Opis:
The standard test for waterproofing is to build up water pressure on the surface of the fabric and measure how much it can withstand before it allows water to pass through. Imagine a very tall, open-ended laboratory test tube standing on the fabric and being slowly filled with water. As more water is added, the pressure on the fabric will slowly increase. When we talk about the level of waterproofness in a particular fabric, we are expressing the height of that column before the waterproofing surrenders e.g. 20,000mm. This measurement is known as the hydrostatic head.