[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.A2]

[Page 91]

           Appendix A-2 to Part 60--Test Methods 2G through 3C

Method 2G--Determination of Stack Gas Velocity and Volumetric Flow Rate 
With Two-Dimensional Probes
Method 2H--Determination of Stack Gas Velocity Taking Into Account 
Velocity Decay Near the Stack Wall
Method 3--Gas analysis for the determination of dry molecular weight
Method 3A--Determination of Oxygen and Carbon Dioxide Concentrations in 
Emissions From Stationary Sources (Instrumental Analyzer Procedure)
Method 3B--Gas analysis for the determination of emission rate 
correction factor or excess air
Method 3C--Determination of carbon dioxide, methane, nitrogen, and 
oxygen 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 2G--Determination of Stack Gas Velocity and Volumetric Flow Rate 
                       With Two-Dimensional Probes

    Note: This method does not include all of the specifications (e.g., 
equipment and supplies) and procedures (e.g., sampling) essential to its 
performance. Some material has been incorporated from other methods in 
this part. Therefore, to obtain reliable results, those using this 
method should have a thorough knowledge of at least the following



additional test methods: Methods 1, 2, 3 or 3A, and 4.

                        1.0 Scope and Application

    1.1 This method is applicable for the determination of yaw angle, 
near-axial velocity, and the volumetric flow rate of a gas stream in a 
stack or duct using a two-dimensional (2-D) probe.

                          2.0 Summary of Method

2.1 A 2-D probe is used to measure the velocity pressure and the yaw 
angle of the flow velocity vector in a stack or duct. Alternatively, 
these measurements may be made by operating one of the three-dimensional 
(3-D) probes described in Method 2F, in yaw determination mode only. 
From these measurements and a determination of the stack gas density, 
the average near-axial velocity of the stack gas is calculated. The 
near-axial velocity accounts for the yaw, but not the pitch, component 
of flow. The average gas volumetric flow rate in the stack or duct is 
then determined from the average near-axial velocity.

                             3.0 Definitions

    3.1. Angle-measuring Device Rotational Offset (RADO). The rotational 
position of an angle-measuring device relative to the reference scribe 
line, as determined during the pre-test rotational position check 
described in section 8.3.
    3.2 Calibration Pitot Tube. The standard (Prandtl type) pitot tube 
used as a reference when calibrating a probe under this method.
    3.3 Field Test. A set of measurements conducted at a specific unit 
or exhaust stack/duct to satisfy the applicable regulation (e.g., a 
three-run boiler performance test, a single-or multiple-load nine-run 
relative accuracy test).
    3.4 Full Scale of Pressure-measuring Device. Full scale refers to 
the upper limit of the measurement range displayed by the device. For 
bi-directional pressure gauges, full scale includes the entire pressure 
range from the lowest negative value to the highest positive value on 
the pressure scale.
    3.5 Main probe. Refers to the probe head and that section of probe 
sheath directly attached to the probe head. The main probe sheath is 
distinguished from probe extensions, which are sections of sheath added 
onto the main probe to extend its reach.
    3.6 ``May,'' ``Must,'' ``Shall,'' ``Should,'' and the imperative 
form of verbs.
    3.6.1 ``May'' is used to indicate that a provision of this method is 
optional.
    3.6.2 ``Must,'' ``Shall,'' and the imperative form of verbs (such as 
``record'' or ``enter'') are used to indicate that a provision of this 
method is mandatory.
    3.6.3 ``Should'' is used to indicate that a provision of this method 
is not mandatory, but is highly recommended as good practice.
    3.7 Method 1. Refers to 40 CFR part 60, appendix A, ``Method 1--
Sample and velocity traverses for stationary sources.''
    3.8 Method 2. Refers to 40 CFR part 60, appendix A, ``Method 2--
Determination of stack gas velocity and volumetric flow rate (Type S 
pitot tube).''
    3.9 Method 2F. Refers to 40 CFR part 60, appendix A, ``Method 2F--
Determination of stack gas velocity and volumetric flow rate with three-
dimensional probes.''
    3.10 Near-axial Velocity. The velocity vector parallel to the axis 
of the stack or duct that accounts for the yaw angle component of gas 
flow. The term ``near-axial'' is used herein to indicate that the 
velocity and volumetric flow rate results account for the measured yaw 
angle component of flow at each measurement point.
    3.11 Nominal Velocity. Refers to a wind tunnel velocity setting that 
approximates the actual wind tunnel velocity to within 1.5 m/sec (5 ft/sec).
    3.12 Pitch Angle. The angle between the axis of the stack or duct 
and the pitch component of flow, i.e., the component of the total 
velocity vector in a plane defined by the traverse line and the axis of 
the stack or duct. (Figure 2G-1 illustrates the ``pitch plane.'') From 
the standpoint of a tester facing a test port in a vertical stack, the 
pitch component of flow is the vector of flow moving from the center of 
the stack toward or away from that test port. The pitch angle is the 
angle described by this pitch component of flow and the vertical axis of 
the stack.
    3.13 Readability. For the purposes of this method, readability for 
an analog measurement device is one half of the smallest scale division. 
For a digital measurement device, it is the number of decimals displayed 
by the device.
    3.14 Reference Scribe Line. A line permanently inscribed on the main 
probe sheath (in accordance with section 6.1.5.1) to serve as a 
reference mark for determining yaw angles.
    3.15 Reference Scribe Line Rotational Offset (RSLO). The rotational 
position of a probe's reference scribe line relative to the probe's yaw-
null position, as determined during the yaw angle calibration described 
in section 10.5.
    3.16 Response Time. The time required for the measurement system to 
fully respond to a change from zero differential pressure and ambient 
temperature to the stable stack or duct pressure and temperature 
readings at a traverse point.
    3.17 Tested Probe. A probe that is being calibrated.
    3.18 Three-dimensional (3-D) Probe. A directional probe used to 
determine the velocity

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pressure and the yaw and pitch angles in a flowing gas stream.
    3.19 Two-dimensional (2-D) Probe. A directional probe used to 
measure velocity pressure and yaw angle in a flowing gas stream.
    3.20 Traverse Line. A diameter or axis extending across a stack or 
duct on which measurements of velocity pressure and flow angles are 
made.
    3.21 Wind Tunnel Calibration Location. A point, line, area, or 
volume within the wind tunnel test section at, along, or within which 
probes are calibrated. At a particular wind tunnel velocity setting, the 
average velocity pressures at specified points at, along, or within the 
calibration location shall vary by no more than 2 percent or 0.3 mm 
H20 (0.01 in. H2O), whichever is less restrictive, 
from the average velocity pressure at the calibration pitot tube 
location. Air flow at this location shall be axial, i.e., yaw and pitch 
angles within 3[deg] of 0[deg]. Compliance with 
these flow criteria shall be demonstrated by performing the procedures 
prescribed in sections 10.1.1 and 10.1.2. For circular tunnels, no part 
of the calibration location may be closer to the tunnel wall than 10.2 
cm (4 in.) or 25 percent of the tunnel diameter, whichever is farther 
from the wall. For elliptical or rectangular tunnels, no part of the 
calibration location may be closer to the tunnel wall than 10.2 cm (4 
in.) or 25 percent of the applicable cross-sectional axis, whichever is 
farther from the wall.
    3.22 Wind Tunnel with Documented Axial Flow. A wind tunnel facility 
documented as meeting the provisions of sections 10.1.1 (velocity 
pressure cross-check) and 10.1.2 (axial flow verification) using the 
procedures described in these sections or alternative procedures 
determined to be technically equivalent.
    3.23 Yaw Angle. The angle between the axis of the stack or duct and 
the yaw component of flow, i.e., the component of the total velocity 
vector in a plane perpendicular to the traverse line at a particular 
traverse point. (Figure 2G-1 illustrates the ``yaw plane.'') From the 
standpoint of a tester facing a test port in a vertical stack, the yaw 
component of flow is the vector of flow moving to the left or right from 
the center of the stack as viewed by the tester. (This is sometimes 
referred to as ``vortex flow,'' i.e., flow around the centerline of a 
stack or duct.) The yaw angle is the angle described by this yaw 
component of flow and the vertical axis of the stack. The algebraic sign 
convention is illustrated in Figure 2G-2.
    3.24 Yaw Nulling. A procedure in which a Type-S pitot tube or a 3-D 
probe is rotated about its axis in a stack or duct until a zero 
differential pressure reading (``yaw null'') is obtained. When a Type S 
probe is yaw-nulled, the rotational position of its impact port is 
90[deg] from the direction of flow in the stack or duct and the [Delta]P 
reading is zero. When a 3-D probe is yaw-nulled, its impact pressure 
port (P1) faces directly into the direction of flow in the 
stack or duct and the differential pressure between pressure ports 
P2 and P3 is zero.

                      4.0 Interferences [Reserved]

                               5.0 Safety

    5.1 This test method may involve hazardous operations and the use of 
hazardous materials or equipment. This method does not purport to 
address all of the safety problems associated with its use. It is the 
responsibility of the user to establish and implement appropriate safety 
and health practices and to determine the applicability of regulatory 
limitations before using this test method.

                       6.0 Equipment and Supplies

    6.1 Two-dimensional Probes. Probes that provide both the velocity 
pressure and the yaw angle of the flow vector in a stack or duct, as 
listed in sections 6.1.1 and 6.1.2, qualify for use based on 
comprehensive wind tunnel and field studies involving both inter-and 
intra-probe comparisons by multiple test teams. Each 2-D probe shall 
have a unique identification number or code permanently marked on the 
main probe sheath. Each probe shall be calibrated prior to use according 
to the procedures in section 10. Manufacturer-supplied calibration data 
shall be used as example information only, except when the manufacturer 
calibrates the probe as specified in section 10 and provides complete 
documentation.
    6.1.1 Type S (Stausscheibe or reverse type) pitot tube. This is the 
same as specified in Method 2, section 2.1, except for the following 
additional specifications that enable the pitot tube to accurately 
determine the yaw component of flow. For the purposes of this method, 
the external diameter of the tubing used to construct the Type S pitot 
tube (dimension Dt in Figure 2-2 of Method 2) shall be no 
less than 9.5 mm (3/8 in.). The pitot tube shall also meet the following 
alignment specifications. The angles [alpha]1, 
[alpha]2, [beta]1, and [beta]2, as 
shown in Method 2, Figure 2-3, shall not exceed 2[deg]. The dimensions w and z, shown in Method 2, 
Figure 2-3 shall not exceed 0.5 mm (0.02 in.).
    6.1.1.1 Manual Type S probe. This refers to a Type S probe that is 
positioned at individual traverse points and yaw nulled manually by an 
operator.
    6.1.1.2 Automated Type S probe. This refers to a system that uses a 
computer-controlled motorized mechanism to position the Type S pitot 
head at individual traverse points and perform yaw angle determinations.
    6.1.2 Three-dimensional probes used in 2-D mode. A 3-D probe, as 
specified in sections 6.1.1 through 6.1.3 of Method 2F, may, for the

[[Page 93]]

purposes of this method, be used in a two-dimensional mode (i.e., 
measuring yaw angle, but not pitch angle). When the 3-D probe is used as 
a 2-D probe, only the velocity pressure and yaw-null pressure are 
obtained using the pressure taps referred to as P1, 
P2, and P3. The differential pressure 
P1-P2 is a function of total velocity and 
corresponds to the [Delta]P obtained using the Type S probe. The 
differential pressure P2-P3 is used to yaw null 
the probe and determine the yaw angle. The differential pressure 
P4-P5, which is a function of pitch angle, is not 
measured when the 3-D probe is used in 2-D mode.
    6.1.3 Other probes. [Reserved]
    6.1.4 Probe sheath. The probe shaft shall include an outer sheath 
to: (1) provide a surface for inscribing a permanent reference scribe 
line, (2) accommodate attachment of an angle-measuring device to the 
probe shaft, and (3) facilitate precise rotational movement of the probe 
for determining yaw angles. The sheath shall be rigidly attached to the 
probe assembly and shall enclose all pressure lines from the probe head 
to the farthest position away from the probe head where an angle-
measuring device may be attached during use in the field. The sheath of 
the fully assembled probe shall be sufficiently rigid and straight at 
all rotational positions such that, when one end of the probe shaft is 
held in a horizontal position, the fully extended probe meets the 
horizontal straightness specifications indicated in section 8.2 below.
    6.1.5 Scribe lines.
    6.1.5.1 Reference scribe line. A permanent line, no greater than 1.6 
mm (1/16 in.) in width, shall be inscribed on each manual probe that 
will be used to determine yaw angles of flow. This line shall be placed 
on the main probe sheath in accordance with the procedures described in 
section 10.4 and is used as a reference position for installation of the 
yaw angle-measuring device on the probe. At the discretion of the 
tester, the scribe line may be a single line segment placed at a 
particular position on the probe sheath (e.g., near the probe head), 
multiple line segments placed at various locations along the length of 
the probe sheath (e.g., at every position where a yaw angle-measuring 
device may be mounted), or a single continuous line extending along the 
full length of the probe sheath.
    6.1.5.2 Scribe line on probe extensions. A permanent line may also 
be inscribed on any probe extension that will be attached to the main 
probe in performing field testing. This allows a yaw angle-measuring 
device mounted on the extension to be readily aligned with the reference 
scribe line on the main probe sheath.
    6.1.5.3 Alignment specifications. This specification shall be met 
separately, using the procedures in section 10.4.1, on the main probe 
and on each probe extension. The rotational position of the scribe line 
or scribe line segments on the main probe or any probe extension must 
not vary by more than 2[deg]. That is, the difference between the 
minimum and maximum of all of the rotational angles that are measured 
along the full length of the main probe or the probe extension must not 
exceed 2[deg].
    6.1.6 Probe and system characteristics to ensure horizontal 
stability.
    6.1.6.1 For manual probes, it is recommended that the effective 
length of the probe (coupled with a probe extension, if necessary) be at 
least 0.9 m (3 ft.) longer than the farthest traverse point mark on the 
probe shaft away from the probe head. The operator should maintain the 
probe's horizontal stability when it is fully inserted into the stack or 
duct. If a shorter probe is used, the probe should be inserted through a 
bushing sleeve, similar to the one shown in Figure 2G-3, that is 
installed on the test port; such a bushing shall fit snugly around the 
probe and be secured to the stack or duct entry port in such a manner as 
to maintain the probe's horizontal stability when fully inserted into 
the stack or duct.
    6.1.6.2 An automated system that includes an external probe casing 
with a transport system shall have a mechanism for maintaining 
horizontal stability comparable to that obtained by manual probes 
following the provisions of this method. The automated probe assembly 
shall also be constructed to maintain the alignment and position of the 
pressure ports during sampling at each traverse point. The design of the 
probe casing and transport system shall allow the probe to be removed 
from the stack or duct and checked through direct physical measurement 
for angular position and insertion depth.
    6.1.7 The tubing that is used to connect the probe and the pressure-
measuring device should have an inside diameter of at least 3.2 mm (\1/
8\ in.), to reduce the time required for pressure equilibration, and 
should be as short as practicable.
    6.1.8 If a detachable probe head without a sheath [e.g., a pitot 
tube, typically 15.2 to 30.5 cm (6 to 12 in.) in length] is coupled with 
a probe sheath and calibrated in a wind tunnel in accordance with the 
yaw angle calibration procedure in section 10.5, the probe head shall 
remain attached to the probe sheath during field testing in the same 
configuration and orientation as calibrated. Once the detachable probe 
head is uncoupled or re-oriented, the yaw angle calibration of the probe 
is no longer valid and must be repeated before using the probe in 
subsequent field tests.
    6.2 Yaw Angle-measuring Device. One of the following devices shall 
be used for measurement of the yaw angle of flow.

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    6.2.1 Digital inclinometer. This refers to a digital device capable 
of measuring and displaying the rotational position of the probe to 
within 1[deg]. The device shall be able to be 
locked into position on the probe sheath or probe extension, so that it 
indicates the probe's rotational position throughout the test. A 
rotational position collar block that can be attached to the probe 
sheath (similar to the collar shown in Figure 2G-4) may be required to 
lock the digital inclinometer into position on the probe sheath.
    6.2.2 Protractor wheel and pointer assembly. This apparatus, similar 
to that shown in Figure 2G-5, consists of the following components.
    6.2.2.1 A protractor wheel that can be attached to a port opening 
and set in a fixed rotational position to indicate the yaw angle 
position of the probe's scribe line relative to the longitudinal axis of 
the stack or duct. The protractor wheel must have a measurement ring on 
its face that is no less than 17.8 cm (7 in.) in diameter, shall be able 
to be rotated to any angle and then locked into position on the stack or 
duct test port, and shall indicate angles to a resolution of 1[deg].
    6.2.2.2 A pointer assembly that includes an indicator needle mounted 
on a collar that can slide over the probe sheath and be locked into a 
fixed rotational position on the probe sheath. The pointer needle shall 
be of sufficient length, rigidity, and sharpness to allow the tester to 
determine the probe's angular position to within 1[deg] from the 
markings on the protractor wheel. Corresponding to the position of the 
pointer, the collar must have a scribe line to be used in aligning the 
pointer with the scribe line on the probe sheath.
    6.2.3 Other yaw angle-measuring devices. Other angle-measuring 
devices with a manufacturer's specified precision of 1[deg] or better 
may be used, if approved by the Administrator.
    6.3 Probe Supports and Stabilization Devices. When probes are used 
for determining flow angles, the probe head should be kept in a stable 
horizontal position. For probes longer than 3.0 m (10 ft.), the section 
of the probe that extends outside the test port shall be secured. Three 
alternative devices are suggested for maintaining the horizontal 
position and stability of the probe shaft during flow angle 
determinations and velocity pressure measurements: (1) monorails 
installed above each port, (2) probe stands on which the probe shaft may 
be rested, or (3) bushing sleeves of sufficient length secured to the 
test ports to maintain probes in a horizontal position. Comparable 
provisions shall be made to ensure that automated systems maintain the 
horizontal position of the probe in the stack or duct. The physical 
characteristics of each test platform may dictate the most suitable type 
of stabilization device. Thus, the choice of a specific stabilization 
device is left to the judgement of the testers.
    6.4 Differential Pressure Gauges. The velocity pressure ([Delta]P) 
measuring devices used during wind tunnel calibrations and field testing 
shall be either electronic manometers (e.g., pressure transducers), 
fluid manometers, or mechanical pressure gauges (e.g., 
Magnehelic[Delta] gauges). Use of electronic manometers is 
recommended. Under low velocity conditions, use of electronic manometers 
may be necessary to obtain acceptable measurements.
    6.4.1 Differential pressure-measuring device. This refers to a 
device capable of measuring pressure differentials and having a 
readability of 1 percent of full scale. The device 
shall be capable of accurately measuring the maximum expected pressure 
differential. Such devices are used to determine the following pressure 
measurements: velocity pressure, static pressure, and yaw-null pressure. 
For an inclined-vertical manometer, the readability specification of 
1 percent shall be met separately using the 
respective full-scale upper limits of the inclined anvertical portions 
of the scales. To the extent practicable, the device shall be selected 
such that most of the pressure readings are between 10 and 90 percent of 
the device's full-scale measurement range (as defined in section 3.4). 
In addition, pressure-measuring devices should be selected such that the 
zero does not drift by more than 5 percent of the average expected 
pressure readings to be encountered during the field test. This is 
particularly important under low pressure conditions.
    6.4.2 Gauge used for yaw nulling. The differential pressure-
measuring device chosen for yaw nulling the probe during the wind tunnel 
calibrations and field testing shall be bi-directional, i.e., capable of 
reading both positive and negative differential pressures. If a 
mechanical, bi-directional pressure gauge is chosen, it shall have a 
full-scale range no greater than 2.6 cm (i.e., -1.3 to +1.3 cm) [1 in. 
H2O (i.e., -0.5 in. to +0.5 in.)].
    6.4.3 Devices for calibrating differential pressure-measuring 
devices. A precision manometer (e.g., a U-tube, inclined, or inclined-
vertical manometer, or micromanometer) or NIST (National Institute of 
Standards and Technology) traceable pressure source shall be used for 
calibrating differential pressure-measuring devices. The device shall be 
maintained under laboratory conditions or in a similar protected 
environment (e.g., a climate-controlled trailer). It shall not be used 
in field tests. The precision manometer shall have a scale gradation of 
0.3 mm H2O (0.01 in. H2O), or less, in the range 
of 0 to 5.1 cm H2O (0 to 2 in. H2O) and 2.5 mm 
H2O (0.1 in. H2O), or less, in the range of 5.1 to 
25.4 cm H2O (2 to 10 in. H2O). The manometer shall 
have manufacturer's documentation that it meets an accuracy 
specification of at least 0.5 percent of full scale. The NIST-traceable 
pressure source shall be recertified annually.

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    6.4.4 Devices used for post-test calibration check. A precision 
manometer meeting the specifications in section 6.4.3, a pressure-
measuring device or pressure source with a documented calibration 
traceable to NIST, or an equivalent device approved by the Administrator 
shall be used for the post-test calibration check. The pressure-
measuring device shall have a readability equivalent to or greater than 
the tested device. The pressure source shall be capable of generating 
pressures between 50 and 90 percent of the range of the tested device 
and known to within 1 percent of the full scale of 
the tested device. The pressure source shall be recertified annually.
    6.5 Data Display and Capture Devices. Electronic manometers (if 
used) shall be coupled with a data display device (such as a digital 
panel meter, personal computer display, or strip chart) that allows the 
tester to observe and validate the pressure measurements taken during 
testing. They shall also be connected to a data recorder (such as a data 
logger or a personal computer with data capture software) that has the 
ability to compute and retain the appropriate average value at each 
traverse point, identified by collection time and traverse point.
    6.6 Temperature Gauges. For field tests, a thermocouple or 
resistance temperature detector (RTD) capable of measuring temperature 
to within 3[deg]C (5[deg]F) 
of the stack or duct temperature shall be used. The thermocouple shall 
be attached to the probe such that the sensor tip does not touch any 
metal. The position of the thermocouple relative to the pressure port 
face openings shall be in the same configuration as used for the probe 
calibrations in the wind tunnel. Temperature gauges used for wind tunnel 
calibrations shall be capable of measuring temperature to within 0.6[deg]C (1[deg]F) of the 
temperature of the flowing gas stream in the wind tunnel.
    6.7 Stack or Duct Static Pressure Measurement. The pressure-
measuring device used with the probe shall be as specified in section 
6.4 of this method. The static tap of a standard (Prandtl type) pitot 
tube or one leg of a Type S pitot tube with the face opening planes 
positioned parallel to the gas flow may be used for this measurement. 
Also acceptable is the pressure differential reading of P1-
Pbar from a five-hole prism-shaped 3-D probe, as specified in 
section 6.1.1 of Method 2F (such as the Type DA or DAT probe), with the 
P1 pressure port face opening positioned parallel to the gas 
flow in the same manner as the Type S probe. However, the 3-D spherical 
probe, as specified in section 6.1.2 of Method 2F, is unable to provide 
this measurement and shall not be used to take static pressure 
measurements. Static pressure measurement is further described in 
section 8.11.
    6.8 Barometer. Same as Method 2, section 2.5.
    6.9 Gas Density Determination Equipment. Method 3 or 3A shall be 
used to determine the dry molecular weight of the stack or duct gas. 
Method 4 shall be used for moisture content determination and 
computation of stack or duct gas wet molecular weight. Other methods may 
be used, if approved by the Administrator.
    6.10 Calibration Pitot Tube. Same as Method 2, section 2.7.
    6.11 Wind Tunnel for Probe Calibration. Wind tunnels used to 
calibrate velocity probes must meet the following design specifications.
    6.11.1 Test section cross-sectional area. The flowing gas stream 
shall be confined within a circular, rectangular, or elliptical duct. 
The cross-sectional area of the tunnel must be large enough to ensure 
fully developed flow in the presence of both the calibration pitot tube 
and the tested probe. The calibration site, or ``test section,'' of the 
wind tunnel shall have a minimum diameter of 30.5 cm (12 in.) for 
circular or elliptical duct cross-sections or a minimum width of 30.5 cm 
(12 in.) on the shorter side for rectangular cross-sections. Wind 
tunnels shall meet the probe blockage provisions of this section and the 
qualification requirements prescribed in section 10.1. The projected 
area of the portion of the probe head, shaft, and attached devices 
inside the wind tunnel during calibration shall represent no more than 4 
percent of the cross-sectional area of the tunnel. The projected area 
shall include the combined area of the calibration pitot tube and the 
tested probe if both probes are placed simultaneously in the same cross-
sectional plane in the wind tunnel, or the larger projected area of the 
two probes if they are placed alternately in the wind tunnel.
    6.11.2 Velocity range and stability. The wind tunnel should be 
capable of maintaining velocities between 6.1 m/sec and 30.5 m/sec (20 
ft/sec and 100 ft/sec). The wind tunnel shall produce fully developed 
flow patterns that are stable and parallel to the axis of the duct in 
the test section.
    6.11.3 Flow profile at the calibration location. The wind tunnel 
shall provide axial flow within the test section calibration location 
(as defined in section 3.21). Yaw and pitch angles in the calibration 
location shall be within 3[deg] of 0[deg]. The 
procedure for determining that this requirement has been met is 
described in section 10.1.2.
    6.11.4 Entry ports in the wind tunnel test section.
    6.11.4.1 Port for tested probe. A port shall be constructed for the 
tested probe. This port shall be located to allow the head of the tested 
probe to be positioned within the wind tunnel calibration location (as 
defined in section 3.21). The tested probe shall be able to be locked 
into the 0[deg] pitch angle position. To facilitate alignment of the 
probe during calibration, the test section should include a

[[Page 96]]

window constructed of a transparent material to allow the tested probe 
to be viewed.
    6.11.4.2 Port for verification of axial flow. Depending on the 
equipment selected to conduct the axial flow verification prescribed in 
section 10.1.2, a second port, located 90[deg] from the entry port for 
the tested probe, may be needed to allow verification that the gas flow 
is parallel to the central axis of the test section. This port should be 
located and constructed so as to allow one of the probes described in 
section 10.1.2.2 to access the same test point(s) that are accessible 
from the port described in section 6.11.4.1.
    6.11.4.3 Port for calibration pitot tube. The calibration pitot tube 
shall be used in the port for the tested probe or in a separate entry 
port. In either case, all measurements with the calibration pitot tube 
shall be made at the same point within the wind tunnel over the course 
of a probe calibration. The measurement point for the calibration pitot 
tube shall meet the same specifications for distance from the wall and 
for axial flow as described in section 3.21 for the wind tunnel 
calibration location.

