8 viii CONTENTS 7 Reliability, Choice and Economics of Measurement Systems Reliability of measurement systems Choice of measurement systems Total lifetime operating cost 141 Part B Typical Measurement System Elements Sensing Elements Resistive sensing elements Capacitive sensing elements Inductive sensing elements Electromagnetic sensing elements Thermoelectric sensing elements Elastic sensing elements Piezoelectric sensing elements Piezoresistive sensing elements Electrochemical sensing elements Hall effect sensors Signal Conditioning Elements Deflection bridges Amplifiers A.C. carrier systems Current transmitters Oscillators and resonators Signal Processing Elements and Software Analogue-to-digital (A/D) conversion Computer and microcontroller systems Microcontroller and computer software Signal processing calculations Data Presentation Elements Review and choice of data presentation elements Pointer scale indicators Digital display principles Light-emitting diode (LED) displays Cathode ray tube (CRT) displays Liquid crystal displays (LCDs) Electroluminescence (EL) displays Chart recorders Paperless recorders Laser printers 307
9 CONTENTS ix Part C Specialised Measurement Systems Flow Measurement Systems Essential principles of fluid mechanics Measurement of velocity at a point in a fluid Measurement of volume flow rate Measurement of mass flow rate Measurement of flow rate in difficult situations Intrinsically Safe Measurement Systems Pneumatic measurement systems Intrinsically safe electronic systems Heat Transfer Effects in Measurement Systems Introduction Dynamic characteristics of thermal sensors Constant-temperature anemometer system for fluid velocity measurements Katharometer systems for gas thermal conductivity and composition measurement Optical Measurement Systems Introduction: types of system Sources Transmission medium Geometry of coupling of detector to source Detectors and signal conditioning elements Measurement systems Ultrasonic Measurement Systems Basic ultrasonic transmission link Piezoelectric ultrasonic transmitters and receivers Principles of ultrasonic transmission Examples of ultrasonic measurement systems Gas Chromatography Principles and basic theory Typical gas chromatograph Signal processing and operations sequencing Data Acquisition and Communication Systems Time division multiplexing Typical data acquisition system Parallel digital signals Serial digital signals Error detection and correction Frequency shift keying Communication systems for measurement 493
principles of measurement systems bentley pdf free download
11 Preface to the fourth edition Measurement is an essential activity in every branch of technology and science. We need to know the speed of a car, the temperature of our working environment, the flow rate of liquid in a pipe, the amount of oxygen dissolved in river water. It is important, therefore, that the study of measurement forms part of engineering and science courses in further and higher education. The aim of this book is to provide the fundamental principles of measurement which underlie these studies. The book treats measurement as a coherent and integrated subject by presenting it as the study of measurement systems. A measurement system is an information system which presents an observer with a numerical value corresponding to the variable being measured. A given system may contain four types of element: sensing, signal conditioning, signal processing and data presentation elements. The book is divided into three parts. Part A (Chapters 1 to 7) examines general systems principles. This part begins by discussing the static and dynamic characteristics that individual elements may possess and how they are used to calculate the overall system measurement error, under both steady and unsteady conditions. In later chapters, the principles of loading and two-port networks, the effects of interference and noise on system performance, reliability, maintainability and choice using economic criteria are explained. Part B (Chapters 8 to 11) examines the principles, characteristics and applications of typical sensing, signal conditioning, signal processing and data presentation elements in wide current use. Part C (Chapters 1 to 19) examines a number of specialised measurement systems which have important industrial applications. These are flow measurement systems, intrinsically safe systems, heat transfer, optical, ultrasonic, gas chromatography, data acquisition, communication and intelligent multivariable systems. The fourth edition has been substantially extended and updated to reflect new developments in, and applications of, technology since the third edition was published in Chapter 1 has been extended to include a wider range of examples of basic measurement systems. New material on solid state sensors has been included in Chapter 8; this includes resistive gas, electrochemical and Hall effect sensors. In Chapter 9 there is now a full analysis of operational amplifier circuits which are used in measurement systems. The section on frequency to digital conversion in Chapter 10 has been expanded; there is also new material on microcontroller structure, software and applications. Chapter 11 has been extensively updated with new material on digital displays, chart and paperless recorders and laser printers. The section on vortex flowmeters in Chapter 1 has been extended and updated. Chapter 19 is a new chapter on intelligent multivariable measurement systems which concentrates on structure and modelling methods. There are around 35 additional problems in this new edition; many of these are at a basic, introductory level.
