Measurement and Instrumentation

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1 Measurement and Instrumentation Theory and Application Alan S. Morris Reza Langari ELSEVIER AMSTERDAM BOSTON HEIDELBERG LONDON NEW YORK OXFORD PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO Academic Press is an imprint of Elsevier

Contents Acknowledgement Preface xvii xix Chapter 1 Fundamentals of Measurement Systems 1 1.1 Introduction 1 1.2 Measurement Units 2 1.3 Measurement System Design 3 1.3.1 Elements of a Measurement System 4 1.

2 Contents Acknowledgement Preface xvii xix Chapter 1 Fundamentals of Measurement Systems Introduction Measurement Units Measurement System Design Elements of a Measurement System Choosing Appropriate Measuring Instruments Measurement System Applications Summary Problems 10 Chapter 2 Instrument Types and Performance Characteristics Introduction Review of Instrument Types Active and Passive Instruments Null-Type and Deflection-Type Instruments Analogue and Digital Instruments Indicating Instruments and Instruments with a Signal Output Smart and Nonsmart Instruments Static Characteristics of Instruments Accuracy and Inaccuracy (Measurement Uncertainty) Precision/Repeatability/Reproducibility Tolerance Range or Span Linearity Sensitivity of Measurement Threshold Resolution Sensitivity to Disturbance Hysteresis Effects Dead Space 26 v

vi Contents 2.4 Dynamic Characteristics of Instruments 26 2.4.1 Zero-Order Instrument 28 2.4.2 First-Order Instrument 28 2.4.3 Second-Order Instrument 31 2.5 Necessity for Calibration 33 2.

3 vi Contents 2.4 Dynamic Characteristics of Instruments Zero-Order Instrument First-Order Instrument Second-Order Instrument Necessity for Calibration Summary Problems 34 Chapter 3 Measurement Uncertainty Introduction Sources of Systematic Error System Disturbance due to Measurement Errors due to Environmental Inputs Wear in Instrument Components Connecting Leads Reduction of Systematic Errors Careful Instrument Design Calibration Method of Opposing Inputs High-Gain Feedback Signal Filtering Manual Correction of Output Reading Intelligent Instruments Quantification of Systematic Errors Quantification of Individual Systematic Error Components Calculation of Overall Systematic Error Sources and Treatment of Random Errors Statistical Analysis of Measurements Subject to Random Errors Mean and Median Values Standard Deviation and Variance Graphical Data Analysis Techniques Frequency Distributions Gaussian (Normal) Distribution Standard Gaussian Tables (z Distribution) Standard Error of the Mean Estimation of Random Error in a Single Measurement Distribution of Manufacturing Tolerances Chi-Squared (% 2 ) Distribution Goodness of Fit to a Gaussian Distribution Rogue Data Points (Data Outliers) Student t Distribution Aggregation of Measurement System Errors Combined Effect of Systematic and Random Errors Aggregation of Errors from Separate Measurement System Components Total Error When Combining Multiple Measurements 92

Contents vii 3.8 Summary 92 3.9 Problems 94 Chapter 4 Calibration of Measuring Sensors and Instruments 103 4.1 Introduction 103 4.2 Principles of Calibration 104 4.

4 Contents vii 3.8 Summary Problems 94 Chapter 4 Calibration of Measuring Sensors and Instruments Introduction Principles of Calibration Control of Calibration Environment Calibration Chain and Traceability Calibration Records Summary Problems 113 Chapter 5 Data Acquisition with LabVIEW Introduction Computer-Based Data Acquisition Acquisition of Data National Instruments LabVIEW Virtual Instruments Introduction to Graphical Programming in LabVIEW Elements of the Tools Palette Logic Operations in LabVIEW Loops in LabVIEW Case Structure in LabVIEW Data Acquisition Using LabVIEW LabVIEW Function Generation Summary Problems Appendix: Software Tools for Laboratory Data Acquisition Measurement Foundry DasyLab inet-iwplus WinWedge 133 Chapter 6 Signal Processing with LabVIEW Introduction Analogue Filters Passive Filters Active Filters Using Op-amps Implementation on a Breadboard Building the Circuit Electronic Components Op-amps in Analogue Signal Processing Digital Filters Input Averaging Filter 145

viii Contents 6.3.2 Filter with Memory 146 6.3.3 Example 146 6.3.4 Lab VIEW Implementation 148 6.3.5 Higher Order Digital Filters 150 6.4 Conclusions 151 6.5 Problems 152 6.6 Appendix 156 6.6.1 Simple Filter Solution 156 6.

