ISO 5167-5:2022

Overview

ISO 5167-5:2022 - Measurement of fluid flow by means of pressure differential devices inserted in circular cross‑section conduits running full - Part 5: Cone meters. This part of the ISO 5167 series specifies the geometry, installation and operating requirements for cone meters used to determine flow rate in pipes running full. It covers meter design (pressure tappings, cone and support arrangement), limits of use for uncalibrated cone meters, and provides the background for computing flow using the discharge coefficient (C) and expansibility (ε) factor. The standard applies to single‑phase, subsonic flows and is used together with ISO 5167‑1.

Key Topics and Requirements

• Field of application
  • For circular cross‑section conduits running full; not applicable to pulsating flow.
  • Uncalibrated cone meters may only be used within specified limits: pipe sizes 50 mm to 500 mm and pipe Reynolds numbers between 8×10^4 and 1.2×10^7.
• Meter geometry and design
  • Cone held concentrically with the cone nose upstream.
  • Upstream pressure tappings in the pipe wall; downstream tapping on the cone’s back face routed through the support.
• Measurement principles and computation
  • Flow derived from the differential pressure across the cone using C, ε, β (diameter ratio), Δp and fluid density.
  • Discharge coefficient (C) depends on Reynolds number - iterative computation is required.
  • Expansibility factor (ε) values and guidance are provided (table/formula), with uncertainty treatment.
• Installation requirements
  • Minimum upstream/downstream straight lengths depending on nearby fittings (bends, valves, expanders).
  • Requirements on pipe circularity, cylindricality, surface roughness and thermowell positioning.
• Calibration and uncertainty
  • Clause 7 details flow calibration procedures, test facility and uncertainty analysis - calibration is recommended where uncalibrated uncertainty is unacceptable.
  • Uncertainty of C and ε are addressed per ISO/IEC Guide 98‑3 methodology.

Applications and Who Uses It

• Practical uses: custody transfer, process control, water/wastewater, oil & gas, HVAC, and general industrial flow measurement where a compact primary differential device is preferred.
• Target users: metrology engineers, flow measurement specialists, process engineers, instrument designers, calibration laboratories, and regulatory bodies specifying flow measurement accuracy.
• Benefits: standardized geometry and installation practices improve comparability, repeatability and reduce measurement uncertainty when deploying cone meters.

Related Standards

• ISO 5167‑1 - General principles and requirements for differential pressure devices (use in conjunction with this part)
• ISO 4006 - Vocabulary and symbols for fluid flow in closed conduits
• Other parts of the ISO 5167 series covering orifice plates, nozzles, Venturi tubes and wedge meters.

Keywords: ISO 5167-5:2022, cone meter, fluid flow measurement, differential pressure device, discharge coefficient, expansibility factor, flow calibration, Reynolds number, pipe installation.