GB/T 15331-2020 Test Method for Water Vapor Transmittance of Adhesive Tape, including Test Method for Vertical and Cross Sectional Water Vapor Transmittance of Adhesive Tape. The test method for vertical water vapor transmission rate of adhesive tape is applicable to single-sided or double-sided sub sensitive adhesive tape, and the cross-sectional water vapor of the adhesive tape
The test method for transmittance is only applicable to double-sided sub sensitive adhesive tape.

Testing instruments:Water vapor permeability tester