ISO/TR 3313:2018

Overview - ISO/TR 3313:2018 (Flow pulsations & flow-measurement instruments)

ISO/TR 3313:2018 provides guidelines on pulsating flow in closed conduits and its effects on commonly used flowmeters. The technical report:

• Defines pulsating vs steady flow and explains detection methods.
• Focuses on flowmeter types most susceptible to pulsation: orifice plates, nozzles, Venturi tubes (DP type), turbine and vortex flowmeters.
• Describes when and how flow pulsations cause measurement errors, and gives methods to correct or mitigate those errors.
• Applies where pulsations originate from a single source located upstream or downstream of the primary element, with no flow reversal in the measuring section. Recommendations apply to both liquids and gases (with caveats for gas density changes).

Key topics and technical requirements

• Definitions and thresholds: Distinguishes steady, periodic pulsating and randomly fluctuating flows and specifies thresholds for when pulsation effects become significant (including a practical threshold for turbine meters).
• Detection and characterization: Techniques covered include non‑intrusive and insertion sensors, fast-response differential-pressure (DP) sensing, laser/thermal anemometry, and analysis of existing flowmeter signals to determine amplitude, frequency and waveform.
• Effects on specific meter types:
  • DP primary devices (orifice, nozzle, Venturi): how pulsation and secondary instrumentation response influence indicated flow; design and impulse-line considerations.
  • Turbine flowmeters: rotor dynamic response, systematic error behavior with frequency and amplitude, and guidance on estimating correction factors.
  • Vortex flowmeters: sensitivity to pulsation frequency relative to shedding frequency and methods to minimize errors.
• Correction and mitigation: Where possible, describes algorithms or correction factors to adjust meter output. When correction isn’t feasible, recommends pulsation damping devices, changes in secondary instrumentation, or selecting a less‑susceptible flowmeter type.
• Uncertainty considerations: Guidance for evaluating measurement uncertainty introduced by pulsation and for using damping criteria (see informative annexes).

Practical applications and users

ISO/TR 3313:2018 is intended for:

• Flow measurement engineers and instrument specialists assessing accuracy in industrial and laboratory installations.
• Designers and specifiers selecting flowmeters for systems with pulsating sources (e.g., reciprocating equipment, pulsating pumps).
• Calibration and metrology labs developing test procedures for pulsating flows.
• Process control and energy companies needing to manage measurement uncertainty caused by pulsations.

Practical benefits include improved meter selection, reduced systematic error through correction or damping, and clearer uncertainty budgeting for liquid and gas flow measurements.

Related standards

• ISO 5167 (measurement of fluid flow with primary devices) - note: ISO 5167 is not applicable when periodic pulsation is present.
• Produced by ISO/TC 30 (Measurement of fluid flow in closed conduits).

Keywords: ISO/TR 3313:2018, pulsating flow, flow measurement, flowmeters, differential pressure, turbine meter, vortex meter, orifice plate, Venturi, pulsation damping, flow pulsations detection, measurement uncertainty.