Volume 21, Issue 3 (May 1993)
Infrared Technique as a Research Tool for Measuring Water Vapor Transmission of Roofing Membranes
Measurements of the permeability to water vapor of materials intended to prevent its transmission are time-consuming with the usual cup method . Several instruments have been promoted as being capable of providing results rapidly, but doubts about their agreement with cup measurements have delaved their use for more than quality control.
One instrument with an infrared sensor was studied to investigate its accuracy and to correlate results obtained with the standard cup methods. Factors studied include those that contribute to the inconsistent performance of the instrument, especially for research work Techniques for improving the precision and the accuracy of the instrument are discussed. The permeances of roofing papers and telts and of plastic films by both the modified IR instrument and the cup methods are reported and compared to values given in the literature.