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2075296 
Journal Article 
The Effect of Solid Particle Mass Loading on the Pressure Drop of HEPA Filters 
Novick, VJ; Monson, PR; Ellison, PE 
1992 
Yes 
Journal of Aerosol Science
ISSN: 0021-8502
EISSN: 1879-1964 
NIOSH/00210857 
23 
6 
657-665 
The increase in pressure drop across a high efficiency particulate air (HEPA) filter was investigated as a function of solid mass loading. Three different particle types were used: sodium-chloride (7647145), ammonium-chloride (12125029), and aluminum-oxide (1344281). For a given filtration velocity, the mass of material loaded per unit area of filter per unit pressure decrease was measured for each particle size distribution. As the mass median particle diameter decreased, the specific resistance of the filter cake increased in all studied cases. Good correlation was obtained between these findings and those of measurements of mass median particle diameter independent of the particle density. The authors conclude that this approach is advantageous in that it is convenient, easy to measure particle diameter, and does not require knowledge of the particle cake porosity. This new correlation permits prediction of the final pressure difference across a loaded HEPA filter or the maximum mass than can be loaded onto a filter for a given pressure difference.