40 CFR 89.420 - Background sample.
(a) Background samples are produced by continuously drawing a sample of dilution air during the exhaust collection phase of each test cycle mode.
(1) Individual background samples 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 of the test cycle modes. 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 is stored. All readings taken during the 10-second interval must be stable at the final value to within ±1 percent of full scale.
(c) Measure HC, CO, CO2, and NOX exhaust and background concentrations in the sample bag(s) with approximately the same flow rates and pressures used during calibration.
Title 40 published on 09-Jun-2018 05:24
The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 40 CFR Part 89 after this date.