5 viii Contents Filter with Memory Example Lab VIEW Implementation Higher Order Digital Filters Conclusions Problems Appendix Simple Filter Solution Matlab Solution to the Butterworth Filter Design 158 Chapter 7 Electrical Indicating and Test Instruments Introduction Digital Meters Voltage-to-Time Conversion Digital Voltmeter Potentiometrie Digital Voltmeter Dual-Slope Integration Digital Voltmeter Voltage-to-Frequency Conversion Digital Voltmeter Digital Multimeter Analogue Meters Moving Coil Meter Moving Iron Meter Clamp-on Meters Analogue Multimeter Measuring High-Frequency Signals with Analogue Meters Calculation of Meter Outputs for Nonstandard Waveforms Oscilloscopes Analogue Oscilloscope (Cathode Ray Oscilloscope) Digital Storage Oscilloscopes Digital Phosphor Oscilloscope Digital Sampling Oscilloscope Personal Computer-Based Oscilloscope Summary Problems 181 Chapter 8 Display, Recording, and Presentation of Measurement Data Introduction Display of Measurement Signals Electronic Output Displays Computer Monitor Displays Recording of Measurement Data Chart Recorders Ink-Jet and Laser Printers Other Recording Instruments Digital Data Recorders 190

Contents ix 8.4 Presentation of Data 191 8.4.1 Tabular Data Presentation 191 8.4.2 Graphical Presentation of Data 192 8.5 Summary 202 8.6 Problems 203 Chapter 9 Variable Conversion Elements 207 9.

6 Contents ix 8.4 Presentation of Data Tabular Data Presentation Graphical Presentation of Data Summary Problems 203 Chapter 9 Variable Conversion Elements Introduction Bridge Circuits Null-Type d.c. Bridge (Wheatstone Bridge) Deflection-Type d.c. Bridge Error Analysis a.c. Bridges Commercial Bridges Resistance Measurement d.c. Bridge Circuit Voltmeter-Ammeter Method Resistance-Substitution Method Use of Digital Voltmeter to Measure Resistance Ohmmeter Inductance Measurement Capacitance Measurement Current Measurement Frequency Measurement Digital Counter/Timer Phase-Locked Loop Oscilloscope Wien Bridge Phase Measurement Electronic Counter/Timer X-Y Plotter Oscilloscope Phase-Sensitive Detector Summary Problems 239 Chapter 10 Measurement Signal Transmission Introduction Electrical Transmission Transmission as Varying Voltages Current Loop Transmission Transmission Using an a.c. Carrier Pneumatic Transmission Fiber-Optic Transmission Principles of Fiber Optics 251

x Contents 10.4.2 Transmission Characteristics 254 10.4.3 Multiplexing Schemes 256 10.5 Optical Wireless Telemetry 257 10.6 Radiotelemetry (Radio Wireless Transmission) 258 10.

7 x Contents Transmission Characteristics Multiplexing Schemes Optical Wireless Telemetry Radiotelemetry (Radio Wireless Transmission) Digital Transmission Protocols Summary Problems 263 Chapter 11 Intelligent Devices Introduction Principles of Digital Computation Elements of a Computer Computer Operation Computer Input-Output Interface Practical Considerations in Adding Computers to Measurement Systems Intelligent Devices Intelligent Instruments Smart Sensors Smart Transmitters Communication with Intelligent Devices Input-Output Interface Parallel Data Bus Local Area Networks Digital Fieldbuses Summary Problems 288 Chapter 12 Measurement Reliability and Safety Systems Introduction Reliability Principles of Reliability Laws of Reliability in Complex Systems Improving Measurement System Reliability Software Reliability Safety Systems Introduction to Safety Systems Design of a Safety System Summary Problems 314 Chapter 13 Sensor Technologies Introduction Capacitive Sensors Resistive Sensors 319

Contents xi 13.4 Magnetic Sensors 319 13.5 Hall-Effect Sensors 321 13.6 Piezoelectric Transducers 322 13.7 Strain Gauges 323 13.8 Piezoresistive Sensors 324 13.9 Optical Sensors 324 13.9.1 Optical Sensors (Air Path) 325 13.

