1.1 本试验方法包括纺织织物透气性的测量。 1.2 本试验方法适用于大多数织物，包括机织物、非织造织物、气囊织物、毯子、尿布织物、针织织物、分层织物和绒头织物。织物可以是未处理的、大尺寸的、涂覆的、树脂处理的或以其他方式处理的。 1.3 以国际单位制表示的数值应视为标准。以英寸磅为单位的数值可能是近似值。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 这种测试方法被认为是令人满意的商业货物验收测试，因为目前对实验室间精度的估计是可以接受的，而且这种测试方法在验收测试行业中被广泛使用。 5.1.1 如果两个实验室（或多个实验室）报告的测试结果之间存在实际意义上的差异，则应使用主管的统计协助进行比较测试，以确定它们之间是否存在统计偏差。至少要确保所用的试样尽可能均匀，从获得不同试验结果的材料中提取，并以相同数量随机分配给每个实验室进行试验。两个实验室的测试结果应使用未配对数据的统计测试进行比较，在测试系列之前选择概率水平。 如果发现偏差，必须找到并纠正其原因，或者必须根据已知偏差调整该材料的未来测试结果。 5.2 透气性是影响气体过滤器、气囊织物、服装、蚊帐、降落伞、船帆、帐篷和真空吸尘器等纺织材料性能的重要因素。例如，在过滤中，效率与透气性直接相关。透气性也可用于提供耐候和防雨织物或一般涂层织物的透气性的指示，并用于检测制造过程中的变化。 5.3 工业和军事性能规范都是在透气性的基础上制定的，用于购买感兴趣的透气性织物。 5.4 构造因素和整理技术可以通过改变穿过织物的气流路径的长度来对透气性产生显著影响。热压延可用于压平织物部件，从而降低透气性。两侧表面纹理不同的织物可能具有不同的透气性，这取决于气流的方向。 5.4.1 对于机织物来说，纱线的捻度也很重要。随着捻度的增加，纱线的圆形度和密度增加，从而减小了纱线直径和覆盖系数，并增加了透气性。纱线卷曲和编织会影响纱线之间间隙的形状和面积，并可能使纱线容易延伸。这样的纱线延伸将打开织物，增加自由面积，并增加透气性。 5.4.2 增加纱线的捻度也可以使更圆形、高密度的纱线紧密地堆积在一起，形成透气性降低的紧密编织结构。例如，精纺华达呢织物的透气性可能比羊毛hopsacking织物低。

1.1 This test method covers the measurement of the air permeability of textile fabrics. 1.2 This test method applies to most fabrics including woven fabrics, nonwoven fabrics, air bag fabrics, blankets, napped fabrics, knitted fabrics, layered fabrics, and pile fabrics. The fabrics may be untreated, heavily sized, coated, resin-treated, or otherwise treated. 1.3 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units may be approximate. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 This test method is considered satisfactory for acceptance testing of commercial shipments since current estimates of between-laboratory precision are acceptable, and this test method is used extensively in the trade for acceptance testing. 5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, ensure the test samples to be used are as homogeneous as possible, are drawn from the material from which the disparate test results were obtained, and are randomly assigned in equal number to each laboratory for testing. The test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias. 5.2 Air permeability is an important factor in the performance of such textile materials as gas filters, fabrics for air bags, clothing, mosquito netting, parachutes, sails, tentage, and vacuum cleaners. In filtration, for example, efficiency is directly related to air permeability. Air permeability also can be used to provide an indication of the breathability of weather-resistant and rainproof fabrics, or of coated fabrics in general, and to detect changes during the manufacturing process. 5.3 Performance specifications, both industrial and military, have been prepared on the basis of air permeability and are used in the purchase of fabrics where permeability is of interest. 5.4 Construction factors and finishing techniques can have an appreciable effect upon air permeability by causing a change in the length of airflow paths through a fabric. Hot calendaring can be used to flatten fabric components, thus reducing air permeability. Fabrics with different surface textures on either side can have a different air permeability depending upon the direction of air flow. 5.4.1 For woven fabric, yarn twist also is important. As twist increases, the circularity and density of the yarn increases, thus reducing the yarn diameter and the cover factor and increasing the air permeability. Yarn crimp and weave influence the shape and area of the interstices between yarns and may permit yarns to extend easily. Such yarn extension would open up the fabric, increase the free area, and increase the air permeability. 5.4.2 Increasing yarn twist also may allow the more circular, high-density yarns to be packed closely together in a tightly woven structure with reduced air permeability. For example, a worsted gabardine fabric may have lower air permeability than a woolen hopsacking fabric.