CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 86—CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES > SUBPART P—Emission Regulations for Otto-Cycle Heavy-Duty Engines, New Methanol-Fueled Natural Gas-Fueled, and Liquefied Petroleum Gas-Fueled Diesel-Cycle Heavy-Duty Engines, New Otto-Cycle Ligh > 86.1544—Calculation; idle exhaust emissions.

86.1544—Calculation; idle exhaust emissions.

(a) The final idle emission test results shall be reported as percent for carbon monoxide on a dry basis.
(b) If a CVS sampling system is used, the following procedure shall apply:
(1) Use the procedures, as applicable, in 40 CFR 1065.650 to determine the dilute wet-basis CO and CO2 in percent.
(2) Use the procedure, as applicable, in 40 CFR 1065.650 to determine the raw dry-basis CO2 in percent.
(3) Convert the raw dry-basis CO2 to raw wet-basis. An assumption that the percent of water by volume in the raw sample is equal to the percent of raw dry-basis CO2 minus 0.5 percent is acceptable. For example:

Code of Federal Regulations

10.0% dry CO2−0.5%=9.5% water

Code of Federal Regulations

(1.00−0.095) (10.0% dry CO2)=9.05% wet CO2
(4) Calculate the CVS dilution factor (DF) by:
(5) Convert the dilute wet-basis CO to dilute dry-basis values. An assumption that the percent of water by volume in the sample bag is 2 percent is acceptable. For example:
Dilute dry CO=(dilute wet CO)/(1.00-0.02)
(6) Calculate the raw dry-basis CO values by:
Raw dry CO=(DF) (dilute dry CO)
(c) If the raw exhaust sampling and analysis system specified in 40 CFR part 1065 is used, the percent for carbon monoxide on a dry basis shall be calculated using the procedure, as applicable, in 40 CFR 1065.650.

Code of Federal Regulations

(Secs. 202, 203, 206, 207, 208, 301a, Clean Air Act, as amended; 42 U.S.C. 7521, 7522, 7525, 7541, 7542, 7601a )

Code of Federal Regulations

[48 FR 52252, Nov. 16, 1983, as amended at 49 FR 48149, Dec. 10, 1984; 50 FR 10708, Mar. 15, 1985; 51 FR 24613, July 7, 1986; 70 FR 40441, July 13, 2005. Redesignated at 73 FR 37194, June 30, 2008]