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Hydrostatic head is also used as a measure of the waterproofing of a fabric, commonly in clothing and equipment used for outdoor recreation.It is measured as a length (typically millimetres), representing the maximum height of a vertical column of water that could be placed on top of the fabric before water started seeping through the weave.
A water-resistant garment is similar, perhaps slightly more resistant to water but also not rated to resist a specific hydrostatic head. A garment described as waterproof will have a water-repellent coating, with the seams also taped to prevent water ingress there. Better waterproof garments have a membrane lining designed to keep water out but ...
While only fabrics scoring hydrostatic head measurements of 1000mm or more are technically considered to be fully waterproof, etaProof fabrics (200g to 270g standard versions) achieve measurements no less than 750mm. This is usually considered to be sufficient for reasonable protection against typical rain.
Waterproof fabrics are fabrics that are, inherently, or have been treated to become, ... (9.8 kPa) pressure without leaking (see hydrostatic head). ...
Unlike most "waterproof breathable" fabrics, Analogy can pass out liquid water as well as vapour. Unlike a conventional waterproof fabric, Analogy would fail a hydrostatic head test (if used to seal the bottom of a tube containing water, only a very short column could be supported). However, like fur, Analogy causes water to flow away from the ...
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Since stitching makes tiny holes in a fabric seams are often sealed or taped to block these holes and maintain waterproofness, though in practice a carefully sewn seam can be waterproof. Rain resistance is measured and expressed as hydrostatic head in millimetres (mm). [8] This indicates the pressure of water needed to penetrate a fabric.
In medicine, hydrostatic pressure in blood vessels is the pressure of the blood against the wall. It is the opposing force to oncotic pressure . In capillaries, hydrostatic pressure (also known as capillary blood pressure) is higher than the opposing “colloid osmotic pressure” in blood—a “constant” pressure primarily produced by ...