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 non-wovens, 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.