What is ISO 5167‑3 standard about?

ISO 5167 is a series of international standards measurement of fluid flow that provides the best guidance on the functionality of the procedure adopted. ISO 5167‑3 is the third part of the ISO 5167 multi-series. ISO 5167‑3 specifies the geometry and method of use (installation and operating conditions) of nozzles and Venturi nozzles when they are inserted in a conduit running full to determine the flow rate of the fluid flowing in the conduit.

ISO 5167‑3 also provides background information for calculating the flow rate and is applicable in conjunction with the requirements given in ISO 5167-1.

ISO 5167‑3 applies to nozzles and Venturi nozzles in which the flow remains subsonic

throughout the measuring section and where the fluid can be considered as single-phase. In addition, each of the devices can only be used within specified limits of pipe size and Reynolds number. It does not apply to the measurement of pulsating flow. It does not cover the use of nozzles and Venturi nozzles in pipe sizes less than 50 mm or more than 630 mm, or where the pipe Reynolds numbers are below 10 000.

ISO 5167‑3 deals with

Three types of standard nozzles:

ISA 19325 nozzle
The long radius nozzle6
The throat-tapped nozzle

The Venturi nozzle.

The three types of the standard nozzle are fundamentally different and are described separately in ISO 5167‑3. The Venturi nozzle has the same upstream face as the ISA 1932 nozzle but has a divergent section and, therefore, a different location for the downstream pressure tappings, and is described separately. This design has a lower pressure loss than a similar nozzle. For all of these nozzles and the Venturi nozzle, direct calibration experiments have been made, sufficient in number, spread and quality to enable coherent systems of application to be based on their results and coefficients to be given with certain predictable limits of uncertainty.

Who is ISO 5167‑3 standard for?

ISO 5167‑3 on measurement of fluid flow by nozzles and venturi nozzles is beneficial for:

Manufacturer of nozzles and venturi nozzles
Fluid engineer
Fluid testing laboratories

Why should you use ISO 5167‑3 standard?

Nozzles and Venturi nozzles are used in the measurement of fluid in pressure gradients below critical and in steady flow patterns.

ISO 5167‑3 provide information on principles of the method of measurement and computation, nozzles and venturi nozzles, installation requirements, flow calibration of nozzles

As a user of ISO 5167‑3, you can determine the flow rate of the fluid flowing in the conduit using nozzles and venturi nozzles. ISO 5167‑3 provides the best guidance for the right installation, fitting and operating conditions of nozzles and venturi nozzles. ISO 5167‑3 also assist the user in calculating the flow rate and its associated uncertainty.

What’s changed since the last update?

BS EN ISO 5167‑3:2020 supersedes BS EN ISO 5167‑3:2003, which is withdrawn.

The main changes compared to the previous edition are as follows:

Addition of Subclause 5.3 Throat-tapped nozzles

BS EN ISO 5167-3:2020

Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full - Nozzles and Venturi nozzles

Published:

30 Sep 2020

Withdrawn:

7 Nov 2022