Determination of steam transmission properties

Standard: EN 12086, EN 13469

The apparatus covers the procedures and equipment for determining the water vapor transmission rate, water vapor permeance, and water vapor permeability of test specimens in a steady state under different test assemblies with specific test conditions.

The apparatus is applicable to thermal insulation products.

The apparatus is intended for use with homogeneous materials and with products having surface materials or integrated skins made of different materials.

A material is considered homogeneous if its density is almost the same on all sides, or in other words, if the measured density value is close to the average density.

This test method is generally not used for the individual and separate determination of the water vapor transmission properties of factory-filmed, foil-faced, membrane-faced, or sheet-faced etc. vapor retarders (having high diffusion resistance) because of the long duration of the test.

For vapor retarder or vapor barrier products with a water vapor diffusion value equivalent to an air layer thickness of Sd ≥ 1000 m, other test methods such as infrared (IR) measurement, where the vapor retarder or vapor barrier (individual and separate) measurement is performed, may be used if the values measured according to this standard are in the same range as the obtained results.

Water vapor transmission rate and permeance values are specific values depending on the thickness of the test specimen (or product) being tested. For homogeneous products, water vapor permeability is a property of the material.