用插入圆形横截面管道中的压差装置测量流体流量.第4部分:文丘里管

[中文适用范围]： 本文件规定了文丘里管1)的几何形状和使用方法（安装和操作条件），当文丘里管插入满流的管道以确定管道中流动的流体的流速时。本文件还提供了计算流速的背景信息，可与 ISO 5167-1 中的要求结合使用。本文件仅适用于在整个测量部分中流动保持亚音速且流体可被视为单相的文丘里管。此外，文丘里管只能在未校准的情况下按照本标准在指定的管道尺寸、粗糙度、直径比和雷诺数范围内使用，或者也可以在其校准范围内使用。本文件不适用于脉动流的测量。它不涵盖在管道尺寸小于 50 毫米或大于 1200 毫米或管道雷诺数低于 2 × 105 的情况下使用未校准的文丘里管。本文件涉及三种类型的传统文丘里管：a)“铸造”；b)机加工；c)装配（也称为“粗焊铁皮”）。文丘里管由一个收敛入口组成，该入口连接到圆柱形喉管，而圆柱形喉管又连接到称为发散部分（或扩散器）的圆锥形扩展部分。文丘里喷嘴（和其他喷嘴）在 ISO 5167-3 中处理。注：在美国，经典文丘里管有时被称为赫歇尔文丘里管。 [外文原描述]： This document specifies the geometry and method of use (installation and operating conditions) of Venturi tubes[1] when they are inserted in a conduit running full to determine the flow rate of the fluid flowing in the conduit. This document also provides background information for calculating the flow rate and is applicable in conjunction with the requirements given in ISO 5167-1. This document is applicable only to Venturi tubes in which the flow remains subsonic throughout the measuring section and where the fluid can be considered as single-phase. In addition, Venturi tubes can only be used uncalibrated in accordance with this standard within specified limits of pipe size, roughness, diameter ratio and Reynolds number, or alternatively they can be used across their calibrated range. This document is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated Venturi tubes in pipes sized less than 50 mm or more than 1 200 mm, or where the pipe Reynolds numbers are below 2 × 10 5 . This document deals with the three types of classical Venturi tubes: a) “as cast”; b) machined; c) fabricated (also known as “rough-welded sheet-iron”). A Venturi tube consists of a convergent inlet connected to a cylindrical throat which is in turn connected to a conical expanding section called the divergent section (or alternatively the diffuser). Venturi nozzles (and other nozzles) are dealt with in ISO 5167-3. NOTE In the USA the classical Venturi tube is sometimes called the Herschel Venturi tube. [1] In the USA the classical Venturi tube is sometimes called the Herschel Venturi tube.