Acquiring an accurate measurement of water vapor permeability through some porous materials, such as paper, plastic films, fiberboards, gypsum, plaster products, wood products, and plastics, is essential for compiling a methodical comprehension of materials desired for use. This is the primary interest of ASTM E96/E96M-16 – Standard Test Methods for Water Vapor Transmission of Materials.
ASTM E96/E96M-16 – Standard Test Methods for Water Vapor Transmission of Materials addresses two testing procedures for determining the water vapor transmission (WVT) of materials, both of which can be incredibly useful for knowing the potential risks posed on the materials in different humidity levels. The standard’s testing methods are the Desiccant Method and the Water Method.
In the Desiccant Method, the test specimen is sealed to a test dish containing a desiccant, and the assembly is placed in a controlled atmosphere. Periodic weighings are used to assess rate of water vapor movement through the specimen into the desiccant. The Water Method is somewhat simpler, with the dish containing distilled water, and periodic weighings are used to determine the rate of vapor movement through the specimen from the water.
This process can be complicated, so NTA, Inc., a third-party code evaluation, product certification, and inspection agency, has created the following video to describe an overview of the two methods:
The exact specifications for the Desiccant Method and the Water Method are detailed in the standard document.
If you’d like to learn a little more about this standard, please refer to our past post: ASTM E96/E96M-16 Water Vapor Transmission
ASTM E96/E96M-16 – Standard Test Methods for Water Vapor Transmission of Materials is available on the ANSI Webstore.