[Code of Federal Regulations]
[Title 40, Volume 5]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR53.56]
[Page 89-92]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 53_AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS--Table of
Subpart E_Procedures for Testing Physical (Design) and Performance
Sec. 53.56 Test for effect of variations in ambient pressure.
(a) Overview. (1) This test procedure is designed to test various
sampler performance parameters under variations in ambient (barometric)
pressure. Tests shall be conducted in a pressure-controlled environment
over two 6-hour time periods during which reference pressure and flow
rate measurements shall be made at intervals not to exceed 5 minutes.
Specific parameters to be evaluated at operating pressures of 600 and
800 mm Hg are as follows:
(i) Sample flow rate.
(ii) Flow rate regulation.
(iii) Flow rate measurement accuracy.
(iv) Coefficient of variability measurement accuracy.
(v) Ambient pressure measurement accuracy.
(vi) Proper operation of the sampler when exposed to ambient
pressure extremes.
(2) The performance parameters tested under this procedure, the
corresponding minimum performance specifications, and the applicable
test conditions are summarized in table E-1 of this subpart. Each
performance parameter tested, as described or determined in the test
procedure, must meet or exceed the associated performance specification
given. The candidate sampler must meet all specifications for the
associated PM2.5 or PM10-2.5 method (as
applicable) to pass this test procedure.
(b) Technical definition. Sample flow rate means the quantitative
volumetric flow rate of the air stream caused by the sampler to enter
the sampler inlet and pass through the sample filter, measured in actual
volume units at the temperature and pressure of the air as it enters the
inlet.
(c) Required test equipment. (1) Hypobaric chamber or other
pressure-controlled environment or environments, capable of obtaining
and maintaining pressures at 600 mm Hg and 800 mm Hg required for the
test with an accuracy of 5 mm Hg. Henceforth, where the test procedures
specify a test or environmental chamber, an alternative pressure-
controlled environmental area or areas may be substituted, provided the
test pressure requirements are met. Means for simulating ambient
pressure using a closed-loop sample air system may also be approved for
this test; such a proposed method for simulating the test pressure
conditions may be described and submitted to EPA at the address given in
Sec. 53.4(a) prior to conducting the test for a specific individual
determination of acceptability.
(2) Flow rate meter, suitable for measuring and recording the actual
volumetric sampler flow rate at the sampler downtube, with a minimum
range of 10 to 25 L/min, 2 percent certified, NIST-traceable accuracy.
Optional capability for continuous (analog) recording capability or
digital recording at intervals not to exceed 5 minutes is recommended.
While a flow meter which provides a direct indication of volumetric flow
rate is preferred for this test, an alternative certified flow
measurement device may be used as long as appropriate volumetric
[[Page 90]]
flow rate corrections are made based on measurements of actual ambient
temperature and pressure conditions.
(3) Ambient air temperature recorder (if needed for volumetric
corrections to flow rate measurements) with a range -30 [deg]C to =50
[deg]C, certified accurate to within 0.5 [deg]C. If the certified flow
meter does not provide direct volumetric flow rate readings, ambient
temperature measurements must be made using continuous (analog)
recording capability or digital recording at intervals not to exceed 5
minutes.
(4) Barometer, range 600 mm Hg to 800 mm Hg, certified accurate to 2
mm Hg. Ambient air pressure measurements must be made using continuous
(analog) recording capability or digital recording at intervals not to
exceed 5 minutes.
(5) Flow measurement adaptor (40 CFR part 50, appendix L, figure L-
30) or equivalent adaptor to facilitate measurement of sampler flow rate
at the sampler downtube.
(6) Means for creating an additional pressure drop of 55 mm Hg in
the sampler to simulate a heavily loaded filter, such as an orifice or
flow restrictive plate installed in the filter holder or a valve or
other flow restrictor temporarily installed in the flow path near the
filter.
(7) Teflon sample filter, as specified in section 6 of 40 CFR part
50, appendix L (if required).
(d) Calibration of test measurement instruments. Submit
documentation showing evidence of appropriately recent calibration,
certification of calibration accuracy, and NIST-traceability (if
required) of all measurement instruments used in the tests. The accuracy
of flow rate meters shall be verified at the highest and lowest
pressures and temperatures used in the tests and shall be checked at
zero and at least one flow rate within 3 percent
of 16.7 L/min within 7 days prior to use for this test. Where an
instrument's measurements are to be recorded with an analog recording
device, the accuracy of the entire instrument-recorder system shall be
calibrated or verified.
(e) Test setup. (1) Setup of the sampler shall be performed as
required in this paragraph (e) and otherwise as described in the
sampler's operation or instruction manual referred to in Sec.
53.4(b)(3). The sampler shall be installed upright and set up in the
pressure-controlled chamber in its normal configuration for collecting
PM samples. A sample filter and (or) the device for creating an
additional 55 mm Hg pressure drop shall be installed for the duration of
these tests. The sampler's ambient temperature, ambient pressure, and
flow measurement systems shall all be calibrated per the sampler's
operating manual within 7 days prior to this test.
(2) The inlet of the candidate sampler shall be removed and the flow
measurement adaptor installed on the sampler's downtube. A leak check as
described in the sampler's operation or instruction manual shall be
conducted and must be properly passed before other tests are carried
out.
