This part of ISO 5167 specifies the geometry and method of use (installation and operating conditions) of wedge meters when they are inserted in a conduit running full to determine the flow rate of the fluid flowing in the conduit.

As the uncertainty of an uncalibrated wedge meter can be too large for a particular application, it might be deemed essential to calibrate the flow meter in accordance with Clause 7 of this document. This part of ISO 5167 includes requirements for calibration which, if applied, are for use over the calibrated Reynolds number range. Clause 7 might also be useful guidance for calibration of meters of similar design but which fall outside the scope of this document.

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

This part of ISO 5167 is applicable only to wedge meters in which the flow remains subsonic throughout the measuring section and where the fluid can be considered as single-phase. Uncalibrated wedge meters can only be used within specified limits of pipe size, roughness, beta (or wedge ratio) and Reynolds number. This part of ISO 5167 is not applicable to the measurement of pulsating flow. It does not cover the use of uncalibrated wedge meters in pipes sized less than 50 mm or more than 600 mm, or where the pipe Reynolds numbers are below 1 × 10⁴.

A wedge meter has a primary element which consists of a wedge-shaped restriction of a specific geometry. Alternative designs of wedge meters are available; however, at the time of writing there is insufficient data to fully characterize these devices, and therefore these meters shall be calibrated in accordance with Clause 7.