Air permeability is the ability of a fabric to allow moisture vapor to pass through. It plays a vital role in clothing and medical textiles.

    Air permeability has nothing to do with air exchange. Rather, it is the ability of a fabric to allow moisture vapor to pass through.

    Fabrics can achieve this in many different ways, and air exchange is only one possible way.

    Compared with breathability, moisture vapor permeability (MVP) and moisture vapor transmission (MVT) may be better and more technical.

    Neither ASTM nor the Textile Association defines air permeability, but both MVP and MVT are defined in the test standard.

    According to EN 31092: 1993, water vapor permeability is "the characteristic of textile materials or composite materials, which depends on the water vapor resistance and temperature. Water vapor permeability is expressed in pascals per square meter hour.

    According to BS 3546:2001, water vapor permeability is "the ability of a coated fabric to transmit water vapor to a specified level while maintaining high permeability".

    According to the definition in the standard EN 31092: 1993, the water vapor permeability index is the ratio of thermal resistance to water vapor resistance.

    According to BS 3546:2001, "The difference in water vapor pressure between the two surfaces of a material divided by the evaporation heat flux per unit area in the gradient direction" can be regarded as the "opposite" of water vapor resistance and air permeability.

    Water vapor will transfer from the high concentration (pressure) area to the low concentration area by diffusion. Unobstructed, this can happen easily.

    However, barriers like fabric will slow down the rate at which this happens. It is important to remember that steam pressure drives water vapor: humidity is not the key factor.

    Modern waterproof and breathable fabrics can be divided into three different types, each of which works slightly differently. The breathability and waterproofness of the fabric is not entirely accurate, because the holes in the fabric structure are large enough to allow     water vapor to pass through, but too small to allow water droplets to pass through

    The fabric air permeability tester is a professional and commonly used instrument for measuring air permeability.

    GBPI can provide fabric air permeability tester and Water vapor transmission rate tester and oxygen transmission tester for a long time. Welcome to inquire.