Factors Influencing the Air Permeability of Felt and Felt-Like Structures

Abstract

Variations from the rated air permeability of filter fabrics have, in industry, resulted in impurities in the finished filtered product, inefficiencies of operation, and other dif ficulties. Several investigators have sought to relate the fundamental characteristics of filters with varying degrees of success.

In this paper, the tested air pernieabilities of a random sample population are in vestigated and their relationships to fabric density, thickness, and average fiber diameter are studied. A formulation, Y = C 1/X, is suggested and shown to be vatid for the constant pressure drop across the filter at which the tested air permeabilities are re corded.