HEPA Filter Efficiencies Using Thermal and Air-Jet Generated Dioctyl Phthalate

High Efficiency Particulate Aerosol (HEPA) filters must exhibit a minimum collection efficiency of 99.97% when quality-control tested with a 0.3 micron mono-disperse dioctyl phthalate (DOP) aerosol. Many facilities also test these filters in-place, using a polydisperse DOP aerosol to determine the integrity of the air cleaning system. An experimental test program was carried out to: (a) measure size characteristics of the polydisperse aerosol produced using different commercial forms of DOP, and (b) relate HEPA filter efficiencies using monodisperse and polydisperse DOP aerosols. The relationships developed provide a rational basis for defining “unsatisfactory” HEPA filters using field test data and baseline criteria set for quality-control tests.