Experiments and a model have been made of the effects of mass loading of a HEPA fiber filter during filtration of submicron liquid aerosol particles. The measurements reveal that penetration of the test medium increased during clogging by a liquid aerosol, irrespective of particle size within the chosen range (0.02–0.5 μm). The physicochemical properties of the test aerosol did not seem to affect this phenomenon. Application of a non-stationary filtration model by Payet [1991, Thèse, Université Paris, 150 p] (based on the correlation of Liu and Rubow [1990, 5th World Filt. Congress, Nice 3, 112] showed that the increase in penetration can be explained in part by an increase in interstitial velocity and in part by a decrease in the number of fibers available for capture of particles.
