ISO 5167-4:2003
Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 4: Venturi tubes

Standard No.

ISO 5167-4:2003

Release Date

2003

Published By

International Organization for Standardization (ISO)

Status

Be replaced

Replace By

ISO 5167-4:2022

Latest

ISO 5167-4:2022

Scope

This part of GB/T 2624 specifies the geometric dimensions of the venturi tube and the use method (installation and working conditions) of the venturi tube installed in the pipeline to measure the full pipe fluid flow. This part of GB/T 2624 also provides relevant information used to calculate flow rates and can be used in conjunction with the requirements specified in GB/T 2624.1. This part of GB/T 2624 is only applicable to venturi tubes where the fluid maintains subsonic flow throughout the entire measurement section and can be considered a single-phase flow. Additionally, each device may only be used within specified pipe size, roughness, diameter ratio, and Reynolds number limits. This part of GB/T 2624 does not apply to the measurement of pulsating flow. This section does not cover the use of venturi tubes in pipes with dimensions less than 50 mm or greater than 1 200 mm, or pipe Reynolds numbers lower than 2X10. This part of GB/T 2624 involves three types of classic venturis: a) cast type; b) machined type; c) rough welded iron plate type. The venturi tube is a device composed of an inlet cylindrical section, a conical constriction section, a cylindrical throat and a conical diffusion section. The difference between the uncertainty values of the outflow coefficients of the three types of classical venturis indicates, on the one hand, the number of existing experimental results for each type of classical venturi, and, on the other hand, the uncertainty in the precise definition of the geometric profile degree. These values are based on data collected over many years. Venturi nozzles (and other nozzles) are covered by GB/T 2624.3. Note 1: Research on venturi tubes for high-pressure gases [≥1 MPa (≥10 bar)] is currently in progress (see references [1], [2], [3]). It has been found that the outflow coefficient of machined constriction venturi tubes exceeds the range expected in this part of GB/T 2624 by 2% or more in many cases. For best accuracy, venturis for gases should be calibrated over the required flow range. It is not uncommon to use a single pressure tap (or up to two pressure taps on each plane) in high pressure gases. Note 2: In the United States, the classic venturi is sometimes called the Herschel venturi.

ISO 5167-4:2003 Referenced Document

• ISO 4006:1991 Measurement of fluid flow in closed conduits; vocabulary and symbols
• ISO 5167-1:2003 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 1: General principles and requirements

ISO 5167-4:2003 history

• 2022 ISO 5167-4:2022 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full — Part 4: Venturi tubes
• 2003 ISO 5167-4:2003 Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Part 4: Venturi tubes