.
6.1.1.2 Filter Holder. Borosilicate glass, with a glass frit filter
support and a silicone rubber gasket. Other gasket materials (e.g.,
Teflon or Viton) may be used, subject to the approval of the
Administrator. The holder design shall provide a positive seal against
leakage from the outside or around the filter. The filter holder shall
be placed between the first and second impingers. Do not heat the filter
holder.
6.1.1.3 Impingers. Four, of the Greenburg-Smith design, as shown in
Figure 8-1. The first and third impingers must have standard tips. The
second and fourth impingers must be modified by replacing the insert
with an approximately 13-mm (\1/2\-in.) ID glass tube, having an
unconstricted tip located 13 mm (\1/2\ in.) from the bottom of the
impinger. Similar collection systems, subject to the approval of the
Administrator, may be used.
6.1.1.4 Temperature Sensor. Thermometer, or equivalent, to measure
the temperature of the gas leaving the impinger train to within 1 [deg]C
(2 [deg]F).
6.2 Sample Recovery. The following items are required for sample
recovery:
6.2.1 Wash Bottles. Two polyethylene or glass bottles, 500-ml.
6.2.2 Graduated Cylinders. Two graduated cylinders (volumetric
flasks may be used), 250-ml, 1-liter.
6.2.3 Storage Bottles. Leak-free polyethylene bottles, 1-liter size
(two for each sampling run).
6.2.4 Trip Balance. 500-g capacity, to measure to 0.5 g (necessary only if a moisture content analysis is
to be done).
6.3 Analysis. The following items are required for sample analysis:
6.3.1 Pipettes. Volumetric 10-ml, 100-ml.
6.3.2 Burette. 50-ml.
6.3.3 Erlenmeyer Flask. 250-ml (one for each sample, blank, and
standard).
6.3.4 Graduated Cylinder. 100-ml.
6.3.5 Dropping Bottle. To add indicator solution, 125-ml size.

7.0 Reagents and Standards

7.1 Sample Collection. The following reagents are required for
sample collection:
7.1.1 Filters and Silica Gel. Same as in Method 5, Sections 7.1.1
and 7.1.2, respectively.
7.1.2 Water. Same as in Method 6, Section 7.1.1.
7.1.3 Isopropanol, 80 Percent by Volume. Mix 800 ml of isopropanol
with 200 ml of water.

Note: Check for peroxide impurities using the procedure outlined in
Method 6, Section 7.1.2.1.

7.1.4 Hydrogen Peroxide (H\2\O\2\), 3 Percent by Volume. Dilute 100
ml of 30 percent H2O2) to 1 liter with water.
Prepare fresh daily.
7.1.5 Crushed Ice.

[[Page 295]]

7.2 Sample Recovery. The reagents and standards required for sample
recovery are:
7.2.1 Water. Same as in Section 7.1.2.
7.2.2 Isopropanol, 80 Percent. Same as in Section 7.1.3.
7.3 Sample Analysis. Same as Method 6, Section 7.3.
7.3.1 Quality Assurance Audit Samples. When making compliance
determinations, and upon availability, audit samples may be obtained
from the appropriate EPA Regional Office or from the responsible
enforcement authority.

Note: The responsible enforcement authority should be notified at
least 30 days prior to the test date to allow sufficient time for sample
delivery.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Pretest Preparation. Same as Method 5, Section 8.1, except that
filters should be inspected but need not be desiccated, weighed, or
identified. If the effluent gas can be considered dry (i.e., moisture-
free), the silica gel need not be weighed.
8.2 Preliminary Determinations. Same as Method 5, Section 8.2.
8.3 Preparation of Sampling Train. Same as Method 5, Section 8.3,
with the following exceptions:
8.3.1 Use Figure 8-1 instead of Figure 5-1.
8.3.2 Replace the second sentence of Method 5, Section 8.3.1 with:
Place 100 ml of 80 percent isopropanol in the first impinger, 100 ml of
3 percent H2O2 in both the second and third
impingers; retain a portion of each reagent for use as a blank solution.
Place about 200 g of silica gel in the fourth impinger.
8.3.3 Ignore any other statements in Section 8.3 of Method 5 that
are obviously not applicable to the performance of Method 8.

Note: If moisture content is to be determined by impinger analysis,
weigh each of the first three impingers (plus absorbing solution) to the
nearest 0.5 g, and record these weights. Weigh also the silica gel (or
silica gel plus container) to the nearest 0.5 g, and record.)

8.4 Metering System Leak-Check Procedure. Same as Method 5, Section
8.4.1.
8.5 Pretest Leak-Check Procedure. Follow the basic procedure in
Method 5, Section 8.4.2, noting that the probe heater shall be adjusted
to the minimum temperature required to prevent condensation, and also
that verbage such as ``* * * plugging the inlet to the filter holder * *
* '' found in Section 8.4.2.2 of Method 5 shall be replaced by `` * * *
plugging the inlet to the first impinger * * * ''. The pretest leak-
check is recommended, but is not required.
8.6 Sampling Train Operation. Follow the basic procedures in Method
5, Section 8.5, in conjunction with the following special instructions:
8.6.1 Record the data on a sheet similar to that shown in Figure 8-2
(alternatively, Figure 5-2 in Method 5 may be used). The sampling rate
shall not exceed 0.030 m\3\/min (1.0 cfm) during the run. Periodically
during the test, observe the connecting line between the probe and first
impinger for signs of condensation. If condensation does occur, adjust
the probe heater setting upward to the minimum temperature required to
prevent condensation. If component changes become necessary during a
run, a leak-check shall be performed immediately before each change,
according to the procedure outlined in Section 8.4.3 of Method 5 (with
appropriate modifications, as mentioned in Section 8.5 of this method);
record all leak rates. If the leakage rate(s) exceeds the specified
rate, the tester shall either void the run or plan to correct the sample
volume as outlined in Section 12.3 of Method 5. Leak-checks immediately
after component changes are recommended, but not required. If these
leak-checks are performed, the procedure in Section 8.4.2 of Method 5
(with appropriate modifications) shall be used.
8.6.2 After turning off the pump and recording the final readings at
the conclusion of each run, remove the probe from the stack. Conduct a
post-test (mandatory) leak-check as outlined in Section 8.4.4 of Method
5 (with appropriate modifications), and record the leak rate. If the
post-test leakage rate exceeds the specified acceptable rate, either
correct the sample volume, as outlined in Section 12.3 of Method 5, or
void the run.
8.6.3 Drain the ice bath and, with the probe disconnected, purge the
remaining part of the train by drawing clean ambient air through the
system for 15 minutes at the average flow rate used for sampling.

Note: Clean ambient air can be provided by passing air through a
charcoal filter. Alternatively, ambient air (without cleaning) may be
used.

8.7 Calculation of Percent Isokinetic. Same as Method 5, Section
8.6.
8.8 Sample Recovery. Proper cleanup procedure begins as soon as the
probe is removed from the stack at the end of the sampling period. Allow
the probe to cool. Treat the samples as follows:
8.8.1 Container No. 1.
8.8.1.1 If a moisture content analysis is to be performed, clean and
weigh the first impinger (plus contents) to the nearest 0.5 g, and
record this weight.
8.8.1.2 Transfer the contents of the first impinger to a 250-ml
graduated cylinder. Rinse the probe, first impinger, all connecting
glassware before the filter, and the front half of the filter holder
with 80 percent isopropanol. Add the isopropanol rinse solution to the
cylinder. Dilute the contents of the cylinder to 225 ml with 80 percent

[[Page 296]]

isopropanol, and transfer the cylinder contents to the storage
container. Rinse the cylinder with 25 ml of 80 percent isopropanol, and
transfer the rinse to the storage container. Add the filter to the
solution in the storage container and mix. Seal the container to protect
the solution against evaporation. Mark the level of liquid on the
container, and identify the sample container.
8.8.2 Container No. 2.
8.8.2.1 If a moisture content analysis is to be performed, clean and
weigh the second and third impingers (plus contents) to the nearest 0.5
g, and record the weights. Also, weigh the spent silica gel (or silica
gel plus impinger) to the nearest 0.5 g, and record the weight.
8.8.2.2 Transfer the solutions from the second and third impingers
to a 1-liter graduated cylinder. Rinse all connecting glassware
(including back half of filter holder) between the filter and silica gel
impinger with water, and add this rinse water to the cylinder. Dilute
the contents of the cylinder to 950 ml with water. Transfer the solution
to a storage container. Rinse the cylinder with 50 ml of water, and
transfer the rinse to the storage container. Mark the level of liquid on
the container. Seal and identify the sample container.

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
7.1.3......................... Isopropanol check Ensure acceptable
level of peroxide
impurities in
isopropanol.
8.4, 8.5, 10.1................ Sampling Ensure accurate
equipment leak- measurement of stack
check and gas flow rate,
calibration. sample volume.
10.2.......................... Barium standard Ensure normality
solution determination.
standardization.
11.2.......................... Replicate Ensure precision of
titrations. titration
determinations.
11.3.......................... Audit sample Evaluate analyst's
analysis. technique and
standards
preparation.
------------------------------------------------------------------------

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardization

10.1 Sampling Equipment. Same as Method 5, Section 10.0.
10.2 Barium Standard Solution. Same as Method 6, Section 10.5.

11.0 Analytical Procedure

11.1. Sample Loss. Same as Method 6, Section 11.1.
11.2. Sample Analysis.
11.2.1 Container No. 1. Shake the container holding the isopropanol
solution and the filter. If the filter breaks up, allow the fragments to
settle for a few minutes before removing a sample aliquot. Pipette a
100-ml aliquot of this solution into a 250-ml Erlenmeyer flask, add 2 to
4 drops of thorin indicator, and titrate to a pink endpoint using 0.0100
N barium standard solution. Repeat the titration with a second aliquot
of sample, and average the titration values. Replicate titrations must
agree within 1 percent or 0.2 ml, whichever is greater.
11.2.2 Container No. 2. Thoroughly mix the solution in the container
holding the contents of the second and third impingers. Pipette a 10-ml
aliquot of sample into a 250-ml Erlenmeyer flask. Add 40 ml of
isopropanol, 2 to 4 drops of thorin indicator, and titrate to a pink
endpoint using 0.0100 N barium standard solution. Repeat the titration
with a second aliquot of sample, and average the titration values.
Replicate titrations must agree within 1 percent or 0.2 ml, whichever is
greater.
11.2.3 Blanks. Prepare blanks by adding 2 to 4 drops of thorin
indicator to 100 ml of 80 percent isopropanol. Titrate the blanks in the
same manner as the samples.
11.3 Audit Sample Analysis.
11.3.1 When the method is used to analyze samples to demonstrate
compliance with a source emission regulation, EPA audit samples must be
analyzed, subject to availability.
11.3.2 Concurrently analyze audit samples and the compliance samples
in the same manner to evaluate the technique of the analyst and the
standards preparation.

Note: It is recommended that known quality control samples be
analyzed prior to the compliance and audit sample analyses to optimize
the system accuracy and precision. These quality control samples may be
obtained by contacting the appropriate EPA regional Office or the
responsible enforcement authority.

11.3.3 The same analyst, analytical reagents, and analytical system
shall be used for the compliance samples and the EPA audit samples. If
this condition is met, duplicate auditing of subsequent compliance
analyses for the same enforcement agency within a 30-day period is
waived. Audit samples may not be used to validate different compliance
samples under the jurisdiction of separate enforcement agencies, unless
prior arrangements have been made with both enforcement agencies.

[[Page 297]]

11.4 Audit Sample Results.
11.4.1 Calculate the audit sample concentrations in mg/dscm and
submit results using the instructions provided with the audit samples.
11.4.2 Report the results of the audit samples and the compliance
determination samples along with their identification numbers, and the
analyst's name to the responsible enforcement authority. Include this
information with reports of any subsequent compliance analyses for the
same enforcement authority during the 30-day period.
11.4.3 The concentrations of the audit samples obtained by the
analyst shall agree within 5 percent of the actual concentrations. If
the 5 percent specification is not met, reanalyze the compliance and
audit samples, and include initial and reanalysis values in the test
report.
11.4.4 Failure to meet the 5 percent specification may require
retests until the audit problems are resolved. However, if the audit
results do not affect the compliance or noncompliance status of the
affected facility, the Administrator may waive the reanalysis
requirement, further audits, or retests and accept the results of the
compliance test. While steps are being taken to resolve audit analysis
problems, the Administrator may also choose to use the data to determine
the compliance or noncompliance status of the affected facility.

