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BS ISO 3966:2020 Measurement of fluid flow in closed conduits. Velocity area method using Pitot static tubes >
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BS ISO 3966:2020 Measurement of fluid flow in closed conduits. Velocity area method using Pitot static tubes, 2020
- undefined
- Foreword
- 1 Scope
- 2 Normative references
- 3 Terms, definitions and symbols
- 3.1 Terms and definitions
- 3.2 Symbols
- 4 Principle
- 4.1 General principle
- 4.1.1 Graphical integration of the velocity area (see Clause 9)
- 4.1.2 Numerical integration of the velocity area (see Clause 10)
- 4.1.3 Arithmetical methods (see Clause 11)
- 4.2 Measurement of the measuring cross-section
- 4.2.1 Circular cross-sections
- 4.2.2 Rectangular cross-sections
- 4.3 Measurement of local velocities
- 4.3.1 Method of exploring traverse section
- 4.3.2 Reference measurement
- 4.3.3 Checking of velocity distribution
- 4.4 Location and number of measuring points in the cross-section
- 4.4.1 General requirements
- 4.4.2 Circular cross-sections
- 4.4.3 Rectangular cross-sections
- 5 Design of Pitot tubes
- 5.1 General description
- 5.2 Criteria to be fulfilled by the Pitot tube
- 6 Requirements for use of Pitot tubes
- 6.1 Selection of the measuring cross-section
- 6.1.1 Location of the measuring cross-section (of selection)
- 6.1.2 Avoidance of asymmetry, swirl and turbulences
- 6.1.3 Maximum flow deviation
- 6.1.4 Preliminary traverse tests
- 6.2 Devices for improving flow conditions
- 6.2.1 Anti-swirl device
- 6.2.2 Profile developer
- 6.2.3 Positioning/Location of devices
- 6.2.4 Provisional guiding installation
- 6.3 Limits of use
- 6.3.1 Nature of the fluid
- 6.3.2 Range of velocities
- 6.3.3 Nature of the flow
- 6.3.4 Dimensional limitations
- 6.3.5 Influence of turbulence
- 6.4 Performance of measurements
- 6.4.1 Measurement of differential pressure
- 6.4.2 Differential pressure fluctuations
- 6.4.3 Determination of fluid density
- 6.5 Inspection and maintenance of the Pitot tube
- 7 Positioning of Pitot tube
- 8 Velocity computation
- 8.1 Verification of conditions for a measurement
- 8.2 Formulae for velocity computation
- 9 Determination of the discharge velocity by graphical integration of the velocity area
- 9.1 Circular cross-section
- 9.2 Rectangular cross-sections
- 10 Determination of the discharge velocity by numerical integration of the velocity area
- 10.1 Circular cross-sections
- 10.2 Rectangular cross-sections
- 11 Determination of the discharge velocity by arithmetic methods
- 11.1 “Log-linear” method
- 11.1.1 Circular cross-sections
- 11.1.2 Rectangular cross-sections
- 11.2 Log-Chebyshev method
- 11.2.1 Circular cross-sections
- 11.2.2 Rectangular cross-sections
- 12 Corrections of local velocity measurements
- 12.1 Correction for stem blockage
- 12.1.1 Case where the correction can be neglected
- 12.1.2 Estimation of the correction of local velocity measurement
- 12.1.3 Estimation of the overall correction of the flow-rate value (application to arithmetic methods)
- 12.2 Correction for transverse velocity gradient
- 12.2.1 Correction for measuring point position
- 12.2.2 Overall correction of flow rate
- 12.3 Correction for turbulence
- 12.4 Correction for head loss
- 13 Errors
- 13.1 Definition of the error
- 13.2 Errors in the estimation of the local velocity
- 13.2.1 Random errors
- 13.2.2 Systematic errors
- 13.3 Errors in the estimation of flow rate
- 13.3.1 Random errors
- 13.3.2 Systematic errors
- 13.4 Definition of the standard deviation
- 13.5 Definition of the tolerance
- 13.6 Calculation of standard deviation
- 13.6.1 Standard deviation on local velocity measurement
- 13.6.2 Standard deviation on flow-rate measurement
- Annex A (normative) Pitot tubes
- Annex B (normative) Correction to the measuring position of Pitot tubes used in a transverse velocity gradient
- Annex C (normative) Study concerning turbulence correction
- Annex D (normative) Damping of pressure gauges
- Annex E (normative) Measurements with a Pitot tube in a compressible fluid
- Annex F (normative) Determination of coefficient m for extrapolation near the wall
- Annex G (informative) Example of calculation of the uncertainty on the flow-rate measurement by means of Pitot tubes
- Bibliography [Go to Page]