MATHEMATICAL CORRELATION OF TEST METHODS FOR MEASURING WATER-VAPOR TRANSMISSION THROUGH FABRICS

Abstract

The purpose of this study was to investigate the relationship between resistance to evaporated heat loss from the sweating guarded hot plate (ISO 11092) and water-vapor permeability of fabrics measured using the evaporative dish method (BS 7209). Experimental correlation was studied for air-permeable fabrics that follow Fick's Law, hybrid membrane containing microporous and hydrophilic components and multilayer systems consisting of their combinations, with the intention to cover as wide a range of breathability as possible. A mathematical correlation was established between the two methods. Thus, one can easily determine the resistance to evaporated heat loss (Ret) based on the water-vapor transmission rate of fabrics (WVTR) measured by the evaporative dish method, and using a simple numerical method (bisection method, tangent method, etc.). WVTR may be determined knowing Ret measured by the sweating guarded hot plate (skin model), with a good accuracy.