本文件规定了超声波气体流量计（USM）的要求和建议，该流量计利用声波信号的传输时间测量封闭管道中单相均质气体的流量。 本文件适用于用于托管转移和分配计量的过渡时间超声波气体流量计，如全径、缩小面积、高压和低压流量计或这些流量计的任何组合。仪表的最小或最大尺寸没有限制。本文件可用于测量几乎任何类型的气体，如空气、天然气和乙烷。 包括适用于监护转移和分配测量等应用的两种精度等级的流量计的流量测量性能要求。 本文件规定了气体流量测量用超声波流量计的结构、性能、校准、仪表验证诊断和输出特性，并说明了安装条件。 注:国家或其他法规可能比本文件更严格。

This document specifies requirements and recommendations for ultrasonic gas flowmeters (USMs), which utilize the transit time of acoustic signals to measure the flow of single phase homogenous gases in closed conduits. This document applies to transit time ultrasonic gas flowmeters used for custody transfer and allocation metering, such as full-bore, reduced-area, high-pressure, and low-pressure meters or any combination of these. There are no limits on the minimum or maximum sizes of the meter. This document can be applied to the measurement of almost any type of gas, such as air, natural gas, and ethane. Included are flow measurement performance requirements for meters of two accuracy classes suitable for applications such as custody transfer and allocation measurement. This document specifies construction, performance, calibration, diagnostics for meter verification, and output characteristics of ultrasonic meters for gas flow measurement and deals with installation conditions. NOTE It is possible that national or other regulations apply which can be more stringent than those in this document.