What is ISO 5167-2 - Measurement of fluid flow with orifice plates about?

ISO 5167-2 is the second in a six-part series on measuring fluid flow using pressure differential devices. BS EN ISO 5167-2:2022 deals with orifice plates and has been revised to implement minor corrections, harmonize changes across the series and achieve consistency with the Guide to Uncertainty of Measurement (GUM).

Who is ISO 5167-2 - Measurement of fluid flow with orifice plates for?

• 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

What does ISO 5167-2 - Measurement of fluid flow with orifice plates cover?

This part of ISO 5167 specifies the geometry and method of use (installation and operating conditions) of orifice plates 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 5167-2 applies to primary devices having an orifice plate used with flange pressure tappings, or with corner pressure tappings, or with D and D/2 pressure tappings. Other pressure tappings such as “vena contracta” and pipe tappings are not covered by this part of ISO 5167.

NOTE: ISO 5167-2 only applies to a flow which remains subsonic throughout the measuring section and where the fluid can be considered as single phase. It is not applicable to the measurement of pulsating flow. It does not cover the use of orifice plates in pipe sizes less than 50 mm or more than 1 000 mm, or for pipe Reynolds numbers below 5 000.

Why should you use ISO 5167-2 - Measurement of fluid flow with orifice plates?

• ISO 5167-2 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 5167-2 contributes to UN Sustainable Development Goal 7 on affordable and clean energy.

What’s new about ISO 5167-2 - Measurement of fluid flow with orifice plates?

This is a revision of BS EN ISO 5167-2:2003. The major changes in BS EN ISO 5167-2:2022 are:

1. A revised maximum orifice edge thickness is given for β < 0,2
2. A correction has been made to the required spacing between two 45° bends for which the straight length upstream of an orifice plate is stated
3. A clearer specification has been given for the tee for which the straight length upstream of an orifice plate is stated
4. Flow calibration of orifice plates is included
5. There is improved wording of the rules for spacing of multiple fittings but no change in actual requirements