[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: 40CFR92.130]

[Page 462-464]
 
                   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. 92.130  Determination of steady-state concentrations.

    (a)(1) For HC and NOX emissions, a steady-state 
concentration measurement, measured after 300 seconds (or 840 seconds 
for notch 8) of testing shall be used instead of an integrated 
concentration for the calculations in Sec. 92.132 if the concentration 
response meets either of the criteria of paragraph (b) of this section 
and the criterion of paragraph (c) of this section.
    (2) For CO and CO2 emissions, a steady-state 
concentration measurement, measured after 300 seconds (or 840 seconds 
for notch 8) of testing shall be used. The provisions of paragraphs (b) 
through (f) of this section do not apply for CO and CO2 
emissions.
    (b) (1) The steady-state concentration is considered representative 
of the entire measurement period if the time-weighted concentration is 
not more than 10 percent higher than the steady-state concentration. The 
time-weighted concentration is determined by integrating the 
concentration response (with respect to time in seconds) over the first 
360 seconds (or 900 seconds for notch 8) of measurement, and dividing 
the area by 360 seconds (or 900 seconds for notch 8).
    (2) A steady-state concentration is considered representative of the 
entire measurement period if the estimated peak area is not more than 10 
percent of the product of the steady-state concentration and 360 seconds 
(or 900 seconds for notch 8). The estimated peak area is calculated as 
follows, and as shown in Figure B130-1 of this section):
    (i) Draw the peak baseline as a straight horizontal line 
intersecting the steady-state response.
    (ii) Measure the peak height from the baseline with the same units 
as the steady-state concentration; this value is h.
    (iii) Bisect the peak height by drawing a straight horizontal line 
halfway between the top of the peak and the baseline.
    (iv) Draw a straight line from the top of the peak to the baseline 
such that it intersects the response curve at the same point at which 
the line described in paragraph (b)(2)(iii) of this section intersects 
the response curve.

[[Page 463]]

    (v) Determine the time between the point at which the notch was 
changed and the point at which the line described in paragraph 
(b)(2)(iv) of this section intersects the baseline; this value is t.
    (vi) The estimated peak area is equal to the product of h and t, 
divided by 2.
    (c) In order to be considered to be a steady-state measurement, a 
measured response may not vary by more than 5 percent after the first 60 
seconds of measurement.
    (d) For responses meeting either of the criteria of paragraph (b) of 
this section, but not meeting the criterion of paragraph (c) of this 
section, one of the following values shall be used instead of a steady-
state or integrated concentration:
    (1) The highest value of the response that is measured after the 
first 60 seconds of measurement (excluding peaks lasting less than 5 
seconds, caused by such random events as the cycling of an air 
compressor); or
    (2) The highest 60-second, time-weighted, average concentration of 
the response after the first 60 seconds of measurement.
    (e) For responses not meeting the criterion in paragraph (c) of this 
section, the Administrator may require that the manufacturer or 
remanufacturer identify the cause of the variation, and demonstrate that 
it is not caused by a defeat device.
    (f) The integrated concentration used for calculations shall be from 
the highest continuous 120 seconds of measurement.
    (g) Compliance with paragraph (b)(2) of this section does not 
require calculation where good engineering practice allows compliance to 
be determined visually (i.e., that the area of the peak is much less 
than the limits set forth in paragraph (b)(2) of this section).

[[Page 464]]

                          Figure to Sec. 92.130
[GRAPHIC] [TIFF OMITTED] TR16AP98.007