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Test evaluation of water permeability of textiles
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Hydrostatic Pressure Pressure Test Standard: ISO 811, AATCC 127, JIS L 1092, GB/T 4744
ISO 811: Textile fabrics - Test method for water penetration - Hydrostatic pressure test method
The test principle of ISO 811 is to use the hydrostatic pressure of the fabric to express the resistance that water encounters through the fabric. The results of each test and their mean values are expressed in cm H2O.
Under standard atmospheric pressure conditions, one side of the sample is subjected to increasing water pressure until there are three water seeps, and the pressure at this time is recorded, and the water pressure can be applied from above and below the sample.
AATCC 127: Water Resistance - Hydrostatic Pressure Test Method
The test principle of AATCC 127 is that one side of the sample is subjected to a hydrostatic pressure which increases at a certain rate until water droplets ooze out from three places on the surface of the sample. Water pressure can be applied from above or below the specimen.
JIS L 1092: Test method for water permeability of textiles
The low water pressure method measures the water level at one or two overflows and reports the situation. The high water pressure method calculates the average value of five tests and retains one decimal place. If the water level rises and the water does not overflow in all three places, measure the water pressure when there is water overflow in one or two places and describe the situation in the report.
GB/T 4744: Hydrostatic pressure test method for testing and evaluation of water permeability of textiles
Under standard atmospheric conditions, one side of the test piece was subjected to continuously increasing water pressure until three water seepage points appeared on the other side of the test piece, and the pressure value at the third water seepage point was recorded to evaluate the waterproof performance of the test piece. The hydrostatic pressure value of each sample and its average value kPa(cmH)2O), with one decimal place. For the same sample, the average hydrostatic pressure is calculated separately for different types of samples.
In the test of the specified pressure value, if there are no water seepage points on the surface of the five test pieces and no trace of wetting, the test piece will pass, otherwise it will fail; the final hydrostatic pressure test takes the average value of the five test pieces and retains the integer of the result.
Different testing standards have different requirements for the hydrostatic pressure test of textiles. The main differences are as follows.
ISO 811, AATCC 127 and GB/T 4744 all use the supercharging method to test the hydrostatic pressure, and JIS L 1092 provides two test methods: the supercharging method and the constant pressure method. When using the supercharging method, the four standard tests are the hydrostatic pressure values of the third drop.
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