12.0 Data Analysis and Calculations

Carry out calculations retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature. Same as Method 5, Section 12.1, with the
following additions and exceptions:

Ca=Actual concentration of SO2 in audit sample,
mg/dscm.
Cd=Determined concentration of SO2 in audit
sample, mg/dscm.
CH2SO4=Sulfuric acid (including SO3)
concentration, g/dscm (lb/dscf).
CSO2=Sulfur dioxide concentration, g/dscm (lb/dscf).
N=Normality of barium perchlorate titrant, meq/ml.
RE=Relative error of QA audit sample analysis, percent
Va=Volume of sample aliquot titrated, 100 ml for
H2SO4 and 10 ml for SO2.
Vsoln=Total volume of solution in which the sample is
contained, 250 ml for the SO2 sample and 1000 ml for the
H2SO4 sample.
Vt=Volume of barium standard solution titrant used for the
sample, ml.
Vtb=Volume of barium standard solution titrant used for the
blank, ml.

12.2 Average Dry Gas Meter Temperature and Average Orifice Pressure
Drop. See data sheet (Figure 8-2).
12.3 Dry Gas Volume. Same as Method 5, Section 12.3.
12.4 Volume of Water Vapor Condensed and Moisture Content. Calculate
the volume of water vapor using Equation 5-2 of Method 5; the weight of
water collected in the impingers and silica gel can be converted
directly to milliliters (the specific gravity of water is 1 g/ml).
Calculate the moisture content of the stack gas (Bws) using
Equation 5-3 of Method 5. The Note in Section 12.5 of Method 5 also
applies to this method. Note that if the effluent gas stream can be
considered dry, the volume of water vapor and moisture content need not
be calculated.
12.5 Sulfuric Acid Mist (Including SO3) Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.223

Where:

K3=0.04904 g/meq for metric units,
K3=1.081 x 10^-4 lb/meq for English units.

12.6 Sulfur Dioxide Concentration.
[GRAPHIC] [TIFF OMITTED] TR17OC00.224

Where:

K4=0.03203 g/meq for metric units,
K4=7.061 x 10^-5 lb/meq for English units.

12.7 Isokinetic Variation. Same as Method 5, Section 12.11.
12.8 Stack Gas Velocity and Volumetric Flow Rate. Calculate the
average stack gas velocity and volumetric flow rate, if needed, using
data obtained in this method and the equations in Sections 12.6 and 12.7
of Method 2.
12.9 Relative Error (RE) for QA Audit Samples. Same as Method 6,
Section 12.4.

[[Page 298]]

13.0 Method Performance

13.1 Analytical Range. Collaborative tests have shown that the
minimum detectable limits of the method are 0.06 mg/m³ (4 x
10^-9 lb/ft³) for H2SO4 and
1.2 mg/m³ (74 x 10^-9 lb/ft³) for
SO2. No upper limits have been established. Based on
theoretical calculations for 200 ml of 3 percent
H2O2 solution, the upper concentration limit for
SO2 in a 1.0 m³ (35.3 ft³) gas sample
is about 12,000 mg/m³ (7.7 x 10^-4 lb/
ft³). The upper limit can be extended by increasing the
quantity of peroxide solution in the impingers.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

Same as Section 17.0 of Methods 5 and 6.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 299]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.225

[[Page 300]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.226

Method 9--Visual Determination of the Opacity of Emissions From
Stationary Sources

Many stationary sources discharge visible emissions into the
atmosphere; these emissions are usually in the shape of a plume. This
method involves the determination of plume opacity by qualified
observers. The method includes procedures for the training and
certification of observers, and procedures to be used in the field for
determination of plume opacity. The appearance of a plume as viewed by
an observer depends upon a number of variables, some of which may be
controllable and some of which may not be controllable in the field.
Variables which can be controlled to an extent to which they no longer
exert a significant influence upon

[[Page 301]]

plume appearance include: Angle of the observer with respect to the
plume; angle of the observer with respect to the sun; point of
observation of attached and detached steam plume; and angle of the
observer with respect to a plume emitted from a rectangular stack with a
large length to width ratio. The method includes specific criteria
applicable to these variables.
Other variables which may not be controllable in the field are
luminescence and color contrast between the plume and the background
against which the plume is viewed. These variables exert an influence
upon the appearance of a plume as viewed by an observer, and can affect
the ability of the observer to accurately assign opacity values to the
observed plume. Studies of the theory of plume opacity and field studies
have demonstrated that a plume is most visible and presents the greatest
apparent opacity when viewed against a contrasting background. It
follows from this, and is confirmed by field trials, that the opacity of
a plume, viewed under conditions where a contrasting background is
present can be assigned with the greatest degree of accuracy. However,
the potential for a positive error is also the greatest when a plume is
viewed under such contrasting conditions. Under conditions presenting a
less contrasting background, the apparent opacity of a plume is less and
approaches zero as the color and luminescence contrast decrease toward
zero. As a result, significant negative bias and negative errors can be
made when a plume is viewed under less contrasting conditions. A
negative bias decreases rather than increases the possibility that a
plant operator will be cited for a violation of opacity standards due to
observer error.
Studies have been undertaken to determine the magnitude of positive
errors which can be made by qualified observers while reading plumes
under contrasting conditions and using the procedures set forth in this
method. The results of these studies (field trials) which involve a
total of 769 sets of 25 readings each are as follows:
(1) For black plumes (133 sets at a smoke generator), 100 percent of
the sets were read with a positive error \1\ of less than 7.5 percent
opacity; 99 percent were read with a positive error of less than 5
percent opacity.
---------------------------------------------------------------------------

\1\ For a set, positive error=average opacity determined by
observers' 25 observations--average opacity determined from trans mis
someter's 25 recordings.
---------------------------------------------------------------------------

(2) For white plumes (170 sets at a smoke generator, 168 sets at a
coal-fired power plant, 298 sets at a sulfuric acid plant), 99 percent
of the sets were read with a positive error of less than 7.5 percent
opacity; 95 percent were read with a positive error of less than 5
percent opacity.
The positive observational error associated with an average of
twenty-five readings is therefore established. The accuracy of the
method must be taken into account when determining possible violations
of applicable opacity standards.

1. Principle and Applicability

1.1 Principle. The opacity of emissions from stationary sources is
determined visually by a qualified observer.
1.2 Applicability. This method is applicable for the determination
of the opacity of emissions from stationary sources pursuant to Sec.
60.11(b) and for qualifying observers for visually determining opacity
of emissions.

2. Procedures

The observer qualified in accordance with section 3 of this method
shall use the following procedures for visually determining the opacity
of emissions:
2.1 Position. The qualified observer shall stand at a distance
sufficient to provide a clear view of the emissions with the sun
oriented in the 140[deg] sector to his back. Consistent with maintaining
the above requirement, the observer shall, as much as possible, make his
observations from a position such that his line of vision is
approximately perpendicular to the plume direction, and when observing
opacity of emissions from rectangular outlets (e.g., roof monitors, open
baghouses, noncircular stacks), approximately perpendicular to the
longer axis of the outlet. The observer's line of sight should not
include more than one plume at a time when multiple stacks are involved,
and in any case the observer should make his observations with his line
of sight perpendicular to the longer axis of such a set of multiple
stacks (e.g., stub stacks on bag houses).
2.2 Field Records. The observer shall record the name of the plant,
emission location, type facility, observer's name and affiliation, a
sketch of the observer's position relative to the source, and the date
on a field data sheet (Figure 9-1). The time, estimated distance to the
emission location, approximate wind direction, estimated wind speed,
description of the sky condition (presence and color of clouds), and
plume background are recorded on a field data sheet at the time opacity
readings are initiated and completed.
2.3 Observations. Opacity observations shall be made at the point of
greatest opacity in that portion of the plume where condensed water
vapor is not present. The observer shall not look continuously at the
plume, but instead shall observe the plume momentarily at 15-second
intervals.
2.3.1 Attached Steam Plumes. When condensed water vapor is present
within the

[[Page 302]]

plume as it emerges from the emission outlet, opacity observations shall
be made beyond the point in the plume at which condensed water vapor is
no longer visible. The observer shall record the approximate distance
from the emission outlet to the point in the plume at which the
observations are made.
2.3.2 Detached Steam Plume. When water vapor in the plume condenses
and becomes visible at a distinct distance from the emission outlet, the
opacity of emissions should be evaluated at the emission outlet prior to
the condensation of water vapor and the formation of the steam plume.
2.4 Recording Observations. Opacity observations shall be recorded
to the nearest 5 percent at 15-second intervals on an observational
record sheet. (See Figure 9-2 for an example.) A minimum of 24
observations shall be recorded. Each momentary observation recorded
shall be deemed to represent the average opacity of emissions for a 15-
second period.
2.5 Data Reduction. Opacity shall be determined as an average of 24
consecutive observations recorded at 15-second intervals. Divide the
observations recorded on the record sheet into sets of 24 consecutive
observations. A set is composed of any 24 consecutive observations. Sets
need not be consecutive in time and in no case shall two sets overlap.
For each set of 24 observations, calculate the average by summing the
opacity of the 24 observations and dividing this sum by 24. If an
applicable standard specifies an averaging time requiring more than 24
observations, calculate the average for all observations made during the
specified time period. Record the average opacity on a record sheet.
(See Figure 9-1 for an example.)

3. Qualifications and Testing

3.1 Certification Requirements. To receive certification as a
qualified observer, a candidate must be tested and demonstrate the
ability to assign opacity readings in 5 percent increments to 25
different black plumes and 25 different white plumes, with an error not
to exceed 15 percent opacity on any one reading and an average error not
to exceed 7.5 percent opacity in each category. Candidates shall be
tested according to the procedures described in section 3.2. Smoke
generators used pursuant to section 3.2 shall be equipped with a smoke
meter which meets the requirements of section 3.3.
The certification shall be valid for a period of 6 months, at which
time the qualification procedure must be repeated by any observer in
order to retain certification.
3.2 Certification Procedure. The certification test consists of
showing the candidate a complete run of 50 plumes--25 black plumes and
25 white plumes--generated by a smoke generator. Plumes within each set
of 25 black and 25 white runs shall be presented in random order. The
candidate assigns an opacity value to each plume and records his
observation on a suitable form. At the completion of each run of 50
readings, the score of the candidate is determined. If a candidate fails
to qualify, the complete run of 50 readings must be repeated in any
retest. The smoke test may be administered as part of a smoke school or
training program, and may be preceded by training or familiarization
runs of the smoke generator during which candidates are shown black and
white plumes of known opacity.
3.3 Smoke Generator Specifications. Any smoke generator used for the
purposes of section 3.2 shall be equipped with a smoke meter installed
to measure opacity across the diameter of the smoke generator stack. The
smoke meter output shall display instack opacity based upon a pathlength
equal to the stack exit diameter, on a full 0 to 100 percent chart
recorder scale. The smoke meter optical design and performance shall
meet the specifications shown in Table 9-1. The smoke meter shall be
calibrated as prescribed in section 3.3.1 prior to the conduct of each
smoke reading test. At the completion of each test, the zero and span
drift shall be checked and if the drift exceeds 1
percent opacity, the condition shall be corrected prior to conducting
any subsequent test runs. The smoke meter shall be demonstrated, at the
time of installation, to meet the specifications listed in Table 9-1.
This demonstration shall be repeated following any subsequent repair or
replacement of the photocell or associated electronic circuitry
including the chart recorder or output meter, or every 6 months,
whichever occurs first.

