This international standard is the fourth in a six-part series on measuring fluid flow using pressure differential devices. ISO 5167-4 deals with venturi tubes and has been revised to implement minor corrections, harmonize changes across the series and achieve consistency with the Guide to Uncertainty of Measurement (GUM).
Manufacturers of pressure differential devices
Those working with this equipment in the natural gas industry, from chief mechanical engineer or chief metrologist to operators and technicians
Anyone measuring other gases or liquids (Newtonian fluids) including e.g. hydrogen or carbon dioxide
This part of ISO 5167 specifies the geometry and method of use (installation and operating conditions) of Venturi tubes when they are inserted in a conduit running full to determine the flowrate of the fluid flowing in the conduit. It also provides background information for calculating the flowrate and is applicable in conjunction with the requirements given in BS EN ISO 5167-1.
ISO 5167-4 applies 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.
ISO 5167-4 deals with the three types of classic Venturi tubes:
“As cast”
Machined
Fabricated (also known as “rough-welded sheet-iron”)
NOTE: 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 BS EN ISO 5167-3.
ISO 5167-4 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 × 105.
In the USA the classic Venturi tube is sometimes called the Herschel Venturi tube.
This standard is reliable and proven, describing a robust approach and an enduringly effective framework for measuring fluid flow
It incorporates revisions that improve, refine, update and future-proof the standard
In particular the revision includes a new section on calibrating meters so that users now have the option of either using the equations outlined in the standard, or to get a better certainty, the new guidance on calibrating meters
Use of the standard can improve efficiency and help manage risk
ISO 5167-4 contributes to UN Sustainable Development Goal 7 on affordable and clean energy.
BS EN ISO 5167-4:2022 is a revision of BS EN ISO 5167-4:2003. The major changes in BS EN ISO 5167-4:2022 are:
EN ISO 5167-4
ISO 5167-4