A logical extension of the ASTM Standard E96 to determine the dependence of water vapor transmission on relative humidity
- National Research Council of Canada, Ottawa, Ontario (Canada). Inst. for Research in Construction
It is well known that the water vapor transmission properties of hygroscopic building materials depend on the local relative humidities(rh). Traditionally, the ASTM Standard E96 specifies only two conditions of rh. The dry cup method in the standard corresponds to a mean rh of 25% and the wet cup to 75%. This information is not enough to describe the behavior of the material through the entire range of rh. European Standards have already proposed an extension of the existing standard to address this issue. ASTM standard should follow this change. A logical extension of the E96 standard to include the effect of rh on water vapor transmission properties has been proposed and is being discussed by one of the C16 Committee Task Groups. This paper presents the application of the proposed extension to several common building materials. The details include the operating principles of a constant temperature-rh chamber and the effects on the test results, of the vapor resistance offered by still air inside the cup, the surface resistances and buoyancy. The experimental data were used to critically assess the above effects. The data as well as the analyses of the data are expected to provide guidance to refine the existing ASTM Standard.
- OSTI ID:
- 543467
- Report Number(s):
- CONF-970582-; TRN: IM9748%%79
- Resource Relation:
- Conference: 3. Insulation materials: testing and applications, Quebec City (Canada), 15-17 May 1997; Other Information: PBD: 1997; Related Information: Is Part Of Insulation materials: Testing and applications. Third volume; Graves, R.S. [ed.] [R and D Services, Inc., Lenoir City, TN (United States)]; Zarr, R.R. [ed.] [National Inst. of Standards and Technology, Gaithersburg, MD (United States)]; PB: [550] p.; ASTM special technical publication 1320
- Country of Publication:
- United States
- Language:
- English
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