The water vapour permeability of fabric is determined by placing the test specimen over the open mouth of a test dish, which contains water and assembly placed in a controlled atmosphere. After a period of established equilibrium of the water vapour pressure gradient across the test specimen, successive weightings of the assembled dish are made and the rate of water vapour permeation through the specimen is determined. The water vapour permeability index is calculated by expressing the water vapour permeability of the test fabric as a percentage of the water vapour permeability of a reference woven fabric which is tested in a similar manner concurrently and along side the test specimen.
It is used for Permeability test on pozzolana cement mortar, and cement mortar with or without water the addition of water proofing compound.
The equipment consists of brass cell of 100mm.dia and 50mm. high. Each cell with collar is clamped in between a base plate and a top plate with the help of tension rods and nuts. The cell assembly is mounted on the stand. The top plate is provided with inlet and air release vent and the base plate is provided with an outlet.
A pressure chamber is fitted with a pressure regulator and a pressure gauge 0-10kg/cm2 indicating chamber pressure, and a pressure gauge 0-7kg/cm2 indicating test pressure.
It is available in the following models: