Axion is typically calibrated using a locally obtained “smog check” calibration gas mix (propane, CO, CO2, NO). Data from several laboratories using various vehicles and fuels shows that when Axion is operated simultaneously with the laboratory system, the difference is typically less than 10% for aggregate mass NOx and CO2. The accuracy of HC and CO measurements depends on the fuel used and on the emission levels. The accuracy of PM measurement has not been quantified at this point. Data from the EPA Laboratory in Ann Arbor, Michigan also shows that the difference between the portable system and two laboratory systems (model and bag sampling) was comparable to the differences between the two laboratory systems.
Laboratory Comparison information is available upon request.