Analysis of test method for water permeability test of protective clothing

The thermal protection performance of protective clothing is a key test item for many protective clothing. Since the human body wears this type of clothing to work in dangerous environments, such as fire scenes or rescue times and other high-temperature operating environments, protective clothing must ensure that the human body is protected. Therefore, a reasonable assessment of the thermal protection performance of protective clothing must be made. Here (Hong Kong) Co., Ltd. uses experimental methods to describe the necessity of such experiments. Subject content and scope of application This standard specifies the performance requirements and test methods for firefighters' ordinary protective clothing. This standard applies to ordinary protective clothing used by firefighters, but not to other protective clothing such as heat insulation clothing and fire protection clothing. Reference standard GB 250 Gray sample card for assessing discoloration GB 3918 Test method for tearing strength of fabrics by trapezoidal method GB 3923 Determination of breaking strength and elongation at break of woven fabrics. 4745 Determination method of moisture resistance of textile fabric surface (wetting test method) GB 5455 Determination of flame retardant properties of textile fabrics Test method of vertical water permeability ①, classified by test method (1) Field test. Field tests are expensive and time-consuming, usually about half a year. During the experiment, the water repellency of the fabric after the waterproof and moisture-permeable finishing was regularly tested to know its durability. Although this method takes a long time and costs more, the data obtained by the test is accurate. (2) Simulation test. Mock tests must have an environmental control room. There is an artificial rain tower in the room, which can remove water from a height of 10 m to 450L/m2·The flow of h is poured into the manikin like a rainstorm, and water droplets with a diameter of about 5 inln are ejected from the top 2000 holes with a speed of about 40 km/h, reaching 90% of the maximum raindrop speed in the air. With adjustment, it is possible to simulate different degrees of showers over an area of ​​about 2m2. The manikin's surface is filled with sensors that measure the time and location of final water penetration, among other metrics. Compared with the field test, this test method can be completed in a few days, but the cost is relatively high. (3) Laboratory tests. Compared with field tests and simulation tests, laboratory tests cost less, take less time, can obtain relative results, and are more practical. The test of the waterproofness of the fabric after the waterproof and moisture-permeable finishing can be divided into three categories. Di Class 1 is hydrostatic pressure test, such as domestic YC312 hydraulic pressure gauge, American standard test method ASTM D-751 and American federal standard test method FED—The Mullen water pressure tester used by STD-191A 5512. The second type is the spray test, that is, continuous dripping or spraying of water from a certain height and angle to the fabric to be tested can measure the time required for the water to penetrate from the sprayed side of the fabric to the other side, or it can be measured after a certain period of time. After that, the amount of water absorbed by the sample or observe the water-stained form of the sample. The domestic ISO 4920 rainproof performance test adopts this principle. ②, according to the form of pressurization (1) dynamic method. Continuously increase the water pressure on one side of the fabric, and measure the hydrostatic pressure that the fabric can withstand until a specified number of water droplets appear on the other side of the fabric. (2) Static method. Maintain a certain water pressure on one side of the fabric and measure the time it takes for the water to penetrate from one side to the other. ③, according to the size of the hydrostatic pressure value can be classified (1) low pressure test method. Standard test methods include Chinese national standard GB/74744—1997 'Hydrostatic pressure test for determination of impermeability of textile fabrics'; Chinese industry standard FZ/T01004—1991 Low pressure method in 'Hydrostatic Pressure Test for Determination of Water Resistance of Coated Fabrics'; Canadian Standard (CGSB) - 4.2No. 26.3—1995 'Hydrostatic Pressure Test for Determination of Impermeability of Textile Fabrics'; International Standard ISO1420—1987 'Hydrostatic Pressure Test for Determination of Water Resistance of Rubber and Plastic Coated Fabrics'; Japanese Industrial Standard JIS L-1092 ((Textile Water Resistance Hydrostatic Pressure Test A); American Association of Textile Chemists and Dyers Standard AATCC 127 (Textiles Hydrostatic Pressure Test for Water Resistance'; American Standard Test Method (or American Society for Testing and Materials) ASTM D751— 1995 (Determination of Water Resistance of Coated Fabrics B' and other methods. (2) High pressure test method. Standard test methods include FZ/T 01004— 1991 High pressure method in Hydrostatic Pressure Test for Determination of Water Resistance of Coated Fabrics; ISO 1420—1987 ~ Hydrostatic Pressure Test for Determination of Water Resistance of Rubber and Plastic Coated Fabrics'; JIS L-1092 (Textile Water Resistance Hydrostatic Pressure Test B'; ASTM D751—95 'Determination of Water Resistance of Coated Fabrics A'; US Federal Standard Test Method FED—STD-191A 5512 and ASTM D3393 (Description of Waterproof Standard for Coated Fabrics) and other methods. Factors affecting the water pressure resistance of fabrics The increase in the distance between the yarns will directly affect the level of water pressure resistance. Generally, the tighter the fabric structure, the better its water resistance performance. (2) The size of the pore size of the coating membrane. The larger the diameter of the membrane, the better the coating The hydrostatic pressure resistance of the fabric is worse. (3) The size of the contact angle is 0. When 0>90. At this time, the fabric has water-repellent performance. At this time, with the increase of 0, the water pressure resistance value of the fabric also increases accordingly. (4) Coating thickness. If the coating is too thin, the coating agent will not be able to form a film continuously on the surface, and the water pressure resistance of the coated fabric will be reduced; if the coating is thicker, the water pressure resistance of the fabric will be improved. (5) The thickness of the fabric. The thicker the fabric, the greater the moisture resistance and the greater the water pressure resistance value. (6) The thickness of the yarn. For tight fabrics woven from fibers with good hygroscopicity, the yarn radius is reduced due to the existence of capillary effect. It can improve the water resistance of the fabric. (7) The performance of warp and weft yarns is good or bad. Under the action of water pressure, the elastic warp and weft yarns are easy to stretch, resulting in the formation of gaps between adjacent warp and weft yarns, and water droplets are more likely to penetrate through them, which reduces the water pressure resistance value of the fabric. (8) Coating quality. It is required that the entire cloth surface is uniform and has a certain fastness. The better the coating quality, the better the water resistance.

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