EVALUATION OF CLOTHING SYSTEMS TO DETERMINE HEAT STRAIN

This article describes the basic evaluation process and test methodolo gy employed when temperature extremes for clothing systems must be con sidered as part of the U.S. Army's Health Hazard Assessment for materi al in the development and acquisition process. The goals of the evalua tion are to select clothing systems that minimize the hazards of heat strain and to predict the heat strain for persons wearing such clothin g. Clothing evaluations begin with biophysical assessments that determ ine the thermal characteristics (vapor permeability and insulation) fo r textiles via guarded hot plate tests and for clothing systems via th ermal manikin tests. The results from biophysical tests can be used to select the textile and/or clothing with the best thermal characterist ics. The data from manikin evaluations also can be used in prediction modeling. Human physiological testing is best done in a controlled lab oratory environment, although for realism and user acceptability field trials may also be conducted. Proven test and measurement methods mus t be employed, and tests must control for confounding variables; subje cts serve as their own controls, and test environment and procedures a re consistent between trials. The process and test methodology describ ed can be applied to the evaluation of civilian clothing systems as we ll as to the military systems for which they were developed.