The Effect of PAO Aerosol Challenge on the Differential Pressure of an ePTFE Media ULPA (Experimental) Filter

A new generic ePTFE (expanded polytetrafluoroethylene) media super ULPA filter was subjected to six hours of continual PAO (polyalphaolefin) challenge to determine the effect on the filter differential pressure and delivered air flow. A continuous challenge concentration of 15 to 16 μg/L was introduced upstream of the filter. To limit the effect of the fan curve, air volume was adjusted to maintain the initial value of 500 f³/min ± 5% for the duration of the study. A volume of 500 f³/min is typical for a terminal housing to limit noise generation in a facility and maximize filter life. Over the test period the air volume and differential pressure were taken every 15 minutes. The results showed a 96% increase in differential pressure over the course of study. As a result of this significant increase in differential pressure, it was determined that the ePTFE is not suited for the intended application requiring semiannual certification using an oil-based aerosol challenge.