[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.309]
[Page 718-719]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
Subpart D_Calibrations and Verifications
Sec. 1065.309 Continuous gas analyzer uniform response verification.
(a) Scope and frequency. If you use more than one continuous gas
analyzer to quantify a gaseous constituent, you must perform this
verification. For example, if you determine NMHC as the difference
between continuous THC and CH4 measurements, you must perform
this verification on your NMHC measurement system. As another example if
you determine NOX as the sum of separate continuous
measurements of NO and NO2, you must perform this
verification on your NOX measurement system. Also, you must
perform this verification if you use one continuous analyzer to apply an
interference compensation algorithm to another continuous gas analyzer.
Perform this verification after initial installation or major
maintenance. Also perform this verification if you reconfigure your
system in a way that would change system response. For example, perform
this verification if you add a significant volume to the transfer lines
by increasing their length or by adding a filter; or if you change the
frequency at which you sample and record gas-analyzer concentrations.
(b) Measurement principles. This procedure verifies the time-
alignment and uniform response of combined continuous gas measurements.
(c) System requirements. Demonstrate that combined continuous
concentration measurements have a uniform rise and fall during a
simultaneous to a step change in both concentrations. During a system
response to a rapid change in multiple gas concentrations, demonstrate
that the t50 times of all combined analyzers all occur at the
same recorded second of data or between the same two recorded seconds of
data.
(d) Procedure. Use the following procedure to verify the response of
a continuous gas analyzer system:
(1) Instrument setup. Follow the analyzer system manufacturer's
start-up and operating instructions. Adjust the system as needed to
optimize performance.
(2) Equipment setup. Using minimal gas transfer line lengths between
all connections, connect a zero-air source to the inlet of a 100 [deg]C
heated line. Connect the heated line outlet to one inlet of a 100 [deg]C
heated fast-acting 3-way valve (2 inlets, 1 outlet). Using a gas
divider, equally blend an NO-CO-CO2-
C3H8-CH4 (balance N2) span
gas with a span gas of NO2 (balance N2). Connect
the gas divider outlet to the inlet of a 50 [deg]C heated line. Connect
the heated line outlet to the inlet of a 50 [deg]C gas bubbler filled
with distilled water. Connect the bubbler outlet to another heated line
at 100 [deg]C. Connect the outlet of the 100 [deg]C line to the other
inlet of the 3-way valve. Connect the valve outlet to an overflow at the
gas analyzer system's probe or to an overflow fitting between the probe
and transfer line to all the analyzers being verified.
(3) Data collection. (i) Switch the valve to flow zero gas.
(ii) Allow for stabilization, accounting for transport delays and
the slowest instrument's full response.
(iii) Start recording data at the frequency used during emission
testing.
(iv) Switch the valve to flow span gas.
(v) Allow for transport delays and the slowest instrument's full
response.
(vi) Repeat the steps in paragraphs (d)(3)(i) through (v) of this
section to record seven full cycles, ending with zero gas flowing to the
analyzers.
(vii) Stop recording.
(e) Performance evaluations. Perform the following evaluations:
(1) Uniform response evaluation. (i) Calculate the mean rise time,
t10-90, mean fall time, t90-10 for each analyzer.
(ii) Determine the maximum mean rise and fall times for the slowest
responding analyzer in each combination of continuous analyzer signals
that you use to determine a single emission concentration.
(iii) If the maximum rise time or fall time is greater than one
second, verify that all other gas analyzers combined with it have mean
rise and fall times of at least 75% of that analyzer's response.
(iv) If any analyzer has shorter rise or fall times, disperse that
signal so that it better matches the rise and fall times of the slowest
signal with which
[[Page 719]]
it is combined. We recommend that you perform dispersion using SAE 2001-
01-3536 (incorporated by reference in Sec. 1065.1010) as a guide.
(v) Repeat this verification after optimizing your systems to ensure
that you dispersed signals correctly. If after repeated attempts at
dispersing signals your system still fails this verification, you may
use the continuous analyzer system if the deficiency does not adversely
affect your ability to show compliance with the applicable standards.
(2) Time alignment evaluation. (i) After all signals are adjusted to
meet the uniform response evaluation, determine the second at which--or
the two seconds between which--each analyzer crossed the midpoint of its
response, t50.
(ii) Verify that all combined gas analyzer signals are time-aligned
such that all of their t50 times occurred at the same second
or between the same two seconds in the recorded data.
(iii) If your system fails to meet this criterion, you may change
the time alignment of your system and retest the system completely. If
after changing the time alignment of your system, some of the
t50 times still are not aligned, take corrective action by
dispersing analyzer signals that have the shortest rise and fall times.
(iv) If some t50 times are still not aligned after
repeated attempts at dispersion and time alignment, you may use the
continuous analyzer system if the deficiency does not adversely affect
your ability to show compliance with the applicable standards.
Measurement of Engine Parameters and Ambient Conditions