A transient method for measuring the water vapor diffusion in porous building materials
Cerny, R., Hoskova, S. and Tofnan, J.
1995 International Symposium On Moisture Problems In Building Walls, Porto - Portugal, 11 - 13 September, pp. 137
Cerny, R., Hoskova, S. and Tofnan, J., (1995), "A transient method for measuring the water vapor diffusion in porous building materials", International Symposium On Moisture Problems In Building Walls, Porto - Portugal, 11 - 13 September, pp. 137.
Abstract:
A fast transient method for measuring the diffusion coefficient of water vapor in porous building materials under isothermal conditions is proposed. The measuring apparatus consists of two airtight glass chambers separated by the specimen of the measured material. In the first chamber, the state neax to 100% relative humidity is kept while in the second one there is the state close to 0% relative humidity. The flux of water vapor on both specimen surfaces is measured, an analytical method for solving the inverse problem of water vapor diffusion is employed. The proposed method is tested by the measurements on selected typical building- and coating materials. The measured results are compared with those obtained by the steady-state method. The agreement of both methods is found to be within 5% which makes using of the transient method very attractive - a comparable accuracy is achieved with a remarkable shortening of the measuring time.
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