1.1本规程涵盖伸长计系统的验证和分类程序，但并不打算成为完整的采购规范。本规程仅适用于指示或记录与拉伸或压缩应变对应的长度变化成比例的值的仪器。伸长计系统根据其误差大小进行分类。 1.2由于应变是无量纲量，因此本文件可用于基于国际单位制或美国常用位移单位的引伸计。 注1:直接连接至试样的粘结电阻应变计无法使用本实施规程中所述的仪器进行校准或验证，以验证具有明确测点的伸长计。（见试验方法E251中所述的程序。 ) 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。

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 gages directly bonded to a specimen cannot be calibrated or verified with the apparatus described in this practice for the verification of extensometers having definite gage 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 and health practices and determine the applicability of regulatory limitations prior to use.