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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.
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www.daviddarling.info/encyclopedia/P/AE_permeance.html
www.daviddarling.info/encyclopedia/P/AE_permeance.html
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WATER VAPOR PERMEANCE OF ROOFING & CONSTRUCTION MATERIALS; By William A. Kirn, RRC; Technical Director; National Coatings Corporation; ... There are numerous ASTM methods for determining permeance. Typical ones used in roofing are ASTM E-96 and ASTM D-1653. The ASTM E-96 method is specifically designed for single ply...
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www.nationalcoatings.com/articles/TP-107-Water-Vapor-Pe...
www.nationalcoatings.com/articles/TP-107-Water-Vapor-Permeance-of-Roofing.pdf
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MHRA: Measured Permeance Values for Selected Interior Wall Assemblies ... Table 1 describes the materials selected for the permeance testing. A testing contractor was selected from several candidates based on pricing, testing capacity and how soon the contractor could complete the tests.
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www.mhrahome.org/pages/perm.htm
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Calculation of the Self-demagnetizing stress and Permeance Coefficient of permanent magnets. ... Calculating Permeance Coefficient; Permeance Coefficients (Pc) are important in material selection to ensure optimal design. The Permeance Coefficient of a magnet is also referred to as the "operating slope", load line or B/H...
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www.arnoldmagnetics.com/mtc/calc_pc.htm
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Reducing Water Permeance in Masonry Walls and Chimneys by John Meredith; President, SaverSystems ... Concave tooling of mortar joints reduces water permeance, while rough cut, raked, or flat-tooled joints have been found to increase water permeance. Separation cracks caused by improper tooling are common.
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www.chimneysaver.com/reducing_water_permeance_in_masonr...
www.chimneysaver.com/reducing_water_permeance_in_masonry_walls_and_chimneys.html
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Implications for the Housing Industry ... Table 1: Average Air Leakage Rates at 75 Pa ... In order to create an air barrier system that achieves the required overall air leakage rate, it is important that the materials composing the air barrier system be resistant to air leakage.
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www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/98109.ht...
www.cmhc-schl.gc.ca/publications/en/rh-pr/tech/98109.htm
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This test method provides for the determination of oxygen gas transmission rate (O2GTR), the permeance of the film to oxygen gas (P'O2), and oxygen permeability coefficient (P''O2) in the case of homogeneous materials at given temperature and %RH levels(s).
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amaec.kicet.re.kr/cd_astm/PAGES/F1927.htm
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Abstract: the definition, application, differences and conversion relations of three water vapor permeable parameters (Water Vapor Transmission Rate, Water Vapor Permeance and Water Vapor Permeability) are introduced in this article.
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www.labthink.cn/service/show878.html
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