Overview
ISO 3354:2008 - Measurement of clean water flow in closed conduits - defines the velocity-area method using propeller-type current-meters for determining volume flow-rate in full, closed conduits under regular, steady flow conditions. The standard covers technology and calibration of current-meters, procedures for measuring local velocities, and calculation of flow-rate by velocity integration. It applies when the fluid is clean water (or treated as clean), the conduit is full, and the velocity distribution is regular.
Key Topics and Requirements
- Scope and limitations: Applicable only to clean water (or considered clean), full conduits, steady and regular velocity distributions. Not suitable for highly turbulent, swirling or highly asymmetric flows without special methods.
- Current-meter technology: Focuses on propeller-type current-meters (rotor axis approximately parallel to flow). Cup-type meters are not permitted for this method.
- Calibration: Requires calibration of current-meters (referenced to ISO 3455) and documented calibration procedures to ensure traceability and accuracy.
- Measurement of cross-section: Measurement of the measuring cross-section area normal to the conduit axis is a core requirement before velocity sampling.
- Location and number of measuring points: Specifies how to distribute measuring points across circular and rectangular sections and how to mount devices (stationary arrays, struts).
- Velocity measurement methods: Details graphical, numerical and arithmetical integration approaches (e.g., log-linear, log‑Chebyshev) to calculate mean axial fluid velocity from local measurements.
- Uncertainty and quality: Provides guidance on sources of error, propagation of errors, and calculation and presentation of measurement uncertainty (aligned with ISO 5168).
- Practical procedures: Includes setting and maintenance of current-meters, blockage correction, boundary-layer extrapolation, and example calculations.
Applications
ISO 3354:2008 is practical for:
- Flow measurement in water distribution and supply mains, pumping stations and gravity pipelines
- Hydrometry and verification of pipeline flow for billing, regulatory compliance, or asset management
- Field calibration and acceptance testing of flow-measuring equipment
- Laboratory and on-site measurements where velocity-area assessment with current-meters is appropriate
Using ISO 3354 helps ensure repeatable, auditable flow measurements and quantified uncertainties for engineering, regulatory and commercial purposes.
Who Should Use It
- Water and wastewater engineers
- Hydrologists and field hydrometry teams
- Calibration laboratories and metrology institutes
- Pipeline operators and asset managers
- Consultants performing flow surveys and acceptance tests
Related Standards
- ISO 3455 - Calibration of current-meters in straight open tanks
- ISO 4006 - Vocabulary and symbols for fluid flow in closed conduits
- ISO 5168 - Procedures for evaluation of uncertainties in fluid flow measurement
- ISO 7194 - Velocity-area methods for swirling or asymmetric flow conditions
Keywords: ISO 3354:2008, measurement of clean water flow, closed conduits, velocity-area method, current-meters, propeller-type current-meters, flow-rate, velocity integration, calibration, measurement uncertainty.
Open preview (PDF)Measurement of clean water flow in closed conduits — Velocity-area method using current-meters in full conduits and under regular flow conditions