Table 9-1--Smoke Meter Design and Performance Specifications
------------------------------------------------------------------------
Parameter Specification
------------------------------------------------------------------------
a. Light source.......................... Incandescent lamp operated at
nominal rated voltage.
b. Spectral response of photocell........ Photopic (daylight spectral
response of the human eye--
Citation 3).
c. Angle of view......................... 15[deg] maximum total angle.
d. Angle of projection................... 15[deg] maximum total angle.
e. Calibration error..................... 3%
opacity, maximum.
f. Zero and span drift................... 1%
opacity, 30 minutes.
g. Response time......................... 5 seconds.
------------------------------------------------------------------------

3.3.1 Calibration. The smoke meter is calibrated after allowing a
minimum of 30 minutes warmup by alternately producing simulated opacity
of 0 percent and 100 percent. When stable response at 0 percent or 100
percent is noted, the smoke meter is adjusted to produce an output of 0
percent or 100 percent, as appropriate. This calibration shall be
repeated until stable 0 percent and 100

[[Page 303]]

percent readings are produced without adjustment. Simulated 0 percent
and 100 percent opacity values may be produced by alternately switching
the power to the light source on and off while the smoke generator is
not producing smoke.
3.3.2 Smoke Meter Evaluation. The smoke meter design and performance
are to be evaluated as follows:
3.3.2.1 Light Source. Verify from manufacturer's data and from
voltage measurements made at the lamp, as installed, that the lamp is
operated within 5 percent of the nominal rated
voltage.
3.3.2.2 Spectral Response of Photocell. Verify from manufacturer's
data that the photocell has a photopic response; i.e., the spectral
sensitivity of the cell shall closely approximate the standard spectral-
luminosity curve for photopic vision which is referenced in (b) of Table
9-1.

[[Page 304]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.154

Figure 9-2--Observation Record
Page ---- of ----
Company........................... Observer................. ........
Location.......................... Type facility............ ........
Test Number....................... Point of emissions....... ........
Date..............................

[[Page 305]]

----------------------------------------------------------------------------------------------------------------
Seconds Steam plume (check if applicable)
Hr. Min. ----------------------------------------------------------------------------- Comments
0 15 30 45 Attached Detached
----------------------------------------------------------------------------------------------------------------
0
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Figure 9-2--Observation Record (Continued)
Page ---- of ----
Company........................... Observer................. ........
Location.......................... Type facility............ ........
Test Number....................... Point of emissions....... ........
Date..............................

[[Page 306]]

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3.3.2.3 Angle of View. Check construction geometry to ensure that
the total angle of view of the smoke plume, as seen by the photocell,
does not exceed 15[deg]. The total angle of view may be calculated from:
[thetas]= 2 tan^-1d/2L, where [thetas]=total angle of view;
d=the sum of the photocell diameter+the diameter of the limiting
aperture; and L=the distance from the photocell to the limiting
aperture. The limiting aperture is the point in the path between the
photocell and the smoke plume where the angle of view is most
restricted. In smoke generator smoke meters this is normally an orifice
plate.
3.3.2.4 Angle of Projection. Check construction geometry to ensure
that the total angle of projection of the lamp on the smoke plume does
not exceed 15[deg]. The total angle of projection may be calculated
from: [thetas]=2 tan^-1d/2L, where [thetas]=total angle of
projection; d=the sum of the length of the lamp filament + the diameter
of the limiting aperture; and

[[Page 307]]

L=the distance from the lamp to the limiting aperture.
3.3.2.5 Calibration Error. Using neutral-density filters of known
opacity, check the error between the actual response and the theoretical
linear response of the smoke meter. This check is accomplished by first
calibrating the smoke meter according to 3.3.1 and then inserting a
series of three neutral-density filters of nominal opacity of 20, 50,
and 75 percent in the smoke meter pathlength. Filters calibrated within
2 percent shall be used. Care should be taken when
inserting the filters to prevent stray light from affecting the meter.
Make a total of five nonconsecutive readings for each filter. The
maximum error on any one reading shall be 3 percent opacity.
3.3.2.6 Zero and Span Drift. Determine the zero and span drift by
calibrating and operating the smoke generator in a normal manner over a
1-hour period. The drift is measured by checking the zero and span at
the end of this period.
3.3.2.7 Response Time. Determine the response time by producing the
series of five simulated 0 percent and 100 percent opacity values and
observing the time required to reach stable response. Opacity values of
0 percent and 100 percent may be simulated by alternately switching the
power to the light source off and on while the smoke generator is not
operating.

4. Bibliography

1. Air Pollution Control District Rules and Regulations, Los Angeles
County Air Pollution Control District, Regulation IV, Prohibitions, Rule
50.
2. Weisburd, Melvin I., Field Operations and Enforcement Manual for
Air, U.S. Environmental Protection Agency, Research Triangle Park, NC.
APTD-1100, August 1972, pp. 4.1-4.36.
3. Condon, E.U., and Odishaw, H., Handbook of Physics, McGraw-Hill
Co., New York, NY, 1958, Table 3.1, p. 6-52.

Alternate Method 1--Determination of the Opacity of Emissions From
Stationary Sources Remotely by Lidar

This alternate method provides the quantitative determination of the
opacity of an emissions plume remotely by a mobile lidar system (laser
radar; Light Detection and Ranging). The method includes procedures for
the calibration of the lidar and procedures to be used in the field for
the lidar determination of plume opacity. The lidar is used to measure
plume opacity during either day or nighttime hours because it contains
its own pulsed light source or transmitter. The operation of the lidar
is not dependent upon ambient lighting conditions (light, dark, sunny or
cloudy).
The lidar mechanism or technique is applicable to measuring plume
opacity at numerous wavelengths of laser radiation. However, the
performance evaluation and calibration test results given in support of
this method apply only to a lidar that employs a ruby (red light) laser
[Reference 5.1].

1. Principle and Applicability

1.1 Principle. The opacity of visible emissions from stationary
sources (stacks, roof vents, etc.) is measured remotely by a mobile
lidar (laser radar).
1.2 Applicability. This method is applicable for the remote
measurement of the opacity of visible emissions from stationary sources
during both nighttime and daylight conditions, pursuant to 40 CFR Sec.
60.11(b). It is also applicable for the calibration and performance
verification of the mobile lidar for the measurement of the opacity of
emissions. A performance/design specification for a basic lidar system
is also incorporated into this method.
1.3 Definitions.
Azimuth angle: The angle in the horizontal plane that designates
where the laser beam is pointed. It is measured from an arbitrary fixed
reference line in that plane.
Backscatter: The scattering of laser light in a direction opposite
to that of the incident laser beam due to reflection from particulates
along the beam's atmospheric path which may include a smoke plume.
Backscatter signal: The general term for the lidar return signal
which results from laser light being backscattered by atmospheric and
smoke plume particulates.
Convergence distance: The distance from the lidar to the point of
overlap of the lidar receiver's field-of-view and the laser beam.
Elevation angle: The angle of inclination of the laser beam
referenced to the horizontal plane.
Far region: The region of the atmosphere's path along the lidar
line-of-sight beyond or behind the plume being measured.
Lidar: Acronym for Light Detection and Ranging.
Lidar range: The range or distance from the lidar to a point of
interest along the lidar line-of-sight.
Near region: The region of the atmospheric path along the lidar
line-of-sight between the lidar's convergence distance and the plume
being measured.
Opacity: One minus the optical transmittance of a smoke plume,
screen target, etc.
Pick interval: The time or range intervals in the lidar backscatter
signal whose minimum average amplitude is used to calculate opacity. Two
pick intervals are required, one in the near region and one in the far
region.
Plume: The plume being measured by lidar.
Plume signal: The backscatter signal resulting from the laser light
pulse passing through a plume.

[[Page 308]]

1/R\2\Correction: The correction made for the systematic decrease in
lidar backscatter signal amplitude with range.
Reference signal: The backscatter signal resulting from the laser
light pulse passing through ambient air.
Sample interval: The time period between successive samples for a
digital signal or between successive measurements for an analog signal.
Signal spike: An abrupt, momentary increase and decrease in signal
amplitude.
Source: The source being tested by lidar.
Time reference: The time (to) when the laser pulse
emerges from the laser, used as the reference in all lidar time or range
measurements.

2. Procedures

The mobile lidar calibrated in accordance with Paragraph 3 of this
method shall use the following procedures for remotely measuring the
opacity of stationary source emissions:
2.1 Lidar Position. The lidar shall be positioned at a distance from
the plume sufficient to provide an unobstructed view of the source
emissions. The plume must be at a range of at least 50 meters or three
consecutive pick intervals (whichever is greater) from the lidar's
transmitter/receiver convergence distance along the line-of-sight. The
maximum effective opacity measurement distance of the lidar is a
function of local atmospheric conditions, laser beam diameter, and plume
diameter. The test position of the lidar shall be selected so that the
diameter of the laser beam at the measurement point within the plume
shall be no larger than three-fourths the plume diameter. The beam
diameter is calculated by Equation (AM1-1):

D(lidar)=A+R[phis]<=0.75 D(Plume) (AM1-1)

Where:

D(Plume)=diameter of the plume (cm),
[phis]=laser beam divergence measured in radians
R=range from the lidar to the source (cm)
D(Lidar)=diameter of the laser beam at range R (cm),
A=diameter of the laser beam or pulse where it leaves the laser.

The lidar range, R, is obtained by aiming and firing the laser at the
emissions source structure immediately below the outlet. The range value
is then determined from the backscatter signal which consists of a
signal spike (return from source structure) and the atmospheric
backscatter signal [Reference 5.1]. This backscatter signal should be
recorded.
When there is more than one source of emissions in the immediate
vicinity of the plume, the lidar shall be positioned so that the laser
beam passes through only a single plume, free from any interference of
the other plumes for a minimum of 50 meters or three consecutive pick
intervals (whichever is greater) in each region before and beyond the
plume along the line-of-sight (determined from the backscatter signals).
The lidar shall initially be positioned so that its line-of-sight is
approximately perpendicular to the plume.
When measuring the opacity of emissions from rectangular outlets
(e.g., roof monitors, open baghouses, noncircular stacks, etc.), the
lidar shall be placed in a position so that its line-of-sight is
approximately perpendicular to the longer (major) axis of the outlet.
2.2 Lidar Operational Restrictions. The lidar receiver shall not be
aimed within an angle of 15[deg] (cone angle) of
the sun.
This method shall not be used to make opacity measurements if
thunderstorms, snowstorms, hail storms, high wind, high-ambient dust
levels, fog or other atmospheric conditions cause the reference signals
to consistently exceed the limits specified in Section 2.3.
2.3 Reference Signal Requirements. Once placed in its proper
position for opacity measurement, the laser is aimed and fired with the
line-of-sight near the outlet height and rotated horizontally to a
position clear of the source structure and the associated plume. The
backscatter signal obtained from this position is called the ambient-air
or reference signal. The lidar operator shall inspect this signal
[Section V of Reference 5.1] to: (1) determine if the lidar line-of-
sight is free from interference from other plumes and from physical
obstructions such as cables, power lines, etc., for a minimum of 50
meters or three consecutive pick intervals (whichever is greater) in
each region before and beyond the plume, and (2) obtain a qualitative
measure of the homogeneity of the ambient air by noting any signal
spikes.
Should there be any signal spikes on the reference signal within a
minimum of 50 meters or three consecutive pick intervals (whichever is
greater) in each region before and beyond the plume, the laser shall be
fired three more times and the operator shall inspect the reference
signals on the display. If the spike(s) remains, the azimuth angle shall
be changed and the above procedures conducted again. If the spike(s)
disappears in all three reference signals, the lidar line-of-sight is
acceptable if there is shot-to-shot consistency and there is no
interference from other plumes.
Shot-to-shot consistency of a series of reference signals over a
period of twenty seconds is verified in either of two ways. (1) The
lidar operator shall observe the reference signal amplitudes. For shot-
to-shot consistency the ratio of Rf to Rn
[amplitudes of the near and far region pick intervals (Section 2.6.1)]
shall vary by not more than 6% between shots; or
(2) the lidar operator shall accept any one of the reference signals and
treat the other two as plume signals; then

