AS ISO 5167.4:2023 identically adopts ISO 5167 4:2022, which specifies the geometry and method of use (installation and operating conditions) of Venturi tubes1 when they are inserted in a conduit running full to determine the flow rate of the fluid flowing in the conduit
Table of contents
Header
About this publication
Preface
Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Principles of the method of measurement and computation
5 Classical Venturi tubes
5.1 Field of application
5.1.1 General
5.1.2 Classical Venturi tube with an “as cast” convergent section
5.1.3 Classical Venturi tube with a machined convergent section
5.1.4 Classical Venturi tube with a fabricated convergent section
5.2 General shape
5.2.1 General
5.2.2 Entrance cylinder
5.2.3 Convergent section
5.2.4 Throat
5.2.5 Divergent section
5.2.6 Truncated Venturi tube
5.2.7 Roughness
5.2.8 Classical Venturi tube with an “as cast” convergent section
5.2.9 Classical Venturi tube with a machined convergent section
5.2.10 Classical Venturi tube with a fabricated convergent section
5.3 Material and manufacture
5.3.1
5.3.2
5.3.3
5.4 Pressure tappings
5.4.1
5.4.2
5.4.3
5.4.4
5.4.5
5.4.6
5.4.7
5.4.8
5.5 Discharge coefficient, C
5.5.1 Limits of use
5.5.2 Discharge coefficient of the classical Venturi tube with an “as cast” convergent section
5.5.3 Discharge coefficient of the classical Venturi tube with a machined convergent section
5.5.4 Discharge coefficient of the classical Venturi tube with a fabricated convergent section
5.6 Expansibility [expansion] factor, ε
5.7 Uncertainty of the discharge coefficient, C
5.7.1 Classical Venturi tube with an “as cast” convergent section
5.7.2 Classical Venturi tube with a machined convergent section
5.7.3 Classical Venturi tube with a fabricated convergent section
5.8 Uncertainty of the expansibility [expansion] factor, ε
5.9 Pressure loss
5.9.1 Definition of the pressure loss
5.9.2 Relative pressure loss
6 Installation requirements
6.1 General
6.2 Minimum upstream and downstream straight lengths for installation between various fittings and the Venturi tube
6.2.1
6.2.2
6.2.3
6.2.4
6.2.5
6.2.6
6.2.7
6.2.8
6.2.9
6.3 Flow conditioners
6.4 Additional specific installation requirements for classical Venturi tubes
6.4.1 Circularity and cylindricality of the pipe and alignment of the classical Venturi tube
6.4.1.1
6.4.1.2
6.4.1.3
6.4.2 Roughness of the upstream pipe
7 Flow calibration of Venturi tubes
7.1 General
7.2 Test facility
7.3 Meter installation
7.4 Design of the test programme
7.5 Reporting the calibration results
7.6 Uncertainty analysis of the calibration
7.6.1 General
7.6.2 Uncertainty of the test facility
7.6.3 Uncertainty of the Venturi tube
Annex A
Annex B
B.1 General
B.2 Effect of the diameter ratio, β
B.3 Influence of the Reynolds number, ReD
B.3.1 General
B.3.2 Classical Venturi tube with an “as cast” convergent section
B.3.3 Classical Venturi tube with a machined convergent section
B.3.4 Classical Venturi tube with a fabricated convergent section
B.3.5 Classical Venturi tube with a profile as specified for an “as cast” convergent section but with the entrance cylinder and convergent section machined
B.4 Effects of the relative roughness, Ra/D
B.4.1 Roughness of the classical Venturi tube
B.4.2 Roughness of the upstream pipe
Annex C
C.1 General
C.2 Mean value of the pressure loss and influence of the relative roughness
C.3 Influence of the Reynolds number
C.4 Influence of the angle of the divergent section
