Baker R.C. Flow Measurement Handbook: Industrial Designs, Operating Principles, Performance, and Applications
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FLOW MEASUREMENT HANDBOOK
Flow Measurement
Handbook
is an information-packed reference for
engineers on flow-measuring techniques and instruments. Striking a
balance between laboratory ideal and the realities of field experience,
it provides a wealth of practical advice on the design, operation, and
performance of a broad range of flowmeters.
The book begins with a brief review of essentials of accuracy and
flow, how to select a flowmeter, and various calibration methods. Fol-
lowing this, each chapter is devoted to a class of flowmeter and in-
cludes detailed information on design, application, installation, cali-
bration, operation, advantages, and disadvantages.
Among the flowmeters discussed are orifice plates, venturi meters,
standard nozzles, critical flow venturi nozzles, variable area and other
devices depending on momentum of the flow, volumetric flowme-
ters such as positive displacement, turbine, vortex shedding, swirl,
fluidic, electromagnetic and ultrasonic meters, and mass flowmeters
including thermal and Coriolis. More than 80 different types and 250
applications are listed in the index. There are also chapters covering
probes, a brief introduction to modern control, and manufacturing
implications.
For those readers who want more background information, many
chapters conclude with an appendix on the mathematical theory be-
hind the techniques discussed. The final chapter takes a look at direc-
tions in which the technology is likely to go in the future.
Engineers will use this practical handbook to solve problems in
flowmeter design and application and to improve performance.
Roger
C.
Baker is a Visiting Industrial Fellow in the Manufacturing and
Management Division of the Department of Engineering, University
of Cambridge; Visiting Professor, Cranfield University; and Director
of Technical Programmes, the Gatsby Charitable Foundation.
Flow Measurement
Handbook
INDUSTRIAL DESIGNS, OPERATING PRINCIPLES,
PERFORMANCE, AND APPLICATIONS
ROGER C. BAKER
CAMBRIDGE
UNIVERSITY PRESS
CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, Sao Paulo
Cambridge University Press
The Edinburgh Building, Cambridge CB2 2RU, UK
Published in the United States of America by Cambridge University Press, New York
www. Cambridge. org
Information on this title: www.cambridge.org/9780521480109
© Cambridge University Press 2000
This book is in copyright. Subject to statutory exception
and to the provisions of relevant collective licensing agreements,
no reproduction of any part may take place without
the written permission of Cambridge University Press.
First published 2000
This digitally printed first paperback version 2005
A catalogue record for this publication is available from the British Library
Library of Congress Cataloguing in Publication data
Baker, R. C.
Flow measurement handbook : industrial designs, operating
principles, performance, and applications / Roger C. Baker.
p.
cm.
Includes bibliographical references.
ISBN 0-521-48010-8
1. Flow meters - Handbooks, manuals, etc. I. Title.
TA357.5.M43B35 2000
681'.28-dc21 99-14190
CIP
ISBN-13 978-0-521-48010-9 hardback
ISBN-10 0-521-48010-8 hardback
ISBN-13 978-0-521-01765-7 paperback
ISBN-10 0-521-01765-3 paperback
DISCLAIMER
Every effort has been made in preparing this book to provide accurate and up-to-date data
and information that is in accord with accepted standards and practice at the time of publi-
cation and has been included in good faith. Nevertheless, the author, editors, and publisher
can make no warranties that the data and information contained herein is totally free from
error, not least because industrial design and performance is constantly changing through
research, development, and regulation. Data, discussion, and conclusions developed by
the author are for information only and are not intended for use without independent
substantiating investigation on the part of the potential users. The author, editors, and pub-
lisher therefore disclaim all liability or responsibility for direct or consequential damages
resulting from the use of
data,
designs, or constructions based on any of the information
supplied or materials described in this book. Readers are strongly advised to pay careful
attention to information provided by the manufacturer of any equipment that they plan to
use and should refer to the most recent standards documents relating to their application.