(3) The inlet of the flow measurement adaptor shall be connected to
the outlet of the flow rate meter.
(4) The barometer shall be installed in the test chamber such that
it will accurately measure the air pressure to which the candidate
sampler is subjected.
(f) Procedure. (1) Set up the sampler as specified in paragraph (e)
of this section and otherwise prepare the sampler for normal sample
collection operation as directed in the sampler's operation or
instruction manual.
(2) The test shall consist of two test runs, one at each of the
following conditions of chamber pressure:
(i) 600 mm Hg.
(ii) 800 mm Hg.
(3) For each of the two test runs, set the selected chamber pressure
for the test run. Upon achieving each pressure setpoint in the chamber,
the candidate sampler shall be pressure-equilibrated for a period of at
least 30 minutes prior to the test run. Following the conditioning time,
set the sampler to automatically start a 6-hour sample collection period
at a convenient time.
(4) During each 6-hour test period:
(i) Measure and record the sample flow rate with the flow rate meter
at intervals not to exceed 5 minutes. If ambient temperature and
pressure corrections are necessary to calculate volumetric flow rate,
ambient temperature and pressure shall be measured at
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the same frequency as that of the certified flow rate measurements. Note
and record the actual start and stop times for the 6-hour flow rate test
period.
(ii) Determine and record the ambient (chamber) pressure indicated
by the sampler and the corresponding ambient (chamber) pressure measured
by the barometer specified in paragraph (c)(4) of this section at
intervals not to exceed 5 minutes.
(5) At the end of each test period, terminate the sample period (if
not automatically terminated by the sampler) and download all archived
instrument data for the test run from the test sampler.
(g) Test results. For each of the two test runs, examine the chamber
pressure measurements. Verify that the pressure met the requirements
specified in paragraph (f) of this section at all times during the test.
If not, the test run is not valid and must be repeated. Determine the
test results as follows:
(1) Mean sample flow rate. (i) From the certified measurements
(Qref) of the test sampler flow rate, tabulate each flow rate
measurement in units of L/min. If ambient temperature and pressure
corrections are necessary to calculate volumetric flow rate, each
measured flow rate shall be corrected using its corresponding
temperature and pressure measurement values. Calculate the mean flow
rate for the sample period (Qref,ave) as follows:
Equation 17
[GRAPHIC] [TIFF OMITTED] TR18JY97.079
where:
n equals the number of discrete certified flow measurements over the 6-
hour test period.
(ii)(A) Calculate the percent difference between this mean flow rate
value and the design value of 16.67 L/min, as follows:
Equation 18
[GRAPHIC] [TIFF OMITTED] TR18JY97.080
(B) To successfully pass this test, the percent difference
calculated in Equation 18 of this paragraph (g)(1) must be within 5 percent for each test run.
(2) Sample flow rate regulation. (i) From the certified measurements
of the test sampler flow rate, calculate the sample coefficient of
variation of the discrete measurements as follows:
Equation 19
[GRAPHIC] [TIFF OMITTED] TR18JY97.081
(ii) To successfully pass this test, the calculated coefficient of
variation for the certified flow rates must not exceed 2 percent.
(3) Flow rate measurement accuracy. (i) Using the mean volumetric
flow rate reported by the candidate test sampler at the completion of
each 6-hour test (Qind,ave), determine the accuracy of the
reported mean flow rate as:
Equation 20
[GRAPHIC] [TIFF OMITTED] TR18JY97.082
(ii) To successfully pass this test, the percent difference
calculated in Equation 20 of this paragraph (g)(3) shall not exceed 2
percent for each test run.
(4) Flow rate CV measurement accuracy. (i) Using the flow rate
coefficient of variation indicated by the candidate test sampler at the
completion of the 6-hour test (%CVind), determine the
accuracy of the reported coefficient of variation as:
Equation 21
[GRAPHIC] [TIFF OMITTED] TR18JY97.083
(ii) To successfully pass this test, the absolute difference in
values calculated in Equation 21 of this paragraph (g)(4) must not
exceed 0.3 (CV%) for each test run.
[[Page 92]]
(5) Ambient pressure measurement accuracy. (i) Calculate the
absolute difference between the mean ambient air pressure indicated by
the test sampler and the ambient (chamber) air pressure measured with
the reference barometer as:
Equation 22
[GRAPHIC] [TIFF OMITTED] TR18JY97.084
where:
Pind,ave = mean ambient pressure indicated by the test
sampler, mm Hg; and
Pref,ave = mean barometric pressure measured by the reference
barometer, mm Hg.
(ii) The calculated pressure difference must be less than 10 mm Hg
for each test run to pass the test.
(6) Sampler functionality. To pass the sampler functionality test,
the following two conditions must both be met for each test run:
(i) The sampler must not shut down during any part of the 6-hour
tests; and
(ii) An inspection of the downloaded data from the test sampler
verifies that all the data are consistent with normal operation of the
sampler.
[62 FR 38799, July 18, 1997; 63 FR 7714, Feb. 17, 1998, as amended at 71
FR 61292, Oct. 17, 2006]