Automobile cabin air filter test method, repeatability and reproducibility

The Society of Automotive Engineers wrote an air filter test code to standardize test methods for automotive cabin air filters. The intent of any standardized test method is to permit results from one laboratory to be compared to the results of another laboratory with some degree of confidence. Rather than prescribe specify test system configuration, the test code describes the characteristics of the system. For example the code requires the flow approaching the filter under test to be uniform, it does not require a specific arrangement of hardware to obtain the uniform flow. The test method includes measurement of filter pressure drop, initial efficiency as a function of particle size, the life of the filter when subjected to a test contaminant, and efficiency as a function of particle size throughout the life of the filter. A pilot study has been undertaken to determine the repeatability and reproducibility of the test method. Results from pressure drop and initial efficiency tests at several laboratories are presented along with analysis of the possible causes of the variability observed in the results.