BS EN ISO 811:2018 pdf download – Textiles – Determination of resistance to water penetration – Hydrostatic pressure test 6 Apparatus The usual laboratory apparatus and, in particular, the following. 6.1 Fabric clamp. It should be possible to clamp the specimen of fabric in such a way thata] it is horizontal and is not bulging; b) an area of the fabric of 10 000 mm2 (100 cm2) is subjected to steadily increasing water pressure from below or from above the fabric; c no leakage of water takes place at the clamps during the test period; d) the specimen does not slip in the clamps; e) any tendency for penetration to occur at the clamped edge of the specimen is minimized. With some forms of apparatus, it is recommended that the clamps are faced with a suitable grade ofrubber. It can be helpful to use a sealing wax around the clamps to help prevent water from leaking. 6.2 Mechanism for measuring the increase in water pressure. The rate of increase of water pressure shall be 10 cm H20/min土0,5 cm H20/min or 60 cm H20/min 土3 cm H20/min (9,8 mbar H20/min土0,5 mbar H20/min or 58,8 mbar H20/min土2,9 mbar H20/min). Results obtained by different rates may not be the same. The chosen alternative rate shall be stated in the test report. NOTE The higher rate of increase of water pressure is more applicable when testing fabrics with high water resistance. 6.3 Manometer (for manual types of equipment that are not electronic]. The accuracy of the manometer, if used, shall be stated in the test report. If used, the following conditions apply. a) It is necessary to provide a manometer of suitable range. 1] A manometer which provides for pressures up to 1 m H20 is suitable for fabrics similar in construction to gabardines. 2) For fabrics of closer construction, it is advisable to use a manometer which provides for pressures up to 2 m H20. b] If more than one testing head is used in conjunction with the manometer, means shall be provided for separately disconnecting them. This is to prevent a high rate of leakage through test specimens already penetrated at three places. With most forms of apparatus, such a leakage can markedly reduce the rate of increase of pressure on the remaining specimens still under test. 7 Atmosphere for conditioning and testing Conditioning and testing shall be carried out according to...

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