                  7.0 Reagents and Standards [Reserved]

                   8.0 Sample Collection and Analysis

    8.1 Equipment Inspection and Set Up
    8.1.1 All 2-D and 3-D probes, differential pressure-measuring 
devices, yaw angle-measuring devices, thermocouples, and barometers 
shall have a current, valid calibration before being used in a field 
test. (See sections 10.3.3, 10.3.4, and 10.5 through 10.10 for the 
applicable calibration requirements.)
    8.1.2 Before each field use of a Type S probe, perform a visual 
inspection to verify the physical condition of the pitot tube. Record 
the results of the inspection. If the face openings are noticeably 
misaligned or there is visible damage to the face openings, the probe 
shall not be used until repaired, the dimensional specifications 
verified (according to the procedures in section 10.2.1), and the probe 
recalibrated.
    8.1.3 Before each field use of a 3-D probe, perform a visual 
inspection to verify the physical condition of the probe head according 
to the procedures in section 10.2 of Method 2F. Record the inspection 
results on a form similar to Table 2F-1 presented in Method 2F. If there 
is visible damage to the 3-D probe, the probe shall not be used until it 
is recalibrated.
    8.1.4 After verifying that the physical condition of the probe head 
is acceptable, set up the apparatus using lengths of flexible tubing 
that are as short as practicable. Surge tanks installed between the 
probe and pressure-measuring device may be used to dampen pressure 
fluctuations provided that an adequate measurement system response time 
(see section 8.8) is maintained.
    8.2 Horizontal Straightness Check. A horizontal straightness check 
shall be performed before the start of each field test, except as 
otherwise specified in this section. Secure the fully assembled probe 
(including the probe head and all probe shaft extensions) in a 
horizontal position using a stationary support at a point along the 
probe shaft approximating the location of the stack or duct entry port 
when the probe is sampling at the farthest traverse point from the stack 
or duct wall. The probe shall be rotated to detect bends. Use an angle-
measuring device or trigonometry to determine the bend or sag between 
the probe head and the secured end. (See Figure 2G-6.) Probes that are 
bent or sag by more than 5[deg] shall not be used. Although this check 
does not apply when the probe is used for a vertical traverse, care 
should be taken to avoid the use of bent probes when conducting vertical 
traverses. If the probe is constructed of a rigid steel material and 
consists of a main probe without probe extensions, this check need only 
be performed before the initial field use of the probe, when the probe 
is recalibrated, when a change is made to the design or material of the 
probe assembly, and when the probe becomes bent. With such probes, a 
visual inspection shall be made of the fully assembled probe before each 
field test to determine if a bend is visible. The probe shall be rotated 
to detect bends. The inspection results shall be documented in the field 
test report. If a bend in the probe is visible, the horizontal 
straightness check shall be performed before the probe is used.
    8.3 Rotational Position Check. Before each field test, and each time 
an extension is added to the probe during a field test, a rotational 
position check shall be performed on all manually operated probes 
(except as noted in section 8.3.5 below) to ensure that, throughout 
testing, the angle-measuring device is either: aligned to within 1[deg] of the rotational position of the reference 
scribe line; or is affixed to the probe such that the rotational offset 
of the device from the reference scribe line is known to within 1[deg]. This check shall consist of direct measurements 
of the rotational positions of the reference scribe line and angle-
measuring device sufficient to verify that these specifications are met. 
Annex A in section 18 of this method gives recommended procedures for 
performing the rotational position check, and Table 2G-2 gives an 
example data form. Procedures other than those recommended in Annex A in 
section 18 may be used, provided they demonstrate whether the alignment 
specification is met and are explained in detail in the field test 
report.
    8.3.1 Angle-measuring device rotational offset. The tester shall 
maintain a record of the angle-measuring device rotational offset, 
RADO, as defined in section 3.1. Note that RADO is 
assigned a value of 0[deg] when the angle-

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measuring device is aligned to within 1[deg] of 
the rotational position of the reference scribe line. The 
RADO shall be used to determine the yaw angle of flow in 
accordance with section 8.9.4.
    8.3.2 Sign of angle-measuring device rotational offset. The sign of 
RADO is positive when the angle-measuring device (as viewed 
from the ``tail'' end of the probe) is positioned in a clockwise 
direction from the reference scribe line and negative when the device is 
positioned in a counterclockwise direction from the reference scribe 
line.
    8.3.3 Angle-measuring devices that can be independently adjusted 
(e.g., by means of a set screw), after being locked into position on the 
probe sheath, may be used. However, the RADO must also take 
into account this adjustment.
    8.3.4 Post-test check. If probe extensions remain attached to the 
main probe throughout the field test, the rotational position check 
shall be repeated, at a minimum, at the completion of the field test to 
ensure that the angle-measuring device has remained within 2[deg] of its rotational position established prior to 
testing. At the discretion of the tester, additional checks may be 
conducted after completion of testing at any sample port or after any 
test run. If the 2[deg] specification is not met, 
all measurements made since the last successful rotational position 
check must be repeated. Section 18.1.1.3 of Annex A provides an example 
procedure for performing the post-test check.
    8.3.5 Exceptions.
    8.3.5.1 A rotational position check need not be performed if, for 
measurements taken at all velocity traverse points, the yaw angle-
measuring device is mounted and aligned directly on the reference scribe 
line specified in sections 6.1.5.1 and 6.1.5.3 and no independent 
adjustments, as described in section 8.3.3, are made to device's 
rotational position.
    8.3.5.2 If extensions are detached and re-attached to the probe 
during a field test, a rotational position check need only be performed 
the first time an extension is added to the probe, rather than each time 
the extension is re-attached, if the probe extension is designed to be 
locked into a mechanically fixed rotational position (e.g., through the 
use of interlocking grooves), that can re-establish the initial 
rotational position to within 1[deg].
    8.4 Leak Checks. A pre-test leak check shall be conducted before 
each field test. A post-test check shall be performed at the end of the 
field test, but additional leak checks may be conducted after any test 
run or group of test runs. The post-test check may also serve as the 
pre-test check for the next group of test runs. If any leak check is 
failed, all runs since the last passed leak check are invalid. While 
performing the leak check procedures, also check each pressure device's 
responsiveness to changes in pressure.
    8.4.1 To perform the leak check on a Type S pitot tube, pressurize 
the pitot impact opening until at least 7.6 cm H2O (3 in. 
H2O) velocity pressure, or a pressure corresponding to 
approximately 75 percent of the pressure device's measurement scale, 
whichever is less, registers on the pressure device; then, close off the 
impact opening. The pressure shall remain stable (2.5 mm H2O, 0.10 in. 
H2O) for at least 15 seconds. Repeat this procedure for the 
static pressure side, except use suction to obtain the required 
pressure. Other leak-check procedures may be used, if approved by the 
Administrator.
    8.4.2 To perform the leak check on a 3-D probe, pressurize the 
probe's impact (P1) opening until at least 7.6 cm 
H2O (3 in. H2O) velocity pressure, or a pressure 
corresponding to approximately 75 percent of the pressure device's 
measurement scale, whichever is less, registers on the pressure device; 
then, close off the impact opening. The pressure shall remain stable 
(2.5 mm H2O, 0.10 
in. H2O) for at least 15 seconds. Check the P2 and 
P3 pressure ports in the same fashion. Other leak-check 
procedures may be used, if approved by the Administrator.
    8.5 Zeroing the Differential Pressure-measuring Device. Zero each 
differential pressure-measuring device, including the device used for 
yaw nulling, before each field test. At a minimum, check the zero after 
each field test. A zero check may also be performed after any test run 
or group of test runs. For fluid manometers and mechanical pressure 
gauges (e.g., Magnehelic[Delta] gauges), the zero reading 
shall not deviate from zero by more than 0.8 mm 
H2O (0.03 in. H2O) or one 
minor scale division, whichever is greater, between checks. For 
electronic manometers, the zero reading shall not deviate from zero 
between checks by more than: 0.3 mm H2O 
(0.01 in. H2O), for full scales less 
than or equal to 5.1 cm H2O (2.0 in. H2O); or 
0.8 mm H2O (0.03 
in. H2O), for full scales greater than 5.1 cm H2O 
(2.0 in. H2O). (Note: If negative zero drift is not directly 
readable, estimate the reading based on the position of the gauge oil in 
the manometer or of the needle on the pressure gauge.) In addition, for 
all pressure-measuring devices except those used exclusively for yaw 
nulling, the zero reading shall not deviate from zero by more than 5 
percent of the average measured differential pressure at any distinct 
process condition or load level. If any zero check is failed at a 
specific process condition or load level, all runs conducted at that 
process condition or load level since the last passed zero check are 
invalid.
    8.6 Traverse Point Verification. The number and location of the 
traverse points shall be selected based on Method 1 guidelines.

[[Page 98]]

The stack or duct diameter and port nipple lengths, including any 
extension of the port nipples into the stack or duct, shall be verified 
the first time the test is performed; retain and use this information 
for subsequent field tests, updating it as required. Physically measure 
the stack or duct dimensions or use a calibrated laser device; do not 
use engineering drawings of the stack or duct. The probe length 
necessary to reach each traverse point shall be recorded to within 
6.4 mm (\1/4\ in.) and, for 
manual probes, marked on the probe sheath. In determining these lengths, 
the tester shall take into account both the distance that the port 
flange projects outside of the stack and the depth that any port nipple 
extends into the gas stream. The resulting point positions shall reflect 
the true distances from the inside wall of the stack or duct, so that 
when the tester aligns any of the markings with the outside face of the 
stack port, the probe's impact port shall be located at the appropriate 
distance from the inside wall for the respective Method 1 traverse 
point. Before beginning testing at a particular location, an out-of-
stack or duct verification shall be performed on each probe that will be 
used to ensure that these position markings are correct. The distances 
measured during the verification must agree with the previously 
calculated distances to within \1/4\ in. For 
manual probes, the traverse point positions shall be verified by 
measuring the distance of each mark from the probe's impact pressure 
port (the P1 port for a 3-D probe). A comparable out-of-stack 
test shall be performed on automated probe systems. The probe shall be 
extended to each of the prescribed traverse point positions. Then, the 
accuracy of the positioning for each traverse point shall be verified by 
measuring the distance between the port flange and the probe's impact 
pressure port.
    8.7 Probe Installation. Insert the probe into the test port. A solid 
material shall be used to seal the port.
    8.8 System Response Time. Determine the response time of the probe 
measurement system. Insert and position the ``cold'' probe (at ambient 
temperature and pressure) at any Method 1 traverse point. Read and 
record the probe differential pressure, temperature, and elapsed time at 
15-second intervals until stable readings for both pressure and 
temperature are achieved. The response time is the longer of these two 
elapsed times. Record the response time.
    8.9 Sampling.
    8.9.1 Yaw angle measurement protocol. With manual probes, yaw angle 
measurements may be obtained in two alternative ways during the field 
test, either by using a yaw angle-measuring device (e.g., digital 
inclinometer) affixed to the probe, or using a protractor wheel and 
pointer assembly. For horizontal traversing, either approach may be 
used. For vertical traversing, i.e., when measuring from on top or into 
the bottom of a horizontal duct, only the protractor wheel and pointer 
assembly may be used. With automated probes, curve-fitting protocols may 
be used to obtain yaw-angle measurements.
    8.9.1.1 If a yaw angle-measuring device affixed to the probe is to 
be used, lock the device on the probe sheath, aligning it either on the 
reference scribe line or in the rotational offset position established 
under section 8.3.1.
    8.9.1.2 If a protractor wheel and pointer assembly is to be used, 
follow the procedures in Annex B of this method.
    8.9.1.3 Curve-fitting procedures. Curve-fitting routines sweep 
through a range of yaw angles to create curves correlating pressure to 
yaw position. To find the zero yaw position and the yaw angle of flow, 
the curve found in the stack is computationally compared to a similar 
curve that was previously generated under controlled conditions in a 
wind tunnel. A probe system that uses a curve-fitting routine for 
determining the yaw-null position of the probe head may be used, 
provided that it is verified in a wind tunnel to be able to determine 
the yaw angle of flow to within 1[deg].
    8.9.1.4 Other yaw angle determination procedures. If approved by the 
Administrator, other procedures for determining yaw angle may be used, 
provided that they are verified in a wind tunnel to be able to perform 
the yaw angle calibration procedure as described in section 10.5.
    8.9.2 Sampling strategy. At each traverse point, first yaw-null the 
probe, as described in section 8.9.3, below. Then, with the probe 
oriented into the direction of flow, measure and record the yaw angle, 
the differential pressure and the temperature at the traverse point, 
after stable readings are achieved, in accordance with sections 8.9.4 
and 8.9.5. At the start of testing in each port (i.e., after a probe has 
been inserted into the flue gas stream), allow at least the response 
time to elapse before beginning to take measurements at the first 
traverse point accessed from that port. Provided that the probe is not 
removed from the flue gas stream, measurements may be taken at 
subsequent traverse points accessed from the same test port without 
waiting again for the response time to elapse.
    8.9.3 Yaw-nulling procedure. In preparation for yaw angle 
determination, the probe must first be yaw nulled. After positioning the 
probe at the appropriate traverse point, perform the following 
procedures.
    8.9.3.1 For Type S probes, rotate the probe until a null 
differential pressure reading is obtained. The direction of the probe 
rotation shall be such that the thermocouple is located downstream of 
the probe pressure ports at the yaw-null position. Rotate the

[[Page 99]]

probe 90[deg] back from the yaw-null position to orient the impact 
pressure port into the direction of flow. Read and record the angle 
displayed by the angle-measuring device.
    8.9.3.2 For 3-D probes, rotate the probe until a null differential 
pressure reading (the difference in pressures across the P2 
and P3 pressure ports is zero, i.e., 
P2=P3) is indicated by the yaw angle pressure 
gauge. Read and record the angle displayed by the angle-measuring 
device.
    8.9.3.3 Sign of the measured angle. The angle displayed on the 
angle-measuring device is considered positive when the probe's impact 
pressure port (as viewed from the ``tail'' end of the probe) is oriented 
in a clockwise rotational position relative to the stack or duct axis 
and is considered negative when the probe's impact pressure port is 
oriented in a counterclockwise rotational position (see Figure 2G-7).
    8.9.4 Yaw angle determination. After performing the applicable yaw-
nulling procedure in section 8.9.3, determine the yaw angle of flow 
according to one of the following procedures. Special care must be 
observed to take into account the signs of the recorded angle reading 
and all offsets.
    8.9.4.1 Direct-reading. If all rotational offsets are zero or if the 
angle-measuring device rotational offset (RADO) determined in 
section 8.3 exactly compensates for the scribe line rotational offset 
(RSLO) determined in section 10.5, then the magnitude of the 
yaw angle is equal to the displayed angle-measuring device reading from 
section 8.9.3.1 or 8.9.3.2. The algebraic sign of the yaw angle is 
determined in accordance with section 8.9.3.3. [Note: Under certain 
circumstances (e.g., testing of horizontal ducts) a 90[deg] adjustment 
to the angle-measuring device readings may be necessary to obtain the 
correct yaw angles.]
    8.9.4.2 Compensation for rotational offsets during data reduction. 
When the angle-measuring device rotational offset does not compensate 
for reference scribe line rotational offset, the following procedure 
shall be used to determine the yaw angle:
    (a) Enter the reading indicated by the angle-measuring device from 
section 8.9.3.1 or 8.9.3.2.
    (b) Associate the proper algebraic sign from section 8.9.3.3 with 
the reading in step (a).
    (c) Subtract the reference scribe line rotational offset, 
RSLO, from the reading in step (b).
    (d) Subtract the angle-measuring device rotational offset, 
RADO, if any, from the result obtained in step (c).
    (e) The final result obtained in step (d) is the yaw angle of flow.

    [Note: It may be necessary to first apply a 90[deg] adjustment to 
the reading in step (a), in order to obtain the correct yaw angle.]

    8.9.4.3 Record the yaw angle measurements on a form similar to Table 
2G-3.
    8.9.5 Impact velocity determination. Maintain the probe rotational 
position established during the yaw angle determination. Then, begin 
recording the pressure-measuring device readings. These pressure 
measurements shall be taken over a sampling period of sufficiently long 
duration to ensure representative readings at each traverse point. If 
the pressure measurements are determined from visual readings of the 
pressure device or display, allow sufficient time to observe the 
pulsation in the readings to obtain a sight-weighted average, which is 
then recorded manually. If an automated data acquisition system (e.g., 
data logger, computer-based data recorder, strip chart recorder) is used 
to record the pressure measurements, obtain an integrated average of all 
pressure readings at the traverse point. Stack or duct gas temperature 
measurements shall be recorded, at a minimum, once at each traverse 
point. Record all necessary data as shown in the example field data form 
(Table 2G-3).
    8.9.6 Alignment check. For manually operated probes, after the 
required yaw angle and differential pressure and temperature 
measurements have been made at each traverse point, verify (e.g., by 
visual inspection) that the yaw angle-measuring device has remained in 
proper alignment with the reference scribe line or with the rotational 
offset position established in section 8.3. If, for a particular 
traverse point, the angle-measuring device is found to be in proper 
alignment, proceed to the next traverse point; otherwise, re-align the 
device and repeat the angle and differential pressure measurements at 
the traverse point. In the course of a traverse, if a mark used to 
properly align the angle-measuring device (e.g., as described in section 
18.1.1.1) cannot be located, re-establish the alignment mark before 
proceeding with the traverse.
    8.10 Probe Plugging. Periodically check for plugging of the pressure 
ports by observing the responses on the pressure differential readouts. 
Plugging causes erratic results or sluggish responses. Rotate the probe 
to determine whether the readouts respond in the expected direction. If 
plugging is detected, correct the problem and repeat the affected 
measurements.
    8.11 Static Pressure. Measure the static pressure in the stack or 
duct using the equipment described in section 6.7.
    8.11.1 If a Type S probe is used for this measurement, position the 
probe at or between any traverse point(s) and rotate the probe until a 
null differential pressure reading is obtained. Disconnect the tubing 
from one of the pressure ports; read and record the [Delta]P. For 
pressure devices with one-directional

[[Page 100]]

scales, if a deflection in the positive direction is noted with the 
negative side disconnected, then the static pressure is positive. 
Likewise, if a deflection in the positive direction is noted with the 
positive side disconnected, then the static pressure is negative.
    8.11.2 If a 3-D probe is used for this measurement, position the 
probe at or between any traverse point(s) and rotate the probe until a 
null differential pressure reading is obtained at P2-
P3. Rotate the probe 90[deg]. Disconnect the P2 
pressure side of the probe and read the pressure P1-
Pbar and record as the static pressure. (Note: The spherical 
probe, specified in section 6.1.2 of Method 2F, is unable to provide 
this measurement and shall not be used to take static pressure 
measurements.)
    8.12 Atmospheric Pressure. Determine the atmospheric pressure at the 
sampling elevation during each test run following the procedure 
described in section 2.5 of Method 2.
    8.13 Molecular Weight. Determine the stack or duct gas dry molecular 
weight. For combustion processes or processes that emit essentially 
CO2, O2, CO, and N2, use Method 3 or 
3A. For processes emitting essentially air, an analysis need not be 
conducted; use a dry molecular weight of 29.0. Other methods may be 
used, if approved by the Administrator.
    8.14 Moisture. Determine the moisture content of the stack gas using 
Method 4 or equivalent.
    8.15 Data Recording and Calculations. Record all required data on a 
form similar to Table 2G-3.
    8.15.1 2-D probe calibration coefficient. When a Type S pitot tube 
is used in the field, the appropriate calibration coefficient as 
determined in section 10.6 shall be used to perform velocity 
calculations. For calibrated Type S pitot tubes, the A-side coefficient 
shall be used when the A-side of the tube faces the flow, and the B-side 
coefficient shall be used when the B-side faces the flow.
    8.15.2 3-D calibration coefficient. When a 3-D probe is used to 
collect data with this method, follow the provisions for the calibration 
of 3-D probes in section 10.6 of Method 2F to obtain the appropriate 
velocity calibration coefficient (F2 as derived using 
Equation 2F-2 in Method 2F) corresponding to a pitch angle position of 
0[deg].
    8.15.3 Calculations. Calculate the yaw-adjusted velocity at each 
traverse point using the equations presented in section 12.2. Calculate 
the test run average stack gas velocity by finding the arithmetic 
average of the point velocity results in accordance with sections 12.3 
and 12.4, and calculate the stack gas volumetric flow rate in accordance 
with section 12.5 or 12.6, as applicable.

                           9.0 Quality Control

    9.1 Quality Control Activities. In conjunction with the yaw angle 
determination and the pressure and temperature measurements specified in 
section 8.9, the following quality control checks should be performed.
    9.1.1 Range of the differential pressure gauge. In accordance with 
the specifications in section 6.4, ensure that the proper differential 
pressure gauge is being used for the range of [Delta]P values 
encountered. If it is necessary to change to a more sensitive gauge, 
replace the gauge with a gauge calibrated according to section 10.3.3, 
perform the leak check described in section 8.4 and the zero check 
described in section 8.5, and repeat the differential pressure and 
temperature readings at each traverse point.
    9.1.2 Horizontal stability check. For horizontal traverses of a 
stack or duct, visually check that the probe shaft is maintained in a 
horizontal position prior to taking a pressure reading. Periodically, 
during a test run, the probe's horizontal stability should be verified 
by placing a carpenter's level, a digital inclinometer, or other angle-
measuring device on the portion of the probe sheath that extends outside 
of the test port. A comparable check should be performed by automated 
systems.

