Page 142 - Mechanical Engineers' Handbook (Volume 2)

Mechanical Engineers’ Handbook: Instrumentation, Systems, Controls, and MEMS, Volume 2, Third Edition.
Edited by Myer Kutz

Copyright  2006 by John Wiley & Sons, Inc.

CHAPTER 5
TEMPERATURE AND FLOW TRANSDUCERS
Robert J. Moffat
Department of Mechanical Engineering
Stanford University
Stanford, California
1 INTRODUCTION 132 3.7 Interpreting Temperature from
Resistance: Common Practice 158
2 THERMOCOUPLES 132
2.1 Types and Ranges 132 4 THERMISTORS 161
2.2 Peripheral Equipment 133 4.1 Types and Ranges 161
2.3 Thermoelectric Theory 135 4.2 Physical Characteristics of
2.4 Graphical Analysis of Circuits 137 Typical Probes 161
2.5 Zone-Box Circuits 138 4.3 Electrical Characteristics of
2.6 Laws of Thermoelectricity 139 Typical Probes 163
2.7 Switches, Connectors, Zone 4.4 Thermal Characteristics of
Boxes, and Reference Baths 142 Typical Probes 163
2.8 Obtaining High Accuracy with 4.5 Measuring Circuits and
Thermocouples 144 Peripheral Equipment 165
2.9 Service-Induced Inhomogeneity 4.6 Determining Temperature from
Errors 144 Resistance 166
2.10 Thermoelectric Materials
Connected in Parallel 147 5 OPTICAL METHODS 167
2.11 Spurious emf due to
Corrosion and Strain 148 6 ELECTRON NOISE
2.12 Self-Validating Thermocouples 149 THERMOMETERS 171
2.13 Thermocouple Probe Designs
for Gas Temperature 7 ACOUSTIC VELOCITY PROBES 172
Measurements 150
2.14 Thermocouple Installations for 8 TEMPERATURE-SENSITIVE
Surface Temperature COATINGS 173
Measurement 151
9 FLOW RATE 174
3 RESISTANCE TEMPERATURE 9.1 Nomenclature 174
DETECTORS 152 9.2 Basic Principles Used in Flow
3.1 Types and Ranges 152 Measurement 175
3.2 Physical Characteristics of 9.3 Orifice, Nozzle, and Venturi
Typical Probes 152 Meters 176
3.3 Electrical Characteristics of 9.4 Variable-Area Meters 177
Typical Probes 153 9.5 Laminar Flowmeters 179
3.4 Thermal Characteristics of 9.6 Instability Meters 180
Typical Probes 153 9.7 Ultrasonic Flowmeters 181
3.5 Measuring Circuits 155
3.6 The Standard Relationships for REFERENCES 185
Temperature versus Resistance 157

Reprinted from Instrumentation and Control, Wiley, New York, 1990, by permission of the publisher.

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