Respirator Cartridge Filter Efficiency under Cyclic- and Steady-Flow Conditions

Abstract

Respirator filter cartridges are routinely tested under steady-flow conditions to provide a basis for predicting their future performance under cyclic-flow breathing conditions. Tests were performed to define aerosol penetration through respirator filter cartridges under both cyclic and steady flow. A breathing pump was used to simulate different human breathing patterns. Steady-flow conditions were identical to those recommended by the U.S. Bureau of Mines for permissibility tests of respiratory protective devices. Solid monodisperse polystyrene latex aerosols ranging from 0.176 to 2.02 μm in size and liquid monodisperse 0.3-μm dioctyl phthalate were used as the test aerosols. Sampling during cyclic flow was performed without altering the flow pattern through the respirator cartridge. Steady- and cyclic-flow experimental data are compared as a function of aerosol size, breathing pattern, and aerosol type. Theoretical steady-flow aerosol penetration is compared to experimental cyclic-flow data.