ISO 5167-1:2022

Overview

ISO 5167-1:2022 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross‑section conduits running full - Part 1 provides the general principles and requirements for measuring flow rate using pressure-differential primary devices (orifice plates, nozzles, Venturi tubes, cone meters and wedge meters). This third edition (2022) defines terms and symbols, specifies system components, installation and measurement requirements, and outlines methods to compute flow rate and its uncertainty. The standard applies to subsonic, single‑phase flow in full circular conduits and excludes pulsating flow.

Key topics and technical requirements

• Scope and definitions: standardized terminology and symbols for differential‑pressure metering systems.
• Primary devices: geometry, selection and requirements for orifice plates, nozzles, Venturi tubes, cone and wedge meters.
• Measurement principle: differential‑pressure method and computation of volumetric or mass flow from pressure drop, density, temperature and pressure.
• System components: distinction of primary (primary device and tappings), secondary (impulse lines, transmitters) and tertiary (flow computer) devices.
• Installation requirements: general siting rules, minimum straight‑pipe runs, flow conditioners and profile requirements to ensure accurate measurements.
• Impulse lines and transmitters: guidance on proper routing, isolation valves and manifolds to reduce error.
• Uncertainty and calibration: procedures for determining measurement uncertainty, practical computation methods and annexed examples (including Annex E).
• Diagnostics and condition monitoring: inclusion of recommendations for meter diagnostics and condition‑based monitoring (CBM).
• Limitations: only for subsonic, single‑phase flows; not applicable to pulsating flow. The document also notes refinements such as the defined role of the primary element within the metering system and profile acceptance rules.

Applications and users

ISO 5167-1:2022 is essential for professionals involved in:

• Flow measurement design, installation and verification
• Instrumentation and process engineering in oil & gas, water/wastewater, chemical, power and HVAC industries
• Calibration laboratories and metrology teams establishing uncertainty budgets
• Asset owners implementing condition‑based monitoring and diagnostics for flow meters

Use this standard when specifying differential‑pressure metering systems, preparing installation instructions, performing uncertainty analysis, or developing flow‑meter commissioning protocols.

Related standards

• ISO 5167 (all parts) - complete series on differential‑pressure devices
• ISO 4006 - Vocabulary and symbols for fluid flow in closed conduits
• ISO 5168 - Procedures for evaluation of uncertainties in flow measurement
• ISO/IEC Guide 98‑3 (GUM) - Guide to the expression of uncertainty in measurement
• ISO/TR 3313, ISO/TR 9464, ISO/TR 12767, ISO/TR 15377 - supplementary technical reports

Keywords: ISO 5167-1:2022, differential pressure flow measurement, orifice plate, Venturi tube, nozzle, cone meter, wedge meter, flow meter installation, measurement uncertainty, flow conditioners.