[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: 40CFR92.102]

[Page 421-422]
 
                   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. 92.102  Definitions and abbreviations.

    The definitions and abbreviations of subpart A of this part apply to 
this subpart. The following definitions and abbreviations, as well as 
those found in Sec. 92.132 (Calculations), also apply:
    Accuracy means the difference between the measured value and the 
true value, where the true value is determined from NIST traceable 
measurements where possible, or otherwise determined by good engineering 
practice.
    Calibration means the act of calibrating an analytical instrument 
using known standards.
    Calibration gas means a gas of known concentration which is used to 
establish the response curve of an analyzer.
    Good engineering practice means those methods and practices which 
the Administrator determines to be consistent with scientific and 
engineering principles.
    Hang-up refers to the process of hydrocarbon molecules being 
adsorbed, condensed, or by any other method removed from the sample flow 
prior to reaching the instrument detector. It also refers to any 
subsequent

[[Page 422]]

desorption of the molecules into the sample flow when they are assumed 
to be absent.
    Parts per million, carbon or ppmC means the concentration of an 
organic compound in a gas expressed as parts per million (by volume or 
by moles) multiplied by the number of carbon atoms in a molecule of that 
compound.
    Precision means the standard deviation of replicated measurements, 
or one-half of the readability, whichever is greater; except where 
explicitly noted otherwise.
    Readability means the smallest difference in measured values that 
can be detected. For example, the readability for a digital display with 
two decimal places would be 0.01.
    Span gas means a gas of known concentration which is used routinely 
to set the output level of an analyzer.
    Standard conditions and standard temperature and pressure mean 68 
deg.F (20  deg.C) and 29.92 in Hg. (101.3 kPa).