1.1 本规范涵盖隔热用蒸汽缓凝剂，特别是渗透性为0.15 perm（8.63 ng·Pa）的柔性材料 –1 ·秒 –1 ·米 –2 )以及25火焰蔓延/50烟或更低的表面燃烧特性。这些材料适用于表面温度为 −20至150°F（−29至66°C）。它不包括液体形式的胶粘剂或屏障涂层，也不包括用作防风雨屏障的材料。 1.2 这是一个材料规范，并不意味着使用这些材料的已安装系统将提供第节中规定的物理财产 6. . 1.3 本规范提供了蒸汽缓凝剂的物理要求。实践 C755 在解决与通过隔热材料的湿气传输有关的问题方面提供了帮助。 1.4 以英寸-磅单位表示的值应视为标准值。括号中给出的值是对SI单位的数学转换，仅供参考，不被视为标准值。 1.5 以下预防性警告仅适用于测试方法部分，第节 10 ，本规范: 本标准并不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建立适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 9.1 由于渗透到隔热层中的水蒸气冷凝而导致的隔热层中水的滞留对隔热层的热阻有害。出于这个原因，在某些安装中，温度和湿度条件有可能产生朝向隔热层的蒸汽驱动力，需要提供阻止这种蒸汽进入已安装隔热层的措施。这是蒸汽缓凝剂的主要功能。 9.2 除了 9.1 ，蒸汽缓凝剂具有为绝缘系统提供物理保护和增加强度的潜力。 9.3 本规范用于按物理性能要求规定材料，以满足上述先决条件。绝缘系统的设计者在确定了绝缘所需的保护程度后，可以使用本规范在需要时指定适当类型的蒸汽缓凝剂。

1.1 This specification covers vapor retarders for thermal insulation, specifically, flexible materials with permeance of 0.15 perm (8.63 ng·Pa –1 · s –1 · m –2 ) or lower and surface burning characteristics of 25 flame spread/50 smoke or lower. These materials are intended for use at surface temperatures of −20 to 150°F (−29 to 66°C). It does not cover mastics or barrier coatings applied in liquid form, nor materials intended for use as weather barriers. 1.2 This is a material specification and does not imply that an installed system using these materials will provide the physical properties specified in Section 6 . 1.3 This specification provides physical requirements for vapor retarders. Practice C755 provides assistance in solving problems related to moisture vapor transmission through thermal insulation materials. 1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.5 The following precautionary caveat pertains to the test methods portion only, Section 10 , of this specification: 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. 1.6 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 ====== 9.1 Entrapment of water in thermal insulation caused by condensation of water vapor that has penetrated into the insulation is detrimental to the thermal resistance of the insulation. For this reason, in certain installations where temperature and moisture conditions have the potential to create a vapor driving force toward the insulation, a deterrent to the passage of such vapor into the installed insulation needs to be provided. This is the primary function of the vapor retarder. 9.2 In addition to the function stated in 9.1 , a vapor retarder has the potential to provide physical protection and added strength to the insulation system. 9.3 This specification is used to specify material by physical property requirements that address the above prerequisites. The designer of an insulation system, after determining the degree of protection needed for the insulation, can use this specification to specify the appropriate type of vapor retarder when one is required.