An automated dynamic water vapor permeation test method

An automated apparatus to determine the steady-state and transient water vapor permeation behavior of fabrics and semipermeable laminates is described. Typical test results for representative types of fabrics and semipermeable membrane laminates are shown, as well as correlations between this test and two other water vapor permeability test methods. The use of the equipment to obtain dynamic data for transient situations is shown to be useful in observing equilibration behavior, and in characterizing temperature changes associated with vapor sorption phenomena.