1.1 本试验方法包括测量具有自由水面的明渠、溪流和封闭管道中的水流量。 1.2 试验方法包括使用声波传输，通过时差或频差技术测量一组或多组相对传感器之间的平均水流速度。 1.3 以国际单位制表示的数值应视为标准。 1.4 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、健康和环境实践，并确定监管限制的适用性。 第节给出了具体的预防说明 6. . 1.5 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《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 当需要在较长时间内进行高精度的速度或连续流量测量，并且由于航道中的低速、可变水位流量关系、复杂水位流量关系或海上交通的存在，其他测量试验方法不可行时，使用本试验方法。它还具有不需要移动部件、无水头损失和提供几乎瞬时读数（每秒1到100个读数）的额外优势。 5.2 试验方法可能需要相对大量的现场工作和调查工作，因此最适合于永久或半永久性装置。

1.1 This test method covers the measurement of flow rate of water in open channels, streams, and closed conduits with a free water surface. 1.2 The test method covers the use of acoustic transmissions to measure the average water velocity along a line between one or more opposing sets of transducers—by the time difference or frequency difference techniques. 1.3 The values stated in SI units are to be regarded as the standard. 1.4 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. Specific precautionary statements are given in Section 6 . 1.5 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 This test method is used where high accuracy of velocity or continuous discharge measurement over a long period of time is required and other test methods of measurement are not feasible due to low velocities in the channel, variable stage-discharge relations, complex stage-discharge relations, or the presence of marine traffic. It has the additional advantages of requiring no moving parts, introducing no head loss, and providing virtually instantaneous readings (1 to 100 readings per second). 5.2 The test method may require a relatively large amount of site work and survey effort and is therefore most suitable for permanent or semi-permanent installations.