About The Book
This Book has been designed as a textbook for the students of Electronics and Instrumentation Engineering, Instrumentation and Control Engineering, and Chemical Engineering courses offered in technical universities all over India. The Topics mainly cover the type of Instruments for the measurements and control of process Variables in various industries. Chapters 1 to 7 cover the parameters like temperature, pressure, force, torque, velocity, acceleration, vibration, density, flow, level, viscosity, humidity and moisture. Fundamentals of measuring instruments has been covered additionally in this second edition. Some special techniques used for Radiation pyrometers are added as Appendix for the benefit of many customers.
This book is an outcome of one of the authors' vast industrial experience and his Academic eminence. The experience gained by the second author as a successful academician has helped to refine the Material throughout the book.
In addition to serving as textbook for engineering students and faculty members, it will serve as a reference book for the professionals in instrumentation and control Held in various Manufacturing and process industries.
About the Author
Prof. K. Krishnaswamy, after graduating Bachelor of Engineering (Electrical) from P.S.G. College of Technology, Coimbatore, Tamil Nadu, has completed Master of Technology (Measurements) from Indian Institute of Technology-Madras, Chennai during 1971. Since then he-was working in Steel Authority of India Limited, Rourkela Steel Plant for 26 years and in Salem Steel Plant for about 4 years. He was associated with erection, commissioning, calibration, testing and maintenance of process control instrumentation and Automation system. During his tenure in Steel Authority of India Limited, he has visited Manufacturing and process Industries in the then West Germany, Japan and United Kingdom. He was also awarded with 'Jawahar Award' for being the Best Engineer for the year 1997.
He entered into active Academic life during 2000 by joining as professor and Head of the Department of Electronics and Instrumentation Engineering, Kongu Engineering College, Perundurai, Erode, Tamil Nadu. At present he is also the Vice Principal of the college. He has contributed number of technical papers in national and international conferences. He is also the convener of Board of Studies of Electronics and Instrumentation course under Anna University, Coimbatore for the last two years.
Mrs. S. Vijayachitra has graduated Bachelor of Engineering in Electronics and Communication Engineering from Mookambigai College of Engineering, Pudukottai, Tamil Nadu during 1994. After serving for about 6 years in a polytechnic college, she pursued Master of Engineering in Process Control and Instrumentation from Annamalai University, Chidambaram, Tamil Nadu and completed during 2001. Since then she is working in Kongu Engineering College, Perundurai, Erode, Tamil Nadu and has become Assistant Professor during 2006. She has pursued her Research work under Anna University, Chennai in the field of Fuzzy Logic and Neural Networks and submitted her thesis for the completion of Doctor of Philosophy during January, 2009. She has published lot of technical papers in national and international journals.
Contents
Foreword
Preface to the Second Edition
Preface to the First Edition
A. Temperature :
I. Basic Behaviour of Materials to Temperature
II. Physical Effects Utilized to Measured Temperature :
1. Expansion of Liquid or a Solid
2. Change in Pressure
3. Change in Electrical Resistance
4. Thermoelectricity
5. Radiation
6. Temperature-Indicating Paints and Crayons
7. Temperature-Indicating Pellets
8. Seger Cones
III. Temperature Scales :
1. Centigrade Scale
2. Kelvin Scale
3. Fahrenheit Scale
4. Rankine Scale
