Effect of air pressure differential on vapor flow through sample building walls
Stewart, W. E.
1998
ASHRAE Transactions, 104(2), pp. 17
Stewart, W. E., (1998), "Effect of air pressure differential on vapor flow through sample building walls", ASHRAE Transactions, 104(2), pp. 17.
| Abstract: |
| Laboratory scale experiments were performed on two small sample composite walls of typical building construction, to determine the approximate opposing air pressure difference required to stop or significantly reduce the transmission of water vapor due to a water vapor pressure difference. The experiments used wall section samples between two controlled atmosphere chambers. One chamber was heldata temperature and humidity condition- approximating that of a typical summer daN, while the other chamber was controlled at a condition typi-cal of indoor conditioned space. Vapor transmission data through the wall samples were obtained over a range of vapor pressure differentials and opposing air pressure differentials. The results show that increasing opposing air pressure differ-ences decrease water vapor transmission, as expected, and relatively small opposing air pressure differentials are required for wall materials of small vapor permeability and large air permeability. The opposing air pressure that stopped or signif-icantly reduced the flow of water vapor through the wall sample ~~'as determined experimentally and also compared to air pres-siires as predicted by an analytical model |
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