[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.