The new permeation test system for measuring high transmission water vapor in moisture barriers. Ideal system for measuring water vapor in such material such as nonwovens, fabrics, textiles, breathable membranes, plastic films and paper. The Permatran-W Model 101K permits testing of up to six samples simultaneously in a single-system module. Other features of this computer controlled system include: sample test time in minutes, precise temperature measurement control, automatic flow and barometric pressure correction.