[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: 40CFR86.114-94]

[Page 462-463]
 
                   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 B_Emission Regulations for 1977 and Later Model Year New Light-
 
Sec. 86.114-94  Analytical gases.

    (a) Analyzer gases. (1) Gases for the CO and CO2 
analyzers shall be single blends of CO and CO2 respectively 
using nitrogen as the diluent.
    (2) Gases for the THC analyzer shall be:
    (i) Single blends of propane using air as the diluent; and
    (ii) Optionally, for response factor determination, single blends of 
methanol using air as the diluent.
    (3) Gases for the methane analyzer shall be single blends of methane 
using air as the diluent.

[[Page 463]]

    (4) Gases for the NOX analyzer shall be single blends of 
NO named as NOX, with a maximum NO2 concentration 
of 5 percent of the nominal value, using nitrogen as the diluent.
    (5) Fuel for FIDs and HFIDs and the methane analyzer shall be a 
blend of 40 2 percent hydrogen with the balance 
being helium. The mixture shall contain less than one ppm equivalent 
carbon response. 98 to 100 percent hydrogen fuel may be used with 
advance approval by the Administrator.
    (6) The allowable zero gas (air or nitrogen) impurity concentrations 
shall not exceed 1 ppm equivalent carbon response, 1 ppm carbon 
monoxide, 0.04 percent (400 ppm) carbon dioxide, and 0.1 ppm nitric 
oxide.
    (7) ``Zero grade air'' includes artificial ``air'' consisting of a 
blend of nitrogen and oxygen with oxygen concentrations between 18 and 
21 mole percent.
    (8) The use of precision blending devices (gas dividers) to obtain 
the required calibration, as defined below, is acceptable, provided that 
the calibration curves they produce name a calibration gas within 2 
percent of its certified concentration. This verification shall be 
performed at between 15 and 50 percent of the full scale concentration 
of the range and shall be included with each gas calibration 
incorporating a blending device. Alternative procedures to verify the 
validity of the analyzer calibration curves generated using a gas 
divider are acceptable provided the procedures are approved in advance 
by the Administrator.
    (b) Calibration gases (not including methanol) shall be traceable to 
within one percent of NIST (formerly NBS) gas standards, or other gas 
standards which have been approved by the Administrator.
    (c) Span gases (not including methanol) shall be accurate to within 
two percent of true concentration, where true concentration refers to 
NIST (formerly NBS) gas standards, or other gas standards which have 
been approved by the Administrator.
    (d) Methanol in air gases used for response factor determination 
shall:
    (1) Be traceable to within 2 percent of NIST 
(formerly NBS) gas standards, or other standards which have been 
approved by the Administrator; and
    (2) Remain within 2 percent of the labeled 
concentration. Demonstration of stability shall be based on a quarterly 
measurement procedure with a precision of 2 
percent (two standard deviations), or other method approved by the 
Administrator. The measurement procedure may incorporate multiple 
measurements. If the true concentration of the gas changes by more than 
two percent, but less than ten percent, the gas may be relabeled with 
the new concentration.

[56 FR 25773, June 5, 1991, as amended at 60 FR 34342, June 30, 1995]