5. Comparison of Temperature Scales
IV. Temperature Measurement :
1. Mechanical Thermometers :
i. Filled-System Thermometers
ii. Metallic-Expansion Thermometers
iii. Special Temperature Indicating Devices
iv. Bulb Installations
2. Electrical Thermometers :
i. Resistance Thermometers
ii. Thermistors
iii. Thermocouples
iv. Radiation Pyrometers
v. Temperature Transducers
5. Problems and Solutions
6. Questions and Problems
B. PRESSURE :
I. Understanding of Pressure
II. Units of Pressure :
1. kg/cm2 (PSI)
2. Bar
3. Liquid Column
4. Conversion of Units
III. Measurement of Pressure :
1. Mechanical Pressure Instruments :
i. Manometers
ii. Elastic Type Pressure Gauges
2. Electrical Methods of Pressure Measurement :
i. Strain-Gauge Pressure Transducers
ii. Capacitance Pressure Transducers
iii. Potentiometric Pressure Transducers
iv. Resonant Wire Pressure Transducers
v. Piezoelectric Pressure Sensors
vi. Magnetic Pressure Transducers
vii. Optical Pressure Transducers
3. Special Pressure Measurements :
i. Piston Type Pressure Gauge
ii. Pressure-Sensitive Wire Transducer : (For Very-high Pressure)
iii. Bulk Modulus Cell Pressure Transducer
iv. Dead-Weight Piston Gauges (Dead-Weight Testers)
4. Vacuum Sensors :
i. Mechanical Vacuum Gauges
ii. Thermal Vacuum Gauges
iii. Ionization Vacuum Gauges
IV. Testing and Calibration of Pressure Detectors :
1. Dead Weight Tester
2. Manometers
V. Problems and Solutions
VI. Questions and Problems
C. FORCE, TORQUE AND VELOCITY :
I. Force, Weight, Mass and Specific Gravity
II. Force (Weight) Measurement :
1. Mechanical Balances
i. Analytical Balance
ii. Pendulum Scale
iii. Platform Scale
2. Accelerometer Type Force Measurement
3. Electromagnetic Balance
4. Mechanical Load Cells :
i. Hydraulic Load Cells
ii. Pneumatic Load Cells
5. Elastic Deflection Force Transducers :
i. Strain-Gauge-Type Load Cells
ii. Piezo Resistive (Semiconductor) Load Cells
iii. Inductive and Reluctance Load Cells
iv. Magnetostrictive Load Cells
6. Gyroscopic Force Measurement
7. Vibrating-wire Force Transducers
8. Nuclear Radiation Weight Sensor
III. Torque Measurement :
1. Rotating Torque Sensors
2. Stationary Sensors
3. Reaction Torque Sensor
4. Prony Brake Torque Measurement
5. DC Cradled Dynamometer Torque Measurement
6. Torsion-Bar Torquemeter
7. Torque Measurement Using Proximity Sensors
IV. Speed and Velocity Measurements :
1. Hand-held Tachometers
2. Capacitor-type Impulse Tachometer
3. Optical Tachometers
4. Stroboscopic Tachometers
5. A.C. Tachometer Generator
6. DC Tachometer Generator
7. Induction Type Speed Sensor
8. Magnetic-type Speed Sensor
9. Eddy-Current Drage-cup Tachometer
10. Translational-Velocity Transducers
11. Mechanical Flyball Angular-Velocity Sensor
12. Velocity Measurement as ∆x/∆t
13. Calibration of Velocity Transducers
V. Problems and Solutions :
VI. Questions and Problems
D. ACCELERATION, VIBRATION AND DENSITY :
I. Acceleration and Vibration
1. Relative-Acceleration Measurements
2. Seismic-(Absolute-) Acceleration Pickups : (Accelerometers) :
i. Seismic Instrument using a Voltage-divider Potentiometer
ii. LVDT Accelerometer
iii. Electrical-resistance Strain Gauge Accelerometer
iv. Piezoelectric Accelerometer
v. Capacitive Accelerometer
vi. Null-Balance-(Servo) Type Accelerators
vii. Angular Accelerometers
3. Variable-Reluctance Accelerometer
4. Accelerometer Using Velocity Sensors
5. Eddy Current Proximity Sensor as Vibration Pickup
6. Mechanical Vibration Sensors
7. Calibrations of Vibrations Pickups :
i. Constant Acceleration Method
ii. Sinusoidal Motion Method
iii. Transient-motion Method
II. Density :
1. Units of Density, Specific Gravity and Viscosity :
i. Density
ii. Relative Density
iii. Viscosity
2. Measurement of Density :
i. Displacement and Float-type Densitometers (For Liquid Density)
ii. Hydrometers
iii. Hydrostatic Densitometer : (Pressure Head Type)
