1.1 该测试方法描述了气流平均速度的测量，以确定烟囱、管道或烟道中的气流。虽然技术上很复杂，但它通常被认为是进行速度测量的最准确且通常是唯一实用的测试方法。 1.2 该测试方法适用于测量大于3m/s（10ft/s）的气体速度。 1.3 本试验方法提供了确定烟道气成分和含水量的程序。 1.4 以国际单位制表示的值应视为标准值。括号中给出的英寸磅单位仅供参考。 1.5 本试验方法适用于发生稳态流动的条件，以及恒定流体条件，其中流动方向垂直于本方法所用皮托管的面管开口。当存在气旋或涡流条件时，该方法不能用于直接测量。 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。 1.7 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====== 5.1 本试验方法中给出的程序部分在试验方法中可用 D3685/D3685米 ，以及ASME方法（PTC 19.10-1968、PTC 19.10-1981和PTC 38-1980） 2.3 以及脚注5， 5. 40 CFR第60部分 2.4 ，以及脚注6中给出的出版物。 6.

1.1 This test method describes measurement of the average velocity of a gas stream for the purpose of determining gas flow in a stack, duct, or flue. Although technically complex, it is generally considered the most accurate and often the only practical test method for taking velocity measurements. 1.2 This test method is suitable for measuring gas velocities above 3 m/s (10 ft/s). 1.3 This test method provides procedures for determining stack gas composition and moisture content. 1.4 The values stated in SI units are to be regarded as standard. The inch-pound units given in parentheses are for information only. 1.5 This test method is applicable to conditions where steady-state flow occurs, and for constant fluid conditions, where the direction of flow is normal to the face tube opening of the pitot tube employed in the method. The method cannot be used for direct measurement when cyclonic or swirling flow conditions are present. 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. ====== Significance And Use ====== 5.1 The procedures presented in this test method are available, in part, in Test Methods D3685/D3685M , as well as the ASME Methods (PTC 19.10-1968, PTC 19.10-1981, and PTC 38-1980) given in 2.3 and Footnote 5, 5 the 40 CFR Part 60 given in 2.4 , and the publication given in Footnote 6. 6