                            10.0 Calibration

    10.1 Wind Tunnel Qualification Checks. To qualify for use in 
calibrating probes, a wind tunnel shall have the design features 
specified in section 6.11 and satisfy the following qualification 
criteria. The velocity pressure cross-check in section 10.1.1 and axial 
flow verification in section 10.1.2 shall be performed before the 
initial use of the wind tunnel and repeated immediately after any 
alteration occurs in the wind tunnel's configuration, fans, interior 
surfaces, straightening vanes, controls, or other properties that could 
reasonably be expected to alter the flow pattern or velocity stability 
in the tunnel. The owner or operator of a wind tunnel used to calibrate 
probes according to this method shall maintain records documenting that 
the wind tunnel meets the requirements of sections 10.1.1 and 10.1.2 and 
shall provide these records to the Administrator upon request.
    10.1.1 Velocity pressure cross-check. To verify that the wind tunnel 
produces the same velocity at the tested probe head as at the 
calibration pitot tube impact port, perform the following cross-check. 
Take three differential pressure measurements at the fixed calibration 
pitot tube location, using the calibration pitot tube specified in 
section 6.10, and take three measurements with the calibration pitot 
tube at the wind tunnel calibration location, as defined in section 
3.21. Alternate the measurements between the two positions. Perform this 
procedure at

[[Page 101]]

the lowest and highest velocity settings at which the probes will be 
calibrated. Record the values on a form similar to Table 2G-4. At each 
velocity setting, the average velocity pressure obtained at the wind 
tunnel calibration location shall be within 2 
percent or 2.5 mm H2O (0.01 in. H2O), whichever is 
less restrictive, of the average velocity pressure obtained at the fixed 
calibration pitot tube location. This comparative check shall be 
performed at 2.5-cm (1-in.), or smaller, intervals across the full 
length, width, and depth (if applicable) of the wind tunnel calibration 
location. If the criteria are not met at every tested point, the wind 
tunnel calibration location must be redefined, so that acceptable 
results are obtained at every point. Include the results of the velocity 
pressure cross-check in the calibration data section of the field test 
report. (See section 16.1.4.)
    10.1.2 Axial flow verification. The following procedures shall be 
performed to demonstrate that there is fully developed axial flow within 
the wind tunnel calibration location and at the calibration pitot tube 
location. Two options are available to conduct this check.
    10.1.2.1 Using a calibrated 3-D probe. A probe that has been 
previously calibrated in a wind tunnel with documented axial flow (as 
defined in section 3.22) may be used to conduct this check. Insert the 
calibrated 3-D probe into the wind tunnel test section using the tested 
probe port. Following the procedures in sections 8.9 and 12.2 of Method 
2F, determine the yaw and pitch angles at all the point(s) in the test 
section where the velocity pressure cross-check, as specified in section 
10.1.1, is performed. This includes all the points in the calibration 
location and the point where the calibration pitot tube will be located. 
Determine the yaw and pitch angles at each point. Repeat these 
measurements at the highest and lowest velocities at which the probes 
will be calibrated. Record the values on a form similar to Table 2G-5. 
Each measured yaw and pitch angle shall be within 3[deg] of 0[deg]. Exceeding the limits indicates 
unacceptable flow in the test section. Until the problem is corrected 
and acceptable flow is verified by repetition of this procedure, the 
wind tunnel shall not be used for calibration of probes. Include the 
results of the axial flow verification in the calibration data section 
of the field test report. (See section 16.1.4.)
    10.1.2.2 Using alternative probes. Axial flow verification may be 
performed using an uncalibrated prism-shaped 3-D probe (e.g., DA or DAT 
probe) or an uncalibrated wedge probe. (Figure 2G-8 illustrates a 
typical wedge probe.) This approach requires use of two ports: the 
tested probe port and a second port located 90[deg] from the tested 
probe port. Each port shall provide access to all the points within the 
wind tunnel test section where the velocity pressure cross-check, as 
specified in section 10.1.1, is conducted. The probe setup shall include 
establishing a reference yaw-null position on the probe sheath to serve 
as the location for installing the angle-measuring device. Physical 
design features of the DA, DAT, and wedge probes are relied on to 
determine the reference position. For the DA or DAT probe, this 
reference position can be determined by setting a digital inclinometer 
on the flat facet where the P1 pressure port is located and 
then identifying the rotational position on the probe sheath where a 
second angle-measuring device would give the same angle reading. The 
reference position on a wedge probe shaft can be determined either 
geometrically or by placing a digital inclinometer on each side of the 
wedge and rotating the probe until equivalent readings are obtained. 
With the latter approach, the reference position is the rotational 
position on the probe sheath where an angle-measuring device would give 
a reading of 0[deg]. After installation of the angle-measuring device in 
the reference yaw-null position on the probe sheath, determine the yaw 
angle from the tested port. Repeat this measurement using the 90[deg] 
offset port, which provides the pitch angle of flow. Determine the yaw 
and pitch angles at all the point(s) in the test section where the 
velocity pressure cross-check, as specified in section 10.1.1, is 
performed. This includes all the points in the wind tunnel calibration 
location and the point where the calibration pitot tube will be located. 
Perform this check at the highest and lowest velocities at which the 
probes will be calibrated. Record the values on a form similar to Table 
2G-5. Each measured yaw and pitch angle shall be within 3[deg] of 0[deg]. Exceeding the limits indicates 
unacceptable flow in the test section. Until the problem is corrected 
and acceptable flow is verified by repetition of this procedure, the 
wind tunnel shall not be used for calibration of probes. Include the 
results in the probe calibration report.
    10.1.3 Wind tunnel audits.
    10.1.3.1 Procedure. Upon the request of the Administrator, the owner 
or operator of a wind tunnel shall calibrate a 2-D audit probe in 
accordance with the procedures described in sections 10.3 through 10.6. 
The calibration shall be performed at two velocities that encompass the 
velocities typically used for this method at the facility. The resulting 
calibration data shall be submitted to the Agency in an audit test 
report. These results shall be compared by the Agency to reference 
calibrations of the audit probe at the same velocity settings obtained 
at two different wind tunnels.
    10.1.3.2 Acceptance criterion. The audited tunnel's calibration 
coefficient is acceptable if it is within 3 
percent of the reference calibrations obtained at each velocity setting 
by

[[Page 102]]

one (or both) of the wind tunnels. If the acceptance criterion is not 
met at each calibration velocity setting, the audited wind tunnel shall 
not be used to calibrate probes for use under this method until the 
problems are resolved and acceptable results are obtained upon 
completion of a subsequent audit.
    10.2 Probe Inspection.
    10.2.1 Type S probe. Before each calibration of a Type S probe, 
verify that one leg of the tube is permanently marked A, and the other, 
B. Carefully examine the pitot tube from the top, side, and ends. 
Measure the angles ([alpha]1, [alpha]2, 
[beta]1, and [beta]2) and the dimensions (w and z) 
illustrated in Figures 2-2 and 2-3 in Method 2. Also measure the 
dimension A, as shown in the diagram in Table 2G-1, and the external 
tubing diameter (dimension Dt, Figure 2-2b in Method 2). For 
the purposes of this method, Dt shall be no less than 9.5 mm 
(\3/8\ in.). The base-to-opening plane distances PA and 
PB in Figure 2-3 of Method 2 shall be equal, and the 
dimension A in Table 2G-1 should be between 2.10Dt and 
3.00Dt. Record the inspection findings and probe measurements 
on a form similar to Table CD2-1 of the ``Quality Assurance Handbook for 
Air Pollution Measurement Systems: Volume III, Stationary Source-
Specific Methods'' (EPA/600/R-94/038c, September 1994). For reference, 
this form is reproduced herein as Table 2G-1. The pitot tube shall not 
be used under this method if it fails to meet the specifications in this 
section and the alignment specifications in section 6.1.1. All Type S 
probes used to collect data with this method shall be calibrated 
according to the procedures outlined in sections 10.3 through 10.6 
below. During calibration, each Type S pitot tube shall be configured in 
the same manner as used, or planned to be used, during the field test, 
including all components in the probe assembly (e.g., thermocouple, 
probe sheath, sampling nozzle). Probe shaft extensions that do not 
affect flow around the probe head need not be attached during 
calibration.
    10.2.2 3-D probe. If a 3-D probe is used to collect data with this 
method, perform the pre-calibration inspection according to procedures 
in Method 2F, section 10.2.
    10.3 Pre-Calibration Procedures. Prior to calibration, a scribe line 
shall have been placed on the probe in accordance with section 10.4. The 
yaw angle and velocity calibration procedures shall not begin until the 
pre-test requirements in sections 10.3.1 through 10.3.4 have been met.
    10.3.1 Perform the horizontal straightness check described in 
section 8.2 on the probe assembly that will be calibrated in the wind 
tunnel.
    10.3.2 Perform a leak check in accordance with section 8.4.
    10.3.3 Except as noted in section 10.3.3.3, calibrate all 
differential pressure-measuring devices to be used in the probe 
calibrations, using the following procedures. At a minimum, calibrate 
these devices on each day that probe calibrations are performed.
    10.3.3.1 Procedure. Before each wind tunnel use, all differential 
pressure-measuring devices shall be calibrated against the reference 
device specified in section 6.4.3 using a common pressure source. 
Perform the calibration at three reference pressures representing 30, 
60, and 90 percent of the full-scale range of the pressure-measuring 
device being calibrated. For an inclined-vertical manometer, perform 
separate calibrations on the inclined and vertical portions of the 
measurement scale, considering each portion of the scale to be a 
separate full-scale range. [For example, for a manometer with a 0-to 
2.5-cm H2O (0-to 1-in. H2O) inclined scale and a 
2.5-to 12.7-cm H2O (1-to 5-in. H2O) vertical 
scale, calibrate the inclined portion at 7.6, 15.2, and 22.9 mm 
H2O (0.3, 0.6, and 0.9 in. H2O), and calibrate the 
vertical portion at 3.8, 7.6, and 11.4 cm H2O (1.5, 3.0, and 
4.5 in. H2O).] Alternatively, for the vertical portion of the 
scale, use three evenly spaced reference pressures, one of which is 
equal to or higher than the highest differential pressure expected in 
field applications.
    10.3.3.2 Acceptance criteria. At each pressure setting, the two 
pressure readings made using the reference device and the pressure-
measuring device being calibrated shall agree to within 2 percent of full scale of the device being calibrated 
or 0.5 mm H2O (0.02 in. H2O), whichever is less 
restrictive. For an inclined-vertical manometer, these requirements 
shall be met separately using the respective full-scale upper limits of 
the inclined and vertical portions of the scale. Differential pressure-
measuring devices not meeting the 2 percent of 
full scale or 0.5 mm H2O (0.02 in. H2O) 
calibration requirement shall not be used.
    10.3.3.3 Exceptions. Any precision manometer that meets the 
specifications for a reference device in section 6.4.3 and that is not 
used for field testing does not require calibration, but must be leveled 
and zeroed before each wind tunnel use. Any pressure device used 
exclusively for yaw nulling does not require calibration, but shall be 
checked for responsiveness to rotation of the probe prior to each wind 
tunnel use.
    10.3.4 Calibrate digital inclinometers on each day of wind tunnel or 
field testing (prior to beginning testing) using the following 
procedures. Calibrate the inclinometer according to the manufacturer's 
calibration procedures. In addition, use a triangular block (illustrated 
in Figure 2G-9) with a known angle [theta], independently determined 
using a protractor or equivalent device, between two adjacent sides to 
verify the inclinometer readings. (Note: If other angle-measuring 
devices meeting the provisions of

[[Page 103]]

section 6.2.3 are used in place of a digital inclinometer, comparable 
calibration procedures shall be performed on such devices.) Secure the 
triangular block in a fixed position. Place the inclinometer on one side 
of the block (side A) to measure the angle of inclination 
(R1). Repeat this measurement on the adjacent side of the 
block (side B) using the inclinometer to obtain a second angle reading 
(R2). The difference of the sum of the two readings from 
180[deg] (i.e., 180[deg]-R1-R2) shall be within 
2[deg] of the known angle, [theta].
    10.4 Placement of Reference Scribe Line. Prior to the first 
calibration of a probe, a line shall be permanently inscribed on the 
main probe sheath to serve as a reference mark for determining yaw 
angles. Annex C in section 18 of this method gives a guideline for 
placement of the reference scribe line.
    10.4.1 This reference scribe line shall meet the specifications in 
sections 6.1.5.1 and 6.1.5.3 of this method. To verify that the 
alignment specification in section 6.1.5.3 is met, secure the probe in a 
horizontal position and measure the rotational angle of each scribe line 
and scribe line segment using an angle-measuring device that meets the 
specifications in section 6.2.1 or 6.2.3. For any scribe line that is 
longer than 30.5 cm (12 in.), check the line's rotational position at 
30.5-cm (12-in.) intervals. For each line segment that is 12 in. or less 
in length, check the rotational position at the two endpoints of the 
segment. To meet the alignment specification in section 6.1.5.3, the 
minimum and maximum of all of the rotational angles that are measured 
along the full length of main probe must not differ by more than 2[deg]. 
(Note: A short reference scribe line segment [e.g., 15.2 cm (6 in.) or 
less in length] meeting the alignment specifications in section 6.1.5.3 
is fully acceptable under this method. See section 18.1.1.1 of Annex A 
for an example of a probe marking procedure, suitable for use with a 
short reference scribe line.)
    10.4.2 The scribe line should be placed on the probe first and then 
its offset from the yaw-null position established (as specified in 
section 10.5). The rotational position of the reference scribe line 
relative to the yaw-null position of the probe, as determined by the yaw 
angle calibration procedure in section 10.5, is the reference scribe 
line rotational offset, RSLO. The reference scribe line 
rotational offset shall be recorded and retained as part of the probe's 
calibration record.
    10.4.3 Scribe line for automated probes. A scribe line may not be 
necessary for an automated probe system if a reference rotational 
position of the probe is built into the probe system design. For such 
systems, a ``flat'' (or comparable, clearly identifiable physical 
characteristic) should be provided on the probe casing or flange plate 
to ensure that the reference position of the probe assembly remains in a 
vertical or horizontal position. The rotational offset of the flat (or 
comparable, clearly identifiable physical characteristic) needed to 
orient the reference position of the probe assembly shall be recorded 
and maintained as part of the automated probe system's specifications.
    10.5 Yaw Angle Calibration Procedure. For each probe used to measure 
yaw angles with this method, a calibration procedure shall be performed 
in a wind tunnel meeting the specifications in section 10.1 to determine 
the rotational position of the reference scribe line relative to the 
probe's yaw-null position. This procedure shall be performed on the main 
probe with all devices that will be attached to the main probe in the 
field [such as thermocouples, resistance temperature detectors (RTDs), 
or sampling nozzles] that may affect the flow around the probe head. 
Probe shaft extensions that do not affect flow around the probe head 
need not be attached during calibration. At a minimum, this procedure 
shall include the following steps.
    10.5.1 Align and lock the angle-measuring device on the reference 
scribe line. If a marking procedure (such as described in section 
18.1.1.1) is used, align the angle-measuring device on a mark within 
1[deg] of the rotational position of the reference 
scribe line. Lock the angle-measuring device onto the probe sheath at 
this position.
    10.5.2 Zero the pressure-measuring device used for yaw nulling.
    10.5.3 Insert the probe assembly into the wind tunnel through the 
entry port, positioning the probe's impact port at the calibration 
location. Check the responsiveness of the pressure-measurement device to 
probe rotation, taking corrective action if the response is 
unacceptable.
    10.5.4 Ensure that the probe is in a horizontal position, using a 
carpenter's level.
    10.5.5 Rotate the probe either clockwise or counterclockwise until a 
yaw null [zero [Delta]P for a Type S probe or zero (P2-
P3) for a 3-D probe] is obtained. If using a Type S probe 
with an attached thermocouple, the direction of the probe rotation shall 
be such that the thermocouple is located downstream of the probe 
pressure ports at the yaw-null position.
    10.5.6 Use the reading displayed by the angle-measuring device at 
the yaw-null position to determine the magnitude of the reference scribe 
line rotational offset, RSLO, as defined in section 3.15. 
Annex D in section 18 of this method gives a recommended procedure for 
determining the magnitude of RSLO with a digital inclinometer 
and a second procedure for determining the magnitude of RSLO 
with a protractor wheel and pointer device. Table 2G-6 gives an example 
data form and Table 2G-7 is a look-up table with the recommended 
procedure. Procedures other than those recommended in Annex D in section 
18 may be used, if they can determine RSLO to within 1[deg] 
and are explained in detail

[[Page 104]]

in the field test report. The algebraic sign of RSLO will 
either be positive if the rotational position of the reference scribe 
line (as viewed from the ``tail'' end of the probe) is clockwise, or 
negative, if counterclockwise with respect to the probe's yaw-null 
position. (This is illustrated in Figure 2G-10.)
    10.5.7 The steps in sections 10.5.3 through 10.5.6 shall be 
performed twice at each of the velocities at which the probe will be 
calibrated (in accordance with section 10.6). Record the values of 
RSLO.
    10.5.8 The average of all of the RSLO values shall be 
documented as the reference scribe line rotational offset for the probe.
    10.5.9 Use of reference scribe line offset. The reference scribe 
line rotational offset shall be used to determine the yaw angle of flow 
in accordance with section 8.9.4.
    10.6 Velocity Calibration Procedure. When a 3-D probe is used under 
this method, follow the provisions for the calibration of 3-D probes in 
section 10.6 of Method 2F to obtain the necessary velocity calibration 
coefficients (F2 as derived using Equation 2F-2 in Method 2F) 
corresponding to a pitch angle position of 0[deg]. The following 
procedure applies to Type S probes. This procedure shall be performed on 
the main probe and all devices that will be attached to the main probe 
in the field (e.g., thermocouples, RTDs, sampling nozzles) that may 
affect the flow around the probe head. Probe shaft extensions that do 
not affect flow around the probe head need not be attached during 
calibration. (Note: If a sampling nozzle is part of the assembly, two 
additional requirements must be satisfied before proceeding. The 
distance between the nozzle and the pitot tube shall meet the minimum 
spacing requirement prescribed in Method 2, and a wind tunnel 
demonstration shall be performed that shows the probe's ability to yaw 
null is not impaired when the nozzle is drawing sample.) To obtain 
velocity calibration coefficient(s) for the tested probe, proceed as 
follows.
    10.6.1 Calibration velocities. The tester may calibrate the probe at 
two nominal wind tunnel velocity settings of 18.3 m/sec and 27.4 m/sec 
(60 ft/sec and 90 ft/sec) and average the results of these calibrations, 
as described in sections 10.6.12 through 10.6.14, in order to generate 
the calibration coefficient, Cp. If this option is selected, 
this calibration coefficient may be used for all field applications 
where the velocities are 9.1 m/sec (30 ft/sec) or greater. 
Alternatively, the tester may customize the probe calibration for a 
particular field test application (or for a series of applications), 
based on the expected average velocity(ies) at the test site(s). If this 
option is selected, generate the calibration coefficients by calibrating 
the probe at two nominal wind tunnel velocity settings, one of which is 
less than or equal to and the other greater than or equal to the 
expected average velocity(ies) for the field application(s), and average 
the results as described in sections 10.6.12 through 10.6.14. Whichever 
calibration option is selected, the probe calibration coefficient(s) 
obtained at the two nominal calibration velocities shall meet the 
conditions specified in sections 10.6.12 through 10.6.14.
    10.6.2 Connect the tested probe and calibration pitot tube to their 
respective pressure-measuring devices. Zero the pressure-measuring 
devices. Inspect and leak-check all pitot lines; repair or replace them, 
if necessary. Turn on the fan, and allow the wind tunnel air flow to 
stabilize at the first of the selected nominal velocity settings.
    10.6.3 Position the calibration pitot tube at its measurement 
location (determined as outlined in section 6.11.4.3), and align the 
tube so that its tip is pointed directly into the flow. Ensure that the 
entry port surrounding the tube is properly sealed. The calibration 
pitot tube may either remain in the wind tunnel throughout the 
calibration, or be removed from the wind tunnel while measurements are 
taken with the probe being calibrated.
    10.6.4 Check the zero setting of each pressure-measuring device.
    10.6.5 Insert the tested probe into the wind tunnel and align it so 
that the designated pressure port (e.g., either the A-side or B-side of 
a Type S probe) is pointed directly into the flow and is positioned 
within the wind tunnel calibration location (as defined in section 
3.21). Secure the probe at the 0[deg] pitch angle position. Ensure that 
the entry port surrounding the probe is properly sealed.
    10.6.6 Read the differential pressure from the calibration pitot 
tube ([Delta]Pstd), and record its value. Read the barometric 
pressure to within 2.5 mm Hg (0.1 in. Hg) and the temperature in the wind tunnel to 
within 0.6[deg]C (1[deg]F). Record these values on a data form similar 
to Table 2G-8.
    10.6.7 After the tested probe's differential pressure gauges have 
had sufficient time to stabilize, yaw null the probe (and then rotate it 
back 90[deg] for Type S probes), then obtain the differential pressure 
reading ([Delta]P). Record the yaw angle and differential pressure 
readings.
    10.6.8 Take paired differential pressure measurements with the 
calibration pitot tube and tested probe (according to sections 10.6.6 
and 10.6.7). The paired measurements in each replicate can be made 
either simultaneously (i.e., with both probes in the wind tunnel) or by 
alternating the measurements of the two probes (i.e., with only one 
probe at a time in the wind tunnel).
    10.6.9 Repeat the steps in sections 10.6.6 through 10.6.8 at the 
same nominal velocity setting until three pairs of [Delta]P readings 
have been obtained from the calibration pitot tube and the tested probe.

[[Page 105]]

    10.6.10 Repeat the steps in sections 10.6.6 through 10.6.9 above for 
the A-side and B-side of the Type S pitot tube. For a probe assembly 
constructed such that its pitot tube is always used in the same 
orientation, only one side of the pitot tube need be calibrated (the 
side that will face the flow). However, the pitot tube must still meet 
the alignment and dimension specifications in section 6.1.1 and must 
have an average deviation ([sigma]) value of 0.01 or less as provided in 
section 10.6.12.4.
    10.6.11 Repeat the calibration procedures in sections 10.6.6 through 
10.6.10 at the second selected nominal wind tunnel velocity setting.
    10.6.12 Perform the following calculations separately on the A-side 
and B-side values.
    10.6.12.1 Calculate a Cp value for each of the three 
replicates performed at the lower velocity setting where the 
calibrations were performed using Equation 2-2 in section 4.1.4 of 
Method 2.
    10.6.12.2 Calculate the arithmetic average, Cp(avg-low), 
of the three Cp values.
    10.6.12.3 Calculate the deviation of each of the three individual 
values of Cp from the A-side average Cp(avg-low) 
value using Equation 2-3 in Method 2.
    10.6.12.4 Calculate the average deviation ([sigma]) of the three 
individual Cp values from Cp(avg-low) using 
Equation 2-4 in Method 2. Use the Type S pitot tube only if the values 
of [sigma] (side A) and [sigma] (side B) are less than or equal to 0.01. 
If both A-side and B-side calibration coefficients are calculated, the 
absolute value of the difference between Cp(avg-low) (side A) 
and Cp(avg-low) (side B) must not exceed 0.01.
    10.6.13 Repeat the calculations in section 10.6.12 using the data 
obtained at the higher velocity setting to derive the arithmetic 
Cp values at the higher velocity setting, 
Cp(avg-high), and to determine whether the conditions in 
10.6.12.4 are met by both the A-side and B-side calibrations at this 
velocity setting.
    10.6.14 Use equation 2G-1 to calculate the percent difference of the 
averaged Cp values at the two calibration velocities.
[GRAPHIC] [TIFF OMITTED] TR14MY99.062

The percent difference between the averaged Cp values shall 
not exceed 3 percent. If the specification is met, 
average the A-side values of Cp(avg-low) and 
Cp(avg-high) to produce a single A-side calibration 
coefficient, Cp. Repeat for the B-side values if calibrations 
were performed on that side of the pitot. If the specification is not 
met, make necessary adjustments in the selected velocity settings and 
repeat the calibration procedure until acceptable results are obtained.
    10.6.15 If the two nominal velocities used in the calibration were 
18.3 and 27.4 m/sec (60 and 90 ft/sec), the average Cp from 
section 10.6.14 is applicable to all velocities 9.1 m/sec (30 ft/sec) or 
greater. If two other nominal velocities were used in the calibration, 
the resulting average Cp value shall be applicable only in 
situations where the velocity calculated using the calibration 
coefficient is neither less than the lower nominal velocity nor greater 
than the higher nominal velocity.
    10.7 Recalibration. Recalibrate the probe using the procedures in 
section 10 either within 12 months of its first field use after its most 
recent calibration or after 10 field tests (as defined in section 3.3), 
whichever occurs later. In addition, whenever there is visible damage to 
the probe head, the probe shall be recalibrated before it is used again.
    10.8 Calibration of pressure-measuring devices used in the field. 
Before its initial use in a field test, calibrate each pressure-
measuring device (except those used exclusively for yaw nulling) using 
the three-point calibration procedure described in section 10.3.3. The 
device shall be recalibrated according to the procedure in section 
10.3.3 no later than 90 days after its first field use following its 
most recent calibration. At the discretion of the tester, more frequent 
calibrations (e.g., after a field test) may be performed. No 
adjustments, other than adjustments to the zero setting, shall be made 
to the device between calibrations.
    10.8.1 Post-test calibration check. A single-point calibration check 
shall be performed on each pressure-measuring device after completion of 
each field test. At the discretion of the tester, more frequent single-
point calibration checks (e.g., after one or more field test runs) may 
be performed. It is recommended that the post-test check be performed 
before leaving the field test site. The check shall be performed at a 
pressure between 50 and 90 percent of full scale by taking a common 
pressure reading with the tested probe and a reference pressure-
measuring device (as described in section 6.4.4) or by challenging the 
tested device with a reference pressure source (as described in section 
6.4.4) or by performing an equivalent check using a reference device 
approved by the Administrator.

