CHARACTERIZATION OF PARTICLE SIZE DISTRIBUTIONS OF ATOMIZERS AND CONDENSATION GENERATORS USED FOR TESTING HIGH EFFICIENCY FILTERS

摘要

High efficiency filters are typically tested both as manufactured and after installation. In many cases,rnsuch as in pharmaceutical applications, these filters are required to be periodically tested in situ. As inrnany filter performance testing, one needs a challenge aerosol. Polystyrene Latex spheres with traceablernsizes are the preferred challenge in the micro electronic industry. For the rest of the filter markets, oilrnaerosols produced either by atomization or by vapor condensation are the common test aerosols.rnFilter performance is size specific and small changes in particle sizes at which they are tested can resultrnin large differences in reported performance. It is quite common in the real world for the same filter to bernacceptable when tested with one aerosol while deficient if tested with another.rnThis paper will report on experimental measurement of the aerosols generated by commonly usedrnatomizers and vapor condensation generators. The size distribution for different oils and test conditionsrnwill be reported. Their implication on filter testing will be addressed especially as it pertains to thernproblem commonly referred to in the trade as “bleed through”.