[[Page 309]]

the opacity for each of the subsequent reference signals is calculated
(Equation AM1-2). For shot-to-shot consistency, the opacity values shall
be within 3% of 0% opacity and the associated
So values less than or equal to 8% (full scale) [Section
2.6].
If a set of reference signals fails to meet the requirements of this
section, then all plume signals [Section 2.4] from the last set of
acceptable reference signals to the failed set shall be discarded.
2.3.1 Initial and Final Reference Signals. Three reference signals
shall be obtained within a 90-second time period prior to any data run.
A final set of three reference signals shall be obtained within three
(3) minutes after the completion of the same data run.
2.3.2 Temporal Criterion for Additional Reference Signals. An
additional set of reference signals shall be obtained during a data run
if there is a change in wind direction or plume drift of 30[deg] or more
from the direction that was prevalent when the last set of reference
signals was obtained. An additional set of reference signals shall also
be obtained if there is an increase in value of SIn (near
region standard deviation, Equation AM1-5) or SIf (far region
standard deviation, Equation AM1-6) that is greater than 6% (full scale)
over the respective values calculated from the immediately previous
plume signal, and this increase in value remains for 30 seconds or
longer. An additional set of reference signals shall also be obtained if
there is a change in amplitude in either the near or the far region of
the plume signal, that is greater than 6% of the near signal amplitude
and this change in amplitude remains for 30 seconds or more.
2.4 Plume Signal Requirements. Once properly aimed, the lidar is
placed in operation with the nominal pulse or firing rate of six pulses/
minute (1 pulse/10 seconds). The lidar operator shall observe the plume
backscatter signals to determine the need for additional reference
signals as required by Section 2.3.2. The plume signals are recorded
from lidar start to stop and are called a data run. The length of a data
run is determined by operator discretion. Short-term stops of the lidar
to record additional reference signals do not constitute the end of a
data run if plume signals are resumed within 90 seconds after the
reference signals have been recorded, and the total stop or interrupt
time does not exceed 3 minutes.
2.4.1 Non-hydrated Plumes. The laser shall be aimed at the region of
the plume which displays the greatest opacity. The lidar operator must
visually verify that the laser is aimed clearly above the source exit
structure.
2.4.2 Hydrated Plumes. The lidar will be used to measure the opacity
of hydrated or so-called steam plumes. As listed in the reference
method, there are two types, i.e., attached and detached steam plumes.
2.4.2.1 Attached Steam Plumes. When condensed water vapor is present
within a plume, lidar opacity measurements shall be made at a point
within the residual plume where the condensed water vapor is no longer
visible. The laser shall be aimed into the most dense region (region of
highest opacity) of the residual plume.
During daylight hours the lidar operator locates the most dense
portion of the residual plume visually. During nighttime hours a high-
intensity spotlight, night vision scope, or low light level TV, etc.,
can be used as an aid to locate the residual plume. If visual
determination is ineffective, the lidar may be used to locate the most
dense region of the residual plume by repeatedly measuring opacity,
along the longitudinal axis or center of the plume from the emissions
outlet to a point just beyond the steam plume. The lidar operator should
also observe color differences and plume reflectivity to ensure that the
lidar is aimed completely within the residual plume. If the operator
does not obtain a clear indication of the location of the residual
plume, this method shall not be used.
Once the region of highest opacity of the residual plume has been
located, aiming adjustments shall be made to the laser line-of-sight to
correct for the following: movement to the region of highest opacity out
of the lidar line-of-sight (away from the laser beam) for more than 15
seconds, expansion of the steam plume (air temperature lowers and/or
relative humidity increases) so that it just begins to encroach on the
field-of-view of the lidar's optical telescope receiver, or a decrease
in the size of the steam plume (air temperature higher and/or relative
humidity decreases) so that regions within the residual plume whose
opacity is higher than the one being monitored, are present.
2.4.2.2 Detached Steam Plumes. When the water vapor in a hydrated
plume condenses and becomes visible at a finite distance from the stack
or source emissions outlet, the opacity of the emissions shall be
measured in the region of the plume clearly above the emissions outlet
and below condensation of the water vapor.
During daylight hours the lidar operators can visually determine if
the steam plume is detached from the stack outlet. During nighttime
hours a high-intensity spotlight, night vision scope, low light level
TV, etc., can be used as an aid in determining if the steam plume is
detached. If visual determination is ineffective, the lidar may be used
to determine if the steam plume is detached by repeatedly measuring
plume opacity from the outlet to the steam plume along the plume's
longitudinal axis or center line. The lidar operator should also observe
color differences and plume reflectivity to detect a

[[Page 310]]

detached plume. If the operator does not obtain a clear indication of
the location of the detached plume, this method shall not be used to
make opacity measurements between the outlet and the detached plume.
Once the determination of a detached steam plume has been confirmed,
the laser shall be aimed into the region of highest opacity in the plume
between the outlet and the formation of the steam plume. Aiming
adjustments shall be made to the lidar's line-of-sight within the plume
to correct for changes in the location of the most dense region of the
plume due to changes in wind direction and speed or if the detached
steam plume moves closer to the source outlet encroaching on the most
dense region of the plume. If the detached steam plume should move too
close to the source outlet for the lidar to make interference-free
opacity measurements, this method shall not be used.
2.5 Field Records. In addition to the recording recommendations
listed in other sections of this method the following records should be
maintained. Each plume measured should be uniquely identified. The name
of the facility, type of facility, emission source type, geographic
location of the lidar with respect to the plume, and plume
characteristics should be recorded. The date of the test, the time
period that a source was monitored, the time (to the nearest second) of
each opacity measurement, and the sample interval should also be
recorded. The wind speed, wind direction, air temperature, relative
humidity, visibility (measured at the lidar's position), and cloud cover
should be recorded at the beginning and end of each time period for a
given source. A small sketch depicting the location of the laser beam
within the plume should be recorded.
If a detached or attached steam plume is present at the emissions
source, this fact should be recorded. Figures AM1-I and AM1-II are
examples of logbook forms that may be used to record this type of data.
Magnetic tape or paper tape may also be used to record data.

[[Page 311]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.155

[[Page 312]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.156

[[Page 313]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.157

2.6 Opacity Calculation and Data Analysis. Referring to the
reference signal and plume signal in Figure AM1-III, the measured
opacity (Op) in percent for each lidar measurement is
calculated using Equation AM1-2. (Op=1-Tp;
Tp is the plume transmittance.)

[[Page 314]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.158

Where:

In=near-region pick interval signal amplitude, plume signal,
1/R\2\ corrected,
If=far-region pick interval signal amplitude, plume signal,
1/R\2\ corrected,
Rn=near-region pick interval signal amplitude, reference
signal, 1/R\2\ corrected, and
Rf=far-region pick interval signal amplitude, reference
signal, 1/R\2\ corrected.

The 1/R\2\ correction to the plume and reference signal amplitudes
is made by multiplying the amplitude for each successive sample interval
from the time reference, by the square of the lidar time (or range)
associated with that sample interval [Reference 5.1].
The first step in selecting the pick intervals for Equation AM1-2 is
to divide the plume signal amplitude by the reference signal amplitude
at the same respective ranges to obtain a ``normalized'' signal. The
pick intervals selected using this normalized signal, are a minimum of
15 m (100 nanoseconds) in length and consist of at least 5 contiguous
sample intervals. In addition, the following criteria, listed in order
of importance, govern pick interval selection. (1) The intervals shall
be in a region of the normalized signal where the reference signal meets
the requirements of Section 2.3 and is everywhere greater than zero. (2)
The intervals (near and far) with the minimum average amplitude are
chosen. (3) If more than one interval with the same minimum average
amplitude is found, the interval closest to the plume is chosen. (4) The
standard deviation, So, for the calculated opacity shall be
8% or less. (So is calculated by Equation AM1-7).
If So is greater than 8%, then the far pick interval
shall be changed to the next interval of minimal average amplitude. If
So is still greater than 8%, then this procedure is repeated
for the far pick interval. This procedure may be repeated once again for
the near pick interval, but if So remains greater than 8%,
the plume signal shall be discarded.
The reference signal pick intervals, Rn and
Rf, must be chosen over the same time interval as the plume
signal pick intervals, In and If, respectively
[Figure AM1-III]. Other methods of selecting pick intervals may be used
if they give equivalent results. Field-oriented examples of pick
interval selection are available in Reference 5.1.
The average amplitudes for each of the pick intervals,
In, If, Rn, Rf, shall be
calculated by averaging the respective individual amplitudes of the
sample intervals from the plume signal and the associated reference
signal each corrected for 1/R\2\. The amplitude of In shall
be calculated according to Equation (AM-3).
[GRAPHIC] [TIFF OMITTED] TC01JN92.159

Where:

Ini=the amplitude of the ith sample interval (near-region),
[Sigma]=sum of the individual amplitudes for the sample
intervals,
m=number of sample intervals in the pick interval, and
In=average amplitude of the near-region pick interval.

Similarly, the amplitudes for If, Rn, and
Rf are calculated with the three expressions in Equation
(AM1-4).
[GRAPHIC] [TIFF OMITTED] TC01JN92.160

The standard deviation, SIn, of the set of amplitudes for
the near-region pick interval, In, shall be calculated using
Equation (AM1-5).
Similarly, the standard deviations SIf, SRn,
and SRf are calculated with the three expressions in Equation
(AM1-6).

[[Page 315]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.161

[GRAPHIC] [TIFF OMITTED] TC01JN92.162

The standard deviation, So, for each associated opacity
value, Op, shall be calculated using Equation (AM1-7).
[GRAPHIC] [TIFF OMITTED] TC01JN92.163

The calculated values of In, If,
Rn, Rf, SIn, SIf,
SRn, SRf, Op, and So should
be recorded. Any plume signal with an So greater than 8%
shall be discarded.
2.6.1 Azimuth Angle Correction. If the azimuth angle correction to
opacity specified in this section is performed, then the elevation angle
correction specified in Section 2.6.2 shall not be performed. When
opacity is measured in the residual region of an attached steam plume,
and the lidar line-of-sight is not perpendicular to the plume, it may be
necessary to correct the opacity measured by the lidar to obtain the
opacity that would be measured on a path perpendicular to the plume. The
following method, or any other method which produces equivalent results,
shall be used to determine the need for a correction, to calculate the
correction, and to document the point within the plume at which the
opacity was measured.
Figure AM1-IV(b) shows the geometry of the opacity correction. L' is
the path through the plume along which the opacity measurement is made.
P' is the path perpendicular to the plume at the same point. The angle
[egr] is the angle between L' and the plume center line. The angle
([pi]/2-[egr]), is the angle between the L' and P'. The measured
opacity, Op, measured along the path L' shall be corrected to
obtain the corrected opacity, Opc, for the path P', using
Equation (AM1-8).
[GRAPHIC] [TIFF OMITTED] TC01JN92.164

[[Page 316]]

The correction in Equation (AM1-8) shall be performed if the inequality
in Equation (AM1-9) is true.
[GRAPHIC] [TIFF OMITTED] TC01JN92.165

Figure AM1-IV(a) shows the geometry used to calculate [egr] and the
position in the plume at which the lidar measurement is made. This
analysis assumes that for a given lidar measurement, the range from the
lidar to the plume, the elevation angle of the lidar from the horizontal
plane, and the azimuth angle of the lidar from an arbitrary fixed
reference in the horizontal plane can all be obtained directly.

[[Page 317]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.166

Rs=range from lidar to source*
[beta]s=elevation angle of Rs*
Rp=range from lidar to plume at the opacity measurement
point*
[beta]p=elevation angle of Rp*
Ra=range from lidar to plume at some arbitrary point,
Pa, so the drift angle of the plume can be determined*

[[Page 318]]

[beta]a=elevation angle of Ra*
[alpha]=angle between Rp and Ra
R's=projection of Rs in the horizontal plane
R'p=projection of Rp in the horizontal plane
R'a=projection of Ra in the horizontal plane
[psi]'=angle between R's and R'p*
[alpha]'=angle between R'p and R'a*
R<==distance from the source to the opacity measurement point projected
in the horizontal plane
R[thetas]=distance from opacity measurement point
Pp to the point in the plume Pa.
[GRAPHIC] [TIFF OMITTED] TC01JN92.167

The correction angle [egr] shall be determined using Equation AM1-
10.
---------------------------------------------------------------------------

*Obtained directly from lidar. These values should be recorded.

Where:

[alpha]=Cos^-1 (Cos[beta]p Cos[beta]a
Cos[alpha]'+Sin[beta]p Sin[beta]a),
and
R[thetas]=(Rp2+Ra2-2 Rp
Ra Cos[alpha])^1/2

R<=, the distance from the source to the opacity measurement point
projected in the horizontal plane, shall be determined using Equation
AM1-11.
[GRAPHIC] [TIFF OMITTED] TC01JN92.168

Where:

R's=Rs Cos [beta]s, and
R'p=Rp Cos [beta]p.

