Correlation of Chemical Warfare Surrogate Tests on Air-Permeable Chemical Protective Uniforms

摘要

Air-permeable chemical protective uniforms provide percutaneous protection against chemical liquids released as vapor and droplets by adsorbing the chemical in a layer of activated carbon. The air that flows through the uniform fabric evaporates sweat, providing cooling. The protective capacity of a material is tested by measuring the breakthrough time of chemical warfare agent (CWA) applied on a sample at a vapor concentration and wind speed representing average field conditions. Breakthrough time is many days for the dilute vapors of high-boiling percutaneous-threat agents and so testing has been reduced to one day using increased mass flow rate of the chemical vapor. CWA tests can only be carried out in a limited number of facilities equipped to handle toxic chemical warfare agents. Low toxicity surrogates are tested by the same procedure to see how well they mimic live agents. One-to-one correlation would enable the testing of CP uniform material in a standard chemistry laboratory setting. The properties of the CWA surrogate must mimic the properties of the CWA itself for a good correlation outcome between the surrogate test results and live agent resistance performance. Tests with a standard HD simulant were carried out in our laboratory to standardize sampling of activated carbon materials and procedures. Simulant and agent testing at low and high relative humidity was carried out at Calspan Univ. of Buffalo Research Center (CUBRC). Comparison of the results obtained from vapor permeation testing showed excellent correlation of permeation behavior between CWA's and simulants at high humidity. Liquid drop tests revealed a divergence for GD and DMMP (dimethyl methylphosphonate) only for early penetration results at both low and high relative humidity, where MeS provided the match. The effect of humidity is small for HD and MeS (methyl salicylate). The same effects are seen in thickened drops.