8 Contents xi 13.4 Magnetic Sensors Hall-Effect Sensors Piezoelectric Transducers Strain Gauges Piezoresistive Sensors Optical Sensors Optical Sensors (Air Path) Optical Sensors (Fiber Optic) Ultrasonic Transducers Transmission Speed Directionality of Ultrasound Waves Relationship Between Wavelength, Frequency, and Directionality of Ultrasound Waves Attenuation of Ultrasound Waves Ultrasound as a Range Sensor Effect of Noise in Ultrasonic Measurement Systems Exploiting Doppler Shift in Ultrasound Transmission Nuclear Sensors Microsensors Summary Problems 345 Chapter 14 Temperature Measurement Introduction Thermoelectric Effect Sensors (Thermocouples) Thermocouple Tables Nonzero Reference Junction Temperature Thermocouple Types Thermocouple Protection Thermocouple Manufacture Thermopile Digital Thermometer Continuous Thermocouple Varying Resistance Devices Resistance Thermometers (Resistance Temperature Devices) Thermistors Semiconductor Devices Radiation Thermometers Optical Pyrometer Radiation Pyrometers Thermography (Thermal Imaging) Thermal Expansion Methods Liquid-in-Glass Thermometers Bimetallic Thermometer Pressure Thermometers 377

xii Contents 14.8 Quartz Thermometers 377 14.9 Fiber-Optic Temperature Sensors 378 14.10 Color Indicators 379 14.11 Change of State of Materials 380 14.

9 xii Contents 14.8 Quartz Thermometers Fiber-Optic Temperature Sensors Color Indicators Change of State of Materials Intelligent Temperature-Measuring Instruments Choice between Temperature Transducers Calibration of Temperature Transducers Reference Instruments and Special Calibration Equipment Calculating Frequency of Calibration Checks Procedures for Calibration Summary Problems 392 Chapter 15 Pressure Measurement Introduction Diaphragms Capacitive Pressure Sensor Fiber-Optic Pressure Sensors Bellows Bourdon Tube Manometers U-Tube Manometer Well-Type Manometer (Cistern Manometer) Inclined Manometer (Draft Gauge) Resonant Wire Devices Electronic Pressure Gauges Special Measurement Devices for Low Pressures Thermocouple Gauge Thermistor Gauge Pirani Gauge McLeod Gauge Ionization Gauge High-Pressure Measurement (Greater than 7000 bar) Intelligent Pressure Transducers Differential Pressure-Measuring Devices Selection of Pressure Sensors Calibration of Pressure Sensors Reference Calibration Instruments Calculating Frequency of Calibration Checks Procedures for Calibration Summary Problems 422 Chapter 16 Flow Measurement Introduction Mass Flow Rate 427

Contents xiii 16.2.1 Conveyor-Based Methods 427 16.2.2 Coriolis Flowmeter 427 16.2.3 Thermal Mass Flow Measurement 429 16.2.4 Joint Measurement of Volume Flow Rate and Fluid Density 429 16.