iv. Ultrasonic and Sonic Densitometers
v. Radiation Densitometers
vi. Gas Densitometers
III. Problems and Solutions
IV. Questions and Answers
E. FLOW :
I. Introduction
II. Units of Flow
III. Measurement of Flow
IV. Mechanical Flow Meters :
1. Theory of Fixed Restriction Variable Head Type Flow Meters :
i. Flow of Incompressible Fluids in Pipes
ii. β Ratio
iii. Reynolds Number
iv. Discharge Coefficient (Cd)
v. Flow Coefficient (K)
vi. Flow of Compressible Fluids in Pipes
2. Orifice Flow Meter :
i. Principle of Operation
ii. Types of Orifice Plates
iii. Machining Methods of Orifices
iv. Materials Chosen For Orifices
v. Position of Taps in Orifices
3. Venturi Tubes :
i. Classic Venturi Construction : [Long Form Venturi]
ii. Short Form Venturi Tubes
iii. Types of Venturi Tubes
iv. Installation of Venturi Tubes
4. Flow Nozzle :
i. Flange Type Flow Nozzle
ii. Different Designs of Flow Nozzle
iii. Advantages
iv. Disadvantages
5. Dall Tube :
i. Construction and Working
ii. Advantages
iii. Disadvantages
6. Installation of Head Flow Meters :
i. Pressure Pipe Layout
ii. Installation of Condensation Pots
iii. Installation of Sealing Pots
iv. Factors to be considered in Piping Arrangement
7. Pitot Tube :
i. Principle
ii. Averaging Pitot Tube (Annubar)
iii. Advantages
iv. Disadvantages
8. Differential Pressure Transmitters
9. Quantity Meters :
i. Positive Displacement Meters
10. Inferential Flow Meters :
i. Principle
ii. Variable Area Flow Meters
iii. Target Flow Meters
11. Mass Flow Meters :
i. Angular-Momentum-Type Mass Flow Meters
ii. Constant-Torque-Hysteresis Clutch
iii. Impeller-Turbine Flow Meters
iv. Twin-Turbine Mass Flow Meter
v. Gyroscopic Mass Flow Meter
vi. Coriolis Mass Flow Meter
vii. Thermal Mass Flow Meters
viii. Volume Flow Meters Plus Density Measurement : (Radiation-Type Mass Flow Meters)
V. Electrical Flow Meters :
1. Electromagnetic Flow Meter :
i. Principle
ii. AC and DC Excitation Schemes
iii. Dual-Frequency Excitation
iv. Construction of Electromagnetic Flow Meter
v. Limitation of Electromagnetic Flow Meters
vi. Advantages of Electromagnetic Flow Meter
vii. Disadvantages of Electromagnetic Flow Meter
viii. Application of Electromagnetic Flow Meters
2. Ultrasonic Flow Meters :
i. Introduction
ii. Principle
iii. Types of Ultrasonic Flow Meters
iv. Flow Meter Construction
v. Performance
vi. Doppler Flow Meters
vii. Application and Performance
3. Laser Doppler Anemometer Systems :
i. Principle of Operation
ii. Working
iii. Applications
VI. Other Types of Flow Meters :
1. Purge Flow Regulators :
i. Introduction
ii. Rotameter Type Purge Meter
iii. Applications
2. Cross Correlation Flow Meter :
i. Introduction
ii. Working Principle
iii. Advantages
iv. Applications
3. Solids Flow Measurement :
i. Introduction
ii. Belt Type Gravimetric Feeder
iii. Belt Type Electromechanical Gravimetric Feeder
iv. Belt Type Gravimetric Feeder with Pneumatic System
4. Vortex Shedding Flow Meter :
i. Vortex Shedding Phenomenon
ii. Vortex Flow Meter Detection
iii. Features of Vortex Shedding Flow Meter
iv. Selection of Vortex Shedding Flow Meter
5. Flow Switches :
i. Design Variations
6. Anemometers :
i. Hot Wire Filament
ii. Principle
iii. Types of Hot Wire Anemometers
iv. Comparison between Constant-Current Type and Constant Temperature Type
7. Mechanical Anemometer :
i. Vane Anemometer
ii. Three-Cup Anemometer
iii. Impeller Anemometer
VII. Flow Meter Calibration :
1. Introduction :
2. Methods of Calibration of Flow Meter with Liquids :
i. Dynamic Weighing (Gravimetric) Method
ii. Pipe Prover Method
iii. Master Meters Method
3. Methods of Calibrating of Flow Meters with Gases :
i. Soap Film Burettes
ii. Bell Prover System
iii. Sonic Venturi-Nozzles
iv. Gravimetric System for Gas-Meter Calibrator
v. PVT System
VIII. Flow Meter Selection :
1. Factors to be Considered :
