GB/T 40910-2021 Textiles - Evaluation of Waterproof and Moisture Permeable Properties

For what products?

All kinds of fabrics and their products Main products: ski suits, jackets, sleeping bags, protective clothing, etc.

What is waterproof and breathable?

Waterproof: resists wetting by water (wetting) and penetration (hydrostatic pressure).

Moisture permeability: allows water vapor to escape moisture permeability.

Are waterproof and breathable contradictory?

not contradictory

Waterproof: Large water droplets cannot pass through.

Moisture permeability: small water vapor can pass through.

foggy rain   drizzle     moderate rain    heavy rain

100um      500um      2000um         3000um

What is hydrostatic pressure?

The pressure per unit area when permeated by liquid water. Hydrostatic pressure is related to pore size.

How is hydrostatic pressure classified?

According to the diameter of the raindrop and the closing speed:

Light rain 10kPa~30kPa

Moderate rain and heavy rain 30kPa~50kPa

Heavy rain 50kPa~80kPa

What is the water level?

The degree to which a surface resists being wetted by water (related to surface tension).

Spray the sample with a certain amount of distilled water, and rate the wetness and wetting of the sample after spraying.

What is moisture permeability?

The mass of water vapor that passes through the unit area of the sample vertically within the specified time under the condition of maintaining the specified temperature and humidity on both sides. (related to pore size)

How is moisture permeability classified?

According to the amount of human sweat and its evaporation:

1. Sweat volume during routine activities: up to about 3000g/(m2.24h)

2. Evaporation in hot and humid environment for extreme activities: 5000g/(m2.24h)

3. Evaporation in dry and hot environment for extreme activities: 8000g/(m2.24h)

How to evaluate waterproof and moisture permeability

Grade III: Excellent

Grade II: good

Class I: has

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