Moisture Transfer in Textile Systems, Part I

Abstract

From theoretical considerations a new clothing parameter, the moisture permeability index, has been developed, which describes the efficiency of fabrics or fabric systems in transferring moisture and its associated latent heat. This index extends the existing "clo" formula, which related dry or nonsweating heat loss to clothing insulation and ambient temperature, to include the heat losses from sweat evaporation. Using this index, it is possible to predict the environmental range over which man may maintain thermal balance with a given heat production or, alternatively, the range of activity and associated heat dissipation for any given environment. It thus supplies not only the missing parameter for quantitatively describing the effect of clothing in hot weather but also permits the same theory to be applied in hot, temperature, or cold environments. The experimental method of determining this index is outlined, and typical results are given.