EXPERIMENTAL RESULTS OF SOLID MONODISPERSE PARTICLE CLOGGING OF FIBROUS FILTERS

An apparatus is shown which provides useful filtration performance res ponses of flat fibrous filter media to aerosol challenges of solid par ticles of practical monodispersity (geometric standard deviation less than 1.25). Examples are given of the changes in the instantaneous pen etration and pressure drop of filter papers of different structures fr om the initial stages to the final filter cake formation states of fil ter loading. For filters of large pore diameter, the plots of pressure drop against mass loading display three regions: an initial region of slow increase, a transition region and a final linear region of cake filtration. The changing responses of penetration and pressure drop wi th particle loading are both sensitive to the effective pore diameter of the filter structure. After filter cake formation, the slopes of pr essure drop with mass loading were identical for a specific particle d iameter regardless of the filter structure, yielding a technique for d etermining the porosity of filter cakes for different particle size ch allenges.