i. Measurement Requirements
ii. External Conditions of the Flow Pipe
iii. Conditions Internal to the Flow Pipe
iv. Properties of the Fluid
v. Accessories
vi. Economic Factors
2. List of Desirable Characteristics
3. Highest Possible Accuracy
4. Guidelines for Flow Meter Selection
Problems and Solutions
Questions and Problems
F. LEVEL :
I. Introduction
II. Level Measurement Using Gauge Glass Technique :
1. Construction and Working
2. Remote Indication
3. Ranges
4. Advantages
5. Disadvantages
III. Float Type Level Indication :
1. Float Level Switch :
i. Construction and Working
ii. Advantages
iii. Disadvantages
2. Float/Rope Method :
i. Construction and Working
ii. Advantages
iii. Disadvantages
3. Float Operated Spring Loaded Level Switch
4. Magnetic Float Device
IV. Level Measurement Using Displacer and Torque Tube :
1. Construction
2. Materials of Construction
3. Principle
4. Working
5. Advantages
6. Disadvantages
V. Air Purge System/Bubbler System :
1. Principle
2. Construction
3. Operation
4. Operating Considerations
5. Advantages
VI. Boiler Drum Level Measurement :
1. Thermal Level Sensors :
i. Low Level Conductivity Switch
ii. Thermal Level Sensor with Heater and Probes
iii. Capsule Type Thermal Level Sensor
iv. Expansion Type Thermal Level Sensor
2. Hydrostatic Pressure Method :
i. Principle
ii. Hydrostatic Pressure Measurement in Open Tank
iii. Hydrostatic Pressure Measurement in Closed Tank
iv. Practical Application
v. Applications
vi. Calibration
3. Differential Pressure Method :
i. Differential Pressure Method for Open Tanks and Closed Tanks
ii. Electronic DP Transmitters
iii. Points to be Kept in Mind
iv. Location Correction for Hydrostatic Pressure Level Measurement
v. Calibration of the Receiving Instrument
VII. Level Measurement by Electrical Methods :
1. Level Measurement Using Resistance Tapes :
i. Resistance Tapes
ii. Actuation Depth
iii. Pressure Effect
iv. Temperature and Other Effects
2. Capacitance Level Detection and Level Measurement :
i. Principle of Capacitance Level Measurement
ii. Practical Application
iii. Capacitance Level Detection
iv. Bare Capacitance Probe
v. Teflon Coated Capacitance Probes
vi. Selection of Probe Configurations
vii. Capacitance Measurement Techniques
viii. Advantages
ix. Disadvantages
3. Radiometric Level Detection and Measurement :
i. Principle
ii. Radiation-Type Instruments
iii. Practical Application
iv. The Components of a Nucleonic Level System
v. Mounting and Practical Examples
4. Level Measurement Using Ultrasonic Sensors :
i. Operating Principle
ii. Block Diagram
iii. Practical Application as a Level Switch
iv. Dampened Vibration Type Level Switches
v. Absorption-Type Level Switches
vi. Ultrasonic Level Transmitters
vii. Advantages
viii. Limitations
5. Microwave Time of Flight Method :
i. Principle
ii. Advantages
iii. Disadvantages
6. Optical Level Devices :
i. Principle
ii. Non-conducting Optical Level Sensor
iii. Optical Sludge Level Detector
iv. Light Refraction Type Level Switch
v. Level Detection Using Fiber Optics
vi. Limitations
7. Radar Level Transmitters :
i. Principle
ii. Radar Antenna Types
iii. Time-of-Flight Determination
iv. Applications
8. Laser Level Devices :
i. Principle
ii. Time-of-Reflection Measurement
iii. Installation
iv. Applications
9. Level Switches :
i. Rotating Paddle Switches
ii. Vibration Damping Method
iii. Microwave Level Switch
iv. Field Effect Level Switch
v. Conductivity Level Switch
10. Interface Measurement :
i. Principle
ii. Interface Level Switches
VIII. Problems and Solutions
IX. Questions and Problems
G. VISCOSITY, HUMIDITY AND MOISTURE :
I. Viscosity :
1. Terms (or Terminology) :
i. Absolute (or Dynamic) Viscosity (u)
ii. Consistency
iii. Other Terms Related to Absolute (Dynamic) Viscosity
iv. Some Other Important Terms
2. Measurement of Viscosity :
