BS ISO 3966:2020
$198.66
Measurement of fluid flow in closed conduits. Velocity area method using Pitot static tubes
| Published By | Publication Date | Number of Pages |
| BSI | 2020 | 64 |
This document specifies a method for the determination in a closed conduit of the volume rate of flow of a regular flow
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of a fluid of substantially constant density or corresponding to a Mach number not exceeding 0,25,
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with substantially uniform stagnation temperature across the measuring cross-section,
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running full in the conduit, and
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under steady flow conditions.
In particular, it deals with the technology and maintenance of Pitot static tubes, with the calculation of local velocities from measured differential pressures and with the computation of the flow rate by velocity integration.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | undefined |
| 7 | Foreword |
| 9 | 1 Scope 2 Normative references 3 Terms, definitions and symbols 3.1 Terms and definitions |
| 10 | 3.2 Symbols |
| 11 | 4 Principle 4.1 General principle |
| 12 | 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 |
| 13 | 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 |
| 14 | 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 |
| 15 | 5 Design of Pitot tubes 5.1 General description 5.2 Criteria to be fulfilled by the Pitot tube |
| 16 | 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 |
| 17 | 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 |
| 18 | 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 |
| 19 | 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 |
| 20 | 8.2 Formulae for velocity computation |
| 21 | 9 Determination of the discharge velocity by graphical integration of the velocity area |
| 22 | 9.1 Circular cross-section |
| 23 | 9.2 Rectangular cross-sections |
| 25 | 10 Determination of the discharge velocity by numerical integration of the velocity area 10.1 Circular cross-sections |
| 27 | 10.2 Rectangular cross-sections 11 Determination of the discharge velocity by arithmetic methods |
| 28 | 11.1 “Log-linear” method 11.1.1 Circular cross-sections 11.1.2 Rectangular cross-sections |
| 30 | 11.2 Log-Chebyshev method 11.2.1 Circular cross-sections 11.2.2 Rectangular cross-sections |
| 31 | 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 |
| 33 | 12.1.3 Estimation of the overall correction of the flow-rate value (application to arithmetic methods) 12.2 Correction for transverse velocity gradient |
| 34 | 12.2.1 Correction for measuring point position 12.2.2 Overall correction of flow rate |
| 35 | 12.3 Correction for turbulence |
| 36 | 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 |
| 37 | 13.2.2 Systematic errors |
| 38 | 13.3 Errors in the estimation of flow rate 13.3.1 Random errors 13.3.2 Systematic errors |
| 39 | 13.4 Definition of the standard deviation 13.5 Definition of the tolerance |
| 40 | 13.6 Calculation of standard deviation 13.6.1 Standard deviation on local velocity measurement |
| 41 | 13.6.2 Standard deviation on flow-rate measurement |
| 42 | Annex A (normative) Pitot tubes |
| 48 | Annex B (normative) Correction to the measuring position of Pitot tubes used in a transverse velocity gradient |
| 50 | Annex C (normative) Study concerning turbulence correction |
| 53 | Annex D (normative) Damping of pressure gauges |
| 55 | Annex E (normative) Measurements with a Pitot tube in a compressible fluid |
| 59 | Annex F (normative) Determination of coefficient m for extrapolation near the wall |
| 60 | Annex G (informative) Example of calculation of the uncertainty on the flow-rate measurement by means of Pitot tubes |
| 63 | Bibliography |