[[Page 106]]

    10.8.2 Acceptance criterion. At the selected pressure setting, the 
pressure readings made using the reference device and the tested device 
shall agree to within 3 percent of full scale of 
the tested device or 0.8 mm H2O (0.03 in. H2O), 
whichever is less restrictive. If this specification is met, the test 
data collected during the field test are valid. If the specification is 
not met, all test data collected since the last successful calibration 
or calibration check are invalid and shall be repeated using a pressure-
measuring device with a current, valid calibration. Any device that 
fails the calibration check shall not be used in a field test until a 
successful recalibration is performed according to the procedures in 
section 10.3.3.
    10.9 Temperature Gauges. Same as Method 2, section 4.3. The 
alternative thermocouple calibration procedures outlined in Emission 
Measurement Center (EMC) Approved Alternative Method (ALT-011) 
``Alternative Method 2 Thermocouple Calibration Procedure'' may be 
performed. Temperature gauges shall be calibrated no more than 30 days 
prior to the start of a field test or series of field tests and 
recalibrated no more than 30 days after completion of a field test or 
series of field tests.
    10.10 Barometer. Same as Method 2, section 4.4. The barometer shall 
be calibrated no more than 30 days prior to the start of a field test or 
series of field tests.

                        11.0 Analytical Procedure

    Sample collection and analysis are concurrent for this method (see 
section 8.0).

                   12.0 Data Analysis and Calculations

    These calculations use the measured yaw angle and the differential 
pressure and temperature measurements at individual traverse points to 
derive the near-axial flue gas velocity (va(i)) at each of 
those points. The near-axial velocity values at all traverse points that 
comprise a full stack or duct traverse are then averaged to obtain the 
average near-axial stack or duct gas velocity (va(avg)).

                            12.1 Nomenclature

A=Cross-sectional area of stack or duct at the test port location, m \2\ 
(ft \2\).
Bws=Water vapor in the gas stream (from Method 4 or 
alternative), proportion by volume.
Cp=Pitot tube calibration coefficient, dimensionless.
F2(i)=3-D probe velocity coefficient at 0 pitch, applicable 
at traverse point i.
Kp=Pitot tube constant,
[GRAPHIC] [TIFF OMITTED] TR14MY99.063

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.064

for the English system.

Md=Molecular weight of stack or duct gas, dry basis (see 
section 8.13), g/g-mole (lb/lb-mole).
Ms=Molecular weight of stack or duct gas, wet basis, g/g-mole 
(lb/lb-mole).
[GRAPHIC] [TIFF OMITTED] TR14MY99.065

Pbar=Barometric pressure at velocity measurement site, mm Hg 
(in. Hg).
Pg=Stack or duct static pressure, mm H2O (in. 
H2O).
Ps=Absolute stack or duct pressure, mm Hg (in. Hg),
[GRAPHIC] [TIFF OMITTED] TR14MY99.066

Pstd=Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
13.6=Conversion from mm H2O (in. H2O) to mm Hg 
(in. Hg).
Qsd=Average dry-basis volumetric stack or duct gas flow rate 
corrected to standard conditions, dscm/hr (dscf/hr).
Qsw=Average wet-basis volumetric stack or duct gas flow rate 
corrected to standard conditions, wscm/hr (wscf/hr).
ts(i)=Stack or duct temperature, [deg]C ([deg]F), at traverse 
point i.
Ts(i)=Absolute stack or duct temperature, [deg]K ([deg]R), at 
traverse point i.
[GRAPHIC] [TIFF OMITTED] TR14MY99.067

for the metric system, and
[GRAPHIC] [TIFF OMITTED] TR14MY99.068

for the English system.

Ts(avg)=Average absolute stack or duct gas temperature across 
all traverse points.
Tstd=Standard absolute temperature, 293[deg]K (528[deg]R).
va(i)=Measured stack or duct gas impact velocity, m/sec (ft/
sec), at traverse point i.
va(avg)=Average near-axial stack or duct gas velocity, m/sec 
(ft/sec) across all traverse points.
[Delta]Pi=Velocity head (differential pressure) of stack or 
duct gas, mm H2O (in. H2O), applicable at traverse 
point i.
(P1-P2)=Velocity head (differential pressure) of 
stack or duct gas measured by a 3-D probe, mm H2O (in. 
H2O), applicable at traverse point i.
3,600=Conversion factor, sec/hr.
18.0=Molecular weight of water, g/g-mole (lb/lb-mole).

[[Page 107]]

[theta]y(i)=Yaw angle of the flow velocity vector, at 
traverse point i.
n=Number of traverse points.

    12.2 Traverse Point Velocity Calculations. Perform the following 
calculations from the measurements obtained at each traverse point.
    12.2.1 Selection of calibration coefficient. Select the calibration 
coefficient as described in section 10.6.1.
    12.2.2 Near-axial traverse point velocity. When using a Type S 
probe, use the following equation to calculate the traverse point near-
axial velocity (va(i)) from the differential pressure 
([Delta]Pi), yaw angle ([theta]y(i)), absolute 
stack or duct standard temperature (Ts(i)) measured at 
traverse point i, the absolute stack or duct pressure (Ps), 
and molecular weight (Ms).
[GRAPHIC] [TIFF OMITTED] TR14MY99.069

Use the following equation when using a 3-D probe.
[GRAPHIC] [TIFF OMITTED] TR14MY99.070

    12.2.3 Handling multiple measurements at a traverse point. For 
pressure or temperature devices that take multiple measurements at a 
traverse point, the multiple measurements (or where applicable, their 
square roots) may first be averaged and the resulting average values 
used in the equations above. Alternatively, the individual measurements 
may be used in the equations above and the resulting calculated values 
may then be averaged to obtain a single traverse point value. With 
either approach, all of the individual measurements recorded at a 
traverse point must be used in calculating the applicable traverse point 
value.
    12.3 Average Near-Axial Velocity in Stack or Duct. Use the reported 
traverse point near-axial velocity in the following equation.
[GRAPHIC] [TIFF OMITTED] TR14MY99.071

    12.4 Acceptability of Results. The acceptability provisions in 
section 12.4 of Method 2F apply to 3-D probes used under Method 2G. The 
following provisions apply to Type S probes. For Type S probes, the test 
results are acceptable and the calculated value of va(avg) 
may be reported as the average near-axial velocity for the test run if 
the conditions in either section 12.4.1 or 12.4.2 are met.
    12.4.1 The average calibration coefficient Cp used in 
Equation 2G-6 was generated at nominal velocities of 18.3 and 27.4 m/sec 
(60 and 90 ft/sec) and the value of va(avg) calculated using 
Equation 2G-8 is greater than or equal to 9.1 m/sec (30 ft/sec).
    12.4.2 The average calibration coefficient Cp used in 
Equation 2G-6 was generated at nominal velocities other than 18.3 or 
27.4 m/sec (60 or 90 ft/sec) and the value of va(avg) 
calculated using Equation 2G-8 is greater than or equal to the lower 
nominal velocity and less than or equal to the higher nominal velocity 
used to derive the average Cp.
    12.4.3 If the conditions in neither section 12.4.1 nor section 
12.4.2 are met, the test results obtained from Equation 2G-8 are not 
acceptable, and the steps in sections 12.2 and 12.3 must be repeated 
using an average calibration coefficient Cp that satisfies 
the conditions in section 12.4.1 or 12.4.2.
    12.5 Average Gas Volumetric Flow Rate in Stack or Duct (Wet Basis). 
Use the following equation to compute the average volumetric flow rate 
on a wet basis.

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    12.6 Average Gas Volumetric Flow Rate in Stack or Duct (Dry Basis). 
Use the following equation to compute the average volumetric flow rate 
on a dry basis.
[GRAPHIC] [TIFF OMITTED] TR14MY99.073

                   13.0 Method Performance [Reserved]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                             16.0 Reporting.

    16.1 Field Test Reports. Field test reports shall be submitted to 
the Agency according to applicable regulatory requirements. Field test 
reports should, at a minimum, include the following elements.
    16.1.1 Description of the source. This should include the name and 
location of the test site, descriptions of the process tested, a 
description of the combustion source, an accurate diagram of stack or 
duct cross-sectional area at the test site showing the dimensions of the 
stack or duct, the location of the test ports, and traverse point 
locations and identification numbers or codes. It should also include a 
description and diagram of the stack or duct layout, showing the 
distance of the test location from the nearest upstream and downstream 
disturbances and all structural elements (including breachings, baffles, 
fans, straighteners, etc.) affecting the flow pattern. If the source and 
test location descriptions have been previously submitted to the Agency 
in a document (e.g., a monitoring plan or test plan), referencing the 
document in lieu of including this information in the field test report 
is acceptable.
    16.1.2 Field test procedures. These should include a description of 
test equipment and test procedures. Testing conventions, such as 
traverse point numbering and measurement sequence (e.g., sampling from 
center to wall, or wall to center), should be clearly stated. Test port 
identification and directional reference for each test port should be 
included on the appropriate field test data sheets.
    16.1.3 Field test data.
    16.1.3.1 Summary of results. This summary should include the dates 
and times of testing, and the average near-axial gas velocity and the 
average flue gas volumetric flow results for each run and tested 
condition.
    16.1.3.2 Test data. The following values for each traverse point 
should be recorded and reported:

    (a) Differential pressure at traverse point i ([Delta]Pi)
    (b) Stack or duct temperature at traverse point i (ts(i))
    (c) Absolute stack or duct temperature at traverse point i 
(Ts(i))
    (d) Yaw angle at traverse point i ([theta]y(i))
    (e) Stack gas near-axial velocity at traverse point i 
(va(i))

    16.1.3.3 The following values should be reported once per run:

    (a) Water vapor in the gas stream (from Method 4 or alternative), 
proportion by volume (Bws), measured at the frequency 
specified in the applicable regulation
    (b) Molecular weight of stack or duct gas, dry basis (Md)
    (c) Molecular weight of stack or duct gas, wet basis (Ms)
    (d) Stack or duct static pressure (Pg)
    (e) Absolute stack or duct pressure (Ps)
    (f) Carbon dioxide concentration in the flue gas, dry basis 
(%d CO2)
    (g) Oxygen concentration in the flue gas, dry basis (%d 
O2)
    (h) Average near-axial stack or duct gas velocity 
(va(avg)) across all traverse points
    (i) Gas volumetric flow rate corrected to standard conditions, dry 
or wet basis as required by the applicable regulation (Qsd or 
Qsw)

    16.1.3.4 The following should be reported once per complete set of 
test runs:

    (a) Cross-sectional area of stack or duct at the test location (A)
    (b) Pitot tube calibration coefficient (Cp)
    (c) Measurement system response time (sec)
    (d) Barometric pressure at measurement site (Pbar)

    16.1.4 Calibration data. The field test report should include 
calibration data for all

[[Page 109]]

probes and test equipment used in the field test. At a minimum, the 
probe calibration data reported to the Agency should include the 
following:

    (a) Date of calibration
    (b) Probe type
    (c) Probe identification number(s) or code(s)
    (d) Probe inspection sheets
    (e) Pressure measurements and calculations used to obtain 
calibration coefficients in accordance with section 10.6 of this method
    (f) Description and diagram of wind tunnel used for the calibration, 
including dimensions of cross-sectional area and position and size of 
the test section
    (g) Documentation of wind tunnel qualification tests performed in 
accordance with section 10.1 of this method

    16.1.5 Quality assurance. Specific quality assurance and quality 
control procedures used during the test should be described.

                           17.0 Bibliography.

    (1) 40 CFR Part 60, Appendix A, Method 1--Sample and velocity 
traverses for stationary sources.
    (2) 40 CFR Part 60, Appendix A, Method 2--Determination of stack gas 
velocity and volumetric flow rate (Type S pitot tube) .
    (3) 40 CFR Part 60, Appendix A, Method 2F--Determination of stack 
gas velocity and volumetric flow rate with three-dimensional probes.
    (4) 40 CFR Part 60, Appendix A, Method 2H--Determination of stack 
gas velocity taking into account velocity decay near the stack wall.
    (5) 40 CFR Part 60, Appendix A, Method 3--Gas analysis for carbon 
dioxide, oxygen, excess air, and dry molecular weight.
    (6) 40 CFR Part 60, Appendix A, Method 3A--Determination of oxygen 
and carbon dioxide concentrations in emissions from stationary sources 
(instrumental analyzer procedure).
    (7) 40 CFR Part 60, Appendix A, Method 4--Determination of moisture 
content in stack gases.
    (8) Emission Measurement Center (EMC) Approved Alternative Method 
(ALT-011) ``Alternative Method 2 Thermocouple Calibration Procedure.''
    (9) Electric Power Research Institute, Interim Report EPRI TR-
106698, ``Flue Gas Flow Rate Measurement Errors,'' June 1996.
    (10) Electric Power Research Institute, Final Report EPRI TR-108110, 
``Evaluation of Heat Rate Discrepancy from Continuous Emission 
Monitoring Systems,'' August 1997.
    (11) Fossil Energy Research Corporation, Final Report, ``Velocity 
Probe Tests in Non-axial Flow Fields,'' November 1998, Prepared for the 
U.S. Environmental Protection Agency.
    (12) Fossil Energy Research Corporation, ``Additional Swirl Tunnel 
Tests: E-DAT and T-DAT Probes,'' February 24, 1999, Technical Memorandum 
Prepared for U.S. Environmental Protection Agency, P.O. No. 7W-1193-
NALX.
    (13) Massachusetts Institute of Technology, Report WBWT-TR-1317, 
``Calibration of Eight Wind Speed Probes Over a Reynolds Number Range of 
46,000 to 725,000 Per Foot, Text and Summary Plots,'' Plus appendices, 
October 15, 1998, Prepared for The Cadmus Group, Inc.
    (14) National Institute of Standards and Technology, Special 
Publication 250, ``NIST Calibration Services Users Guide 1991,'' Revised 
October 1991, U.S. Department of Commerce, p. 2.
    (15) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four Prandtl Probes, Four 
S-Type Probes, Four French Probes, Four Modified Kiel Probes,'' Prepared 
for the U.S. Environmental Protection Agency under IAG 
DW13938432-01-0.
    (16) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed In-strumentation, Five Autoprobes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
DW13938432-01-0.
    (17) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Eight Spherical Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG 
DW13938432-01-0.
    (18) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four DAT Probes, `` 
Prepared for the U.S. Environmental Protection Agency under IAG 
DW13938432-01-0.
    (19) Norfleet, S.K., ``An Evaluation of Wall Effects on Stack Flow 
Velocities and Related Overestimation Bias in EPA's Stack Flow Reference 
Methods,'' EPRI CEMS User's Group Meeting, New Orleans, Louisiana, May 
13-15, 1998.
    (20) Page, J.J., E.A. Potts, and R.T. Shigehara, ``3-D Pitot Tube 
Calibration Study,'' EPA Contract No. 68D10009, Work Assignment No. I-
121, March 11, 1993.
    (21) Shigehara, R.T., W.F. Todd, and W.S. Smith, ``Significance of 
Errors in Stack Sampling Measurements,'' Presented at the Annual Meeting 
of the Air Pollution Control Association, St. Louis, Missouri, June 
1419, 1970.
    (22) The Cadmus Group, Inc., May 1999, ``EPA Flow Reference Method 
Testing and Analysis: Findings Report,'' EPA/430-R-99-009.
    (23) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, DeCordova Steam 
Electric Station, Volume

[[Page 110]]

I: Test Description and Appendix A (Data Distribution Package),'' EPA/
430-R-98-015a.
    (24) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, Lake Hubbard Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-017a.
    (25) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Pennsylvania Electric Co., G.P.U. 
Genco Homer City Station: Unit 1, Volume I: Test Description and 
Appendix A (Data Distribution Package),'' EPA/430-R-98-018a.
    (26) The Cadmus Group, Inc., 1997, ``EPA Flow Reference Method 
Testing and Analysis: Wind Tunnel Experimental Results,'' EPA/430-R-97-
013.

                              18.0 Annexes

    Annex A, C, and D describe recommended procedures for meeting 
certain provisions in sections 8.3, 10.4, and 10.5 of this method. Annex 
B describes procedures to be followed when using the protractor wheel 
and pointer assembly to measure yaw angles, as provided under section 
8.9.1.
    18.1 Annex A--Rotational Position Check. The following are 
recommended procedures that may be used to satisfy the rotational 
position check requirements of section 8.3 of this method and to 
determine the angle-measuring device rotational offset 
(RADO).
    18.1.1 Rotational position check with probe outside stack. Where 
physical constraints at the sampling location allow full assembly of the 
probe outside the stack and insertion into the test port, the following 
procedures should be performed before the start of testing. Two angle-
measuring devices that meet the specifications in section 6.2.1 or 6.2.3 
are required for the rotational position check. An angle measuring 
device whose position can be independently adjusted (e.g., by means of a 
set screw) after being locked into position on the probe sheath shall 
not be used for this check unless the independent adjustment is set so 
that the device performs exactly like a device without the capability 
for independent adjustment. That is, when aligned on the probe such a 
device must give the same reading as a device that does not have the 
capability of being independently adjusted. With the fully assembled 
probe (including probe shaft extensions, if any) secured in a horizontal 
position, affix one yaw angle-measuring device to the probe sheath and 
lock it into position on the reference scribe line specified in section 
6.1.5.1. Position the second angle-measuring device using the procedure 
in section 18.1.1.1 or 18.1.1.2.
    18.1.1.1 Marking procedure. The procedures in this section should be 
performed at each location on the fully assembled probe where the yaw 
angle-measuring device will be mounted during the velocity traverse. 
Place the second yaw angle-measuring device on the main probe sheath (or 
extension) at the position where a yaw angle will be measured during the 
velocity traverse. Adjust the position of the second angle-measuring 
device until it indicates the same angle (1[deg]) 
as the reference device, and affix the second device to the probe sheath 
(or extension). Record the angles indicated by the two angle-measuring 
devices on a form similar to table 2G-2. In this position, the second 
angle-measuring device is considered to be properly positioned for yaw 
angle measurement. Make a mark, no wider than 1.6 mm (\1/16\ in.), on 
the probe sheath (or extension), such that the yaw angle-measuring 
device can be re-affixed at this same properly aligned position during 
the velocity traverse.
    18.1.1.2 Procedure for probe extensions with scribe lines. If, 
during a velocity traverse the angle-measuring device will be affixed to 
a probe extension having a scribe line as specified in section 6.1.5.2, 
the following procedure may be used to align the extension's scribe line 
with the reference scribe line instead of marking the extension as 
described in section 18.1.1.1. Attach the probe extension to the main 
probe. Align and lock the second angle-measuring device on the probe 
extension's scribe line. Then, rotate the extension until both measuring 
devices indicate the same angle (1[deg]). Lock the 
extension at this rotational position. Record the angles indicated by 
the two angle-measuring devices on a form similar to table 2G-2. An 
angle-measuring device may be aligned at any position on this scribe 
line during the velocity traverse, if the scribe line meets the 
alignment specification in section 6.1.5.3.
    18.1.1.3 Post-test rotational position check. If the fully assembled 
probe includes one or more extensions, the following check should be 
performed immediately after the completion of a velocity traverse. At 
the discretion of the tester, additional checks may be conducted after 
completion of testing at any sample port. Without altering the alignment 
of any of the components of the probe assembly used in the velocity 
traverse, secure the fully assembled probe in a horizontal position. 
Affix an angle-measuring device at the reference scribe line specified 
in section 6.1.5.1. Use the other angle-measuring device to check the 
angle at each location where the device was checked prior to testing. 
Record the readings from the two angle-measuring devices.
    18.1.2 Rotational position check with probe in stack. This section 
applies only to probes that, due to physical constraints, cannot be 
inserted into the test port as fully assembled with all necessary 
extensions needed to reach the inner-most traverse point(s).
    18.1.2.1 Perform the out-of-stack procedure in section 18.1.1 on the 
main probe and

[[Page 111]]

any attached extensions that will be initially inserted into the test 
port.
    18.1.2.2 Use the following procedures to perform additional 
rotational position check(s) with the probe in the stack, each time a 
probe extension is added. Two angle-measuring devices are required. The 
first of these is the device that was used to measure yaw angles at the 
preceding traverse point, left in its properly aligned measurement 
position. The second angle-measuring device is positioned on the added 
probe extension. Use the applicable procedures in section 18.1.1.1 or 
18.1.1.2 to align, adjust, lock, and mark (if necessary) the position of 
the second angle-measuring device to within 1[deg] 
of the first device. Record the readings of the two devices on a form 
similar to Table 2G-2.
    18.1.2.3 The procedure in section 18.1.2.2 should be performed at 
the first port where measurements are taken. The procedure should be 
repeated each time a probe extension is re-attached at a subsequent 
port, unless the probe extensions are designed to be locked into a 
mechanically fixed rotational position (e.g., through use of 
interlocking grooves), which can be reproduced from port to port as 
specified in section 8.3.5.2.
    18.2 Annex B--Angle Measurement Protocol for Protractor Wheel and 
Pointer Device. The following procedure shall be used when a protractor 
wheel and pointer assembly, such as the one described in section 6.2.2 
and illustrated in Figure 2G-5 is used to measure the yaw angle of flow. 
With each move to a new traverse point, unlock, re-align, and re-lock 
the probe, angle-pointer collar, and protractor wheel to each other. At 
each such move, particular attention is required to ensure that the 
scribe line on the angle pointer collar is either aligned with the 
reference scribe line on the main probe sheath or is at the rotational 
offset position established under section 8.3.1. The procedure consists 
of the following steps:
    18.2.1 Affix a protractor wheel to the entry port for the test probe 
in the stack or duct.
    18.2.2 Orient the protractor wheel so that the 0[deg] mark 
corresponds to the longitudinal axis of the stack or duct. For stacks, 
vertical ducts, or ports on the side of horizontal ducts, use a digital 
inclinometer meeting the specifications in section 6.2.1 to locate the 
0[deg] orientation. For ports on the top or bottom of horizontal ducts, 
identify the longitudinal axis at each test port and permanently mark 
the duct to indicate the 0[deg] orientation. Once the protractor wheel 
is properly aligned, lock it into position on the test port.
    18.2.3 Move the pointer assembly along the probe sheath to the 
position needed to take measurements at the first traverse point. Align 
the scribe line on the pointer collar with the reference scribe line or 
at the rotational offset position established under section 8.3.1. 
Maintaining this rotational alignment, lock the pointer device onto the 
probe sheath. Insert the probe into the entry port to the depth needed 
to take measurements at the first traverse point.
    18.2.4 Perform the yaw angle determination as specified in sections 
8.9.3 and 8.9.4 and record the angle as shown by the pointer on the 
protractor wheel. Then, take velocity pressure and temperature 
measurements in accordance with the procedure in section 8.9.5. Perform 
the alignment check described in section 8.9.6.
    18.2.5 After taking velocity pressure measurements at that traverse 
point, unlock the probe from the collar and slide the probe through the 
collar to the depth needed to reach the next traverse point.
    18.2.6 Align the scribe line on the pointer collar with the 
reference scribe line on the main probe or at the rotational offset 
position established under section 8.3.1. Lock the collar onto the 
probe.
    18.2.7 Repeat the steps in sections 18.2.4 through 18.2.6 at the 
remaining traverse points accessed from the current stack or duct entry 
port.
    18.2.8 After completing the measurement at the last traverse point 
accessed from a port, verify that the orientation of the protractor 
wheel on the test port has not changed over the course of the traverse 
at that port. For stacks, vertical ducts, or ports on the side of 
horizontal ducts, use a digital inclinometer meeting the specifications 
in section 6.2.1 to check the rotational position of the 0[deg] mark on 
the protractor wheel. For ports on the top or bottom of horizontal 
ducts, observe the alignment of the angle wheel 0[deg] mark relative to 
the permanent 0[deg] mark on the duct at that test port. If these 
observed comparisons exceed 2[deg] of 0[deg], all 
angle and pressure measurements taken at that port since the protractor 
wheel was last locked into position on the port shall be repeated.
    18.2.9 Move to the next stack or duct entry port and repeat the 
steps in sections 18.2.1 through 18.2.8.
    18.3 Annex C--Guideline for Reference Scribe Line Placement. Use of 
the following guideline is recommended to satisfy the requirements of 
section 10.4 of this method. The rotational position of the reference 
scribe line should be either 90[deg] or 180[deg] from the probe's impact 
pressure port. For Type-S probes, place separate scribe lines, on 
opposite sides of the probe sheath, if both the A and B sides of the 
pitot tube are to be used for yaw angle measurements.
    18.4 Annex D--Determination of Reference Scribe Line Rotational 
Offset. The following procedures are recommended for determining the 
magnitude and sign of a probe's reference scribe line rotational offset, 
RSLO. Separate procedures are provided for two types of 
angle-measuring devices:

