Evaluation of a Low-Cost Transient Mass Measurement System in Vehicle Inspection and Maintenance Testing: Results of a Gordon-Darby Study

• Published in: Journal of the Air & Waste Management Association (1995) 2003-09, Vol.53 (9), p.1098-1108
• Main Authors: Ensfield, Carl, Gordon, Jay, Lindner, Jim
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Air quality management; Applied sciences; Atmospheric pollution; Automotive emissions; Cost Control; Environmental Monitoring - economics; Environmental Monitoring - methods; Equipment Design; Evaluation; Exact sciences and technology; Measurement; Methods; Motor Vehicles; Pollution; Pollution sources. Measurement results; Reproducibility of Results; Transports; Vehicle Emissions - analysis
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.2003.10466260

A study was performed at a Gordon-Darby centralized inspection and maintenance (I/M) test lane in Phoenix, AZ, in December 1999 for the purpose of evaluating the accuracy of production Vehicle Mass Analysis System (VMAS) equipment relative to standard IM240 equipment. Simultaneous transient mass measurements were made on random vehicles using VMAS and IM240 systems on two test lanes during regular I/M testing. Cumulative mass emissions for 846 valid tests were correlated using least-squares regression analysis. Correlation indices were >0.99 for both carbon monoxide (CO) and nitric oxide (NO) and 0.93 for hydrocarbon (HC), and the standard errors of regression were 1.38 g/mi, 0.123 g/mi, and 0.245 g/mi for CO, NO, and HC, respectively. These strong correlation results are reflected by high excess emission identification rates of 99.4% for CO, 99.3% for NO, and 94.5% for HC when applying final IM240 cut points with a