40 CFR 90.422 - Background sample.
(a) Background samples are produced by drawing a sample of the dilution air during the exhaust collection phase of each test cycle mode.
(1) An individual background sample may be produced and analyzed for each mode. Hence, a unique background value will be used for the emission calculations for each mode.
(2) Alternatively, a single background sample may be produced by drawing a sample during the collection phase of each test cycle mode. Hence, a single cumulative background value will be used for the emission calculations for each mode.
(b) For analysis of the individual sample described in paragraph (a)(1) of this section, a single value representing the average chart deflection over a 10-second stabilized period must be stored. All readings taken during the data logging period must be stable within ±one percent of full scale.
Title 40 published on 2013-07-01
no entries appear in the Federal Register after this date.