Analysis and Experimental Determination of Effective Water Vapor Permeability of Wet Woven Fabrics

Lubos Hes


Abstract: Despite the fact, that protective clothing is very often used in wet state, which reduces its thermal insulation and water vapor permeability (WVP ), just few papers were published on fabric thermal comfort in wet state. Moreover, there are no standards on testing of (WVP) of fabrics in wet state available. In the paper, an analysis of effective WVP of fabrics in wet state is presented, along with related experimental results based on the measurement of relative cooling flow passing through a fabric placed on the measuring surface of the PERMETEST instrument. The difference between the direct measurement and the measurement with a foil inserted between the wet sample and the measuring surface of the tester then presents the required level of the relative cooling flow or relative WVP of fabrics in wet state. From the measurements of effective relative WVP of 30 woven fabrics differing in the used polymer and structure at 4 moisture levels follows, that the most interesting results were achieved at the 50% moisture level, which is may serve as the reference moisture level in the proposed new testing standard.

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