[Code of Federal Regulations]
[Title 40, Volume 18]
[Revised as of July 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR92.119]
[Page 447-449]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 92--CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES--
Table of Contents
Subpart B--Test Procedures
Sec. 92.119 Hydrocarbon analyzer calibration.
The HFID hydrocarbon analyzer shall receive the following initial
and periodic calibration:
(a) Initial and periodic optimization of detector response. Prior to
introduction into service and at least annually thereafter, the HFID
hydrocarbon analyzer shall be adjusted for optimum hydrocarbon response.
Alternate methods yielding equivalent results may be used, if approved
in advance by the Administrator.
(1) Follow good engineering practices for initial instrument start-
up and basic operating adjustment using the appropriate fuel (see
Sec. 92.112) and zero-grade air.
(2) Optimize on the most common operating range. Introduce into the
analyzer a propane-in-air mixture with a propane concentration equal to
approximately 90 percent of the most common operating range.
(3) HFID optimization is performed:
(i) According to the procedures outlined in Society of Automotive
Engineers (SAE) paper No. 770141, ``Optimization of Flame Ionization
Detector for Determination of Hydrocarbons in Diluted Automobile
Exhaust'', author, Glenn D. Reschke (incorporated by reference at
Sec. 92.5); or
(ii) According to the following procedures:
(A) If necessary, follow manufacturer's instructions for instrument
start-up and basic operating adjustments.
(B) Set the oven temperature 5 deg.C hotter than the required
sample-line temperature. Allow at least one-half hour after the oven has
reached temperature for the system to equilibrate.
(C) Initial fuel flow adjustment. With the fuel and air-flow rates
set at the manufacturer's recommendations, introduce a 350 ppmC
75 ppmC span gas to the detector. Determine the response at
a given fuel flow from the difference between the span-gas response and
the zero-gas response. Incrementally adjust the fuel flow above and
below the manufacturer's specification. Record the span and zero
response at these fuel flows. A plot of the difference between the span
and zero response versus fuel flow will be similar to the one shown in
Figure B119-1 of this section. Adjust the fuel-flow rate to the rich
side of the curve, as shown. This is initial flow-rate setting and may
not be the final optimized flow rate.
(D) Oxygen interference optimization. Choose a range where the
oxygen interference check gases (see Sec. 92.112) will fall in the upper
50 percent. Conduct this test with the oven temperature set as required.
Oxygen interference check gas specifications are found in Sec. 92.112.
(1) Zero the analyzer.
(2) Span the analyzer with the 21-percent oxygen blend.
(3) Recheck zero response. If it has changed more than 0.5 percent
of full scale repeat paragraphs (a)(3)(ii)(D) (1) and (2) of this
section.
(4) Introduce the 5 percent and 10 percent oxygen interference check
gases.
(5) Recheck the zero response. If it has changed more 1
percent of full scale, repeat the test.
(6) Calculate the percent of oxygen interference (%O2I)
for each mixture in step in paragraph (a)(3)(ii)(D)(4) of this section.
Percent O2I=((B-Analyzer response (ppmC))/B)x(100)
Analyzer response=((A)/(Percent of full-scale analyzer response due to
A))x(Percent of full-scale analyzer response due to B)
Where:
A=hydrocarbon concentration (ppmC) of the span gas used in step in
paragraph (a)(3)(ii)(D)(2) of this section.
B=hydrocarbon concentration (ppmC) of the oxygen interference check
gases used in step in paragraph (a)(3)(ii)(D)(4) of this section.
(7) The percent of oxygen interference (%O2I) must be
less than 3.0 percent for all required oxygen interference
check gases prior to testing.
(8) If the oxygen interference is greater than the specifications,
incrementally adjust the air flow above and below the manufacturer's
specifications, repeating paragraphs (a)(3)(ii)(D) (1) through (7) of
this section for each flow.
(9) If the oxygen interference is greater than the specification
after adjusting the air flow, vary the fuel flow and thereafter the
sample flow, repeating paragraphs (a)(3)(ii)(D) (1) through (7) of this
section for each new setting.
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(10) If the oxygen interference is still greater than the
specifications, repair or replace the analyzer, FID fuel, or burner air
prior to testing. Repeat this section with the repaired or replaced
equipment or gases.
(E) Linearity check. For each range used, check linearity as
follows:
(1) With the fuel flow, air flow and sample flow adjust to meet the
oxygen interference specification, zero the analyzer.
(2) Span the analyzer using a calibration gas that will provide a
response of approximately 90 percent of full-scale concentration.
(3) Recheck the zero response. If it has changed more than 0.5
percent of full scale, repeat steps in paragraphs (a)(3)(ii)(E) (1) and
(2) of this seciton.
(4) Record the response of calibration gases having nominal
concentrations of 30, 60, and 90 percent of full-scale concentration. It
is permitted to use additional concentrations.
(5) Perform a linear least square regression on the data generated.
Use an equation of the form y = mx, where x is the actual chart
deflection and y is the concentration.
(6) Use the equation z = y/m to find the linear chart deflection (z)
for each calibration gas concentration (y).
(7) Determine the linearity (%L) for each calibration gas by:
Percent L=(100)(z-x)/(Full-scale linear chart deflection)
(8) The linearity criterion is met if the %L is less than
2 percent for each data point generated. Below 40 ppmC the
linearity criterion may be expanded to 4 percent. For each
emission test, a calibration curve of the form y = mx is to be used. The
slope (m) is defined for each range by the spanning process.
(9) If the %L for any point exceeds the specifications in step in
paragraph (a)(3)(ii)(E)(8) of this section, the air fuel, and sample-
flow rates may be varied within the boundaries of the oxygen
interference specifications.
(10) If the %L for any data point still exceeds the specifications,
repair or replace the analyzer, FID fuel, burner air, or calibration
bottles prior to testing. Repeat the procedures of this section with the
repaired or replaced equipment or gases.
(F) Optimized flow rates. The fuel-flow rate, air-flow rate and
sample-flow rate and sample-flow rate are defined as ``optimized'' at
this point.
(iii) Alternative procedures may be used if approved in advance by
the Administrator.
(4) After the optimum flow rates have been determined they are
recorded for future reference.
(b) Initial and periodic calibration. Prior to introduction into
service and monthly thereafter, the HFID hydrocarbon analyzer shall be
calibrated on all normally used instrument ranges. Use the same flow
rate and pressures as when analyzing samples. Calibration gases shall be
introduced directly at the analyzer.
(1) Adjust analyzer to optimize performance.
(2) Zero the hydrocarbon analyzer with zero-grade air.
(3) Calibrate on each used operating range with propane-in-air
calibration gases having nominal concentrations of 15, 30, 45, 60, 75
and 90 percent of that range. For each range calibrated, if the
deviation from a least-squares best-fit straight line is 2 percent or
less of the value at each data point, concentration values may be
calculated by use of single calibration factor for that range. If the
deviation exceeds 2 percent at any point, the best-fit non-linear
equation which represents the data to within 2 percent of each test
point shall be used to determine concentration.
[[Page 449]]
Figure to Sec. 92.119
[GRAPHIC] [TIFF OMITTED] TR16AP98.005
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