[scope of application] It is used for the determination of water vapor permeability of plastic film (including composite plastic film), sheet material and artificial leather [meet a criterion] GBT 1037-2021 Plastic film and sheet water vapor through the performance measurement of glass weight increase and weight reduction method [Test Principle] Place a permeable cup filled with moisture absorbent or water and sealed with a specimen in a sealed environment with a specified temperature and humidity for a certain period of time The permeability is calculated from the change of the internal permeability cup (including sample and moisture absorption or water).