[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: 40CFR92.108]

[Page 425-426]
 
                   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. 92.108  Intake and cooling air measurements.

    (a) Intake air flow measurement. Measurement of the flow rate of 
intake air into the engine is allowed for engine testing, but not 
required. When it is measured, the measurement technique shall conform 
to the following:
    (1) The air flow measurement method used must have a range large 
enough to accurately measure the air flow over the engine operating 
range during the test. Overall measurement accuracy must be 
2 percent of full-scale value of the measurement device for 
all modes except idle. For idle, the measurement accuracy shall be 
5 percent or less of the full-scale value. The Administrator 
must be advised of the method used prior to testing.
    (2) Corrections to the measured air mass flowrate shall be made when 
an engine system incorporates devices that add or subtract air mass (air 
injection, bleed air, etc.). The method used to determine the air mass 
from these devices shall be approved by the Administrator.
    (3) Measurements made in accordance with SAE recommended practice 
J244 (incorporated by reference at Sec. 92.5) are allowed.
    (b) Humidity and temperature measurements. (1) Air that has had its 
absolute

[[Page 426]]

humidity altered is considered humidity-conditioned air. For this type 
of intake air supply, the humidity measurements must be made within the 
intake air supply system, and after the humidity conditioning has taken 
place.
    (2) Humidity measurements for non-conditioned intake air supply 
systems shall be made as closely as possible to the point at which the 
intake air stream enters the locomotive, or downstream of that point.
    (3) Temperature measurements of engine intake air, engine intake air 
after compression and cooling in the charge air cooler(s) (engine 
testing only), and air used to cool the charge air after compression, 
and to cool the engine shall be made as closely as possible to obtain 
accurate results based on engineering judgement. Measurement of ambient 
temperature for locomotive testing shall be made within 48 inches of the 
locomotive, at a location that minimizes the effect of heat generated by 
the locomotive on the measured temperature.
    (4) Temperature measurements shall comply with the requirements of 
Sec. 92.105(c).
    (5) Humidity measurements shall be accurate within 2 percent of the 
measured absolute humidity.