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A METHOD TO MEASURE PROTECTIVE CLOTHING PERMEATION UNDER INTERMITTENT CHEIMCAL CONTACT CONDITIONS
Citation:
Goydan, R., T. Carroll, A. Schwope, AND R. Reid. A METHOD TO MEASURE PROTECTIVE CLOTHING PERMEATION UNDER INTERMITTENT CHEIMCAL CONTACT CONDITIONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-89/004.
Description:
A preliminary method was developed to measure chemical permeation under intermittent chemical contact conditions. Protective clothing permeation is presently measured using ASTM Method F739-85. Because this test measures permeation when the clothing material is in continuous contact with the chemical during the test, the results may overestimate the permeation resulting from intermittent chemical contacts. The proposed method involves repeated contact cycles of duration tcycle: the chemical contacts the material for a short duration, denoted as ton, the chemical is removed, and air sweeps the material surface for the remainder of the cycle. Tests were conducted using nitrile rubber/acetone, natural rubber/tetrachloroethylene, and various ton/tcycle ratios. The results indicate that lower levels of chemical permeation wouldbe measured using the proposed method than those using ASTM F739. The measured breakthrough times were comparable but the permeation rates were greatly reduced. Although only a limited number of experiments was performed the method appears to generate reproducible results which agree fairly well with mathematical model predictions derived from Fick's laws of diffusion.