In the special case where the plume centerline at the opacity
measurement point is horizontal, parallel to the ground, Equation AM1-12
may be used to determine [egr] instead of Equation AM1-10.
[GRAPHIC] [TIFF OMITTED] TC01JN92.169

Where:

R''s=(R'\2\s+Rp\2\Sin\2\[beta]p
)^1/2.

If the angle [egr] is such that [egr]<= 30[deg] or [egr] =
150[deg], the azimuth angle correction shall not be performed and the
associated opacity value shall be discarded.
2.6.2 Elevation Angle Correction. An individual lidar-measured
opacity, Op, shall be corrected for elevation angle if the
laser elevation or inclination angle, [beta]p [Figure AM1-V],
is greater than or equal to the value calculated in Equation AM1-13.
[GRAPHIC] [TIFF OMITTED] TC01JN92.170

The measured opacity, Op, along the lidar path L, is adjusted
to obtain the corrected opacity, Opc, for the actual plume
(horizontal) path, P, by using Equation (AM1-14).

[[Page 319]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.171

Where:

[beta]p=lidar elevation or inclination angle,
Op=measured opacity along path L, and
Opc=corrected opacity for the actual plume thickness P.
The values for [beta]p, Op and Opc
should be recorded.

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[GRAPHIC] [TIFF OMITTED] TC01JN92.172

2.6.3 Determination of Actual Plume Opacity. Actual opacity of the
plume shall be determined by Equation AM1-15.
[GRAPHIC] [TIFF OMITTED] TC01JN92.173

2.6.4 Calculation of Average Actual Plume Opacity. The average of
the actual plume opacity, Opa, shall be calculated as the
average of the consecutive individual actual opacity values,
Opa, by Equation AM1-16.

[[Page 321]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.174

Where:

(Opa)k=the kth actual opacity value in an
averaging interval containing n opacity values; k is a summing index.
[Sigma]=the sum of the individual actual opacity values.
n=the number of individual actual opacity values contained in the
averaging interval.
Opa=average actual opacity calculated over the averaging
interval.

3. Lidar Performance Verification

The lidar shall be subjected to two types of performance
verifications that shall be performed in the field. The annual
calibration, conducted at least once a year, shall be used to directly
verify operation and performance of the entire lidar system. The routine
verification, conducted for each emission source measured, shall be used
to insure proper performance of the optical receiver and associated
electronics.
3.1 Annual Calibration Procedures. Either a plume from a smoke
generator or screen targets shall be used to conduct this calibration.
If the screen target method is selected, five screens shall be
fabricated by placing an opaque mesh material over a narrow frame (wood,
metal extrusion, etc.). The screen shall have a surface area of at least
one square meter. The screen material should be chosen for precise
optical opacities of about 10, 20, 40, 60, and 80%. Opacity of each
target shall be optically determined and should be recorded. If a smoke
generator plume is selected, it shall meet the requirements of Section
3.3 of Reference Method 9. This calibration shall be performed in the
field during calm (as practical) atmospheric conditions. The lidar shall
be positioned in accordance with Section 2.1.
The screen targets must be placed perpendicular to and coincident
with the lidar line-of-sight at sufficient height above the ground
(suggest about 30 ft) to avoid ground-level dust contamination.
Reference signals shall be obtained just prior to conducting the
calibration test.
The lidar shall be aimed through the center of the plume within 1
stack diameter of the exit, or through the geometric center of the
screen target selected. The lidar shall be set in operation for a 6-
minute data run at a nominal pulse rate of 1 pulse every 10 seconds.
Each backscatter return signal and each respective opacity value
obtained from the smoke generator transmissometer, shall be obtained in
temporal coincidence. The data shall be analyzed and reduced in
accordance with Section 2.6 of this method. This calibration shall be
performed for 0% (clean air), and at least five other opacities
(nominally 10, 20, 40, 60, and 80%).
The average of the lidar opacity values obtained during a 6-minute
calibration run shall be calculated and should be recorded. Also the
average of the opacity values obtained from the smoke generator
transmissometer for the same 6-minute run shall be calculated and should
be recorded.
Alternate calibration procedures that do not meet the above
requirements but produce equivalent results may be used.
3.2 Routine Verification Procedures. Either one of two techniques
shall be used to conduct this verification. It shall be performed at
least once every 4 hours for each emission source measured. The
following parameters shall be directly verified.
1) The opacity value of 0% plus a minimum of 5 (nominally 10, 20,
40, 60, and 80%) opacity values shall be verified through the PMT
detector and data processing electronics.
2) The zero-signal level (receiver signal with no optical signal
from the source present) shall be inspected to insure that no spurious
noise is present in the signal. With the entire lidar receiver and
analog/digital electronics turned on and adjusted for normal operating
performance, the following procedures shall be used for Techniques 1 and
2, respectively.
3.2.1 Procedure for Technique 1. This test shall be performed with
no ambient or stray light reaching the PMT detector. The narrow band
filter (694.3 nanometers peak) shall be removed from its position in
front of the PMT detector. Neutral density filters of nominal opacities
of 10, 20, 40, 60, and 80% shall be used. The recommended test
configuration is depicted in Figure AM1-VI.

[[Page 322]]

[GRAPHIC] [TIFF OMITTED] TC01JN92.175

The zero-signal level shall be measured and should be recorded, as
indicated in Figure AM1-VI(a). This simulated clear-air or 0% opacity
value shall be tested in using the selected light source depicted in
Figure AM1-VI(b).
The light source either shall be a continuous wave (CW) laser with
the beam mechanically chopped or a light emitting diode controlled with
a pulse generator (rectangular pulse). (A laser beam may have to be
attenuated so as not to saturate the PMT detector). This signal level
shall be measured

[[Page 323]]

and should be recorded. The opacity value is calculated by taking two
pick intervals [Section 2.6] about 1 microsecond apart in time and using
Equation (AM1-2) setting the ratio Rn/Rf=1. This
calculated value should be recorded.
The simulated clear-air signal level is also employed in the optical
test using the neutral density filters. Using the test configuration in
Figure AM1-VI(c), each neutral density filter shall be separately placed
into the light path from the light source to the PMT detector. The
signal level shall be measured and should be recorded. The opacity value
for each filter is calculated by taking the signal level for that
respective filter (If), dividing it by the 0% opacity signal
level (In) and performing the remainder of the calculation by
Equation (AM1-2) with Rn/Rf=1. The calculated
opacity value for each filter should be recorded.
The neutral density filters used for Technique 1 shall be calibrated
for actual opacity with accuracy of 2% or better.
This calibration shall be done monthly while the filters are in use and
the calibrated values should be recorded.
3.2.2 Procedure for Technique 2. An optical generator (built-in
calibration mechanism) that contains a light-emitting diode (red light
for a lidar containing a ruby laser) is used. By injecting an optical
signal into the lidar receiver immediately ahead of the PMT detector, a
backscatter signal is simulated. With the entire lidar receiver
electronics turned on and adjusted for normal operating performance, the
optical generator is turned on and the simulation signal (corrected for
1/R\2\) is selected with no plume spike signal and with the opacity
value equal to 0%. This simulated clear-air atmospheric return signal is
displayed on the system's video display. The lidar operator then makes
any fine adjustments that may be necessary to maintain the system's
normal operating range.
The opacity values of 0% and the other five values are selected one
at a time in any order. The simulated return signal data should be
recorded. The opacity value shall be calculated. This measurement/
calculation shall be performed at least three times for each selected
opacity value. While the order is not important, each of the opacity
values from the optical generator shall be verified. The calibrated
optical generator opacity value for each selection should be recorded.
The optical generator used for Technique 2 shall be calibrated for
actual opacity with an accuracy of 1% or better.
This calibration shall be done monthly while the generator is in use and
calibrated value should be recorded.
Alternate verification procedures that do not meet the above
requirements but produce equivalent results may be used.
3.3 Deviation. The permissible error for the annual calibration and
routine verification are:
3.3.1 Annual Calibration Deviation.
3.3.1.1 Smoke Generator. If the lidar-measured average opacity for
each data run is not within 5% (full scale) of the
respective smoke generator's average opacity over the range of 0%
through 80%, then the lidar shall be considered out of calibration.
3.3.1.2 Screens. If the lidar-measured average opacity for each data
run is not within 3% (full scale) of the
laboratory-determined opacity for each respective simulation screen
target over the range of 0% through 80%, then the lidar shall be
considered out of calibration.
3.3.2 Routine Verification Error. If the lidar-measured average
opacity for each neutral density filter (Technique 1) or optical
generator selection (Technique 2) is not within 3%
(full scale) of the respective laboratory calibration value then the
lidar shall be considered non-operational.

4. Performance/Design Specification for Basic Lidar System

4.1 Lidar Design Specification. The essential components of the
basic lidar system are a pulsed laser (transmitter), optical receiver,
detector, signal processor, recorder, and an aiming device that is used
in aiming the lidar transmitter and receiver. Figure AM1-VII shows a
functional block diagram of a basic lidar system.

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[GRAPHIC] [TIFF OMITTED] TC01JN92.176

4.2 Performance Evaluation Tests. The owner of a lidar system shall
subject such a lidar system to the performance verification tests
described in Section 3, prior to first use of this method. The annual
calibration shall be performed for three separate, complete

[[Page 325]]

runs and the results of each should be recorded. The requirements of
Section 3.3.1 must be fulfilled for each of the three runs.
Once the conditions of the annual calibration are fulfilled the
lidar shall be subjected to the routine verification for three separate
complete runs. The requirements of Section 3.3.2 must be fulfilled for
each of the three runs and the results should be recorded. The
Administrator may request that the results of the performance evaluation
be submitted for review.

5. References

5.1 The Use of Lidar for Emissions Source Opacity Determination,
U.S. Environmental Protection Agency, National Enforcement
Investigations Center, Denver, CO. EPA-330/1-79-003-R, Arthur W.
Dybdahl, current edition [NTIS No. PB81-246662].
5.2 Field Evaluation of Mobile Lidar for the Measurement of Smoke
Plume Opacity, U.S. Environmental Protection Agency, National
Enforcement Investigations Center, Denver, CO. EPA/NEIC-TS-128, February
1976.
5.3 Remote Measurement of Smoke Plume Transmittance Using Lidar, C.
S. Cook, G. W. Bethke, W. D. Conner (EPA/RTP). Applied Optics 11, pg
1742. August 1972.
5.4 Lidar Studies of Stack Plumes in Rural and Urban Environments,
EPA-650/4-73-002, October 1973.
5.5 American National Standard for the Safe Use of Lasers ANSI Z
136.1-176, March 8, 1976.
5.6 U.S. Army Technical Manual TB MED 279, Control of Hazards to
Health from Laser Radiation, February 1969.
5.7 Laser Institute of America Laser Safety Manual, 4th Edition.
5.8 U.S. Department of Health, Education and Welfare, Regulations
for the Administration and Enforcement of the Radiation Control for
Health and Safety Act of 1968, January 1976.
5.9 Laser Safety Handbook, Alex Mallow, Leon Chabot, Van Nostrand
Reinhold Co., 1978.

Method 10--Determination of Carbon Monoxide Emissions From Stationary
Sources

1. Principle and Applicability

1.1 Principle. An integrated or continuous gas sample is extracted
from a sampling point and analyzed for carbon monoxide (CO) content
using a Luft-type nondispersive infrared analyzer (NDIR) or equivalent.
1.2 Applicability. This method is applicable for the determination
of carbon monoxide emissions from stationary sources only when specified
by the test procedures for determining compliance with new source
performance standards. The test procedure will indicate whether a
continuous or an integrated sample is to be used.

2. Range and Sensitivity

2.1 Range. 0 to 1,000 ppm.
2.2 Sensitivity. Minimum detectable concentration is 20 ppm for a 0
to 1,000 ppm span.

3. Interferences

Any substance having a strong absorption of infrared energy will
interfere to some extent. For example, discrimination ratios for water
(H2O) and carbon dioxide (CO2) are 3.5 percent
H2O per 7 ppm CO and 10 percent CO2 per 10 ppm CO,
respectively, for devices measuring in the 1,500 to 3,000 ppm range. For
devices measuring in the 0 to 100 ppm range, interference ratios can be
as high as 3.5 percent H2O per 25 ppm CO and 10 percent
CO2 per 50 ppm CO. The use of silica gel and ascarite traps
will alleviate the major interference problems. The measured gas volume
must be corrected if these traps are used.

