Research Projects

Project at a Glance

Project Status: complete

Title: Development of a portable in-use reference PM measurement system

Principal Investigator / Author(s): Johnson, Kent C. and Thomas Durbin

Contractor: UC Riverside

Contract Number: 10-311

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels


As particulate matter (PM) mass emissions continue to be reduced, there is increasing interest in the measurement of in-use PM mass with portable emissions measurement systems (PEMS). Unfortunately, the reliability of currently available PM PEMS is questionable, as comparisons to gravimetric reference methods have shown deviations often on the order of 100% and measurements are highly dependent on composition, particle size, and concentration. Real-time instruments are not necessarily faulty, rather their measurement principles do not correlate with the gravimetric method, and a combination of factors, such as size, shape, composition, and chemistry can contribute to a poor correlation. This report describes the development and evaluation of a high quality, multi-filter indexing gravimetric PM measurement system. The system is referred to as the PM PEMS (G) in this report. The PM PEMS (G) was designed for autonomous, all day in-use operation, for up to 30 gravimetric PM filter events in a single shift while following 40CFR Part 1066 and Part 1065 sampling specifications. The developed system was designed to quantify PM mass for in-use confirmatory testing on gasoline, alternative fuels, bio diesels, and diesel sources (on-highway, non-road, and marine) while utilizing the gravimetric reference method.

The system was evaluated in a laboratory and on-road with a heavy duty vehicle equipped with an exhaust bypass system where PM concentration, composition, and size distribution was varied. This PM source test article was developed during previous evaluations of other PM PEMS for the U.S. Environmental Protection Agency Measurement Allowance program and was fully characterized for its impact on its chemical and physical PM attributes. The bypass tool was also critical in the summary of conclusions identifying the limitation of most PM PEMS systems. The comparison between the University of California at Riverside’s Mobile Emissions Laboratory (MEL) and the PM PEMS (G) was good and found to be on average within ±5% of the reference method from 129.7 mg/hp-h down to 3.6 mg/hp-h. Proportionality exceeded the specifications during not-to-exceed (NTE) operation and low power operation. Several tests did show high relative error between the MEL and PM PEMS (G) when using a flexible carbon containing silicon transfer line. These high relative errors were eliminated with a metallic transfer line. Results suggest that there may be some transfer line losses for sulfate PM. Additional testing is needed to characterize and quantify the impact flexible lines may have on in-use testing.


For questions regarding research reports, contact: Heather Choi at (916) 322-3893

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