[[Page 112]]

digital inclinometers and protractor wheel and pointer assemblies.
    18.4.1 Perform the following procedures on the main probe with all 
devices that will be attached to the main probe in the field [such as 
thermocouples, resistance temperature detectors (RTDs), or sampling 
nozzles] that may affect the flow around the probe head. Probe shaft 
extensions that do not affect flow around the probe head need not be 
attached during calibration.
    18.4.2 The procedures below assume that the wind tunnel duct used 
for probe calibration is horizontal and that the flow in the calibration 
wind tunnel is axial as determined by the axial flow verification check 
described in section 10.1.2. Angle-measuring devices are assumed to 
display angles in alternating 0[deg] to 90[deg] and 90[deg] to 0[deg] 
intervals. If angle-measuring devices with other readout conventions are 
used or if other calibration wind tunnel duct configurations are used, 
make the appropriate calculational corrections. For Type-S probes, 
calibrate the A-side and B-sides separately, using the appropriate 
scribe line (see section 18.3, above), if both the A and B sides of the 
pitot tube are to be used for yaw angle determinations.
    18.4.2.1 Position the angle-measuring device in accordance with one 
of the following procedures.
    18.4.2.1.1 If using a digital inclinometer, affix the calibrated 
digital inclinometer to the probe. If the digital inclinometer can be 
independently adjusted after being locked into position on the probe 
sheath (e.g., by means of a set screw), the independent adjustment must 
be set so that the device performs exactly like a device without the 
capability for independent adjustment. That is, when aligned on the 
probe the device must give the same readings as a device that does not 
have the capability of being independently adjusted. Either align it 
directly on the reference scribe line or on a mark aligned with the 
scribe line determined according to the procedures in section 18.1.1.1. 
Maintaining this rotational alignment, lock the digital inclinometer 
onto the probe sheath.
    18.4.2.1.2 If using a protractor wheel and pointer device, orient 
the protractor wheel on the test port so that the 0[deg] mark is aligned 
with the longitudinal axis of the wind tunnel duct. Maintaining this 
alignment, lock the wheel into place on the wind tunnel test port. Align 
the scribe line on the pointer collar with the reference scribe line or 
with a mark aligned with the reference scribe line, as determined under 
section 18.1.1.1. Maintaining this rotational alignment, lock the 
pointer device onto the probe sheath.
    18.4.2.2 Zero the pressure-measuring device used for yaw nulling.
    18.4.2.3 Insert the probe assembly into the wind tunnel through the 
entry port, positioning the probe's impact port at the calibration 
location. Check the responsiveness of the pressure-measuring device to 
probe rotation, taking corrective action if the response is 
unacceptable.
    18.4.2.4 Ensure that the probe is in a horizontal position using a 
carpenter's level.
    18.4.2.5 Rotate the probe either clockwise or counterclockwise until 
a yaw null [zero [Delta]P for a Type S probe or zero (P2-
P3) for a 3-D probe] is obtained. If using a Type S probe 
with an attached thermocouple, the direction of the probe rotation shall 
be such that the thermocouple is located downstream of the probe 
pressure ports at the yaw-null position.
    18.4.2.6 Read and record the value of [theta]null, the 
angle indicated by the angle-measuring device at the yaw-null position. 
Record the angle reading on a form similar to Table 2G-6. Do not 
associate an algebraic sign with this reading.
    18.4.2.7 Determine the magnitude and algebraic sign of the reference 
scribe line rotational offset, RSLO. The magnitude of 
RSLO will be equal to either [theta]null or 
(90[deg]-[theta]null), depending on the type of probe being 
calibrated and the type of angle-measuring device used. (See Table 2G-7 
for a summary.) The algebraic sign of RSLO will either be 
positive if the rotational position of the reference scribe line is 
clockwise or negative if counterclockwise with respect to the probe's 
yaw-null position. Figure 2G-10 illustrates how the magnitude and sign 
of RSLO are determined.
    18.4.2.8 Perform the steps in sections 18.3.2.3 through 18.3.2.7 
twice at each of the two calibration velocities selected for the probe 
under section 10.6. Record the values of RSLO in a form 
similar to Table 2G-6.
    18.4.2.9 The average of all RSLO values is the reference 
scribe line rotational offset for the probe.

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   Method 2H--Determination of Stack Gas Velocity Taking Into Account 
                   Velocity Decay Near the Stack Wall

                        1.0 Scope and Application

    1.1 This method is applicable in conjunction with Methods 2, 2F, and 
2G (40 CFR Part 60, Appendix A) to account for velocity decay near the 
wall in circular stacks and ducts.
    1.2 This method is not applicable for testing stacks and ducts less 
than 3.3 ft (1.0 m) in diameter.
    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 wall effects adjustment factor is determined. It is used to 
adjust the average stack gas velocity obtained under Method 2, 2F, or 2G 
of this appendix to take into account velocity decay near the stack or 
duct wall.
    2.2 The method contains two possible procedures: a calculational 
approach which derives an adjustment factor from velocity measurements 
and a default procedure which assigns a generic adjustment factor based 
on the construction of the stack or duct.
    2.2.1 The calculational procedure derives a wall effects adjustment 
factor from velocity measurements taken using Method 2, 2F, or 2G at 16 
(or more) traverse points specified under Method 1 of this appendix and 
a total of eight (or more) wall effects traverse points specified under 
this method. The calculational procedure based on velocity measurements 
is not applicable for horizontal circular ducts where build-up of 
particulate matter or other material in the bottom of the duct is 
present.
    2.2.2 A default wall effects adjustment factor of 0.9900 for brick 
and mortar stacks and 0.9950 for all other types of stacks and ducts may 
be used without taking wall effects measurements in a stack or duct.
    2.3 When the calculational procedure is conducted as part of a 
relative accuracy test audit (RATA) or other multiple-run test 
procedure, the wall effects adjustment factor derived from a single 
traverse (i.e., single RATA run) may be applied to all runs of the same 
RATA without repeating the wall effects measurements. Alternatively, 
wall effects adjustment factors may be derived for several traverses and 
an average wall effects adjustment factor applied to all runs of the 
same RATA.

                            3.0 Definitions.

    3.1 Complete wall effects traverse means a traverse in which 
measurements are taken at drem (see section 3.3) and at 1-in. 
intervals in each of the four Method 1 equal-area sectors closest to the 
wall, beginning not farther than 4 in. (10.2 cm) from the wall and 
extending either (1) across the entire width of the Method 1 equal-area 
sector or (2) for stacks or ducts where this width exceeds 12 in. (30.5 
cm) (i.e., stacks or ducts greater than or equal to 15.6 ft [4.8 m] in 
diameter), to a distance of not less than 12 in. (30.5 cm) from the 
wall. Note: Because this method specifies that measurements must be 
taken at whole number multiples of 1 in. from a stack or duct wall, for 
clarity numerical quantities in this method are expressed in English 
units followed by metric units in parentheses. To enhance readability, 
hyphenated terms such as ``1-in. intervals'' or ``1-in. incremented,'' 
are expressed in English units only.
    3.2 dlast Depending on context, dlast means either (1) the distance 
from the wall of the last 1-in. incremented wall effects traverse point 
or (2) the traverse point located at that distance (see Figure 2H-2).
    3.3 drem Depending on context, drem means either (1) the distance 
from the wall of the centroid of the area between dlast and the interior 
edge of the Method 1 equal-area sector closest to the wall or (2) the 
traverse point located at that distance (see Figure 2H-2).
    3.4 ``May,'' ``Must,'' ``Shall,'' ``Should,'' and the imperative 
form of verbs.
    3.4.1 ``May'' is used to indicate that a provision of this method is 
optional.
    3.4.2 ``Must,'' ``Shall,'' and the imperative form of verbs (such as 
``record'' or ``enter'') are used to indicate that a provision of this 
method is mandatory.
    3.4.3 ``Should'' is used to indicate that a provision of this method 
is not mandatory but is highly recommended as good practice.
    3.5 Method 1 refers to 40 CFR part 60, appendix A, ``Method 1--
Sample and velocity traverses for stationary sources.''
    3.6 Method 1 exterior equal-area sector and Method 1 equal-area 
sector closest to the wall mean any one of the four equal-area sectors 
that are closest to the wall for a circular stack or duct laid out in 
accordance with section 2.3.1 of Method 1 (see Figure 2H-1).
    3.7 Method 1 interior equal-area sector means any of the equal-area 
sectors other than the Method 1 exterior equal-area sectors (as defined 
in section 3.6) for a circular stack or duct laid out in accordance with 
section 2.3.1 of Method 1 (see Figure 2H-1).
    3.8 Method 1 traverse point and Method 1 equal-area traverse point 
mean a traverse point located at the centroid of an equal-area sector of 
a circular stack laid out in accordance with section 2.3.1 of Method 1.
    3.9 Method 2 refers to 40 CFR part 60, appendix A, ``Method 2--
Determination of stack gas velocity and volumetric flow rate (Type S 
pitot tube).''
    3.10 Method 2F refers to 40 CFR part 60, appendix A, ``Method 2F--
Determination of stack gas velocity and volumetric flow rate with three-
dimensional probes.''

[[Page 129]]

    3.11 Method 2G refers to 40 CFR part 60, appendix A, ``Method 2G--
Determination of stack gas velocity and volumetric flow rate with two-
dimensional probes.''
    3.12 1-in. incremented wall effects traverse point means any of the 
wall effects traverse points that are located at 1-in. intervals, i.e., 
traverse points d1 through dlast (see Figure 2H-2).
    3.13 Partial wall effects traverse means a traverse in which 
measurements are taken at fewer than the number of traverse points 
required for a ``complete wall effects traverse'' (as defined in section 
3.1), but are taken at a minimum of two traverse points in each Method 1 
equal-area sector closest to the wall, as specified in section 8.2.2.
    3.14 Relative accuracy test audit (RATA) is a field test procedure 
performed in a stack or duct in which a series of concurrent 
measurements of the same stack gas stream is taken by a reference method 
and an installed monitoring system. A RATA usually consists of series of 
9 to 12 sets of such concurrent measurements, each of which is referred 
to as a RATA run. In a volumetric flow RATA, each reference method run 
consists of a complete traverse of the stack or duct.
    3.15 Wall effects-unadjusted average velocity means the average 
stack gas velocity, not accounting for velocity decay near the wall, as 
determined in accordance with Method 2, 2F, or 2G for a Method 1 
traverse consisting of 16 or more points.
    3.16 Wall effects-adjusted average velocity means the average stack 
gas velocity, taking into account velocity decay near the wall, as 
calculated from measurements at 16 or more Method 1 traverse points and 
at the additional wall effects traverse points specified in this method.
    3.17 Wall effects traverse point means a traverse point located in 
accordance with sections 8.2.2 or 8.2.3 of this method.

                      4.0 Interferences [Reserved]

                               5.0 Safety

    5.1 This method may involve hazardous materials, operations, and 
equipment. This method does not purport to address all of the health and 
safety considerations associated with its use. It is the responsibility 
of the user of this method to establish appropriate health and safety 
practices and to determine the applicability of occupational health and 
safety regulatory requirements prior to performing this method.

                       6.0 Equipment and Supplies

    6.1 The provisions pertaining to equipment and supplies in the 
method that is used to take the traverse point measurements (i.e., 
Method 2, 2F, or 2G) are applicable under this method.

                  7.0 Reagents and Standards [Reserved]

                   8.0 Sample Collection and Analysis

    8.1 Default Wall Effects Adjustment Factors. A default wall effects 
adjustment factor of 0.9900 for brick and mortar stacks and 0.9950 for 
all other types of stacks and ducts may be used without conducting the 
following procedures.
    8.2 Traverse Point Locations. Determine the location of the Method 1 
traverse points in accordance with section 8.2.1 and the location of the 
traverse points for either a partial wall effects traverse in accordance 
with section 8.2.2 or a complete wall effects traverse in accordance 
with section 8.2.3.
    8.2.1 Method 1 equal-area traverse point locations. Determine the 
location of the Method 1 equal-area traverse points for a traverse 
consisting of 16 or more points using Table 1-2 (Location of Traverse 
Points in Circular Stacks) of Method 1.
    8.2.2 Partial wall effects traverse. For a partial wall effects 
traverse, measurements must be taken at a minimum of the following two 
wall effects traverse point locations in all four Method 1 equal-area 
sectors closest to the wall: (1) 1 in. (2.5 cm) from the wall (except as 
provided in section 8.2.2.1) and (2) drem, as determined 
using Equation 2H-1 or 2H-2 (see section 8.2.2.2).
    8.2.2.1 If the probe cannot be positioned at 1 in. (2.5 cm) from the 
wall (e.g., because of insufficient room to withdraw the probe shaft) or 
if velocity pressure cannot be detected at 1 in. (2.5 cm) from the wall 
(for any reason other than build-up of particulate matter in the bottom 
of a duct), take measurements at the 1-in. incremented wall effects 
traverse point closest to the wall where the probe can be positioned and 
velocity pressure can be detected.
    8.2.2.2 Calculate the distance of drem from the wall to 
within \1/4\ in. (6.4 mm) using Equation 2H-1 or 
Equation 2H-2 (for a 16-point traverse).
[GRAPHIC] [TIFF OMITTED] TR14MY99.074

Where:

r=the stack or duct radius determined from direct measurement of the 
stack or duct diameter in accordance with section 8.6 of Method 2F or 
Method 2G, in. (cm);
p=the number of Method 1 equal-area traverse points on a diameter, p 
= 8 (e.g., for a 16-point traverse, p=8); dlast and drem are 
defined in sections 3.2 and 3.3 respectively, in. (cm).

For a 16-point Method 1 traverse, Equation 2H-1 becomes:

[[Page 130]]

[GRAPHIC] [TIFF OMITTED] TR14MY99.075

    8.2.2.3 Measurements may be taken at any number of additional wall 
effects traverse points, with the following provisions.
    (a) dlast must not be closer to the center of the stack or duct than 
the distance of the interior edge (boundary), db, of the Method 1 equal-
area sector closest to the wall (see Figure 2H-2 or 2H-3). That is,

Where:
[GRAPHIC] [TIFF OMITTED] TR14MY99.076

Table 2H-1 shows db as a function of the stack or duct radius, r, for 
traverses ranging from 16 to 48 points (i.e., for values of p ranging 
from 8 to 24).
    (b) Each point must be located at a distance that is a whole number 
(e.g., 1, 2, 3) multiple of 1 in. (2.5 cm).
    (c) Points do not have to be located at consecutive 1-in. intervals. 
That is, one or more 1-in. incremented points may be skipped. For 
example, it would be acceptable for points to be located at 1 in. (2.5 
cm), 3 in. (7.6 cm), 5 in. (12.7 cm), dlast, and drem; or at 1 in. (2.5 
cm), 2 in. (5.1 cm), 4 in. (10.2 cm), 7 in. (17.8 cm), dlast, and drem. 
Follow the instructions in section 8.7.1.2 of this method for recording 
results for wall effects traverse points that are skipped. It should be 
noted that the full extent of velocity decay may not be accounted for if 
measurements are not taken at all 1-in. incremented points close to the 
wall.
    8.2.3 Complete wall effects traverse. For a complete wall effects 
traverse, measurements must be taken at the following points in all four 
Method 1 equal-area sectors closest to the wall.
    (a) The 1-in. incremented wall effects traverse point closest to the 
wall where the probe can be positioned and velocity can be detected, but 
no farther than 4 in. (10.2 cm) from the wall.
    (b) Every subsequent 1-in. incremented wall effects traverse point 
out to the interior edge of the Method 1 equal-area sector or to 12 in. 
(30.5 cm) from the wall, whichever comes first. Note: In stacks or ducts 
with diameters greater than 15.6 ft (4.8 m) the interior edge of the 
Method 1 equal-area sector is farther from the wall than 12 in. (30.5 
cm).
    (c) drem, as determined using Equation 2H-1 or 2H-2 (as 
applicable). Note: For a complete traverse of a stack or duct with a 
diameter less than 16.5 ft (5.0 m), the distance between drem 
and dlast is less than or equal to \1/2\ in. (12.7 mm). As 
discussed in section 8.2.4.2, when the distance between drem 
and dlast is less than or equal to \1/2\ in. (12.7 mm), the 
velocity measured at dlast may be used for drem. 
Thus, it is not necessary to calculate the distance of drem 
or to take measurements at drem when conducting a complete 
traverse of a stack or duct with a diameter less than 16.5 ft (5.0 m).
    8.2.4 Special considerations. The following special considerations 
apply when the distance between traverse points is less than or equal to 
\1/2\ in. (12.7 mm).
    8.2.4.1 A wall effects traverse point and the Method 1 traverse 
point. If the distance between a wall effects traverse point and the 
Method 1 traverse point is less than or equal to \1/2\ in. (12.7 mm), 
taking measurements at both points is allowed but not required or 
recommended; if measurements are taken at only one point, take the 
measurements at the point that is farther from the wall and use the 
velocity obtained at that point as the value for both points (see 
sections 8.2.3 and 9.2 for related requirements).
    8.2.4.2 drem and dlast. If the distance 
between drem and dlast is less than or equal to 
\1/2\ in. (12.7 mm), taking measurements at drem is allowed 
but not required or recommended; if measurements are not taken at 
drem, the measured velocity value at dlast must be 
used as the value for both dlast and drem.
    8.3 Traverse Point Sampling Order and Probe Selection. Determine the 
sampling order of the Method 1 and wall effects traverse points and 
select the appropriate probe for the measurements, taking into account 
the following considerations.
    8.3.1 Traverse points on any radius may be sampled in either 
direction (i.e., from the wall toward the center of the stack or duct, 
or vice versa).
    8.3.2 To reduce the likelihood of velocity variations during the 
time of the traverse and the attendant potential impact on the wall 
effects-adjusted and unadjusted average velocities, the following 
provisions of this method shall be met.
    8.3.2.1 Each complete set of Method 1 and wall effects traverse 
points accessed from the same port shall be sampled without 
interruption. Unless traverses are performed simultaneously in all ports 
using separate probes at each port, this provision disallows first 
sampling all Method 1 points at all ports and then sampling all the wall 
effects points.
    8.3.2.2 The entire integrated Method 1 and wall effects traverse 
across all test ports shall be as short as practicable, consistent with 
the measurement system response time

[[Page 131]]

(see section 8.4.1.1) and sampling (see section 8.4.1.2) provisions of 
this method.
    8.3.3 It is recommended but not required that in each Method 1 
equal-area sector closest to the wall, the Method 1 equal-area traverse 
point should be sampled in sequence between the adjacent wall effects 
traverse points. For example, for the traverse point configuration shown 
in Figure 2H-2, it is recommended that the Method 1 equal-area traverse 
point be sampled between dlast and drem. In this 
example, if the traverse is conducted from the wall toward the center of 
the stack or duct, it is recommended that measurements be taken at 
points in the following order: d1, d2, 
dlast, the Method 1 traverse point, drem, and then 
at the traverse points in the three Method 1 interior equal-area 
sectors.
    8.3.4 The same type of probe must be used to take measurements at 
all Method 1 and wall effects traverse points. However, different copies 
of the same type of probe may be used at different ports (e.g., Type S 
probe 1 at port A, Type S probe 2 at port B) or at different traverse 
points accessed from a particular port (e.g., Type S probe 1 for Method 
1 interior traverse points accessed from port A, Type S probe 2 for wall 
effects traverse points and the Method 1 exterior traverse point 
accessed from port A). The identification number of the probe used to 
obtain measurements at each traverse point must be recorded.
    8.4 Measurements at Method 1 and Wall Effects Traverse Points. 
Conduct measurements at Method 1 and wall effects traverse points in 
accordance with Method 2, 2F, or 2G and in accordance with the 
provisions of the following subsections (some of which are included in 
Methods 2F and 2G but not in Method 2), which are particularly important 
for wall effects testing.
    8.4.1 Probe residence time at wall effects traverse points. Due to 
the steep temperature and pressure gradients that can occur close to the 
wall, it is very important for the probe residence time (i.e., the total 
time spent at a traverse point) to be long enough to ensure collection 
of representative temperature and pressure measurements. The provisions 
of Methods 2F and 2G in the following subsections shall be observed.
    8.4.1.1 System response time. Determine the response time of each 
probe measurement system by inserting and positioning the ``cold'' probe 
(at ambient temperature and pressure) at any Method 1 traverse point. 
Read and record the probe differential pressure, temperature, and 
elapsed time at 15-second intervals until stable readings for both 
pressure and temperature are achieved. The response time is the longer 
of these two elapsed times. Record the response time.
    8.4.1.2 Sampling. At the start of testing in each port (i.e., after 
a probe has been inserted into the stack gas stream), allow at least the 
response time to elapse before beginning to take measurements at the 
first traverse point accessed from that port. Provided that the probe is 
not removed from the stack gas stream, measurements may be taken at 
subsequent traverse points accessed from the same test port without 
waiting again for the response time to elapse.
    8.4.2 Temperature measurement for wall effects traverse points. 
Either (1) take temperature measurements at each wall effects traverse 
point in accordance with the applicable provisions of Method 2, 2F, or 
2G; or (2) use the temperature measurement at the Method 1 traverse 
point closest to the wall as the temperature measurement for all the 
wall effects traverse points in the corresponding equal-area sector.
    8.4.3 Non-detectable velocity pressure at wall effects traverse 
points. If the probe cannot be positioned at a wall effects traverse 
point or if no velocity pressure can be detected at a wall effects 
point, measurements shall be taken at the first subsequent wall effects 
traverse point farther from the wall where velocity can be detected. 
Follow the instructions in section 8.7.1.2 of this method for recording 
results for wall effects traverse points where velocity pressure cannot 
be detected. It should be noted that the full extent of velocity decay 
may not be accounted for if measurements are not taken at the 1-in. 
incremented wall effects traverse points closest to the wall.
    8.5 Data Recording. For each wall effects and Method 1 traverse 
point where measurements are taken, record all pressure, temperature, 
and attendant measurements prescribed in section 3 of Method 2 or 
section 8.0 of Method 2F or 2G, as applicable.
    8.6 Point Velocity Calculation. For each wall effects and Method 1 
traverse point, calculate the point velocity value (vi) in accordance 
with sections 12.1 and 12.2 of Method 2F for tests using Method 2F and 
in accordance with sections 12.1 and 12.2 of Method 2G for tests using 
Method 2 and Method 2G. (Note that the term (vi) in this method 
corresponds to the term (va(i)) in Methods 2F and 2G.) When the 
equations in the indicated sections of Method 2G are used in deriving 
point velocity values for Method 2 tests, set the value of the yaw 
angles appearing in the equations to 0[deg].
    8.7 Tabulating Calculated Point Velocity Values for Wall Effects 
Traverse Points. Enter the following values in a hardcopy or electronic 
form similar to Form 2H-1 (for 16-point Method 1 traverses) or Form 2H-2 
(for Method 1 traverses consisting of more than 16 points). A separate 
form must be completed for each of the four Method 1 equal-area sectors 
that are closest to the wall.
    (a) Port ID (e.g., A, B, C, or D)
    (b) Probe type
    (c) Probe ID

[[Page 132]]

    (d) Stack or duct diameter in ft (m) (determined in accordance with 
section 8.6 of Method 2F or Method 2G)
    (e) Stack or duct radius in in. (cm)
    (f) Distance from the wall of wall effects traverse points at 1-in. 
intervals, in ascending order starting with 1 in. (2.5 cm) (column A of 
Form 2H-1 or 2H-2)
    (g) Point velocity values (vd) for 1-in. incremented traverse points 
(see section 8.7.1), including dlast (see section 8.7.2)
    (h) Point velocity value (vdrem) at drem (see section 8.7.3).
    8.7.1 Point velocity values at wall effects traverse points other 
than dlast. For every 1-in. incremented wall effects traverse point 
other than dlast, enter in column B of Form 2H-1 or 2H-2 either the 
velocity measured at the point (see section 8.7.1.1) or the velocity 
measured at the first subsequent traverse point farther from the wall 
(see section 8.7.1.2). A velocity value must be entered in column B of 
Form 2H-1 or 2H-2 for every 1-in. incremented traverse point from d1 
(representing the wall effects traverse point 1 in. [2.5 cm] from the 
wall) to dlast.
    8.7.1.1 For wall effects traverse points where the probe can be 
positioned and velocity pressure can be detected, enter the value 
obtained in accordance with section 8.6.
    8.7.1.2 For wall effects traverse points that were skipped [see 
section 8.2.2.3(c)] and for points where the probe cannot be positioned 
or where no velocity pressure can be detected, enter the value obtained 
at the first subsequent traverse point farther from the wall where 
velocity pressure was detected and measured and follow the entered value 
with a ``flag,'' such as the notation ``NM,'' to indicate that ``no 
measurements'' were actually taken at this point.
    8.7.2 Point velocity value at dlast. For dlast, enter in column B of 
Form 2H-1 or 2H-2 the measured value obtained in accordance with section 
8.6.
    8.7.3 Point velocity value (vdrem) at drem. Enter the point velocity 
value obtained at drem in column G of row 4a in Form 2H-1 or 2H-2. If 
the distance between drem and dlast is less than or equal to \1/2\ in. 
(12.7 mm), the measured velocity value at dlast may be used as the value 
at drem (see section 8.2.4.2).

