Compound injection to assure the performance of motor vehicle emissions sampling systems

摘要

There are many sources of variability when sampling motor vehicle emissions, including intermittent losses to "wetted" sampling system surfaces if water condensation occurs and thermal decomposition if sampling system surfaces get excessively hot. The risk of losses varies during typical transient speed emissions tests and depends upon many variables such as temperature, pressure, exhaust dilution ratio, dilution air humidity, fuel composition, and emissions decomposition. Procedures are described for injection of known concentrations of compounds of interest into transient motor vehicle exhaust for the purpose of characterizing losses between the vehicle tailpipe and emissions analyzer.