1.1 本规程涵盖了引伸计系统的验证和分类程序，但并非完整的采购规范。本规程仅适用于指示或记录与拉伸应变或压缩应变对应的长度变化成比例的值的仪器。引伸计系统根据其误差的大小进行分类。 1.2 由于应变是无量纲量，本文件可用于基于SI或US惯用位移单位的伸长计。 注1: 直接粘结到试样上的粘结电阻应变计不能用本规程中所述的仪器进行校准或验证，以验证具有确定测量点的伸长计。 （参见测试方法中所述的程序 第251页 .) 1.3 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。 1.4 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。

1.1 This practice covers procedures for the verification and classification of extensometer systems, but it is not intended to be a complete purchase specification. The practice is applicable only to instruments that indicate or record values that are proportional to changes in length corresponding to either tensile or compressive strain. Extensometer systems are classified on the basis of the magnitude of their errors. 1.2 Because strain is a dimensionless quantity, this document can be used for extensometers based on either SI or US customary units of displacement. Note 1: Bonded resistance strain gauges directly bonded to a specimen cannot be calibrated or verified with the apparatus described in this practice for the verification of extensometers having definite gauge points. (See procedures as described in Test Methods E251 .) 1.3 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. 1.4 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.