4. Precision and Accuracy

4.1 Precision. The precision of most NDIR analyzers is approximately
2 percent of span.
4.2 Accuracy. The accuracy of most NDIR analyzers is approximately
5 percent of span after calibration.

5. Apparatus

5.1 Continuous Sample (Figure 10-1).
5.1.1 Probe. Stainless steel or sheathed Pyrex\1\ glass, equipped
with a filter to remove particulate matter.
---------------------------------------------------------------------------

\1\ Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
---------------------------------------------------------------------------

5.1.2 Air-Cooled Condenser or Equivalent. To remove any excess
moisture.
5.2 Integrated Sample (Figure 10-2).
5.2.1 Probe. Stainless steel or sheathed Pyrex glass, equipped with
a filter to remove particulate matter.
5.2.2 Air-Cooled Condenser or Equivalent. To remove any excess
moisture.
5.2.3 Valve. Needle valve, or equivalent, to adjust flow rate.
5.2.4 Pump. Leak-free diaphragm type, or equivalent, to transport
gas.
5.2.5 Rate Meter. Rotameter, or equivalent, to measure a flow range
from 0 to 1.0 liter per min (0.035 cfm).
5.2.6 Flexible Bag. Tedlar, or equivalent, with a capacity of 60 to
90 liters (2 to 3 ft \3\). Leak-test the bag in the laboratory before
using by evacuating bag with a pump followed by a dry gas meter. When
evacuation is complete, there should be no flow through the meter.
5.2.7 Pitot Tube. Type S, or equivalent, attached to the probe so
that the sampling

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rate can be regulated proportional to the stack gas velocity when
velocity is varying with the time or a sample traverse is conducted.
5.3 Analysis (Figure 10-3).
5.3.1 Carbon Monoxide Analyzer. Non dis persive infrared
spectrometer, or equivalent. This instrument should be demonstrated,
preferably by the manufacturer, to meet or exceed manufacturer's
specifications and those described in this method.
5.3.2 Drying Tube. To contain approximately 200 g of silica gel.
5.3.3 Calibration Gas. Refer to section 6.1.
5.3.4 Filter. As recommended by NDIR manufacturer.
[GRAPHIC] [TIFF OMITTED] TC01JN92.177

[GRAPHIC] [TIFF OMITTED] TC01JN92.178

5.3.5 CO2 Removal Tube. To contain approximately 500 g of
ascarite.
5.3.6 Ice Water Bath. For ascarite and silica gel tubes.
5.3.7 Valve. Needle valve, or equivalent, to adjust flow rate
5.3.8 Rate Meter. Rotameter or equivalent to measure gas flow rate
of 0 to 1.0 liter per min (0.035 cfm) through NDIR.
5.3.9 Recorder (optional). To provide permanent record of NDIR
readings.

6. Reagents

6.1 Calibration Gases. Known concentration of CO in nitrogen
(N2) for instrument span, prepurified grade of N2
for zero, and two additional concentrations corresponding approximately
to 60 percent and 30 percent span. The span concentration shall not
exceed 1.5 times the applicable source performance standard. The
calibration gases shall be certified by the manufacturer to be within
2 percent of the specified concentration.
[GRAPHIC] [TIFF OMITTED] TC01JN92.179

6.2 Silica Gel. Indicating type, 6 to 16 mesh, dried at 175 [deg]C
(347 [deg]F) for 2 hours.
6.3 Ascarite. Commercially available.

7. Procedure

7.1 Sampling.
7.1.1 Continuous Sampling. Set up the equipment as shown in Figure
10-1 making sure all connections are leak free. Place the probe in the
stack at a sampling point and purge the sampling line. Connect the
analyzer and begin drawing sample into the analyzer. Allow 5 minutes for
the system to stabilize, then record the analyzer reading as required by
the test procedure. (See section 7.2 and 8). CO2 content of
the gas may be determined by using the Method 3 integrated sample
procedure, or by weighing the ascarite CO2 removal tube and
computing CO2 concentration from the gas volume sampled and
the weight gain of the tube.
7.1.2 Integrated Sampling. Evacuate the flexible bag. Set up the
equipment as shown in Figure 10-2 with the bag disconnected. Place the
probe in the stack and purge the sampling line. Connect the bag, making
sure that all connections are leak free. Sample at a rate proportional
to the stack velocity. CO2 content of the gas may be
determined by using the Method 3 integrated sample procedures, or by
weighing the ascarite CO2 removal tube and computing
CO2 concentration from the gas volume sampled and the weight
gain of the tube.
7.2 CO Analysis. Assemble the apparatus as shown in Figure 10-3,
calibrate the instrument, and perform other required operations as
described in section 8. Purge analyzer with N2 prior to
introduction of each sample. Direct the sample stream through the
instrument for the test period, recording the readings. Check the zero
and span again after the test to assure that any drift or malfunction is
detected. Record the sample data on Table 10-1.

8. Calibration

Assemble the apparatus according to Figure 10-3. Generally an
instrument requires a warm-up period before stability is obtained.
Follow the manufacturer's instructions for specific procedure. Allow a
minimum time of 1 hour for warm-up. During this time check

[[Page 327]]

the sample conditioning apparatus, i.e., filter, condenser, drying tube,
and CO2 removal tube, to ensure that each component is in
good operating condition. Zero and calibrate the instrument according to
the manufacturer's procedures using, respectively, nitrogen and the
calibration gases.

Table 10-1--Field data
------------------------------------------------------------------------
Comments
------------------------------------------------------------------------
Location.................................. ............................
Test...................................... ............................
Date...................................... ............................
Operator.................................. ............................
------------------------------------------------------------------------

Rotameter setting, liters per
Clock time minute (cubic feet per minute)
------------------------------------------------------------------------

------------------------------------------------------------------------

9. Calculation

Calculate the concentration of carbon monoxide in the stack using
Equation 10-1.
CCO stack=CCO NDIR(1-Fco2)
Eq. 10-1

Where:

CCO stack=Concentration of CO in stack, ppm by volume (dry
basis).
CCO NDIR=Concentration of CO measured by NDIR analyzer, ppm
by volume (dry basis).
FCO 2=Volume fraction of CO2 in sample, i.e.,
percent CO2 from Orsat analysis divided by 100.

10. Alternative Procedures

10.1 Interference Trap. The sample conditioning system described in
Method 10A, sections 2.1.2 and 4.2, may be used as an alternative to the
silica gel and ascarite traps.

11. Bibliography

1. McElroy, Frank, The Intertech NDIR-CO Analyzer, Presented at 11th
Methods Conference on Air Pollution, University of California, Berkeley,
CA. April 1, 1970.
2. Jacobs, M. B., et al., Continuous Determination of Carbon Monoxide
and Hydrocarbons in Air by a Modified Infrared Analyzer, J. Air
Pollution Control Association, 9(2): 110-114. August 1959.
3. MSA LIRA Infrared Gas and Liquid Analyzer Instruction Book, Mine
Safety Appliances Co., Technical Products Division, Pittsburgh, PA.
4. Models 215A, 315A, and 415A Infrared Analyzers, Beckman Instruments,
Inc., Beckman Instructions 1635-B, Fullerton, CA. October 1967.
5. Continuous CO Monitoring System, Model A5611, Intertech Corp.,
Princeton, NJ.
6. UNOR Infrared Gas Analyzers, Bendix Corp., Ronceverte, WV

Addenda

A. Performance Specifications for NDIR Carbon Monoxide Analyzers
Range (minimum)........................... 0-1000 ppm.
Output (minimum).......................... 0-10mV.
Minimum detectable sensitivity............ 20 ppm.
Rise time, 90 percent (maximum)........... 30 seconds.
Fall time, 90 percent (maximum)........... 30 seconds.
Zero drift (maximum)...................... 10% in 8 hours.
Span drift (maximum)...................... 10% in 8 hours.
Precision (minimum)....................... 2% of
full scale.
Noise (maximum)........................... 1% of
full scale.
Linearity (maximum deviation)............. 2% of full scale.
Interference rejection ratio.............. CO2--1000 to 1, H2O--500 to
1.
------------------------------------------------------------------------

B. Definitions of Performance Specifications.
Range-- The minimum and maximum measurement limits.
Output-- Electrical signal which is proportional to the measurement;
intended for connection to readout or data processing devices. Usually
expressed as millivolts or milliamps full scale at a given impedance.
Full scale-- The maximum measuring limit for a given range.
Minimum detectable sensitivity-- The smallest amount of input
concentration that can be detected as the concentration approaches zero.
Accuracy-- The degree of agreement between a measured value and the
true value; usually expressed as percent of full
scale.
Time to 90 percent response-- The time interval from a step change
in the input concentration at the instrument inlet to a reading of 90
percent of the ultimate recorded concentration.
Rise Time (90 percent)--The interval between initial response time
and time to 90 percent response after a step increase in the inlet
concentration.
Fall Time (90 percent)--The interval between initial response time
and time to 90 percent response after a step decrease in the inlet
concentration.
Zero Drift-- The change in instrument output over a stated time
period, usually 24 hours, of unadjusted continuous operation when the
input concentration is zero; usually expressed as percent full scale.
Span Drift-- The change in instrument output over a stated time
period, usually 24 hours, of unadjusted continuous operation when the
input concentration is a stated upscale value; usually expressed as
percent full scale.
Precision-- The degree of agreement between repeated measurements of
the same concentration, expressed as the average deviation of the single
results from the mean.
Noise--Spontaneous deviations from a mean output not caused by input
concentration changes.

[[Page 328]]

Linearity--The maximum deviation between an actual instrument
reading and the reading predicted by a straight line drawn between upper
and lower calibration points.

Method 10A--Determination of Carbon Monoxide Emissions in Certifying
Continuous Emission Monitoring Systems at Petroleum Refineries

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Carbon monoxide (CO).............. 630-08-0 3 ppmv
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of CO emissions at petroleum refineries. This method serves as the
reference method in the relative accuracy test for nondispersive
infrared (NDIR) CO continuous emission monitoring systems (CEMS) that
are required to be installed in petroleum refineries on fluid catalytic
cracking unit catalyst regenerators (Sec. 60.105(a)(2) of this part).
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

An integrated gas sample is extracted from the stack, passed through
an alkaline permanganate solution to remove sulfur oxides and nitrogen
oxides, and collected in a Tedlar bag. The CO concentration in the
sample is measured spectrophotometrically using the reaction of CO with
p-sulfaminobenzoic acid.

3.0 Definitions [Reserved]

4.0 Interferences

Sulfur oxides, nitric oxide, and other acid gases interfere with the
colorimetric reaction. They are removed by passing the sampled gas
through an alkaline potassium permanganate scrubbing solution. Carbon
dioxide (CO2) does not interfere, but, because it is removed
by the scrubbing solution, its concentration must be measured
independently and an appropriate volume correction made to the sampled
gas.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. The sampling train shown in Figure 10A-1 is
required for sample collection. Component parts are described below:
6.1.1 Probe. Stainless steel, sheathed Pyrex glass, or equivalent,
equipped with a glass wool plug to remove particulate matter.
6.1.2 Sample Conditioning System. Three Greenburg-Smith impingers
connected in series with leak-free connections.
6.1.3 Pump. Leak-free pump with stainless steel and Teflon parts to
transport sample at a flow rate of 300 ml/min (0.01 ft\3\/min) to the
flexible bag.
6.1.4 Surge Tank. Installed between the pump and the rate meter to
eliminate the pulsation effect of the pump on the rate meter.
6.1.5 Rate Meter. Rotameter, or equivalent, to measure flow rate at
300 ml/min (0.01 ft\3\/min). Calibrate according to Section 10.2.
6.1.6 Flexible Bag. Tedlar, or equivalent, with a capacity of 10
liters (0.35 ft\3\) and equipped with a sealing quick-connect plug. The
bag must be leak-free according to Section 8.1. For protection, it is
recommended that the bag be enclosed within a rigid container.