The author, editors, and publisher wish to point out that the inclusion or omission of
a
particular device, design, application, or other material in no way implies anything about
its performance with respect to other devices, etc.
To Liz, Sarah and
Paul,
Mark, John and Rachel
Contents
Preface page
xix
Acknowledgments
xxi
Nomenclature
xxiii
CHAPTER
1 Introduction l
1.1
Initial Considerations
1
1.2
Do We Need
a
Flowmeter?
2
1.3
How Accurate?
4
1.4
A Brief Review
of
the Evaluation
of
Standard Uncertainty
7
1.5
Sensitivity Coefficients
9
1.6
What
Is a
Flowmeter?
9
1.7
Chapter Conclusions
(for
those who plan
to
skip
the
mathematics!)
13
1.8
Mathematical Postscript
15
APPENDIX i.A Statistics
of
Flow Measurement
15
l.A.l Introduction
15
1.A.2 The Normal Distribution
16
1.A.3 The Student
t
Distribution
17
1.A.4 Practical Application
of
Confidence Level
19
I.A.5 Types
of
Error
20
1.A.6 Combination
of
Uncertainties
21
I.A.7 Uncertainty Range Bars, Transfer Standards,
and Youden Analysis
21
CHAPTER
2
Fluid Mechanics Essentials
24
2.1 Introduction
24
2.2 Essential Property Values
24
2.3 Flow
in a
Circular Cross-Section Pipe
24
2.4 Flow Straighteners
and
Conditioners
27
2.5 Essential Equations
30
2.6 Unsteady Flow
and
Pulsation
32
2.7 Compressible Flow
34
2.8 Multiphase Flow
36
2.9 Cavitation, Humidity, Droplets,
and
Particles
38
2.10 Gas Entrapment
39
CONTENTS
2.11 Steam
39
2.12 Chapter Conclusions
41
CHAPTER
3
Specification, Selection, and Audit
42
3.1 Introduction
42
3.2 Specifying the Application
42
3.3 Notes
on the
Specification Form
43
3.4 Flowmeter Selection Summary Tables
46
3.5 Other Guides
to
Selection
and
Specific Applications
53
3.6 Draft Questionnaire
for
Flowmeter Audit
55
3.7 Final Comments
55
APPENDIX 3.A Specification and Audit Questionnaires
56
3.A.1 Specification Questionnaire
56
3.A.2 Supplementary Audit Questionnaire
58
CHAPTER
4 Calibration 61
4.1 Introduction
61
4.1.1 Calibration Considerations
61
4.1.2 Typical Calibration Laboratory Facilities
64
4.1.3 Calibration from
the
Manufacturer's Viewpoint
65
4.2 Approaches
to
Calibration
66
4.3 Liquid Calibration Facilities
69
4.3.1 Flying Start
and
Stop
69
4.3.2 Standing Start
and
Stop
72
4.3.3 Large Pipe Provers
74
4.3.4 Compact Provers
74
4.4 Gas Calibration Facilities
77
4.4.1 Volumetric Measurement
77
4.4.2 Mass Measurement
79
4.4.3 Gas/Liquid Displacement
80
4.4.4
pvT
Method
80
4.4.5 Critical Nozzles
81
4.4.6 Soap Film Burette Method
81
4.5 Transfer Standards
and
Master Meters
82
4.6
In
Situ Calibration
84
4.7 Calibration Uncertainty
91
4.8 Traceability and Accuracy
of
Calibration Facilities
92
4.9 Chapter Conclusions
93
CHAPTER
5
Orifice Plate Meters
95
5.1 Introduction
95
5.2 Essential Background Equations
97
5.3 Design Details
100
5.4 Installation Constraints
102
5.5 Other Orifice Plates
106
CONTENTS
5.6 Deflection of Orifice Plate at High Pressure 106
5.7 Effect of Pulsation 109
5.8 Effects of More Than One Flow Component 113
5.9 Accuracy Under Normal Operation 117
5.10 Industrially Constructed Designs 118