                          9.0 Quality Control.

    9.1 Particulate Matter Build-up in Horizontal Ducts. Wall effects 
testing of horizontal circular ducts should be conducted only if build-
up of particulate matter or other material in the bottom of the duct is 
not present.
    9.2 Verifying Traverse Point Distances. In taking measurements at 
wall effects traverse points, it is very important for the probe impact 
pressure port to be positioned as close as practicable to the traverse 
point locations in the gas stream. For this reason, before beginning 
wall effects testing, it is important to calculate and record the 
traverse point positions that will be marked on each probe for each 
port, taking into account the distance that each port nipple (or probe 
mounting flange for automated probes) extends out of the stack and any 
extension of the port nipple (or mounting flange) into the gas stream. 
To ensure that traverse point positions are properly identified, the 
following procedures should be performed on each probe used.
    9.2.1 Manual probes. Mark the probe insertion distance of the wall 
effects and Method 1 traverse points on the probe sheath so that when a 
mark is aligned with the outside face of the stack port, the probe 
impact port is located at the calculated distance of the traverse point 
from the stack inside wall. The use of different colored marks is 
recommended for designating the wall effects and Method 1 traverse 
points. Before the first use of each probe, check to ensure that the 
distance of each mark from the center of the probe impact pressure port 
agrees with the previously calculated traverse point positions to within 
\1/4\ in. (6.4 mm).
    9.2.2 Automated probe systems. For automated probe systems that 
mechanically position the probe head at prescribed traverse point 
positions, activate the system with the probe assemblies removed from 
the test ports and sequentially extend the probes to the programmed 
location of each wall effects traverse point and the Method 1 traverse 
points. Measure the distance between the center of the probe impact 
pressure port and the inside of the probe assembly mounting flange for 
each traverse point. The measured distances must agree with the 
previously calculated traverse point positions to within \1/4\ in. (6.4 mm).
    9.3 Probe Installation. Properly sealing the port area is 
particularly important in taking measurements at wall effects traverse 
points. For testing involving manual probes, the area between the probe 
sheath and the port should be sealed with a tightly fitting flexible 
seal made of an appropriate material such as heavy cloth so that leakage 
is minimized. For automated probe systems, the probe assembly mounting 
flange area should be checked to verify that there is no leakage.
    9.4 Velocity Stability. This method should be performed only when 
the average gas velocity in the stack or duct is relatively constant 
over the duration of the test. If the average gas velocity changes 
significantly during the course of a wall effects test, the test results 
should be discarded.

                            10.0 Calibration

    10.1 The calibration coefficient(s) or curves obtained under Method 
2, 2F, or 2G and used to perform the Method 1 traverse are applicable 
under this method.

[[Page 133]]

                        11.0 Analytical Procedure

    11.1 Sample collection and analysis are concurrent for this method 
(see section 8).

                   12.0 Data Analysis and Calculations

    12.1 The following calculations shall be performed to obtain a wall 
effects adjustment factor (WAF) from (1) the wall effects-unadjusted 
average velocity (T4avg), (2) the replacement velocity (vej) for each of 
the four Method 1 sectors closest to the wall, and (3) the average stack 
gas velocity that accounts for velocity decay near the wall (vavg).
    12.2 Nomenclature. The following terms are listed in the order in 
which they appear in Equations 2H-5 through 2H-21.

vavg=the average stack gas velocity, unadjusted for wall effects, actual 
ft/sec (m/sec);
vii=stack gas point velocity value at Method 1 interior equal-area 
sectors, actual ft/sec (m/sec);
vej=stack gas point velocity value, unadjusted for wall effects, at 
Method 1 exterior equal-area sectors, actual ft/sec (m/sec);
i=index of Method 1 interior equal-area traverse points;
j=index of Method 1 exterior equal-area traverse points;
n=total number of traverse points in the Method 1 traverse;
vdecd=the wall effects decay velocity for a sub-sector located between 
the traverse points at distances d-1 (in metric units, d-2.5) and d from 
the wall, actual ft/sec (m/sec);
vd=the measured stack gas velocity at distance d from the wall, actual 
ft/sec (m/sec); Note: v0=0;
d=the distance of a 1-in. incremented wall effects traverse point from 
the wall, for traverse points d1 through dlast, in. (cm);
Ad=the cross-sectional area of a sub-sector located between the traverse 
points at distances d-1 (in metric units, d-2.5) and d from the wall, 
in.\2\ (cm \2\) ( e.g., sub-sector A2 shown in Figures 2H-3 
and 2H-4);
r=the stack or duct radius, in. (cm);
Qd=the stack gas volumetric flow rate for a sub-sector located between 
the traverse points at distances d-1 (in metric units, d-2.5) and d from 
the wall, actual ft-in.\2\/sec (m-cm \2\/sec);
Qd1[rarr]dlast=the total stack gas volumetric flow rate for all sub-
sectors located between the wall and dlast, actual ft-in.\2\/sec (m-cm 
\2\/sec);
dlast=the distance from the wall of the last 1-in. incremented wall 
effects traverse point, in. (cm);
Adrem=the cross-sectional area of the sub-sector located between dlast 
and the interior edge of the Method 1 equal-area sector closest to the 
wall, in.\2\ (cm \2\) (see Figure 2H-4);
p=the number of Method 1 traverse points per diameter, p=8 
(e.g., for a 16-point traverse, p=8);
drem=the distance from the wall of the centroid of the area between 
dlast and the interior edge of the Method 1 equal-area sector closest to 
the wall, in. (cm);
Qdrem=the total stack gas volumetric flow rate for the sub-sector 
located between dlast and the interior edge of the Method 1 equal-area 
sector closest to the wall, actual ft-in.\2\/sec (m-cm \2\/sec);
vdrem=the measured stack gas velocity at distance drem from the wall, 
actual ft/sec (m/sec);
QT=the total stack gas volumetric flow rate for the Method 1 equal-area 
sector closest to the wall, actual ft-in.\2\/sec (m-cm \2\/sec);
vej=the replacement stack gas velocity for the Method 1 equal-area 
sector closest to the wall, i.e., the stack gas point velocity value, 
adjusted for wall effects, for the jth Method 1 equal-area 
sector closest to the wall, actual ft/sec (m/sec);
vavg=the average stack gas velocity that accounts for velocity decay 
near the wall, actual ft/sec (m/sec);
WAF=the wall effects adjustment factor derived from vavg and vavg for a 
single traverse, dimensionless;
vfinal=the final wall effects-adjusted average stack gas velocity that 
replaces the unadjusted average stack gas velocity obtained using Method 
2, 2F, or 2G for a field test consisting of a single traverse, actual 
ft/sec (m/sec);
WAF=the wall effects adjustment factor that is applied to the average 
velocity, unadjusted for wall effects, in order to obtain the final wall 
effects-adjusted stack gas velocity, vfinal or, vfinal(k), 
dimensionless;
vfinal(k)=the final wall effects-adjusted average stack gas velocity 
that replaces the unadjusted average stack gas velocity obtained using 
Method 2, 2F, or 2G on run k of a RATA or other multiple-run field test 
procedure, actual ft/sec (m/sec);
vavg(k)=the average stack gas velocity, obtained on run k of a RATA or 
other multiple-run procedure, unadjusted for velocity decay near the 
wall, actual ft/sec (m/sec);
k=index of runs in a RATA or other multiple-run procedure.

    12.3 Calculate the average stack gas velocity that does not account 
for velocity decay near the wall (vavg) using Equation 2H-5.
[GRAPHIC] [TIFF OMITTED] TR14MY99.077


[[Page 134]]


(Note that vavg in Equation 2H-5 is the same as v(a)avg in Equations 2F-
9 and 2G-8 in Methods 2F and 2G, respectively.)
    For a 16-point traverse, Equation 2H-5 may be written as follows:
    [GRAPHIC] [TIFF OMITTED] TR14MY99.078
    
    12.4 Calculate the replacement velocity, vej, for each of the four 
Method 1 equal-area sectors closest to the wall using the procedures 
described in sections 12.4.1 through 12.4.8. Forms 2H-1 and 2H-2 provide 
sample tables that may be used in either hardcopy or spreadsheet format 
to perform the calculations described in sections 12.4.1 through 12.4.8. 
Forms 2H-3 and 2H-4 provide examples of Form 2H-1 filled in for partial 
and complete wall effects traverses.
    12.4.1 Calculate the average velocity (designated the ``decay 
velocity,'' vdecd) for each sub-sector located between the 
wall and dlast (see Figure 2H-3) using Equation 2H-7.
[GRAPHIC] [TIFF OMITTED] TR14MY99.079

For each line in column A of Form 2H-1 or 2H-2 that contains a value of 
d, enter the corresponding calculated value of vdecd in 
column C.
    12.4.2 Calculate the cross-sectional area between the wall and the 
first 1-in. incremented wall effects traverse point and between 
successive 1-in. incremented wall effects traverse points, from the wall 
to dlast (see Figure 2H-3), using Equation 2H-8.
[GRAPHIC] [TIFF OMITTED] TR14MY99.080

For each line in column A of Form 2H-1 or 2H-2 that contains a value of 
d, enter the value of the expression \1/4\ [pi](r-d+1)2 in 
column D, the value of the expression \1/4\ [pi](r-d)2 in 
column E, and the value of Ad in column F. Note that Equation 
2H-8 is designed for use only with English units (in.). If metric units 
(cm) are used, the first term, \1/4\ [pi](r-d+1)2, must be 
changed to \1/4\ [pi](r-d+2.5)2. This change must also be 
made in column D of Form 2H-1 or 2H-2.
    12.4.3 Calculate the volumetric flow through each cross-sectional 
area derived in section 12.4.2 by multiplying the values of vdecd, 
derived according to section 12.4.1, by the cross-sectional areas 
derived in section 12.4.2 using Equation 2H-9.
[GRAPHIC] [TIFF OMITTED] TR14MY99.081

For each line in column A of Form 2H-1 or 2H-2 that contains a value of 
d, enter the corresponding calculated value of Qd in column G.
    12.4.4 Calculate the total volumetric flow through all sub-sectors 
located between the wall and dlast, using Equation 2H-10.
[GRAPHIC] [TIFF OMITTED] TN09JY99.003

Enter the calculated value of Qd1[rarr]cdlast in line 3 of column G of 
Form 2H-1 or 2H-2.
    12.4.5 Calculate the cross-sectional area of the sub-sector located 
between dlast and the interior edge of the Method 1 equal-area sector 
(e.g., sub-sector Adrem shown in Figures 2H-3 and 2H-4) using Equation 
2H-11.
[GRAPHIC] [TIFF OMITTED] TR14MY99.083


[[Page 135]]


For a 16-point traverse (eight points per diameter), Equation 2H-11 may 
be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.084

Enter the calculated value of Adrem in line 4b of column G of 
Form 2H-1 or 2H-2.
    12.4.6 Calculate the volumetric flow for the sub-sector located 
between dlast and the interior edge of the Method 1 equal-
area sector, using Equation 2H-13.
[GRAPHIC] [TIFF OMITTED] TR14MY99.085

In Equation 2H-13, vdrem is either (1) the measured velocity 
value at drem or (2) the measured velocity at 
dlast, if the distance between drem and 
dlast is less than or equal to \1/2\ in. (12.7 mm) and no 
velocity measurement is taken at drem (see section 8.2.4.2). 
Enter the calculated value of Qdrem in line 4c of column G of 
Form 2H-1 or 2H-2.
    12.4.7 Calculate the total volumetric flow for the Method 1 equal-
area sector closest to the wall, using Equation 2H-14.
[GRAPHIC] [TIFF OMITTED] TR14MY99.086

Enter the calculated value of QT in line 5a of column G of 
Form 2H-1 or 2H-2.
    12.4.8 Calculate the wall effects-adjusted replacement velocity 
value for the Method 1 equal-area sector closest to the wall, using 
Equation 2H-15.
[GRAPHIC] [TIFF OMITTED] TR14MY99.087

For a 16-point traverse (eight points per diameter), Equation 2H-15 may 
be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.088

Enter the calculated value of vej in line 5B of column G of Form 2H-1 or 
2H-2.
    12.5 Calculate the wall effects-adjusted average velocity, vavg, by 
replacing the four values of vej shown in Equation 2H-5 with 
the four wall effects-adjusted replacement velocity 
values,vej, calculated according to section 12.4.8, using 
Equation 2H-17.
[GRAPHIC] [TIFF OMITTED] TR14MY99.089

For a 16-point traverse, Equation 2H-17 may be written as follows:
[GRAPHIC] [TIFF OMITTED] TR14MY99.090

    12.6 Calculate the wall effects adjustment factor, WAF, using 
Equation 2H-19.
[GRAPHIC] [TIFF OMITTED] TR14MY99.091

    12.6.1 Partial wall effects traverse. If a partial wall effects 
traverse (see section 8.2.2) is conducted, the value obtained from 
Equation 2H-19 is acceptable and may be reported as the wall effects 
adjustment factor provided that the value is greater than or equal to 
0.9800. If the value is less than 0.9800, it shall not be used and a 
wall effects adjustment factor of 0.9800 may be used instead.
    12.6.2 Complete wall effects traverse. If a complete wall effects 
traverse (see section 8.2.3) is conducted, the value obtained from 
Equation 2H-19 is acceptable and may be reported as the wall effects 
adjustment factor provided that the value is greater than or equal to 
0.9700. If the value is less than 0.9700, it shall not be used and a 
wall effects adjustment factor of 0.9700 may be used instead. If the 
wall effects adjustment factor for a particular stack or duct is less 
than 0.9700, the tester may (1) repeat the wall effects test, taking 
measurements at more Method 1 traverse points and (2) recalculate the 
wall effects adjustment factor from these measurements, in an attempt to 
obtain a wall effects adjustment factor that meets the 0.9700 
specification and completely characterizes the wall effects.
    12.7 Applying a Wall Effects Adjustment Factor. A default wall 
effects adjustment factor, as specified in section 8.1, or a calculated 
wall effects adjustment factor meeting the requirements of section 
12.6.1 or 12.6.2

[[Page 136]]

may be used to adjust the average stack gas velocity obtained using 
Methods 2, 2F, or 2G to take into account velocity decay near the wall 
of circular stacks or ducts. Default wall effects adjustment factors 
specified in section 8.1 and calculated wall effects adjustment factors 
that meet the requirements of section 12.6.1 and 12.6.2 are summarized 
in Table 2H-2.
    12.7.1 Single-run tests. Calculate the final wall effects-adjusted 
average stack gas velocity for field tests consisting of a single 
traverse using Equation 2H-20.
[GRAPHIC] [TIFF OMITTED] TR14MY99.092

The wall effects adjustment factor, WAF, shown in Equation 2H-20, may be 
(1) a default wall effects adjustment factor, as specified in section 
8.1, or (2) a calculated adjustment factor that meets the specifications 
in sections 12.6.1 or 12.6.2. If a calculated adjustment factor is used 
in Equation 2H-20, the factor must have been obtained during the same 
traverse in which vavg was obtained.
    12.7.2 RATA or other multiple run test procedure. Calculate the 
final wall effects-adjusted average stack gas velocity for any run k of 
a RATA or other multiple-run procedure using Equation 2H-21.
[GRAPHIC] [TIFF OMITTED] TR14MY99.093

The wall effects adjustment factor, WAF, shown in Equation 2H-21 may be 
(1) a default wall effects adjustment factor, as specified in section 
8.1; (2) a calculated adjustment factor (meeting the specifications in 
sections 12.6.1 or 12.6.2) obtained from any single run of the RATA that 
includes run k; or (3) the arithmetic average of more than one WAF (each 
meeting the specifications in sections 12.6.1 or 12.6.2) obtained 
through wall effects testing conducted during several runs of the RATA 
that includes run k. If wall effects adjustment factors (meeting the 
specifications in sections 12.6.1 or 12.6.2) are determined for more 
than one RATA run, the arithmetic average of all of the resulting 
calculated wall effects adjustment factors must be used as the value of 
WAF and applied to all runs of that RATA. If a calculated, not a 
default, wall effects adjustment factor is used in Equation 2H-21, the 
average velocity unadjusted for wall effects, vavg(k) must be 
obtained from runs in which the number of Method 1 traverse points 
sampled does not exceed the number of Method 1 traverse points in the 
runs used to derive the wall effects adjustment factor, WAF, shown in 
Equation 2H-21.
    12.8 Calculating Volumetric Flow Using Final Wall Effects-Adjusted 
Average Velocity Value. To obtain a stack gas flow rate that accounts 
for velocity decay near the wall of circular stacks or ducts, replace 
vs in Equation 2-10 in Method 2, or va(avg) in 
Equations 2F-10 and 2F-11 in Method 2F, or va(avg) in 
Equations 2G-9 and 2G-10 in Method 2G with one of the following.
    12.8.1 For single-run test procedures, use the final wall effects-
adjusted average stack gas velocity, vfinal, calculated according to 
Equation 2H-20.
    12.8.2 For RATA and other multiple run test procedures, use the 
final wall effects-adjusted average stack gas velocity, vfinal(k), 
calculated according to Equation 2H-21.

                   13.0 Method Performance [Reserved]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                             16.0 Reporting

    16.1 Field Test Reports. Field test reports shall be submitted to 
the Agency according to the applicable regulatory requirements. When 
Method 2H is performed in conjunction with Method 2, 2F, or 2G to derive 
a wall effects adjustment factor, a single consolidated Method 2H/2F (or 
2H/2G) field test report should be prepared. At a minimum, the 
consolidated field test report should contain (1) all of the general 
information, and data for Method 1 points, specified in section 16.0 of 
Method 2F (when Method 2H is used in conjunction with Method 2F) or 
section 16.0 of Method 2G (when Method 2H is used in conjunction with 
Method 2 or 2G) and (2) the additional general information, and data for 
Method 1 points and wall effects points, specified in this section (some 
of which are included in section 16.0 of Methods 2F and 2G and are 
repeated in this section to ensure complete reporting for wall effects 
testing).
    16.1.1 Description of the source and site. The field test report 
should include the descriptive information specified in section 16.1.1 
of Method 2F (when using Method 2F) or 2G (when using either Method 2 or 
2G). It should also include a description of the stack or duct's 
construction material along with the diagram showing the dimensions of 
the stack or duct at the test port elevation prescribed in Methods 2F 
and 2G. The diagram should indicate the location of all wall effects 
traverse points where measurements were taken as well as the Method 1 
traverse points. The diagram should provide a unique identification 
number for each wall effects and Method 1 traverse point, its distance 
from the wall, and its location relative to the probe entry ports.
    16.1.2 Field test forms. The field test report should include a copy 
of Form 2H-1, 2H-2, or an equivalent for each Method 1 exterior equal-
area sector.
    16.1.3 Field test data. The field test report should include the 
following data for the Method 1 and wall effects traverse.
    16.1.3.1 Data for each traverse point. The field test report should 
include the values

[[Page 137]]

specified in section 16.1.3.2 of Method 2F (when using Method 2F) or 2G 
(when using either Method 2 or 2G) for each Method 1 and wall effects 
traverse point. The provisions of section 8.4.2 of Method 2H apply to 
the temperature measurements reported for wall effects traverse points. 
For each wall effects and Method 1 traverse point, the following values 
should also be included in the field test report.
    (a) Traverse point identification number for each Method 1 and wall 
effects traverse point.
    (b) Probe type.
    (c) Probe identification number.
    (d) Probe velocity calibration coefficient (i.e., Cp when Method 2 
or 2G is used; F2 when Method 2F is used).

    For each Method 1 traverse point in an exterior equal-area sector, 
the following additional value should be included.
    (e) Calculated replacement velocity, vej, accounting for wall 
effects.
    16.1.3.2 Data for each run. The values specified in section 16.1.3.3 
of Method 2F (when using Method 2F) or 2G (when using either Method 2 or 
2G) should be included in the field test report once for each run. The 
provisions of section 12.8 of Method 2H apply for calculating the 
reported gas volumetric flow rate. In addition, the following Method 2H 
run values should also be included in the field test report.
    (a) Average velocity for run, accounting for wall effects, vavg.
    (b) Wall effects adjustment factor derived from a test run, WAF.
    16.1.3.3 Data for a complete set of runs. The values specified in 
section 16.1.3.4 of Method 2F (when using Method 2F) or 2G (when using 
either Method 2 or 2G) should be included in the field test report once 
for each complete set of runs. In addition, the field test report should 
include the wall effects adjustment factor, WAF, that is applied in 
accordance with section 12.7.1 or 12.7.2 to obtain the final wall 
effects-adjusted average stack gas velocity vfinal or vfinal(k).
    16.1.4 Quality assurance and control. Quality assurance and control 
procedures, specifically tailored to wall effects testing, should be 
described.
    16.2 Reporting a Default Wall Effects Adjustment Factor. When a 
default wall effects adjustment factor is used in accordance with 
section 8.1 of this method, its value and a description of the stack or 
duct's construction material should be reported in lieu of submitting a 
test report.

