本文件确定了使用同心、方边、法兰螺纹孔板流量计测量流体流量的设计和安装参数。本文件概述了使用孔板流量计设计计量设施时应考虑的各种设计参数。本文件中的机械公差包括各种孔板直径比，可获得实验结果。对于所有现有装置，升级以满足本标准要求的决定应由相关各方自行决定。双方应认识到，如果仪表安装未升级以满足本标准，由于流量调节和上游直管长度不足，可能存在测量偏差误差。 建议在现有设备上使用API MPMS第14.3.1章/AGA第3号报告第1部分和API MPMS第14.3.3章/AGA第3号报告第3部分所示的计算程序和技术，因为这些是对之前方法的重大改进。使用现有设备进行流量测量的不确定度水平可能不同于API MPMS第14.3.1章/AGA第3号报告第1部分中引用的不确定度水平。应尽可能避免在直径比（βr）范围内的极端情况下使用孔板流量计。良好的计量设计和实践往往有些保守。这意味着在中径比（βr）范围内使用最严格的公差将有最大的可能性产生最佳测量。 API MPMS第14.3.1章/AGA第3号报告第1部分中关于不确定性的章节对此进行了说明。本标准基于0.10至0.75之间的βr。当βr介于0.2和0.6之间，且孔板孔径大于或等于0.45英寸时，孔板流量系数（Cd）的最小不确定度可达到。可以使用直径比和超出该范围的孔孔径；用户应参考API MPMS第14.3.1章/AGA第3号报告第1部分中的不确定性部分了解限制。达到最佳测量不确定度水平始于但不限于适当的设计。测量过程的另外两个方面必须伴随设计工作； 否则它就没有什么价值。这些方面是计量系统的应用和仪表的维护，本标准中不直接考虑这两个方面。这些方面不能由单一标准来管理，因为它们涵盖了在流量、流体类型和操作要求方面可能存在巨大差异的计量应用。用户应确定应用的最佳仪表选择，以及所考虑的测量系统的维护水平。

This document establishes design and installation parameters for measurement of fluid flow using concentric, square-edged, flanged tapped orifice meters.This document outlines the various design parameters that shall be considered when designing metering facilities using orifice meters. The mechanical tolerances found in this document encompass a wide range of orifice diameter ratios for which experimental results are available.For all existing installations, the decision to upgrade to meet the requirements of this standard shall be at the discretion of the parties involved. The parties should be cognizant that if a meter installation is not upgraded to meet this standard, measurement bias errors may exist due to inadequate flow conditioning and upstream straight pipe lengths.Use of the calculation procedures and techniques shown in the API MPMS Ch.14.3.1/AGA Report No. 3, Part 1 and API MPMS Ch.14.3.3/AGA Report No. 3, Part 3, with existing equipment is recommended, since these represent significant improvements over the previous methods. The uncertainty levels for flow measurement using existing equipment may be different from those quoted in API MPMS Chapter 14.3.1/AGA Report No. 3, Part 1.Use of orifice meters at the extremes of their diameter ratio (β r) ranges should be avoided whenever possible. Good metering design and practice tend to be somewhat conservative. This means that the use of the tightest tolerances in the mid-diameter ratio (β r) ranges would have the highest probability of producing the best measurement. An indication of this is found in the section on uncertainty in API MPMS Chapter 14.3.1/AGA Report No. 3, Part 1.This standard is based on β r between 0.10 and 0.75. Minimum uncertainty of the orifice plate coefficient of discharge (Cd) is achieved with β r between 0.2 and 0.6 and orifice bore diameters greater than or equal to 0.45 inch. Diameter ratios and orifice bore diameters outside of this range may be used; the user should consult the uncertainty section in API MPMS Chapter 14.3.1/AGA Report No. 3, Part 1 for limitations.Achieving the best level of measurement uncertainty begins with, but is not limited to, proper design. Two other aspects of the measurement process have to accompany the design effort; otherwise it is of little value. These aspects are the application of the metering system and the maintenance of the meters, neither of which is considered directly in this standard. These aspects cannot be governed by a single standard as they cover metering applications that can differ widely in flow rate, fluid type, and operational requirements. The user shall determine the best meter selection for the application and the level of maintenance for the measurement system under consideration.