Water vapour permeability is a feature that determines the quality and practicality of application of a given fabric. Clothes or footwear made of materials of inadequate permeability may be unhealthy and uncomfortable. In order to determine water vapour permeability, RADWAG moisture analyzer has to be equipped with a water vapour permeability determination set.
The developed method of testing water vapour permeability consists in placing required amount of water in a vessel made of aluminium alloy, inside which a fabric sample, cut using a blanking die, is clamped. Prior to the test, the sample should be left in a room with stable ambient conditions for 24 hours. It is recommended to place the vessel containing water and sample in the
moisture analyzer
and start the drying process at 40°C. The advantage of this method is a very short drying time. It takes up to 50 minutes to obtain the result. In contrast, measurement carried out using standard method takes up to 72 hours. Measurement results are presented in mg H2O / 1000 mm2 / 24h or as the percentage amount of water vapour passed through the material to the amount of water vapour passed without the tested fabric.
The water vapour permeability determination set is used in moisture analyzers of max capacity greater than 50g.