                            17.0 References.

    (1) 40 CFR Part 60, Appendix A, Method 1--Sample and velocity 
traverses for stationary sources.
    (2) 40 CFR Part 60, Appendix A, Method 2--Determination of stack gas 
velocity and volumetric flow rate (Type S pitot tube).
    (3) 40 CFR Part 60, Appendix A, Method 2F--Determination of stack 
gas velocity and volumetric flow rate with three-dimensional probes.
    (4) 40 CFR Part 60, Appendix A, Method 2G--Determination of stack 
gas velocity and volumetric flow rate with two-dimensional probes.
    (5) 40 CFR Part 60, Appendix A, Method 3--Gas analysis for carbon 
dioxide, oxygen, excess air, and dry molecular weight.
    (6) 40 CFR Part 60, Appendix A, Method 3A--Determination of oxygen 
and carbon dioxide concentrations in emissions from stationary sources 
(instrumental analyzer procedure).
    (7) 40 CFR Part 60, Appendix A, Method 4--Determination of moisture 
content in stack gases.
    (8) Emission Measurement Center (EMC) Approved Alternative Method 
(ALT-011) ``Alternative Method 2 Thermocouple Calibration Procedure.''
    (9) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, DeCordova Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-015a.
    (10) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Texas Utilities, Lake Hubbard Steam 
Electric Station, Volume I: Test Description and Appendix A (Data 
Distribution Package),'' EPA/430-R-98-017a.
    (11) The Cadmus Group, Inc., 1998, ``EPA Flow Reference Method 
Testing and Analysis: Data Report, Pennsylvania Electric Co., G.P.U. 
Genco Homer City Station: Unit 1, Volume I: Test Description and 
Appendix A (Data Distribution Package),'' EPA/430-R-98-018a.
    (12) The Cadmus Group, Inc., May 1999, ``EPA Flow Reference Method 
Testing and Analysis: Findings Report,'' EPA/430-R-99-009.
    (13) The Cadmus Group, Inc., 1997, ``EPA Flow Reference Method 
Testing and Analysis: Wind Tunnel Experimental Results,'' EPA/430-R-97-
013.
    (14) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four Prandtl Probes, Four 
S-Type Probes, Four French Probes, Four Modified Kiel Probes,'' Prepared 
for the U.S. Environmental Protection Agency under IAG No. DW13938432-
01-0.
    (15) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Five Autoprobes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.

[[Page 138]]

    (16) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Eight Spherical Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.
    (17) National Institute of Standards and Technology, 1998, ``Report 
of Special Test of Air Speed Instrumentation, Four DAT Probes,'' 
Prepared for the U.S. Environmental Protection Agency under IAG No. 
DW13938432-01-0.
    (18) Massachusetts Institute of Technology (MIT), 1998, 
``Calibration of Eight Wind Speed Probes Over a Reynolds Number Range of 
46,000 to 725,000 per Foot, Text and Summary Plots,'' Plus Appendices, 
WBWT-TR-1317, Prepared for The Cadmus Group, Inc., under EPA Contract 
68-W6-0050, Work Assignment 0007AA-3.
    (19) Fossil Energy Research Corporation, Final Report, ``Velocity 
Probe Tests in Non-axial Flow Fields,'' November 1998, Prepared for the 
U.S. Environmental Protection Agency.
    (20) Fossil Energy Research Corporation, ``Additional Swirl Tunnel 
Tests: E-DAT and T-DAT Probes,'' February 24, 1999, Technical Memorandum 
Prepared for U.S. Environmental Protection Agency, P.O. No. 7W-1193-
NALX.
[GRAPHIC] [TIFF OMITTED] TR14MY99.036


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[GRAPHIC] [TIFF OMITTED] TR14MY99.043


[[Page 146]]


[GRAPHIC] [TIFF OMITTED] TR14MY99.044

  Method 3--Gas Analysis for the Determination of Dry Molecular Weight

    Note: This method does not include all of the specifications (e.g., 
equipment and supplies) and procedures (e.g., sampling) 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 also have a thorough knowledge of Method 1.

                        1.0 Scope and Application

    1.1 Analytes.

[[Page 147]]



------------------------------------------------------------------------
             Analytes                   CAS No.          Sensitivity
------------------------------------------------------------------------
Oxygen (O2).......................       7782-44-7  2,000 ppmv.
Nitrogen (N2).....................       7727-37-9  N/A.
Carbon dioxide (CO2)..............        124-38-9  2,000 ppmv.
Carbon monoxide (CO)..............        630-08-0  N/A.
------------------------------------------------------------------------

    1.2 Applicability. This method is applicable for the determination 
of CO2 and O2 concentrations and dry molecular 
weight of a sample from an effluent gas stream of a fossil-fuel 
combustion process or other process.
    1.3 Other methods, as well as modifications to the procedure 
described herein, are also applicable for all of the above 
determinations. Examples of specific methods and modifications include: 
(1) A multi-point grab sampling method using an Orsat analyzer to 
analyze the individual grab sample obtained at each point; (2) a method 
for measuring either CO2 or O2 and using 
stoichiometric calculations to determine dry molecular weight; and (3) 
assigning a value of 30.0 for dry molecular weight, in lieu of actual 
measurements, for processes burning natural gas, coal, or oil. These 
methods and modifications may be used, but are subject to the approval 
of the Administrator. The method may also be applicable to other 
processes where it has been determined that compounds other than 
CO2, O2, carbon monoxide (CO), and nitrogen 
(N2) are not present in concentrations sufficient to affect 
the results.
    1.4 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 stack by one of the following 
methods: (1) single-point, grab sampling; (2) single-point, integrated 
sampling; or (3) multi-point, integrated sampling. The gas sample is 
analyzed for percent CO2 and percent O2. For dry 
molecular weight determination, either an Orsat or a Fyrite analyzer may 
be used for the analysis.

                       3.0 Definitions [Reserved]

                            4.0 Interferences

    4.1 Several compounds can interfere, to varying degrees, with the 
results of Orsat or Fyrite analyses. Compounds that interfere with 
CO2 concentration measurement include acid gases (e.g., 
sulfur dioxide, hydrogen chloride); compounds that interfere with 
O2 concentration measurement include unsaturated hydrocarbons 
(e.g., acetone, acetylene), nitrous oxide, and ammonia. Ammonia reacts 
chemically with the O2 absorbing solution, and when present 
in the effluent gas stream must be removed before analysis.

                               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 determine the applicability of regulatory limitations 
prior to performing this test method.
    5.2 Corrosive Reagents.
    5.2.1 A typical Orsat analyzer requires four reagents: a gas-
confining solution, CO2 absorbent, O2 absorbent, 
and CO absorbent. These reagents may contain potassium hydroxide, sodium 
hydroxide, cuprous chloride, cuprous sulfate, alkaline pyrogallic acid, 
and/or chromous chloride. Follow manufacturer's operating instructions 
and observe all warning labels for reagent use.
    5.2.2 A typical Fyrite analyzer contains zinc chloride, hydrochloric 
acid, and either potassium hydroxide or chromous chloride. Follow 
manufacturer's operating instructions and observe all warning labels for 
reagent use.

                       6.0 Equipment and Supplies

    Note: As an alternative to the sampling apparatus and systems 
described herein, other sampling systems (e.g., liquid displacement) may 
be used, provided such systems are capable of obtaining a representative 
sample and maintaining a constant sampling rate, and are, otherwise, 
capable of yielding acceptable results. Use of such systems is subject 
to the approval of the Administrator.

    6.1 Grab Sampling (See Figure 3-1).
    6.1.1 Probe. Stainless steel or borosilicate glass tubing equipped 
with an in-stack or out-of-stack filter to remove particulate matter (a 
plug of glass wool is satisfactory for this purpose). Any other 
materials, resistant to temperature at sampling conditions and inert to 
all components of the gas stream, may be used for the probe. Examples of 
such materials may include aluminum, copper, quartz glass, and Teflon.
    6.1.2 Pump. A one-way squeeze bulb, or equivalent, to transport the 
gas sample to the analyzer.
    6.2 Integrated Sampling (Figure 3-2).
    6.2.1 Probe. Same as in Section 6.1.1.

[[Page 148]]

    6.2.2 Condenser. An air-cooled or water-cooled condenser, or other 
condenser no greater than 250 ml that will not remove O2, 
CO2, CO, and N2, to remove excess moisture which 
would interfere with the operation of the pump and flowmeter.
    6.2.3 Valve. A needle valve, to adjust sample gas flow rate.
    6.2.4 Pump. A leak-free, diaphragm-type pump, or equivalent, to 
transport sample gas to the flexible bag. Install a small surge tank 
between the pump and rate meter to eliminate the pulsation effect of the 
diaphragm pump on the rate meter.
    6.2.5 Rate Meter. A rotameter, or equivalent, capable of measuring 
flow rate to 2 percent of the selected flow rate. 
A flow rate range of 500 to 1000 ml/min is suggested.
    6.2.6 Flexible Bag. Any leak-free plastic (e.g., Tedlar, Mylar, 
Teflon) or plastic-coated aluminum (e.g., aluminized Mylar) bag, or 
equivalent, having a capacity consistent with the selected flow rate and 
duration of the test run. A capacity in the range of 55 to 90 liters 
(1.9 to 3.2 ft3) is suggested. To leak-check the bag, connect 
it to a water manometer, and pressurize the bag to 5 to 10 cm 
H2O (2 to 4 in. H2O). Allow to stand for 10 
minutes. Any displacement in the water manometer indicates a leak. An 
alternative leak-check method is to pressurize the bag to 5 to 10 cm (2 
to 4 in.) H2O and allow to stand overnight. A deflated bag 
indicates a leak.
    6.2.7 Pressure Gauge. A water-filled U-tube manometer, or 
equivalent, of about 30 cm (12 in.), for the flexible bag leak-check.
    6.2.8 Vacuum Gauge. A mercury manometer, or equivalent, of at least 
760 mm (30 in.) Hg, for the sampling train leak-check.
    6.3 Analysis. An Orsat or Fyrite type combustion gas analyzer.

                       7.0 Reagents and Standards

    7.1 Reagents. As specified by the Orsat or Fyrite-type combustion 
analyzer manufacturer.
    7.2 Standards. Two standard gas mixtures, traceable to National 
Institute of Standards and Technology (NIST) standards, to be used in 
auditing the accuracy of the analyzer and the analyzer operator 
technique:
    7.2.1. Gas cylinder containing 2 to 4 percent O2 and 14 
to 18 percent CO2.
    7.2.2. Gas cylinder containing 2 to 4 percent CO2 and 
about 15 percent O2.

       8.0 Sample Collection, Preservation, Storage, and Transport

    8.1 Single Point, Grab Sampling Procedure.
    8.1.1 The sampling point in the duct shall either be at the centroid 
of the cross section or at a point no closer to the walls than 1.0 m 
(3.3 ft), unless otherwise specified by the Administrator.
    8.1.2 Set up the equipment as shown in Figure 3-1, making sure all 
connections ahead of the analyzer are tight. If an Orsat analyzer is 
used, it is recommended that the analyzer be leak-checked by following 
the procedure in Section 11.5; however, the leak-check is optional.
    8.1.3 Place the probe in the stack, with the tip of the probe 
positioned at the sampling point. Purge the sampling line long enough to 
allow at least five exchanges. Draw a sample into the analyzer, and 
immediately analyze it for percent CO2 and percent 
O2 according to Section 11.2.
    8.2 Single-Point, Integrated Sampling Procedure.
    8.2.1 The sampling point in the duct shall be located as specified 
in Section 8.1.1.
    8.2.2 Leak-check (optional) the flexible bag as in Section 6.2.6. 
Set up the equipment as shown in Figure 3-2. Just before sampling, leak-
check (optional) the train by placing a vacuum gauge at the condenser 
inlet, pulling a vacuum of at least 250 mm Hg (10 in. Hg), plugging the 
outlet at the quick disconnect, and then turning off the pump. The 
vacuum should remain stable for at least 0.5 minute. Evacuate the 
flexible bag. Connect the probe, and place it in the stack, with the tip 
of the probe positioned at the sampling point. Purge the sampling line. 
Next, connect the bag, and make sure that all connections are tight.
    8.2.3 Sample Collection. Sample at a constant rate (10 percent). The sampling run should be simultaneous 
with, and for the same total length of time as, the pollutant emission 
rate determination. Collection of at least 28 liters (1.0 
ft3) of sample gas is recommended; however, smaller volumes 
may be collected, if desired.
    8.2.4 Obtain one integrated flue gas sample during each pollutant 
emission rate determination. Within 8 hours after the sample is taken, 
analyze it for percent CO2 and percent O2 using 
either an Orsat analyzer or a Fyrite type combustion gas analyzer 
according to Section 11.3.

    Note: When using an Orsat analyzer, periodic Fyrite readings may be 
taken to verify/confirm the results obtained from the Orsat.

    8.3 Multi-Point, Integrated Sampling Procedure.
    8.3.1 Unless otherwise specified in an applicable regulation, or by 
the Administrator, a minimum of eight traverse points shall be used for 
circular stacks having diameters less than 0.61 m (24 in.), a minimum of 
nine shall be used for rectangular stacks having equivalent diameters 
less than 0.61 m (24 in.), and a minimum of 12 traverse points shall be 
used for all other cases. The traverse points shall be located according 
to Method 1.
    8.3.2 Follow the procedures outlined in Sections 8.2.2 through 
8.2.4, except for the following: Traverse all sampling points, and

[[Page 149]]

sample at each point for an equal length of time. Record sampling data 
as shown in Figure 3-3.

                           9.0 Quality Control

------------------------------------------------------------------------
                                 Quality control
            Section                  measure               Effect
------------------------------------------------------------------------
8.2...........................  Use of Fyrite to   Ensures the accurate
                                 confirm Orsat      measurement of CO2
                                 results.           and O2.
10.1..........................  Periodic audit of  Ensures that the
                                 analyzer and       analyzer is
                                 operator           operating properly
                                 technique.         and that the
                                                    operator performs
                                                    the sampling
                                                    procedure correctly
                                                    and accurately.
11.3..........................  Replicable         Minimizes
                                 analyses of        experimental error.
                                 integrated
                                 samples.
------------------------------------------------------------------------

                  10.0 Calibration and Standardization

    10.1 Analyzer. The analyzer and analyzer operator's technique should 
be audited periodically as follows: take a sample from a manifold 
containing a known mixture of CO2 and O2, and 
analyze according to the procedure in Section 11.3. Repeat this 
procedure until the measured concentration of three consecutive samples 
agrees with the stated value 0.5 percent. If 
necessary, take corrective action, as specified in the analyzer users 
manual.
    10.2 Rotameter. The rotameter need not be calibrated, but should be 
cleaned and maintained according to the manufacturer's instruction.

                        11.0 Analytical Procedure

    11.1 Maintenance. The Orsat or Fyrite-type analyzer should be 
maintained and operated according to the manufacturers specifications.
    11.2 Grab Sample Analysis. Use either an Orsat analyzer or a Fyrite-
type combustion gas analyzer to measure O2 and CO2 
concentration for dry molecular weight determination, using procedures 
as specified in the analyzer user's manual. If an Orsat analyzer is 
used, it is recommended that the Orsat leak-check, described in Section 
11.5, be performed before this determination; however, the check is 
optional. Calculate the dry molecular weight as indicated in Section 
12.0. Repeat the sampling, analysis, and calculation procedures until 
the dry molecular weights of any three grab samples differ from their 
mean by no more than 0.3 g/g-mole (0.3 lb/lb-mole). Average these three 
molecular weights, and report the results to the nearest 0.1 g/g-mole 
(0.1 lb/lb-mole).
    11.3 Integrated Sample Analysis. Use either an Orsat analyzer or a 
Fyrite-type combustion gas analyzer to measure O2 and 
CO2 concentration for dry molecular weight determination, 
using procedures as specified in the analyzer user's manual. If an Orsat 
analyzer is used, it is recommended that the Orsat leak-check, described 
in Section 11.5, be performed before this determination; however, the 
check is optional. Calculate the dry molecular weight as indicated in 
Section 12.0. Repeat the analysis and calculation procedures until the 
individual dry molecular weights for any three analyses differ from 
their mean by no more than 0.3 g/g-mole (0.3 lb/lb-mole). Average these 
three molecular weights, and report the results to the nearest 0.1 g/g-
mole (0.1 lb/lb-mole).
    11.4 Standardization. A periodic check of the reagents and of 
operator technique should be conducted at least once every three series 
of test runs as outlined in Section 10.1.
    11.5 Leak-Check Procedure for Orsat Analyzer. Moving an Orsat 
analyzer frequently causes it to leak. Therefore, an Orsat analyzer 
should be thoroughly leak-checked on site before the flue gas sample is 
introduced into it. The procedure for leak-checking an Orsat analyzer is 
as follows:
    11.5.1 Bring the liquid level in each pipette up to the reference 
mark on the capillary tubing, and then close the pipette stopcock.
    11.5.2 Raise the leveling bulb sufficiently to bring the confining 
liquid meniscus onto the graduated portion of the burette, and then 
close the manifold stopcock.
    11.5.3 Record the meniscus position.
    11.5.4 Observe the meniscus in the burette and the liquid level in 
the pipette for movement over the next 4 minutes.
    11.5.5 For the Orsat analyzer to pass the leak-check, two conditions 
must be met:
    11.5.5.1 The liquid level in each pipette must not fall below the 
bottom of the capillary tubing during this 4-minute interval.
    11.5.5.2 The meniscus in the burette must not change by more than 
0.2 ml during this 4-minute interval.
    11.5.6 If the analyzer fails the leak-check procedure, check all 
rubber connections and stopcocks to determine whether they might be the 
cause of the leak. Disassemble, clean, and regrease any leaking 
stopcocks. Replace leaking rubber connections. After the analyzer is 
reassembled, repeat the leak-check procedure.

                   12.0 Calculations and Data Analysis

    12.1 Nomenclature.


[[Page 150]]


Md=Dry molecular weight, g/g-mole (lb/lb-mole).
%CO2=Percent CO2 by volume, dry basis.
%O2=Percent O2 by volume, dry basis.
%CO=Percent CO by volume, dry basis.
%N2=Percent N2 by volume, dry basis.
0.280 =Molecular weight of N2 or CO, divided by 100.
0.320 =Molecular weight of O2 divided by 100.
0.440 =Molecular weight of CO2 divided by 100.

    12.2 Nitrogen, Carbon Monoxide Concentration. Determine the 
percentage of the gas that is N2 and CO by subtracting the 
sum of the percent CO2 and percent O2 from 100 
percent.
    12.3 Dry Molecular Weight. Use Equation 3-1 to calculate the dry 
molecular weight of the stack gas.
[GRAPHIC] [TIFF OMITTED] TR17OC00.090

    Note: The above Equation 3-1 does not consider the effect on 
calculated dry molecular weight of argon in the effluent gas. The 
concentration of argon, with a molecular weight of 39.9, in ambient air 
is about 0.9 percent. A negative error of approximately 0.4 percent is 
introduced. The tester may choose to include argon in the analysis using 
procedures subject to approval of the Administrator.

                   13.0 Method Performance [Reserved]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                             16.0 References

    1. Altshuller, A.P. Storage of Gases and Vapors in Plastic Bags. 
International Journal of Air and Water Pollution. 6:75-81. 1963.
    2. Conner, William D. and J.S. Nader. Air Sampling with Plastic 
Bags. Journal of the American Industrial Hygiene Association. 25:291-
297. 1964.
    3. Burrell Manual for Gas Analysts, Seventh edition. Burrell 
Corporation, 2223 Fifth Avenue, Pittsburgh, PA. 15219. 1951.
    4. Mitchell, W.J. and M.R. Midgett. Field Reliability of the Orsat 
Analyzer. Journal of Air Pollution Control Association. 26:491-495. May 
1976.
    5. Shigehara, R.T., R.M. Neulicht, and W.S. Smith. Validating Orsat 
Analysis Data from Fossil Fuel-Fired Units. Stack Sampling News. 
4(2):21-26. August 1976.

         17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.091


[[Page 151]]


[GRAPHIC] [TIFF OMITTED] TR17OC00.092


----------------------------------------------------------------------------------------------------------------
                 Time                       Traverse point           Q (liter/min)            % Deviation a
----------------------------------------------------------------------------------------------------------------

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

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

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

--------------------------------------
Average
----------------------------------------------------------------------------------------------------------------
a % Dev.=[(Q-Qavg)/Qavg]x100 (Must be <=10%)

                     Figure 3-3. Sampling Rate Data

Method 3A--Determination of Oxygen and Carbon Dioxide Concentrations in 
   Emissions From Stationary Sources (Instrumental Analyzer Procedure)

                     1. Applicability and Principle

    1.1 Applicability. This method is applicable to the determination of 
oxygen (O2) and carbon dioxide (CO2) 
concentrations in emissions from stationary sources only when specified 
within the regulations.
    1.2 Principle. A sample is continuously extracted from the effluent 
stream: a portion of the sample stream is conveyed to an instrumental 
analyzer(s) for determination of O2 and CO2 
concentration(s). Performance specifications and test procedures are 
provided to ensure reliable data.

[[Page 152]]

                        2. Range and Sensitivity

    Same as Method 6C, Sections 2.1 and 2.2, except that the span of the 
monitoring system shall be selected such that the average O2 
or CO2 concentration is not less than 20 percent of the span.

                             3. Definitions

    3.1 Measurement System. The total equipment required for the 
determination of the O2 or CO2 concentration. The 
measurement system consists of the same major subsystems as defined in 
Method 6C, Sections 3.1.1, 3.1.2, and 3.1.3.
    3.2 Span, Calibration Gas, Analyzer Calibration Error, Sampling 
System Bias, Zero Drift, Calibration Drift, Response Time, and 
Calibration Curve. Same as Method 6C, Sections 3.2 through 3.8, and 
3.10.
    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 O2 or 
CO2 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:
    5.1.1 Sample Probe. A leak-free probe, of sufficient length to 
traverse the sample points.
    5.1.2 Sample Line. Tubing, to transport the sample gas from the 
probe to the moisture removal system. A heated sample line is not 
required for systems that measure the O2 or CO2 
concentration on a dry basis, or transport dry gases.
    5.1.3 Sample Transport Line, Calibration Value Assembly, Moisture 
Removal System, Particulate Filter, Sample Pump, Sample Flow Rate 
Control, Sample Gas Manifold, and Data Recorder. Same as Method 6C, 
Sections 5.1.3 through 5.1.9, and 5.1.11, except that the requirements 
to use stainless steel, Teflon, and nonreactive glass filters do not 
apply.
    5.1.4 Gas Analyzer. An analyzer to determine continuously the 
O2 or CO2 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. The requirements for measuring and controlling the 
analyzer flow rate are not applicable if data are presented that 
demonstrate the analyzer is insensitive to flow variations over the 
range encountered during the test.
    5.2 Calibration Gases. The calibration gases for CO2 
analyzers shall be CO2 in N2 or CO2 in 
air. Alternatively, CO2/SO2, O2/
SO2 , or O2/CO2/SO2 gas 
mixtures in N2 may be used. Three calibration gases, as 
specified Section 5.3.1 through 5.3.3 of Method 6C, shall be used. For 
O2 monitors that cannot analyze zero gas, a calibration gas 
concentration equivalent to less than 10 percent of the span may be used 
in place of zero gas.

            6. Measurement System Performance Test Procedures

    Perform the following procedures before measurement of emissions 
(Section 7).
    6.1 Calibration Concentration Verification. Follow Section 6.1 of 
Method 6C, except if calibration gas analysis is required, use Method 3 
and change the acceptance criteria for agreement among Method 3 results 
to 5 percent (or 0.2 percent by volume, 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 type of gas 
detector). Conduct the interference response in accordance with Section 
5.4 of Method 20.
    6.3 Measurement System Preparation, Analyzer Calibration Error, and 
Sampling System Bias Check. Follow Sections 6.2 through 6.4 of Method 
6C.

                       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 3.
    7.2 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 tests conducted using Method 3 
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. Quality Control Procedures

    The following quality control procedures are recommended when the 
results of this

[[Page 153]]

method are used for an emission rate correction factor, or excess air 
determination. The tester should select one of the following options for 
validating measurement results:
    8.1 If both O2 and CO2 are measured using 
Method 3A, the procedures described in Section 4.4 of Method 3 should be 
followed to validate the O2 and CO2 measurement 
results.
    8.2 If only O2 is measured using Method 3A, measurements 
of the sample stream CO2 concentration should be obtained at 
the sample by-pass vent discharge using an Orsat or Fyrite analyzer, or 
equivalent. Duplicate samples should be obtained concurrent with at 
least one run. Average the duplicate Orsat or Fyrite analysis results 
for each run. Use the average CO2 values for comparison with 
the O2 measurements in accordance with the procedures 
described in Section 4.4 of Method 3.
    8.3 If only CO2 is measured using Method 3A, concurrent 
measurements of the sample stream CO2 concentration should be 
obtained using an Orsat or Fyrite analyzer as described in Section 8.2. 
For each run, differences greater than 0.5 percent between the Method 3A 
results and the average of the duplicate Fyrite analysis should be 
investigated.

