Experimental study of air filtration by fibrous filters

The purpose of this study is to investigate the filtration characteristics of low efficiency air filters. An experimental filter test system and method for measuring filter efficiency has been developed using a moderate aerosol generator and an electrical detector. In the first part, the pressure drop and particle collection efficiency of three ASHRAE grade fibrous filters were measured from 180 ft/min to 620 ft/min using potassium chloride particles of 0.3 to 10 mum diameter and a particle counter. The filters were re-treated by designed filter oil to improve the collection efficiency.; The filtration characteristics were strongly by dependent on the fiber diameter and packing density. Particle bounce was important at high flow velocities (>620 fpm). The collection efficiency was significantly improved by treatment using the designed oil at high face velocities.; The experimental results were compared using the available theories and a generalized model was developed to predict the performance. A good agreement between the experimental data and the results of the developed model was obtained.