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This paper summarizes the validation testing of the Horiba Instruments OBS-2200 gaseous portable emissions measurement system (PEMS) for in-use compliance testing per Title 40 of the Code of Federal Regulations (CFR) Part 1065.920 (Section 1065.920). The qualification process included analyzer verifications as well as engine testing on a model-year 2007 heavy-duty diesel engine produced by Volvo Powertrain. The measurements of brake-specific emissions with the OBS-2200 were compared to those of a CFR Part 1065-compliant CVS test cell over a series of not-to-exceed (NTE) events. The OBS-2200 passed all linearity verifications and analyzer checks required of PEMS. Engine test validation was achieved for all three regulated gaseous emissions (CO, NMHC, and NOX) per 40 CFR Part 1065.920(b)(5)(i), which requires a minimum of 91 percent of the measurement allowance adjusted deltas to be less than or equal to zero.

Automotive emissions have been regulated to very low mass emissions. Various collection techniques have been utilized to measure the emitted gases. Some sample collection techniques utilize dilution gases that have concentrations below ambient air background values. For these applications analyzers with very low ranges have been produced. When using analyzers with ranges below 10 ppm, gas accuracy and impurities become very critical to the successful operation of these analyzers. A general demonstration of analyzer accuracy will be presented for various ranges. The availability and accuracy of the reference gases will be discussed. The relationship between the accuracy of the gas labeling and the analyzer's calibration accuracy will be evaluated. Gas delivery components can also affect the purity of zero gases and the accuracy of gas mixtures. Oxygen cleaned gas cylinder regulators will be compared to standard regulators for THC background contribution.