                         9. Emission Calculation

    For all CO2 analyzers, and for O2 analyzers 
that can be calibrated with zero gas, follow Section 8 of Method 6C, 
except express all concentrations as percent, rather than ppm.
    For O2 analyzers that use a low-level calibration gas in 
place of a zero gas, calculate the effluent gas concentration using 
Equation 3A-1.
[GRAPHIC] [TIFF OMITTED] TC16NO91.116

Where:

Cgas=Effluent gas concentration, dry basis, percent.
Cma=Actual concentration of the upscale calibration gas, 
percent.
Coa=Actual concentration of the low-level calibration gas, 
percent.
Cm=Average of initial and final system calibration bias check 
responses for the upscale calibration gas, percent.
Co=Average of initial and final system calibration bias check 
responses for the low-level gas, percent.
C=Average gas concentration indicated by the gas analyzer, dry basis, 
percent.

                            10. Bibliography

    Same as bibliography of Method 6C.

     Method 3B--Gas Analysis for the Determination of Emission Rate 
                     Correction Factor or Excess Air

    Note: This method does not include all of the specifications (e.g., 
equipment and supplies) and procedures (e.g., sampling) 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 and 3.

                        1.0 Scope and Application

    1.1 Analytes.

------------------------------------------------------------------------
              Analyte                   CAS No.          Sensitivity
------------------------------------------------------------------------
Oxygen (O2).......................       7782-44-7  2,000 ppmv.
Carbon Dioxide (CO2)..............        124-38-9  2,000 ppmv.
Carbon Monoxide (CO)..............        630-08-0  N/A.
------------------------------------------------------------------------

    1.2 Applicability. This method is applicable for the determination 
of O2, CO2, and CO concentrations in the effluent 
from fossil-fuel combustion processes for use in excess air or emission 
rate correction factor calculations. Where compounds other than 
CO2, O2, CO, and nitrogen (N2) are 
present in concentrations sufficient to affect the results, the 
calculation procedures presented in this method must be modified, 
subject to the approval of the Administrator.
    1.3 Other methods, as well as modifications to the procedure 
described herein, are also applicable for all of the above 
determinations. Examples of specific methods and modifications include: 
(1) A multi-point sampling method using an Orsat analyzer to analyze 
individual grab samples obtained at each point, and (2) a method using 
CO2 or O2 and stoichiometric calculations to 
determine excess air. These methods and modifications

[[Page 154]]

may be used, but are subject to the approval of the Administrator.
    1.4 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 stack by one of the following 
methods: (1) Single-point, grab sampling; (2) single-point, integrated 
sampling; or (3) multi-point, integrated sampling. The gas sample is 
analyzed for percent CO2, percent O2, and, if 
necessary, percent CO using an Orsat combustion gas analyzer.

                       3.0 Definitions [Reserved]

                            4.0 Interferences

    4.1 Several compounds can interfere, to varying degrees, with the 
results of Orsat analyses. Compounds that interfere with CO2 
concentration measurement include acid gases (e.g., sulfur dioxide, 
hydrogen chloride); compounds that interfere with O2 
concentration measurement include unsaturated hydrocarbons (e.g., 
acetone, acetylene), nitrous oxide, and ammonia. Ammonia reacts 
chemically with the O2 absorbing solution, and when present 
in the effluent gas stream must be removed before analysis.

                               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 determine the applicability of regulatory limitations 
prior to performing this test method.
    5.2 Corrosive Reagents. A typical Orsat analyzer requires four 
reagents: a gas-confining solution, CO2 absorbent, 
O2 absorbent, and CO absorbent. These reagents may contain 
potassium hydroxide, sodium hydroxide, cuprous chloride, cuprous 
sulfate, alkaline pyrogallic acid, and/or chromous chloride. Follow 
manufacturer's operating instructions and observe all warning labels for 
reagent use.

                       6.0 Equipment and Supplies

    Note: As an alternative to the sampling apparatus and systems 
described herein, other sampling systems (e.g., liquid displacement) may 
be used, provided such systems are capable of obtaining a representative 
sample and maintaining a constant sampling rate, and are, otherwise, 
capable of yielding acceptable results. Use of such systems is subject 
to the approval of the Administrator.

    6.1 Grab Sampling and Integrated Sampling. Same as in Sections 6.1 
and 6.2, respectively for Method 3.
    6.2 Analysis. An Orsat analyzer only. For low CO2 (less 
than 4.0 percent) or high O2 (greater than 15.0 percent) 
concentrations, the measuring burette of the Orsat must have at least 
0.1 percent subdivisions. For Orsat maintenance and operation 
procedures, follow the instructions recommended by the manufacturer, 
unless otherwise specified herein.

                       7.0 Reagents and Standards

    7.1 Reagents. Same as in Method 3, Section 7.1.
    7.2 Standards. Same as in Method 3, Section 7.2.

       8.0 Sample Collection, Preservation, Storage, and Transport

    Note: Each of the three procedures below shall be used only when 
specified in an applicable subpart of the standards. The use of these 
procedures for other purposes must have specific prior approval of the 
Administrator. A Fyrite-type combustion gas analyzer is not acceptable 
for excess air or emission rate correction factor determinations, unless 
approved by the Administrator. If both percent CO2 and 
percent O2 are measured, the analytical results of any of the 
three procedures given below may also be used for calculating the dry 
molecular weight (see Method 3).
    8.1 Single-Point, Grab Sampling and Analytical Procedure.
    8.1.1 The sampling point in the duct shall either be at the centroid 
of the cross section or at a point no closer to the walls than 1.0 m 
(3.3 ft), unless otherwise specified by the Administrator.
    8.1.2 Set up the equipment as shown in Figure 3-1 of Method 3, 
making sure all connections ahead of the analyzer are tight. Leak-check 
the Orsat analyzer according to the procedure described in Section 11.5 
of Method 3. This leak-check is mandatory.
    8.1.3 Place the probe in the stack, with the tip of the probe 
positioned at the sampling point; purge the sampling line long enough to 
allow at least five exchanges. Draw a sample into the analyzer. For 
emission rate correction factor determinations, immediately analyze the 
sample for percent CO2 or percent O2, as outlined 
in Section 11.2. For excess air determination, immediately analyze the 
sample for percent CO2, O2, and CO, as outlined in 
Section 11.2, and calculate excess air as outlined in Section 12.2.
    8.1.4 After the analysis is completed, leak-check (mandatory) the 
Orsat analyzer once again, as described in Section 11.5 of Method 3. For 
the results of the analysis to be valid, the Orsat analyzer must pass 
this leak-test before and after the analysis.

[[Page 155]]

    8.2 Single-Point, Integrated Sampling and Analytical Procedure.
    8.2.1 The sampling point in the duct shall be located as specified 
in Section 8.1.1.
    8.2.2 Leak-check (mandatory) the flexible bag as in Section 6.2.6 of 
Method 3. Set up the equipment as shown in Figure 3-2 of Method 3. Just 
before sampling, leak-check (mandatory) the train by placing a vacuum 
gauge at the condenser inlet, pulling a vacuum of at least 250 mm Hg (10 
in. Hg), plugging the outlet at the quick disconnect, and then turning 
off the pump. The vacuum should remain stable for at least 0.5 minute. 
Evacuate the flexible bag. Connect the probe, and place it in the stack, 
with the tip of the probe positioned at the sampling point; purge the 
sampling line. Next, connect the bag, and make sure that all connections 
are tight.
    8.2.3 Sample at a constant rate, or as specified by the 
Administrator. The sampling run must be simultaneous with, and for the 
same total length of time as, the pollutant emission rate determination. 
Collect at least 28 liters (1.0 ft\3\) of sample gas. Smaller volumes 
may be collected, subject to approval of the Administrator.
    8.2.4 Obtain one integrated flue gas sample during each pollutant 
emission rate determination. For emission rate correction factor 
determination, analyze the sample within 4 hours after it is taken for 
percent CO2 or percent O2 (as outlined in Section 
11.2).
    8.3 Multi-Point, Integrated Sampling and Analytical Procedure.
    8.3.1 Unless otherwise specified in an applicable regulation, or by 
the Administrator, a minimum of eight traverse points shall be used for 
circular stacks having diameters less than 0.61 m (24 in.), a minimum of 
nine shall be used for rectangular stacks having equivalent diameters 
less than 0.61 m (24 in.), and a minimum of 12 traverse points shall be 
used for all other cases. The traverse points shall be located according 
to Method 1.
    8.3.2 Follow the procedures outlined in Sections 8.2.2 through 
8.2.4, except for the following: Traverse all sampling points, and 
sample at each point for an equal length of time. Record sampling data 
as shown in Figure 3-3 of Method 3.

                           9.0 Quality Control

    9.1 Data Validation Using Fuel Factor. Although in most instances, 
only CO2 or O2 measurement is required, it is 
recommended that both CO2 and O2 be measured to 
provide a check on the quality of the data. The data validation 
procedure of Section 12.3 is suggested.

    Note: Since this method for validating the CO2 and 
O2 analyses is based on combustion of organic and fossil 
fuels and dilution of the gas stream with air, this method does not 
apply to sources that (1) remove CO2 or O2 through 
processes other than combustion, (2) add O2 (e.g., oxygen 
enrichment) and N2 in proportions different from that of air, 
(3) add CO2 (e.g., cement or lime kilns), or (4) have no fuel 
factor, FO, values obtainable (e.g., extremely variable waste 
mixtures). This method validates the measured proportions of 
CO2 and O2 for fuel type, but the method does not 
detect sample dilution resulting from leaks during or after sample 
collection. The method is applicable for samples collected downstream of 
most lime or limestone flue-gas desulfurization units as the 
CO2 added or removed from the gas stream is not significant 
in relation to the total CO2 concentration. The 
CO2 concentrations from other types of scrubbers using only 
water or basic slurry can be significantly affected and would render the 
fuel factor check minimally useful.

                  10.0 Calibration and Standardization

    10.1 Analyzer. The analyzer and analyzer operator technique should 
be audited periodically as follows: take a sample from a manifold 
containing a known mixture of CO2 and O2, and 
analyze according to the procedure in Section 11.3. Repeat this 
procedure until the measured concentration of three consecutive samples 
agrees with the stated value 0.5 percent. If 
necessary, take corrective action, as specified in the analyzer users 
manual.
    10.2 Rotameter. The rotameter need not be calibrated, but should be 
cleaned and maintained according to the manufacturer's instruction.

                        11.0 Analytical Procedure

    11.1 Maintenance. The Orsat analyzer should be maintained according 
to the manufacturers specifications.
    11.2 Grab Sample Analysis. To ensure complete absorption of the 
CO2, O2, or if applicable, CO, make repeated 
passes through each absorbing solution until two consecutive readings 
are the same. Several passes (three or four) should be made between 
readings. (If constant readings cannot be obtained after three 
consecutive readings, replace the absorbing solution.) Although in most 
cases, only CO2 or O2 concentration is required, 
it is recommended that both CO2 and O2 be 
measured, and that the procedure in Section 12.3 be used to validate the 
analytical data.

    Note: Since this single-point, grab sampling and analytical 
procedure is normally conducted in conjunction with a single-point, grab 
sampling and analytical procedure for a pollutant, only one analysis is 
ordinarily conducted. Therefore, great care must be taken to obtain a 
valid sample and analysis.


[[Page 156]]


    11.3 Integrated Sample Analysis. The Orsat analyzer must be leak-
checked (see Section 11.5 of Method 3) before the analysis. If excess 
air is desired, proceed as follows: (1) within 4 hours after the sample 
is taken, analyze it (as in Sections 11.3.1 through 11.3.3) for percent 
CO2, O2, and CO; (2) determine the percentage of 
the gas that is N2 by subtracting the sum of the percent 
CO2, percent O2, and percent CO from 100 percent; 
and (3) calculate percent excess air, as outlined in Section 12.2.
    11.3.1 To ensure complete absorption of the CO2, 
O2, or if applicable, CO, follow the procedure described in 
Section 11.2.

    Note: Although in most instances only CO2 or 
O2 is required, it is recommended that both CO2 
and O2 be measured, and that the procedures in Section 12.3 
be used to validate the analytical data.

    11.3.2 Repeat the analysis until the following criteria are met:
    11.3.2.1 For percent CO2, repeat the analytical procedure 
until the results of any three analyses differ by no more than (a) 0.3 
percent by volume when CO2 is greater than 4.0 percent or (b) 
0.2 percent by volume when CO2 is less than or equal to 4.0 
percent. Average three acceptable values of percent CO2, and 
report the results to the nearest 0.2 percent.
    11.3.2.2 For percent O2, repeat the analytical procedure 
until the results of any three analyses differ by no more than (a) 0.3 
percent by volume when O2 is less than 15.0 percent or (b) 
0.2 percent by volume when O2 is greater than or equal to 
15.0 percent. Average the three acceptable values of percent 
O2, and report the results to the nearest 0.1 percent.
    11.3.2.3 For percent CO, repeat the analytical procedure until the 
results of any three analyses differ by no more than 0.3 percent. 
Average the three acceptable values of percent CO, and report the 
results to the nearest 0.1 percent.
    11.3.3 After the analysis is completed, leak-check (mandatory) the 
Orsat analyzer once again, as described in Section 11.5 of Method 3. For 
the results of the analysis to be valid, the Orsat analyzer must pass 
this leak-test before and after the analysis.
    11.4 Standardization. A periodic check of the reagents and of 
operator technique should be conducted at least once every three series 
of test runs as indicated in Section 10.1.

                   12.0 Calculations and Data Analysis

    12.1 Nomenclature. Same as Section 12.1 of Method 3 with the 
addition of the following:
%EA=Percent excess air.
0.264=Ratio of O2 to N2 in air, v/v.

    12.2 Percent Excess Air. Determine the percentage of the gas that is 
N2 by subtracting the sum of the percent CO2, 
percent CO, and percent O2 from 100 percent. Calculate the 
percent excess air (if applicable) by substituting the appropriate 
values of percent O2, CO, and N2 into Equation 3B-
1.
[GRAPHIC] [TIFF OMITTED] TR17OC00.093

    Note: The equation above assumes that ambient air is used as the 
source of O2 and that the fuel does not contain appreciable 
amounts of N2 (as do coke oven or blast furnace gases). For 
those cases when appreciable amounts of N2 are present (coal, 
oil, and natural gas do not contain appreciable amounts of 
N2) or when oxygen enrichment is used, alternative methods, 
subject to approval of the Administrator, are required.

    12.3 Data Validation When Both CO2 and O2 Are 
Measured.
    12.3.1 Fuel Factor, Fo. Calculate the fuel factor (if 
applicable) using Equation 3B-2:
[GRAPHIC] [TIFF OMITTED] TR17OC00.094

Where:

%O2=Percent O2 by volume, dry basis.
%CO2=Percent CO2 by volume, dry basis.
20.9=Percent O2 by volume in ambient air.

    If CO is present in quantities measurable by this method, adjust the 
O2 and CO2 values using Equations 3B-3 and 3B-4 
before performing the calculation for Fo:
[GRAPHIC] [TIFF OMITTED] TR17OC00.095

[GRAPHIC] [TIFF OMITTED] TR17OC00.096

Where:
%CO=Percent CO by volume, dry basis.

    12.3.2 Compare the calculated Fo factor with the expected 
Fo values. Table 3B-1 in Section 17.0 may be used in 
establishing acceptable ranges for the expected Fo if the 
fuel being burned is known. When fuels are burned in combinations, 
calculate the combined fuel Fd and Fc factors (as 
defined in Method 19, Section 12.2) according to the procedure in Method 
19, Sections 12.2 and 12.3.

[[Page 157]]

Then calculate the Fo factor according to Equation 3B-5.
[GRAPHIC] [TIFF OMITTED] TR17OC00.097

    12.3.3 Calculated Fo values, beyond the acceptable ranges 
shown in this table, should be investigated before accepting the test 
results. For example, the strength of the solutions in the gas analyzer 
and the analyzing technique should be checked by sampling and analyzing 
a known concentration, such as air; the fuel factor should be reviewed 
and verified. An acceptability range of 12 percent 
is appropriate for the Fo factor of mixed fuels with variable 
fuel ratios. The level of the emission rate relative to the compliance 
level should be considered in determining if a retest is appropriate; 
i.e., if the measured emissions are much lower or much greater than the 
compliance limit, repetition of the test would not significantly change 
the compliance status of the source and would be unnecessarily time 
consuming and costly.

                   13.0 Method Performance [Reserved]

                  14.0 Pollution Prevention [Reserved]

                    15.0 Waste Management [Reserved]

                             16.0 References

    Same as Method 3, Section 16.0.

         17.0 Tables, Diagrams, Flowcharts, and Validation Data

                Table 3B-1--Fo Factors for Selected Fuels
------------------------------------------------------------------------
                        Fuel type                            Fo range
------------------------------------------------------------------------
Coal:
    Anthracite and lignite..............................     1.016-1.130
    Bituminous..........................................     1.083-1.230
Oil:
    Distillate..........................................     1.260-1.413
    Residual............................................     1.210-1.370
Gas:
    Natural.............................................     1.600-1.836
    Propane.............................................     1.434-1.586
    Butane..............................................     1.405-1.553
Wood....................................................     1.000-1.120
Wood bark...............................................     1.003-1.130
------------------------------------------------------------------------

   Method 3C--Determination of Carbon Dioxide, Methane, Nitrogen, and 
                     Oxygen From Stationary Sources

                     1. Applicability and Principle

    1.1 Applicability. This method applies to the analysis of carbon 
dioxide (CO2), methane (CH4), nitrogen 
(N2), and oxygen (O2) in samples from municipal 
solid waste landfills and other sources when specified in an applicable 
subpart.
    1.2 Principle. A portion of the sample is injected into a gas 
chromatograph (GC) and the CO2, CH4, 
N2, and O2 concentrations are determined by using 
a thermal conductivity detector (TCD) and integrator.

                        2. Range and Sensitivity

    2.1 Range. The range of this method depends upon the concentration 
of samples. The analytical range of TCD's is generally between 
approximately 10 ppmv and the upper percent range.
    2.2 Sensitivity. The sensitivity limit for a compound is defined as 
the minimum detectable concentration of that compound, or the 
concentration that produces a signal-to-noise ratio of three to one. For 
CO2, CH4, N2, and O2, the 
sensitivity limit is in the low ppmv range.

                            3. Interferences

    Since the TCD exhibits universal response and detects all gas 
components except the carrier, interferences may occur. Choosing the 
appropriate GC or shifting the retention times by changing the column 
flow rate may help to eliminate resolution interferences.
    To assure consistent detector response, helium is used to prepare 
calibration gases. Frequent exposure to samples or carrier gas 
containing oxygen may gradually destroy filaments.

                              4. Apparatus

    4.1 Gas Chromatograph. GC having at least the following components:
    4.1.1 Separation Column. Appropriate column(s) to resolve 
CO2, CH4, N2, O2, and other 
gas components that may be present in the sample.
    4.1.2 Sample Loop. Teflon or stainless steel tubing of the 
appropriate diameter. Note: Mention of trade names or specific products 
does not constitute endorsement or recommendation by the U. S. 
Environmental Protection Agency.
    4.1.3 Conditioning System. To maintain the column and sample loop at 
constant temperature.
    4.1.4 Thermal Conductivity Detector.
    4.2 Recorder. Recorder with linear strip chart. Electronic 
integrator (optional) is recommended.
    4.3 Teflon Tubing. Diameter and length determined by connection 
requirements of cylinder regulators and the GC.
    4.4 Regulators. To control gas cylinder pressures and flow rates.
    4.5 Adsorption Tubes. Applicable traps to remove any O2 
from the carrier gas.

                               5. Reagents

    5.1 Calibration and Linearity Gases. Standard cylinder gas mixtures 
for each

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compound of interest with at least three concentration levels spanning 
the range of suspected sample concentrations. The calibration gases 
shall be prepared in helium.
    5.2 Carrier Gas. Helium, high-purity.

                               6. Analysis

    6.1 Sample Collection. Use the sample collection procedures 
described in Methods 3 or 25C to collect a sample of landfill gas (LFG).
    6.2 Preparation of GC. Before putting the GC analyzer into routine 
operation, optimize the operational conditions according to the 
manufacturer's specifications to provide good resolution and minimum 
analysis time. Establish the appropriate carrier gas flow and set the 
detector sample and reference cell flow rates at exactly the same 
levels. Adjust the column and detector temperatures to the recommended 
levels. Allow sufficient time for temperature stabilization. This may 
typically require 1 hour for each change in temperature.
    6.3 Analyzer Linearity Check and Calibration. Perform this test 
before sample analysis. Using the gas mixtures in section 5.1, verify 
the detector linearity over the range of suspected sample concentrations 
with at least three points per compound of interest. This initial check 
may also serve as the initial instrument calibration. All subsequent 
calibrations may be performed using a single-point standard gas provided 
the calibration point is within 20 percent of the sample component 
concentration. For each instrument calibration, record the carrier and 
detector flow rates, detector filament and block temperatures, 
attenuation factor, injection time, chart speed, sample loop volume, and 
component concentrations. Plot a linear regression of the standard 
concentrations versus area values to obtain the response factor of each 
compound. Alternatively, response factors of uncorrected component 
concentrations (wet basis) may be generated using instrumental 
integration. Note: Peak height may be used instead of peak area 
throughout this method.
    6.4 Sample Analysis. Purge the sample loop with sample, and allow to 
come to atmospheric pressure before each injection. Analyze each sample 
in duplicate, and calculate the average sample area (A). The results are 
acceptable when the peak areas for two consecutive injections agree 
within 5 percent of their average. If they do not agree, run additional 
samples until consistent area data are obtained. Determine the tank 
sample concentrations according to section 7.2.

                             7. Calculations

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

A=average sample area
Bw=moisture content in the sample, fraction
C=component concentration in the sample, dry basis, ppmv
Ct=calculated NMOC concentration, ppmv C equivalent
Ctm=measured NMOC concentration, ppmv C equivalent
Pbar=barometric pressure, mm Hg
Pti=gas sample tank pressure after evacuation, mm Hg absolute
Pt=gas sample tank pressure after sampling, but before 
pressurizing, mm Hg absolute
Ptf=final gas sample tank pressure after pressurizing, mm Hg 
absolute
Pw=vapor pressure of H2O (from table 3C-1), mm Hg
Tti=sample tank temperature before sampling, [deg]K
Tt=sample tank temperature at completion of sampling, [deg]K
Ttf=sample tank temperature after pressurizing, [deg]K
r=total number of analyzer injections of sample tank during analysis 
(where j=injection number, 1 . . . r)
R=Mean calibration response factor for specific sample component, area/
ppmv

                     Table 3C-1--Moisture Correction
------------------------------------------------------------------------
                                                                Vapor
                     Temperature [deg]C                      Pressure of
                                                              H2O, mm Hg
------------------------------------------------------------------------
4..........................................................          6.1
6..........................................................          7.0
8..........................................................          8.0
10.........................................................          9.2
12.........................................................         10.5
14.........................................................         12.0
16.........................................................         13.6
18.........................................................         15.5
20.........................................................         17.5
22.........................................................         19.8
24.........................................................         22.4
26.........................................................         25.2
28.........................................................         28.3
30.........................................................         31.8
------------------------------------------------------------------------

    7.2 Concentration of Sample Components. Calculate C for each 
compound using Equations 3C-1 and 3C-2. Use the temperature and 
barometric pressure at the sampling site to calculate Bw. If the sample 
was diluted with helium using the procedures in Method 25C, use Equation 
3C-3 to calculate the concentration.



[GRAPHIC] [TIFF OMITTED] TR12MR96.031

                             8. Bibliography

    1. McNair, H.M., and E.J. Bonnelli. Basic Gas Chromatography. 
Consolidated Printers, Berkeley, CA. 1969.

[36 FR 24877, Dec. 23, 1971]

    Editorial Note: For Federal Register citations affecting part 60, 
appendix A-2, see the List of CFR Sections Affected, which appears in 
the Finding Aids section of the printed volume and on GPO Access.

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