Permeation of protective clothing materials: comparison of liquid contact, liquid splashes and vapors on breakthrough times.

Abstract

A disturbing number of common liquid chemicals permeated the best available protective clothing material when evaluated by the ASTM Standard Test Method F739-81. Since this method involved continuous liquid contact during the 3-hr test used by the Coast Guard, it was considered unusually severe. The question then arose as to whether intermittent contact--better approximating conditions likely to be encountered in real-world situations--would give usable breakthrough times (longer than pure liquid). Comparative tests were conducted with liquid exposure for 3 hr, and three levels of intermittent exposure (splashes every 15 min or every 30 min until breakthrough, or a single initial splash), and with saturated vapor at 25 degrees C and 0 degree C [decreasing amounts of exposure]. Chemicals displayed two distinct modes of behavior. In one mode, the results were as might be expected: the more prolonged or concentrated the liquid contact, the faster the breakthrough. In the other mode, there was little difference between a single splash and continuous liquid contact. In the latter case, it was observed that the liquid wet the surface of the clothing material. There are serious implications in the second mode of behaviour, not only for those wearing totally encapsulated suits, but for those wearing protective gloves. The work reported here is the basis for a proposed modification of the standard ASTM permeation test to include intermittent liquid contact (splash testing).