[[Page 329]]

6.1.7 Valves. Stainless-steel needle valve to adjust flow rate, and
stainless-steel three-way valve, or equivalent.
6.1.8 CO2 Analyzer. Fyrite, or equivalent, to measure
CO2 concentration to within O.5 percent.
6.1.9 Volume Meter. Dry gas meter, capable of measuring the sample
volume under calibration conditions of 300 ml/min (0.01 ft\3\/min) for
10 minutes.
6.1.10 Pressure Gauge. A water filled U-tube manometer, or
equivalent, of about 30 cm (12 in.) to leak-check the flexible bag.
6.2 Sample Analysis.
6.2.1 Spectrophotometer. Single- or double-beam to measure
absorbance at 425 and 600 nm. Slit width should not exceed 20 nm.
6.2.2 Spectrophotometer Cells. 1-cm pathlength.
6.2.3 Vacuum Gauge. U-tube mercury manometer, 1 meter (39 in.), with
1-mm divisions, or other gauge capable of measuring pressure to within 1
mm Hg.
6.2.4 Pump. Capable of evacuating the gas reaction bulb to a
pressure equal to or less than 40 mm Hg absolute, equipped with coarse
and fine flow control valves.
6.2.5 Barometer. Mercury, aneroid, or other barometer capable of
measuring atmospheric pressure to within 1 mm Hg.
6.2.6 Reaction Bulbs. Pyrex glass, 100-ml with Teflon stopcock
(Figure 10A-2), leak-free at 40 mm Hg, designed so that 10 ml of the
colorimetric reagent can be added and removed easily and accurately.
Commercially available gas sample bulbs such as Supelco Catalog No. 2-
2161 may also be used.
6.2.7 Manifold. Stainless steel, with connections for three reaction
bulbs and the appropriate connections for the manometer and sampling bag
as shown in Figure 10A-3.
6.2.8 Pipets. Class A, 10-ml size.
6.2.9 Shaker Table. Reciprocating-stroke type such as Eberbach
Corporation, Model 6015. A rocking arm or rotary-motion type shaker may
also be used. The shaker must be large enough to accommodate at least
six gas sample bulbs simultaneously. It may be necessary to construct a
table top extension for most commercial shakers to provide sufficient
space for the needed bulbs (Figure 10A-4).
6.2.10 Valve. Stainless steel shut-off valve.
6.2.11 Analytical Balance. Capable of weighing to 0.1 mg.

7.0 Reagents and Standards

Unless otherwise indicated, all reagents shall conform to the
specifications established by the Committee on Analytical Reagents of
the American Chemical Society, where such specifications are available;
otherwise, the best available grade shall be used.
7.1 Sample Collection.
7.1.1 Water. Deionized distilled, to conform to ASTM D 1193-77 or
91, Type 3 (incorporated by reference--see Sec. 60.17). If high
concentrations of organic matter are not expected to be present, the
potassium permanganate test for oxidizable organic matter may be
omitted.
7.1.2 Alkaline Permanganate Solution, 0.25 M KMnO4/1.5 M
Sodium Hydroxide (NaOH). Dissolve 40 g KMnO4 and 60 g NaOH in
approximately 900 ml water, cool, and dilute to 1 liter.
7.2 Sample Analysis.
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 1 M Sodium Hydroxide Solution. Dissolve 40 g NaOH in
approximately 900 ml of water, cool, and dilute to 1 liter.
7.2.3 0.1 M NaOH Solution. Dilute 50 ml of the 1 M NaOH solution
prepared in Section 7.2.2 to 500 ml.
7.2.4 0.1 M Silver Nitrate (AgNO3) Solution. Dissolve 8.5
g AgNO3 in water, and dilute to 500 ml.
7.2.5 0.1 M Para-Sulfaminobenzoic Acid (p-SABA) Solution. Dissolve
10.0 g p-SABA in 0.1 M NaOH, and dilute to 500 ml with 0.1 M NaOH.
7.2.6 Colorimetric Solution. To a flask, add 100 ml of 0.1 M p-SABA
solution and 100 ml of 0.1 M AgNO3 solution. Mix, and add 50
ml of 1 M NaOH with shaking. The resultant solution should be clear and
colorless. This solution is acceptable for use for a period of 2 days.
7.2.7 Standard Gas Mixtures. Traceable to National Institute of
Standards and Technology (NIST) standards and containing between 50 and
1000 ppm CO in nitrogen. At least two concentrations are needed to span
each calibration range used (Section 10.3). The calibration gases must
be certified by the manufacturer to be within 2 percent of the specified
concentrations.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Sample Bag Leak-Checks. While a bag leak-check is required after
bag use, it should also be done before the bag is used for sample
collection. The bag should be leak-checked in the inflated and deflated
condition according to the following procedure:
8.1.1 Connect the bag to a water manometer, and pressurize the bag
to 5 to 10 cm H2O (2 to 4 in H2O). Allow the bag
to stand for 60 minutes. Any displacement in the water manometer
indicates a leak.
8.1.2 Evacuate the bag with a leakless pump that is connected to the
downstream side of a flow indicating device such as a 0- to 100-ml/min
rotameter or an impinger containing water. When the bag is completely
evacuated, no flow should be evident if the bag is leak-free.
8.2 Sample Collection.
8.2.1 Evacuate the Tedlar bag completely using a vacuum pump.
Assemble the apparatus as shown in Figure 10A-1. Loosely pack glass wool
in the tip of the probe. Place 400

[[Page 330]]

ml of alkaline permanganate solution in the first two impingers and 250
ml in the third. Connect the pump to the third impinger, and follow this
with the surge tank, rate meter, and 3-way valve. Do not connect the
Tedlar bag to the system at this time.
8.2.2 Leak-check the sampling system by plugging the probe inlet,
opening the 3-way valve, and pulling a vacuum of approximately 250 mm Hg
on the system while observing the rate meter for flow. If flow is
indicated on the rate meter, do not proceed further until the leak is
found and corrected.
8.2.3 Purge the system with sample gas by inserting the probe into
the stack and drawing the sample gas through the system at 300 ml/min
10 percent for 5 minutes. Connect the evacuated
Tedlar bag to the system, record the starting time, and sample at a rate
of 300 ml/min for 30 minutes, or until the Tedlar bag is nearly full.
Record the sampling time, the barometric pressure, and the ambient
temperature. Purge the system as described above immediately before each
sample.
8.2.4 The scrubbing solution is adequate for removing sulfur oxides
and nitrogen oxides from 50 liters (1.8 ft\3\) of stack gas when the
concentration of each is less than 1,000 ppm and the CO2
concentration is less than 15 percent. Replace the scrubber solution
after every fifth sample.
8.3 Carbon Dioxide Measurement. Measure the CO2 content
in the stack to the nearest 0.5 percent each time a CO sample is
collected. A simultaneous grab sample analyzed by the Fyrite analyzer is
acceptable.

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardization

Note: Maintain a laboratory log of all calibrations.

10.1 Gas Bulb Calibration. Weigh the empty bulb to the nearest 0.1
g. Fill the bulb to the stopcock with water, and again weigh to the
nearest 0.1 g. Subtract the tare weight, and calculate the volume in
liters to three significant figures using the density of water at the
measurement temperature. Record the volume on the bulb. Alternatively,
mark an identification number on the bulb, and record the volume in a
notebook.
10.2 Rate Meter Calibration. Assemble the system as shown in Figure
10A-1 (the impingers may be removed), and attach a volume meter to the
probe inlet. Set the rotameter at 300 ml/min, record the volume meter
reading, start the pump, and pull ambient air through the system for 10
minutes. Record the final volume meter reading. Repeat the procedure and
average the results to determine the volume of gas that passed through
the system.
10.3 Spectrophotometer Calibration Curve.
10.3.1 Collect the standards as described in Section 8.2. Prepare at
least two sets of three bulbs as standards to span the 0 to 400 or 400
to 1000 ppm range. If any samples span both concentration ranges,
prepare a calibration curve for each range using separate reagent
blanks. Prepare a set of three bulbs containing colorimetric reagent but
no CO to serve as a reagent blank. Analyze each standard and blank
according to the sample analysis procedure of Section 11.0 Reject the
standard set where any of the individual bulb absorbances differs from
the set mean by more than 10 percent.
10.3.2 Calculate the average absorbance for each set (3 bulbs) of
standards using Equation 10A-1 and Table 10A-1. Construct a graph of
average absorbance for each standard against its corresponding
concentration. Draw a smooth curve through the points. The curve should
be linear over the two concentration ranges discussed in Section 13.3.

11.0 Analytical Procedure

11.1 Assemble the system shown in Figure 10A-3, and record the
information required in Table 10A-1 as it is obtained. Pipet 10.0 ml of
the colorimetric reagent into each gas reaction bulb, and attach the
bulbs to the system. Open the stopcocks to the reaction bulbs, but leave
the valve to the Tedlar bag closed. Turn on the pump, fully open the
coarse-adjust flow valve, and slowly open the fine-adjust valve until
the pressure is reduced to at least 40 mm Hg. Now close the coarse
adjust valve, and observe the manometer to be certain that the system is
leak-free. Wait a minimum of 2 minutes. If the pressure has increased
less than 1 mm Hg, proceed as described below. If a leak is present,
find and correct it before proceeding further.

[[Page 331]]

11.2 Record the vacuum pressure (Pv) to the nearest 1 mm
Hg, and close the reaction bulb stopcocks. Open the Tedlar bag valve,
and allow the system to come to atmospheric pressure. Close the bag
valve, open the pump coarse adjust valve, and evacuate the system again.
Repeat this fill/evacuation procedure at least twice to flush the
manifold completely. Close the pump coarse adjust valve, open the Tedlar
bag valve, and let the system fill to atmospheric pressure. Open the
stopcocks to the reaction bulbs, and let the entire system come to
atmospheric pressure. Close the bulb stopcocks, remove the bulbs, record
the room temperature and barometric pressure (Pbar, to
nearest mm Hg), and place the bulbs on the shaker table with their main
axis either parallel to or perpendicular to the plane of the table top.
Purge the bulb-filling system with ambient air for several minutes
between samples. Shake the samples for exactly 2 hours.
11.3 Immediately after shaking, measure the absorbance (A) of each
bulb sample at 425 nm if the concentration is less than or equal to 400
ppm CO or at 600 nm if the concentration is above 400 ppm.

Note: This may be accomplished with multiple bulb sets by
sequentially collecting sets and adding to the shaker at staggered
intervals, followed by sequentially removing sets from the shaker for
absorbance measurement after the two-hour designated intervals have
elapsed.

11.4 Use a small portion of the sample to rinse a spectrophotometer
cell several times before taking an aliquot for analysis. If one cell is
used to analyze multiple samples, rinse the cell with deionized
distilled water several times between samples. Prepare and analyze
standards and a reagent blank as described in Section 10.3. Use water as
the reference. Reject the analysis if the blank absorbance is greater
than 0.1. All conditions should be the same for analysis of samples and
standards. Measure the absorbances as soon as possible after shaking is
completed.
11.5 Determine the CO concentration of each bag sample using the
calibration curve for the appropriate concentration range as discussed
in Section 10.3.

12.0 Calculations and Data Analysis

Carry out calculations retaining at least one extra decimal figure
beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature.

A=Sample absorbance, uncorrected for the reagent blank.
Ar=Absorbance of the reagent blank.
As=Average sample absorbance per liter, units/liter.
Bw=Moisture content in the bag sample.
C=CO concentration in the stack gas, dry basis, ppm.
Cb=CO concentration of the bag sample, dry basis, ppm.
Cg=CO concentration from the calibration curve, ppm.
F=Volume fraction of CO2 in the stack.
n=Number of reaction bulbs used per bag sample.
Pb=Barometric pressure, mm Hg.
Pv=Residual pressure in the sample bulb after evacuation, mm
Hg.
Pw=Vapor pressure of H2O in the bag (from Table
10A-2), mm Hg.
Vb=Volume of the sample bulb, liters.
Vr=Volume of reagent added to the sample bulb, 0.0100 liter.