i. Capillary Viscometers (Laboratory Type)
ii. Efflux Cup Viscometers (Saybolt Viscometer)
iii. Capillary Viscometers (Industrial Type)
iv. Falling-Ball Viscometers
v. Float Viscometers (Rotameter Type Viscometers)
vi. Rotational Industrial Viscometers
vii. Gyrating—Element Viscometer
viii. Vibrating Reed Viscometer
ix. Oscillating Type Viscometers
x. Plastometer
3. Measurement of Consistency :
i. Probe Type Consistency Meter
ii. Blade Type Consistency Meter
iii. Float Type Consistency Meter
iv. Rotating Type Consistency Meter
v. Optical Type Consistency Meter
vi. Level Consistency Meter
vii. Flow Bridge Consistency Meter
4. Selection of Viscometers and Consistency Meters :
II. Humidity
1. Terms (or Terminology)
2. Measurement of Humidity :
i. Dry and Wet Bulb Psychrometers
ii. Hair Hygrometers
iii. Solution Resistance Elements (Dunmore Cells)
iv. Polystyrene Surface Resistively Cells (Pope Cells)
v. Thin-Film Capacitance Humidity Sensor
vi. Dew-point Hygrometers
vii. Electrolytic Hygrometers
III. Moisture :
1. Terms (or Terminology)
2. Measurement of Moisture in Gases and Liquids :
. Electrolytic Hygrometer
. Capacitance Hygrometer
. Impedance Hygrometer
. Piezoelectric Hygrometer
. Heat-of-adsorption Hygrometer
. Infrared Absorption Hygrometer
. Microwave Absorption Hygrometer
3. Measurement of Moisture in Solids
. Nuclear Moisture Gauge
. Infrared Absorption or Reflection Moisture Gauge
. Microwave Solid Moisture Analyser
. Capacitance Moisture Gauge
. Conductance (or Resistance) Moisture Gauges
. Other Moisture Gauge Types
IV. Problems and Solutions
V. Questions and Problems
H. FUNDAMENTALS OF MEASURING INSTRUMENTS :
I. Introduction
II. Units :
1. SI Mechanical Units
2. Electrical Units
3. Scientific Notation and Metric Prefixes
4. Other Unit Systems
5. Units of Process Parameters
III. Dimensions :
IV. Standards and Calibration
V. Functional Elements of Measurement System
VI. Methods of Measurement and Classification of Instruments :
1. Basic Classification of Measuring Instruments
2. Classification According to Effects Utilized
3. Classification According to Way of Presentation of Results
4. Classification Based on Mode of Operation
5. Classification Based on Energy Requirement
6. Other Classifications
VII. Performance Characteristics :
1. Static Characteristics
i. Accuracy
ii. Sensitivity
iii. Reproducibility
iv. Drift
v. Dead Time and Dead zone
vi. Other Characteristics
vii. Static Errors
2. Dynamic Characteristics
VIII. Combination of Errors :
1. Sum of Quantities (Addition)
2. Difference of Quantities (Subtraction)
3. Product of Quantities (Multiplication)
4. Quotient of Quantities (Division)
5. Quantity Raised to a Power (Indices)
IX. Statistical Analysis of Errors:
1. Normal Distribution of Errors
2. Probable Error
3. Limiting or Guarantee Error
X. Uncertainty Analysis :
XI. Chi-Square Test
XII. Method of Least Squares (Curve Fitting)
XIII. Chauvenet's Criterion
XIV. Transfer Function : Zero, First and Second Order Instruments :
1. Zero-Order Instruments
2. First-Order Instruments
3. Second-Order Instruments
XV. Experimental Determination of Measurement-System Parameters :
1. Zero-Order Instruments
2. First-Order Instruments
3. Second-Order Instruments
XVI. Loading Effect under Dynamic Conditions
XVII. Input-output Configuration of Instruments and Measurement Systems :
1. Methods of Correction of Interfering and Modifying Inputs
XVIII. Computer-aided Calibration and Measurement : Multiple Regression
XIX. Display Devices and Systems :
1. Cathode Ray Tube Display (CRT Display)
2. Light-Emitting Diodes (LED)
3. Liquid Crystal Display (LCD)
4. Gas Discharge Plasma Displays
5. Electro-luminescent (EL) Display
6. Incandescent Display
7. Electrophoretic Image Display (EPID)
8. Liquid Vapour Display (LVD)
XX. Problems and Solutions
XXI. Questions and Problems