5.11 Pressure Connections 119
5.12 Pressure Measurement 122
5.13 Temperature and Density Measurement 124
5.14 Flow Computers 124
5.15 Detailed Studies of Flow Through the Orifice Plate, Both
Experimental and Computational 124
5.16 Application, Advantages, and Disadvantages 127
5.17 Chapter Conclusions 127
APPENDIX 5.A Orifice Discharge Coefficient 128
CHAPTER 6 Venturi Meter and Standard Nozzles 130
6.1 Introduction 130
6.2 Essential Background Equations 131
6.3 Design Details 134
6.4 Commercially Available Devices 135
6.5 Installation Effects 135
6.6 Applications, Advantages, and Disadvantages 137
6.7 Chapter Conclusions 138
CHAPTER 7 Critical Flow Venturi Nozzle 140
7.1 Introduction 140
7.2 Design Details of a Practical Flowmeter Installation 141
7.3 Practical Equations 143
7.4 Discharge Coefficient C 145
7.5 Critical Flow Function
C*
146
7.6 Design Considerations 147
7.7 Measurement Uncertainty 148
7.8 Example 149
7.9 Industrial and Other Experience 151
7.10 Advantages, Disadvantages, and Applications 152
7.11 Chapter Conclusions 152
CHAPTER
8 Other Momentum-Sensing Meters 153
8.1 Introduction 153
8.2 Variable Area Meter 153
8.2.1 Operating Principle and Background 154
8.2.2 Design Variations 154
8.2.3 Remote Readout Methods 155
8.2.4 Design Features 156
8.2.5 Calibration and Sources of Error 157
CONTENTS
8.2.6 Installation 157
8.2.7 Unsteady and Pulsating Flows 158
8.2.8 Industrial Types, Ranges, and Performance 158
8.2.9 Computational Analysis of the Variable Area Flowmeter 159
8.2.10
Applications 159
8.3 Spring-Loaded Diaphragm (Variable Area) Meters 159
8.4 Target (Drag Plate) Meter 162
8.5 Integral Orifice Meters 163
8.6 Dall Tubes and Devices that Approximate to Venturis
and Nozzles 163
8.7 Wedge and V-Cone Designs 165
8.8 Differential Devices with a Flow Measurement Mechanism
in the Bypass 167
8.9 Slotted Orifice Plate 168
8.10 Pipework Features - Inlets 168
8.11 Pipework Features - Bend or Elbow Used as a Meter 169
8.12 Averaging Pitot 170
8.13 Laminar or Viscous Flowmeters 173
8.14 Chapter Conclusions 176
APPENDIX 8.A History, Equations, and Accuracy Classes
for the
VA
Meter 177
8.A.1 Some History 177
8.A.2 Equations 178
8.A.3 Accuracy Classes 180
CHAPTER
9 Positive Displacement Flowmeters 182
9.1 Introduction 182
9.1.1 Background 182
9.1.2 Qualitative Description of Operation 183
9.2 Principal Designs of Liquid Meters 184
9.2.1 Nutating Disk Meter 184
9.2.2 Oscillating Circular Piston Meter 184
9.2.3 Multirotor Meters 185
9.2.4 Oval Gear Meter 185
9.2.5 Sliding Vane Meters 187
9.2.6 Helical Rotor Meter 189
9.2.7 Reciprocating Piston Meters 190
9.2.8 Precision Gear Flowmeters 190
9.3 Calibration, Environmental Compensation, and Other Factors
Relating to the Accuracy of Liquid Flowmeters 191
9.3.1 Calibration Systems 192
9.3.2 Clearances 194
9.3.3 Leakage Through the Clearance Gap Between Vane
and Wall 194
9.3.4 Slippage Tests 196
9.3.5 The Effects of Temperature and Pressure Changes 197
9.3.6 The Effects of Gas in Solution 197