Home > Term: permeance
permeance
A unit of measurement for the ability of a material to retard the diffusion of water vapor at 73.4 F (23 C). A perm, short for permeance, is the number of grains of water vapor that pass through a square foot of material per hour at a differential vapor pressure equal to one inch of mercury.
- Part of Speech: noun
- Industry/Domain: Energy
- Category: Energy efficiency
- Company: U.S. DOE
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- mara nicaru
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