[Code of Federal Regulations]
[Title 40, Volume 17]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR86.329-79]
[Page 601-602]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 86_CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND
ENGINES--Table of Contents
Subpart D_Emission Regulations for New Gasoline-Fueled and Diesel-Fueled
Heavy-Duty Engines; Gaseous Exhaust Test Procedures
Sec. 86.329-79 System response time; check procedure.
(a) Check the system response time by the following procedure:
(1) Stabilize the operating temperature of the sample line, sample
pump, and heated filters.
(2) Introduce an HC span gas into the sampling system at the sample
probe or valve V2 at atmospheric pressure. Simultaneously, start the
time measurement.
(3) When the HC instrument response is 95 percent of the span gas
concentration used, stop the time measurement.
(4) If the elapsed time is more than 20.0 seconds, make necessary
adjustments.
(5) Repeat with the CO, CO2, and NOX
instruments and span gases.
(b) Option. If the following parameters are determined, the initial
system response time may be generally applied to future checks.
(1) Analyzer and bypass flow rates. (i) Determine by experimentation
the minimum analyzer and bypass flow rates individually and in
combination that will produce a response time as close as possible to
20.0 seconds per paragraph (a) of this section.
(ii) Record the highest minimum flow rate for each flow meter as
determined in step (i).
[[Page 602]]
(2) Capillary flow analyzers. This procedure is applicable only to
analyzers that have sample capillaries such as the HFID and CL
analyzers. It is also assumed that the system has sample/span valves
that perform the function of valves V9 and V13 in Figure D79-1.
(i) Operate the analyzer(s) at the in-use capillary pressure.
(ii) Adjust the bypass flow rate to the flow rate recorded in
paragraph (b)(1)(ii) of this section.
(iii) Measure and record the response time from the sample/span
valve(s) per paragraph (a) of this section.
(iv) The response time (step (iii)) can be determined by switching
from the ``sample'' position to the ``span'' position of the sample/span
valve and observing the analyzer response on a chart recorder. Normally,
the ``sample'' position would select a ``room air'' sample and the
``span'' position would select a span gas.
(v) Adjust the bypass flow rate to the normal in-use value.
(vi) Measure and record the response time from the sample/span
valve(s) per paragraph (a) of this section.
(vii) Determine the slowest response time (step (iii) or step (iv))
and add 2 seconds to it.