[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: 40CFR92.109]
[Page 426-427]
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. 92.109 Analyzer specifications.
(a) General analyzer specifications.--(1) Analyzer response time.
Analyzers for THC, CO2, CO, and NOX must respond
to an instantaneous step change at the entrance to the analyzer with a
response equal to 95 percent of that step change in 6.0 seconds or less
on all ranges used. The step change shall be at least 60 percent of
full-scale chart deflection. For NOX analyzers using a water
trap, the response time increase due to the water trap and associated
plumbing need not be included in the analyzer response time.
(2) Precision. The precision of the analyzers for THC,
CO2, CO, and NOX must be no greater than
1 percent of full-scale concentration for each range used
above 155 ppm (or ppmC), or 2 percent for each range used
below 155 ppm (or ppmC). The precision is defined as 2.5 times the
standard deviation(s) of 10 repetitive responses to a given calibration
or span gas.
(3) Noise. The analyzer peak-to-peak response to zero and
calibration or span gases over any 10-second period shall not exceed 2
percent of full/scale chart deflection on all ranges used.
(4) Zero drift. For THC, CO2, CO, and NOX
analyzers, the zero-response drift during a 1-hour period shall be less
than 2 percent of full-scale chart deflection on the lowest range used.
The zero-response is defined as the mean response including noise to a
zero-gas during a 30-second time interval.
(5) Span drift. For THC, CO2, CO, and NOX
analyzers, the span drift during a 1-hour period shall be less than 2
percent of full-scale chart deflection on the lowest range used. The
analyzer span is defined as the difference between the span-response and
the zero-response. The span-response is defined as the mean response
including noise to a span gas during a 30-second time interval.
(b) Carbon monoxide and carbon dioxide analyzer specifications. (1)
Carbon monoxide and carbon dioxide measurements are to be made with
nondispersive infrared (NDIR) analyzers.
(2) The use of linearizing circuits is permitted.
(3) The minimum water rejection ratio (maximum CO2
interference) as measured in Sec. 92.120(a) shall be:
(i) For CO analyzers, 1000:1.
(ii) For CO2 analyzers, 100:1.
(4) The minimum CO2 rejection ratio (maximum
CO2 interference) as measured in Sec. 92.120(b) for CO
analyzers shall be 5000:1.
(5) Zero suppression. Various techniques of zero suppression may be
used to increase readability, but only with prior approval by the
Administrator.
(6) Option: if the range of CO concentrations encountered during the
different test modes is too broad to allow accurate measurement using a
single analyzer, then multiple CO analyzers may be used.
(c) Hydrocarbon analyzer specifications. (1) Hydrocarbon
measurements are to be made with a heated flame ionization detector
(HFID) analyzer. An overflow sampling system is recommended but not
required. (An overflow system is one in which excess zero gas or span
gas spills out of the probe
[[Page 427]]
when zero or span checks of the analyzer are made.
(i) Option. A non-heated flame ionization detector (FID) that
measures hydrocarbon emissions on a dry basis is permitted for petroleum
fuels other than diesel and biodiesel; Provided, that equivalency is
demonstrated to the Administrator prior to testing. With the exception
of temperatures, all specifications contained in Subpart B of this part
apply to the optional system.
(ii) The analyzer shall be fitted with a constant temperature oven
housing the detector and sample-handling components. It shall maintain
temperature with 3.6 deg.F (2 deg.C) of the set point. The detector,
oven, and sample-handling components within the oven shall be suitable
for continuous operation at temperatures to 395 deg.F (200 deg.C).
(iii) Fuel and burner air shall conform to the specifications in
Sec. 92.112(e).
(iv) The percent of oxygen interference must be less than 3 percent,
as specified in Sec. 92.119(3).
(v) Premixed burner air. (A) For diesel and biodiesel fueled
engines, premixing a small amount of air with the HFID fuel prior to
combustion within the HFID burner is not recommended as a means of
improving oxygen interference (%O2I). However, this procedure
may be used if the engine manufacturer demonstrates on each basic
combustion system (i.e., four-cycle direct injection, two-cycle direct
injection, four-cycle indirect injection, etc.) that an HFID using this
procedure produces comparable results to an HFID not using this
procedure. These data must be submitted to the Administrator for his/her
approval prior to testing.
(B) For engines operating on fuels other than diesel or biodiesel,
premixing burner air with the HFID fuel is not allowed.
(2) Methane analyzer. The analytical system for methane consists of
a gas chromatograph (GC) combined with a flame ionization detector
(FID).
(3) Alcohols and Aldehydes. The sampling and analysis procedures for
alcohols and aldehydes, where applicable, shall be approved by the
Administrator prior to the start of testing. Procedures consistent with
the general requirements of 40 CFR Part 86 for sampling and analysis of
alcohols and aldehydes emitted by on-highway alcohol-fueled engines, and
consistent with good engineering practice are allowed.
(4) Other methods of measuring organics that are shown to yield
equivalent results can be used upon approval of the Administrator prior
to the start of testing.
(d) Oxides of nitrogen analyzer specifications. (1) Oxides of
nitrogen are to be measured with a chemiluminescence (CL) analyzer.
(i) The NOX sample must be heated per Sec. 92.114 up to
the NO2 to NO converter.
(ii) For high vacuum CL analyzers with heated capillary modules,
supplying a heated sample to the capillary module is sufficient.
(iii) The NO2 to NO converter efficiency shall be at
least 90 percent.
(iv) The CO2 quench interference must be less than 3.0
percent as measured in Sec. 92.121(a).