Definitions for "MOISTURE VAPOR TRANSMISSION"
Keywords:  permeates, vapor, humidity, psid, perm
Using perms to measure the amount of water vapor able to pass through a material. Perm = one grain of water vapor per square foot, per hour, per inch of mercury pressure differential (0.491 psid).
A sheet of paper's rate of water vapor penetration.
The rate of movement of moisture vapor in unit time through a unit area of a membrane.