Oxygen Content Variation in “Zero” Grade Air Due to Production, Treatment and Distribution

Clean Dry Air and Zero grade air are used for both dilution and analyzer support gas in exhaust gas analysis for emission testing. Variation in the oxygen content can make a significant impact on the accuracy of test results evaluated for Super Ultra Low Emission Vehicle (SULEV) standards.

“Air” is often assumed to retain a constant ratio of nitrogen and oxygen - yet typically the oxygen content is not measured on a real time continuous basis. Production, treatment and distribution methods - the compression, purification and pressure management of air, have been shown to be capable of modifying the transient oxygen concentration by more than 10%.

The results of the testing performed identify the oxygen variation behavior of several components found in Zero Air systems.