10 Contents xiii Conveyor-Based Methods Coriolis Flowmeter Thermal Mass Flow Measurement Joint Measurement of Volume Flow Rate and Fluid Density Volume Flow Rate Differential Pressure (Obstruction-Type) Meters Variable Area Flowmeters (Rotameters) Positive Displacement Flowmeters Turbine Meters Electromagnetic Flowmeters Vortex-Shedding Flowmeters Ultrasonic Flowmeters Other Types of Flowmeters for Measuring Volume Flow Rate Open Channel Flowmeters Intelligent Flowmeters Choice between Flowmeters for Particular Applications Calibration of Flowmeters Calibration Equipment and Procedures for Mass Flow-Measuring Instruments Calibration Equipment and Procedures for Instruments Measuring Volume Flow Rate of Liquids Calibration Equipment and Procedures for Instruments Measuring Volume Flow Rate of Gases Reference Standards Summary Problems 459 Chapter 17 Level Measurement Introduction Dipsticks Float Systems Pressure-Measuring Devices (Hydrostatic Systems) Capacitive Devices Ultrasonic Level Gauge Radar (Microwave) Sensors Nucleonic (or Radiometric) Sensors Other Techniques Vibrating Level Sensor Laser Methods Intelligent Level-Measuring Instruments Choice between Different Level Sensors Calibration of Level Sensors Summary Problems 475

xiv Contents Chapter 18 Mass, Force, and Torque Measurement 477 18.1 Introduction 478 18.2 Mass (Weight) Measurement 478 18.2.1 Electronic Load Cell (Electronic Balance) 479 18.2.2 Pneumatic and Hydraulic Load Cells 481 18.

11 xiv Contents Chapter 18 Mass, Force, and Torque Measurement Introduction Mass (Weight) Measurement Electronic Load Cell (Electronic Balance) Pneumatic and Hydraulic Load Cells Intelligent Load Cells Mass Balance (Weighing) Instruments Spring Balance Force Measurement Use of Accelerometers Vibrating Wire Sensor Use of Load Cells Torque Measurement Measurement of Induced Strain Optical Torque Measurement Reaction Forces in Shaft Bearings Prony Brake Calibration of Mass, Force, and Torque Measuring Sensors Mass Calibration Force Sensor Calibration Calibration of Torque Measuring Systems Summary Problems 496 Chapter 19 Translational Motion, Vibration, and Shock Measurement Introduction Displacement Resistive Potentiometer Linear Variable Differential Transformer (LVDT) Variable Capacitance Transducers Variable Inductance Transducers Strain Gauges Piezoelectric Transducers Nozzle Flapper Other Methods of Measuring Small/Medium-Sized Displacements Measurement of Large Displacements (Range Sensors) Proximity Sensors Choosing Translational Measurement Transducers Calibration of Translational Displacement Measurement Transducers Velocity Differentiation of Displacement Measurements Integration of Output of an Accelerometer Conversion to Rotational Velocity Calibration of Velocity Measurement Systems 518

Contents xv 19.4 Acceleration 519 19.4.1 Selection of Accelerometers 521 19.4.2 Calibration of Accelerometers 521 19.5 Vibration 522 19.5.1 Nature of Vibration 522 19.5.2 Vibration Measurement 523 19.

12 Contents xv 19.4 Acceleration Selection of Accelerometers Calibration of Accelerometers Vibration Nature of Vibration Vibration Measurement Calibration of Vibration Sensors Shock Calibration of Shock Sensors Summary Problems 528 Chapter 20 Rotational Motion Transducers Introduction Rotational Displacement Circular and Helical Potentiometers Rotational Differential Transformer Incremental Shaft Encoders Coded Disc Shaft Encoders TheResolver The Synchro The Induction Potentiometer The Rotary Inductosyn Gyroscopes Choice between Rotational Displacement Transducers Calibration of Rotational Displacement Transducers Rotational Velocity Digital Tachometers Stroboscopic Methods Analogue Tachometers The Rate Gyroscope Fiber-Optic Gyroscope Differentiation of Angular Displacement Measurements Integration of Output from an Accelerometer Choice between Rotational Velocity Transducers Calibration of Rotational Velocity Transducers Rotational Acceleration Calibration of Rotational Accelerometers Summary Problems 560 Appendix 1 Imperial-Metric-Si Coversion Tables 561 Appendix 2 Thevenin's Theorem 569 Appendix 3 Thermocouple Tables 575 Index 581

Principles of Measurement Systems

Principles of Measurement Systems Fourth Edition John P. Bentley Emeritus Professor of Measurement Systems University of Teesside PEARSON Prentice Hall Harlow, England London New York Boston San Francisco