A brief analysis of the experimental methods for testing the water permeability of fabrics

1. Experimental Principle of Determination of Hydrostatic Pressure Resistance to Water Permeability of Fabrics<br /
<br /
　　静水压测试是考核面料抗水性的常用方法� When using a hydrostatic pressure tester to conduct a water permeability test on waterproof fabrics, it was found that some fabrics did not actually experience the test termination phenomenon described in the standard. Therefore, this article discusses the current standards used in laboratories to measure water permeability, so as to provide guidance for fabrics. It provides reference for the production process and actual testing and judgment, and is beneficial to the improvement of current standards. �<br /
<br /
2. Current situation<br /
1. Standard<br /
　　GB/T 4744—1997《纺织织物抗渗水性测定静水压试验》规定了一种测试织物抗渗水性的静水压试验方法。主要适用于紧密织物，例如帆布、油布、帐篷布和防雨服装布等。测试方法是在标准大气下，试样的一面承受一个持续上升的水压,直到有三处渗水为止记录此时的压力。此标准的测试原理是以织物承受的静水压来表示水透过织物所遇到的阻力，水压可以从试样的正面或背面施加[2]。

2. Test instruments<br /
Hydrostatic pressure tester;<br /
The pressure range of the instrument: 0~999mbar;<br /
　　水压上升的速率：（10±0.5）cmH2O/min，以及60±0.5cm H2O/min。

3. Problems encountered<br /
　　在日常测试中，经常会遇到现行标准中未涉及的现象，使得测试结果的表示没有统一性，甚至影响对整个产品的性能评价。
①、Coated waterproof fabric<br /
1) Record of average value<br /
　　标准中规定记录所有试验样品的平均值。但有些样品出现如表1所示检测结果，使如何表示其平均值成为难题。

Test data mbar (cmH2O)</p

<tbody
<t
<

样品编号（灰色涤纶涂层防水机织面料）

</
<

检测结果

</
</t
<t
<

1
</
<

58
</
</t
<t
<

2
</
99
</
</t
<t
<

3
</
<

62
</
</t
<t
<

4
</
99
</
</t
<t
<

5
</
<

59
</
</t
</tbody

2) Testing of seams<br /
　　遇到防雨服装等服装产品,考核静水压应该全面到服装的每个部位，特别是接缝部位（见图2），如下摆缝、腋下缝、肩部缝等。而目前我国的标准主要针对面料的方法标准中找不到相关检测方法的描述，给测试带来困惑，对企业生产产品的把关以及整件服装的防水质量的评价找不到依据。
3) The sample has single penetration<br /
Some products have small local damages due to lack of coating technology. During the test, it is often found that water droplets continue to seep out somewhere and spread to the entire edge, but the second and third spots have not yet appeared. For this How to record the test results of samples becomes a problem �<br /
<br /
②、Laminated composite waterproof fabric<br /
1) The sample has no water droplets but feels moist<br /
　　复合面料因为其性能优越，使用也越来越广泛。反面起绒的层压复合防水织物在做静水压测试时出现，水在织物和复合层之间，但肉眼未发现有水珠渗出，而用手抚摸表面会有潮湿感。
<br /
　2) The sample burst suddenly during the test<br /
For a period of time after the test starts, no water droplets seep out of the sample. However, when the water pressure rises to a certain point, the sample will suddenly burst somewhere, and the water will continue to flow, and the value displayed on the instrument will disappear instantly, especially for some plastic films. type composite layer (as shown in Figure 5) �<br /
<br /
3. Analysis and Solutions<br /
　　鉴于以上不常规的试验现象，本文通过多次静水压测试进行系统的原因分析并提出了以下几点建议供读者参考。
　　（1）织物表面的涂层质量是影响面料静水压值的因素之一，要获得织物好的抗渗水性，就要求涂层分布均匀，具有一定的牢度。出现上述结果差异大的静水压值，很可能是织物表面的涂层不均匀。实验室可以与客户进行沟通,检测结果只出具每个样品的实测值,不出具整块面料的平均值,因为上述的检测值无法进行准确计算。
　　（2）目前我国对防水服装的抗渗水性测定没有细化到具体部位，如风雨衣等相关服装� For this type of clothing, it is impossible to test only the fabric or only the seams, because it cannot represent the waterproof performance of the entire garment. However, if both seams and fabrics are tested, then choose the number of seams and fabrics to test. How to determine, how the test results will be expressed, and whether the results are averaged of all measured values or the test values of seams and fabrics are averaged separately, etc. There is no solution.�. Therefore, the laboratory can adopt the following solutions:
　　①、对于该类服装面料,实验室可以建议客户对织物面料和织物的下摆﹑腋下﹑肩部等所有的接缝部位分别进行检测。
　　②、可以与客户协商分别给出所有检测面料和各个接缝处的检测值或平均值作为终的检测结果。
　　（3）只有单处渗水的防水服装面料很可能在某处涂层有破损现象，致使水不断在该处渗出，蔓延至整个边圈。实验室在出具结果的时候可以给出第一个出水值作为该面料的抗静水压值，但在原始记录以及检测报告中要给予备注。
(4) For laminated composite waterproof fabrics, during the process of hydrostatic pressure, the water droplets that seep out are very small, while the composite fleece fabric has a certain degree of water absorption and will absorb the small water droplets that seep out, but cannot be detected by the naked eye. It has been observed that an ideal solution is to tightly attach a thin layer of tissue paper with good water absorption to the non-tested surface of the fabric, but this requires toughness of the paper. �如图6所示� �在测试的过程中仔细观察纸张的吸湿情况,当发现有第三处吸湿立即记录此时的静水压值� �<br /
<br /
　　（5）延展性较差的塑料、薄膜等材料复合，随着水压的上升，塑料无法像织物一样释放出足够的延展性，张力积聚到一定程度，就突然出现爆裂的现象� �检测员在测试该产品前好先与客户沟通，获得他们的要求值，实验室在检测过程中，样品达到要求值时立即停止，防止喷出的水对仪器的某些部件有影响� If there is no required value, the testing personnel should always pay attention to the non-tested surface of the sample during the testing process. Once a composite layer is found to bulge instantly, the hand should stay on the "Pause" button, and press it immediately at the moment the sample explodes. and record data �<br /
　　（6）GB/T 4744—1997《纺织织物抗渗水性测定静水压试验》标准的不完善，建议适时对其修订，特别是对服装和复合材料静水压的测定进行规范和描述。对操作进行统一，确保检测结果的正确性。
<br /
4. Conclusion<br /
　　防水透气织物是高附加值产品，防水透气功能目前已成为户外作业、户外运动、医疗防护、航空航天、军用、警用服装研究者为关注的一项服用功能[3]� Due to the emergence of various types of waterproof fabrics, the current GB/T 4744-1997 "Hydrostatic Pressure Test for Determination of Water Permeability Resistance of Textile Fabrics" can no longer satisfy the testing of all fabrics. This article aims to pass through the problems and solutions found in actual tests. Improve current testing standards