Juxtaposition of In-Use Vehicular Emissions Measurement Equipment

A study was performed to compare measurement capabilities of two commercially available in-use portable emissions measurement systems, from different generations, in order to determine how or if changes to emissions testing standards have affected in-use equipment. The two in-use systems from different generations were the Sensors, Inc. SEMTECH-D, which would be considered first generation because it was built under the CFR 40, Part 86 standard, and the Horiba, Ltd. OBS-2200, which was considered second generation because it was built under the updated CFR 40, Part 1065 standards. Both systems underwent a series of tests in the laboratory and on-road. For the tests, five cycles were developed from on-road data collection and created into dynamometer cycles. Then those same five cycles were run on-road to generate a comparison to show differences in test methods. For the equipment comparison, both systems were tested against West Virginia University\u27s Transportable Laboratory, which was developed according to CFR 40, Part 1065 standards for emissions testing. The comparisons were completed using both distance specific and brake specific measurements. The SEMTECH-D performed well and measured CO2, THC, and NOx within five percent of the laboratory. The SEMTECH-D was not as accurate with the CO measurement, which was greater than 70 percent from the laboratory readings. The OBS-2200 measured well in comparison to the laboratory for CO 2 and NOx. These constituents were measured within four percent of the laboratory. CO and THC emissions were measured with a percent difference greater than 20 and 32 percent, respectively. Overall, neither unit outperformed the other. Each measured certain parameters and constituents better than the other but not with complete consistency. Therefore, no conclusion could be drawn on the influence of the equipment\u27s generation on emissions testing