12.2 Average Sample Absorbance per Liter. Calculate As
for each gas bulb using Equation 10A-1, and record the value in Table
10A-1. Calculate the average As for each bag sample, and
compare the three values to the average. If any single value differs by
more than 10 percent from the average, reject this value, and calculate
a new average using the two remaining values.
[GRAPHIC] [TIFF OMITTED] TR17OC00.227

Note: A and Ar must be at the same wavelength.

12.3 CO Concentration in the Bag. Calculate Cb using
Equations 10A-2 and 10A-3. If condensate is visible in the Tedlar bag,
calculate Bw using Table 10A-2 and the temperature and
barometric pressure in the analysis room. If condensate is not visible,
calculate Bw using the temperature and barometric pressure at
the sampling site.
[GRAPHIC] [TIFF OMITTED] TR17OC00.228

[GRAPHIC] [TIFF OMITTED] TR17OC00.229

12.4 CO Concentration in the Stack.
[GRAPHIC] [TIFF OMITTED] TR17OC00.230

13.0 Method Performance

13.1 Precision. The estimated intralaboratory standard deviation of
the method is 3 percent of the mean for gas samples analyzed in
duplicate in the concentration range of 39 to 412 ppm. The
interlaboratory precision has not been established.
13.2 Accuracy. The method contains no significant biases when
compared to an NDIR analyzer calibrated with NIST standards.
13.3 Range. Approximately 3 to 1800 ppm CO. Samples having
concentrations below 400 ppm are analyzed at 425 nm, and samples

[[Page 332]]

having concentrations above 400 ppm are analyzed at 600 nm.
13.4 Sensitivity. The detection limit is 3 ppmv based on a change in
concentration equal to three times the standard deviation of the reagent
blank solution.
13.5 Stability. The individual components of the colorimetric
reagent are stable for at least 1 month. The colorimetric reagent must
be used within 2 days after preparation to avoid excessive blank
correction. The samples in the Tedlar bag should be stable for at least
1 week if the bags are leak-free.

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

1. Butler, F.E., J.E. Knoll, and M.R. Midgett. Development and
Evaluation of Methods for Determining Carbon Monoxide Emissions. U.S.
Environmental Protection Agency, Research Triangle Park, N.C. June 1985.
33 pp.
2. Ferguson, B.B., R.E. Lester, and W.J. Mitchell. Field Evaluation
of Carbon Monoxide and Hydrogen Sulfide Continuous Emission Monitors at
an Oil Refinery. U.S. Environmental Protection Agency, Research Triangle
Park, N.C. Publication No. EPA-600/4-82-054. August 1982. 100 pp.
3. Lambert, J.L., and R.E. Weins. Induced Colorimetric Method for
Carbon Monoxide. Analytical Chemistry. 46(7):929-930. June 1974.
4. Levaggi, D.A., and M. Feldstein. The Colorimetric Determination
of Low Concentrations of Carbon Monoxide. Industrial Hygiene Journal.
25:64-66. January-February 1964.
5. Repp, M. Evaluation of Continuous Monitors For Carbon Monoxide in
Stationary Sources. U.S. Environmental Protection Agency. Research
Triangle Park, N.C. Publication No. EPA-600/2-77-063. March 1977. 155
pp.
6. Smith, F., D.E. Wagoner, and R.P. Donovan. Guidelines for
Development of a Quality Assurance Program: Volume VIII--Determination
of CO Emissions from Stationary Sources by NDIR Spectrometry. U.S.
Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA-650/4-74-005-h. February 1975. 96 pp.

17.0 Tables, Diagrams, Flowcharts, and Validation Data

[[Page 333]]

Table 10A-1--Data Recording Sheet for Samples Analyzed in Triplicate
--------------------------------------------------------------------------------------------------------------------------------------------------------
Partial
Room Bulb Reagent pressure Shaking Abs
Sample No./type temp Stack Bulb vol. vol. in of gas in Pb, mm time, versus A-Ar As Avg As
[deg]C %CO2 No. liters bulb, bulb, mm Hg min water
liter Hg
--------------------------------------------------------------------------------------------------------------------------------------------------------
blank
-----------------------------

------------------------------------------------------------------------------------------------------------------
Std. 1
------------------------------------------------------------------------------------------------------------------

-----------------------------

------------------------------------------------------------------------------------------------------------------
Std. 2
------------------------------------------------------------------------------------------------------------------

-----------------------------

------------------------------------------------------------------------------------------------------------------
Sample 1
------------------------------------------------------------------------------------------------------------------

-----------------------------
Sample 2
------------------------------------------------------------------------------------------------------------------

-----------------------------

------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------------------------------------------------
Sample 3
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 334]]

Table 10A-2--Moisture Correction
----------------------------------------------------------------------------------------------------------------
Vapor Vapor
Temperature [deg]C pressure of Temperature pressure of
H2O, mm Hg [deg]C H2, mm Hg
----------------------------------------------------------------------------------------------------------------
4............................................................... 6.1 18 15.5
6............................................................... 7.0 20 17.5
8............................................................... 8.0 22 19.8
10.............................................................. 9.2 24 22.4
12.............................................................. 10.5 26 25.2
14.............................................................. 12.0 28 28.3
16.............................................................. 13.6 30 31.8
----------------------------------------------------------------------------------------------------------------

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[[Page 335]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.232

[[Page 336]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.233

[[Page 337]]

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Method 10B--Determination of Carbon Monoxide Emissions From Stationary
Sources

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Carbon monoxide (CO)............. 630-08-0 Not determined.
------------------------------------------------------------------------

1.2 Applicability. This method applies to the measurement of CO
emissions at petroleum refineries and from other sources when specified
in an applicable subpart of the regulations.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 An integrated gas sample is extracted from the sampling point,
passed through a conditioning system to remove interferences, and
collected in a Tedlar bag. The CO is separated from the sample by gas
chromatography (GC) and catalytically reduced to methane
(CH4) which is determined by flame ionization detection
(FID). The analytical portion of this method is identical to applicable
sections in Method 25 detailing CO measurement.

[[Page 338]]

3.0 Definitions [Reserved]

4.0 Interferences

4.1 Carbon dioxide (CO2) and organics potentially can
interfere with the analysis. Most of the CO2 is removed from
the sample by the alkaline permanganate conditioning system; any
residual CO2 and organics are separated from the CO by GC.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. Same as in Method 10A, Section 6.1.
6.2 Sample Analysis. A GC/FID analyzer, capable of quantifying CO in
the sample and consisting of at least the following major components, is
required for sample analysis. [Alternatively, complete Method 25
analytical systems (Method 25, Section 6.3) are acceptable alternatives
when calibrated for CO and operated in accordance with the Method 25
analytical procedures (Method 25, Section 11.0).]
6.2.1 Separation Column. A column capable of separating CO from
CO2 and organic compounds that may be present. A 3.2-mm (\1/
8\-in.) OD stainless steel column packed with 1.7 m (5.5 ft.) of 60/80
mesh Carbosieve S-II (available from Supelco) has been used successfully
for this purpose.
6.2.2 Reduction Catalyst. Same as in Method 25, Section 6.3.1.2.
6.2.3 Sample Injection System. Same as in Method 25, Section
6.3.1.4, equipped to accept a sample line from the Tedlar bag.
6.2.4 Flame Ionization Detector. Meeting the linearity
specifications of Section 10.3 and having a minimal instrument range of
10 to 1,000 ppm CO.
6.2.5 Data Recording System. Analog strip chart recorder or digital
integration system, compatible with the FID, for permanently recording
the analytical results.

7.0 Reagents and Standards

7.1 Sample Collection. Same as in Method 10A, Section 7.1.
7.2 Sample Analysis.
7.2.1 Carrier, Fuel, and Combustion Gases. Same as in Method 25,
Sections 7.2.1, 7.2.2, and 7.2.3, respectively.
7.2.2 Calibration Gases. Three standard gases with nominal CO
concentrations of 20, 200, and 1,000 ppm CO in nitrogen. The calibration
gases shall be certified by the manufacturer to be 2 percent of the specified concentrations.
7.2.3 Reduction Catalyst Efficiency Check Calibration Gas. Standard
CH4 gas with a nominal concentration of 1,000 ppm in air.

8.0 Sample Collection, Preservation, Storage, and Transport

Same as in Method 10A, Section 8.0.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.0........................... Sample bag/ Ensures that negative
sampling system bias introduced
leak-checks. through leakage is
minimized.
10.1.......................... Carrier gas blank Ensures that positive
check. bias introduced by
contamination of
carrier gas is less
than 5 ppmv.
10.2.......................... Reduction Ensures that negative
catalyst bias introduced by
efficiency check. inefficient
reduction catalyst
is less than 5
percent.
10.3.......................... Analyzer Ensures linearity of
calibration. analyzer response to
standards.
11.2.......................... Triplicate sample Ensures precision of
analyses. analytical results.
------------------------------------------------------------------------

10.0 Calibration and Standardization

10.1 Carrier Gas Blank Check. Analyze each new tank of carrier gas
with the GC analyzer according to Section 11.2 to check for
contamination. The corresponding concentration must be less than 5 ppm
for the tank to be acceptable for use.
10.2 Reduction Catalyst Efficiency Check. Prior to initial use, the
reduction catalyst shall be tested for reduction efficiency. With the
heated reduction catalyst bypassed, make triplicate injections of the
1,000 ppm CH4 gas (Section 7.2.3) to calibrate the analyzer.
Repeat the procedure using 1,000 ppm CO gas (Section 7.2.2) with the
catalyst in operation. The reduction catalyst operation is acceptable if
the CO response is within 5 percent of the certified gas value.
10.3 Analyzer Calibration. Perform this test before the system is
first placed into operation. With the reduction catalyst in operation,
conduct a linearity check of the analyzer using the standards specified
in Section 7.2.2. Make triplicate injections of each calibration gas,
and then calculate the average response factor (area/ppm) for each gas,
as

[[Page 339]]

well as the overall mean of the response factor values. The instrument
linearity is acceptable if the average response factor of each
calibration gas is within 2.5 percent of the overall mean value and if
the relative standard deviation (calculated in Section 12.8 of Method
25) for each set of triplicate injections is less than 2 percent. Record
the overall mean of the response factor values as the calibration
response factor (R).

11.0 Analytical Procedure

11.1 Preparation for Analysis. Before putting the GC analyzer into
routine operation, conduct the calibration procedures listed in Section
10.0. Establish an appropriate carrier flow rate and detector
temperature for the specific instrument used.
11.2 Sample Analysis. Purge the sample loop with sample, and then
inject the sample. Analyze each sample in triplicate, and calculate the
average sample area (A). Determine the bag CO concentration according to
Section 12.2.

12.0 Calculations and Data Analysis

Carry out calculations retaining at least one extra significant
figure beyond that of the acquired data. Round off results only after
the final calculation.
12.1 Nomenclature.
A=Average sample area.
Bw=Moisture content in the bag sample, fraction.
C=CO concentration in the stack gas, dry basis, ppm.
Cb=CO concentration in the bag sample, dry basis, ppm.
F=Volume fraction of CO2 in the stack, fraction.
Pbar=Barometric pressure, mm Hg.
Pw=Vapor pressure of the H2O in the bag (from
Table 10A-2, Method 10A), mm Hg.
R=Mean calibration response factor, area/ppm.

12.2 CO Concentration in the Bag. Calculate Cb using
Equations 10B-1 and 10B-2. If condensate is visible in the Tedlar bag,
calculate Bw using Table 10A-2 of Method 10A and the
temperature and barometric pressure in the analysis room. If condensate
is not visible, calculate Bw using the temperature and
barometric pressure at the sampling site.
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[GRAPHIC] [TIFF OMITTED] TR17OC00.236

12.3 CO Concentration in the Stack
[GRAPHIC] [TIFF OMITTED] TR17OC00.237

13.0 Method Performance [Reserved]

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 References

Same as in Method 25, Section 16.0, with the addition of the
following:

1. Butler, F.E, J.E. Knoll, and M.R. Midgett. Development and
Evaluation of Methods for Determining Carbon Monoxide Emissions. Quality
Assurance Division, Environmental Monitoring Systems Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, NC. June 1985.
33 pp.

17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]

[36 FR 24877, Dec. 23, 1971]

Editorial Note: For Federal Register citations affecting part 60,
appendix A-4, see the List of CFR Sections Affected, which appears in
the Finding Aids section of the printed volume and on GPO Access.