1.1 本规范涵盖了热塑性天然气管道系统中使用的溢流阀的要求和试验方法。然而，预计根据本规范要求制造的溢流阀也可用于其他天然气管道系统。 1.2 本规范涵盖的溢流阀设计用于插入天然气系统的组件，如管道、管子或配件，尺寸为 1. / 2. CTS转换为2 IPS。 1.3 本规范要求的测试旨在确定安装在直管中的溢流阀的性能特征。 溢流阀可能安装在直管、服务三通出口、机械联轴器的一部分或其他配置中。对于每种安装的配置，溢流阀的性能特征可能存在显著差异。用户应自行进行测试，以确定安装的性能特征，或联系EFV制造商获取安装配置的测试数据。有关选择和安装溢流阀的其他指导，请参阅 附录X1 . 1.4 本规范要求的测试不是常规质量控制测试。 1.5 以英寸-磅单位表示的值应被视为标准值。括号中给出的值是对国际单位制的数学转换，仅供参考，不被视为标准值。 1.6 本标准并不旨在解决与其使用相关的所有安全问题（如果有的话）。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。 1.7 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。

1.1 This specification covers requirements and test methods for excess flow valves for use in thermoplastic natural gas piping systems. However, it is expected that excess flow valves manufactured to the requirements of this specification may also be used in other natural gas piping systems. 1.2 Excess flow valves covered by this specification are designed for insertion into components for natural gas systems such as pipe, tubing, or fittings in sizes from 1 / 2 CTS to 2 IPS. 1.3 The tests required by this specification are intended to determine the performance characteristics of an excess flow valve installed in a straight piece of pipe. An excess flow valve could possibly be installed in a straight piece of pipe, in a service tee outlet, as part of a mechanical coupling, or in other configurations. The performance characteristics of the excess flow valve may be significantly different for each installed configuration. Users should conduct their own tests to determine the installed performance characteristics or contact the EFV manufacturer for test data for the installed configuration. Additional guidance on selection and installation of excess flow valves is included in Appendix X1 . 1.4 The tests required by this specification are not intended to be routine quality control tests. 1.5 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. 1.6 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. 1.7 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.