Aerosol Penetration through 9 Mil Hv-70 Filter Paper with and without Pinholes. Hasl-139.

Studies were made of the penetration of two polydispersed dioctylphthalate aerosols of different particle size distri bution through 9 mil HV-70 type filter paper with and without pinholes at several different air velocities. It was found, as was expected from elementary considera tions, that the penetrations of the two aerosols of different particle size differed greatly for an intact filter, but ap proached the same value for the filters containing pinholes. This result implies that in testing filters or filter instal lations for leaks, aerosol particle size is much less important than in evaluating filter materials per se. To account for the pinhole effect, a generalized equation was developed which relates change of aerosol penetration through a filter to air linear velocity. This equation was confirmed within limits.