13 Acknowledgements We are grateful to the following for permission to reproduce copyright material: Figure.1(b) from Repeatability and Accuracy, Council of the Institution of Mechanical Engineers (Hayward, A.T.J., 1977); Figure.17(a) from Measurement of length in Journal Institute Measurement & Control, Vol. 1, July (Scarr, A., 1979), Table 5.1 from Systems analysis of instruments in Journal Institute Measurement & Control, Vol. 4, September (Finkelstein, L. and Watts, R.D., 1971), Table 7.3 from The application of reliability engineering to high integrity plant control systems in Measurement and Control, Vol. 18, June (Hellyer, F.G., 1985), and Figures 8.4(a) and (b) from Institute of Measurement and Control; Tables.3 and.4 from Units of Measurement poster, 8th edition, 1996, and Figures 15.(a) and (b) from Wavelength encoded optical fibre sensors in N.P.L. News, No. 363 (Hutley, M.C., 1985), National Physical Laboratory; Figure 7.1 from The Institution of Chemical Engineers; Table 7.1 from Instrument reliability in Instrument Science and Technology: Volume 1 (Wright, R.I., 1984), and Figure from Medical and industrial applications of high resolution ultrasound in Journal of Physics E: Scientific Instruments, Vol. 18 (Payne, P.A., 1985), Institute of Physics Publishing Ltd.; Table 7. from The reliability of instrumentation in Chemistry and Industry, 6 March 1976, Professor F. Lees, Loughborough University; Table 8. from BS 4937: 1974 International Thermocouple Reference Tables, and Table 1.1 and Figure 1.7 from BS 104: 1981 Methods of measurement of fluid flow in closed conduits, British Standards Institution; Figure 8.(a) from Instrument Transducers: An Introduction to their Performance and Design, nd edition, Oxford University Press (Neubert, H.K.P., 1975); Figure 8.3(a) from Technical Information on Two-point NTC Thermistors, 1974, Mullard Ltd.; Table 8.4 from Technical Data on Ion Selective Electrodes, 1984, E.D.T. Research; Figures 8.4(b) and (c) from Thick film polymer sensors for physical variables in Measurement and Control, Vol. 33, No. 4, May, Institute of Measurement and Control and Professor N. White, University of Southampton (Papakostas, T.V. and White, N., 000); Figures 8.8(a), (b) and (c) from Thick film chemical sensor array allows flexibility in specificity in MTEC 1999, Sensor and Transducer Conference, NEC Birmingham, Trident Exhibitions and Dr. A Cranny, University of Southampton (Jeffrey, P.D. et al., 1999); Figure 8.10 from Ceramics put pressure on conventional transducers in Process Industry Journal, June, Endress and Hauser Ltd. (Stokes, D., 1991); Figure 8.3(b) from Piezoelectric devices: a step nearer problem-free vibration measurement in Transducer Technology, Vol. 4, No. 1 (Purdy, D., 1981), and Figure 8.4 from IC sensors boost potential of measurement systems in Transducer Technology, Vol. 8, No. 4 (Noble, M., 1985), Transducer Technology; Figure 8.5(b) from Analysis with Ion Selective Electrodes, John Wiley
Measurement is an essential activity in every branch oftechnology and science. Weneed to know the speed of a car, thetemperature of our working environment, theow rate of liquid in apipe, the amount of oxygen dissolved in river water. It isimport-ant, therefore, that the study of measurement forms part ofengineering and sciencecourses in further and higher education. Theaim of this book is to provide the funda-mental principles ofmeasurement which underlie these studies.
The book is divided into three parts. Part A (Chapters 1 to 7)examines generalsystems principles. This part begins by discussingthe static and dynamic charac-teristics that individual elementsmay possess and how they are used to calculate theoverall systemmeasurement error, under both steady and unsteady conditions. Inlaterchapters, the principles of loading and two-port networks, theeffects of interferenceand noise on system performance,reliability, maintainability and choice using economic criteria areexplained. Part B (Chapters 8 to 11) examines theprinciples,characteristics and applications of typical sensing,signal conditioning, signal process-ing and data presentationelements in wide current use. Part C (Chapters 12 to 19)examines anumber of specialised measurement systems which haveimportantindustrial applications. These are ow measurement systems,intrinsically safe systems, heat transfer, optical, ultrasonic, gaschromatography, data acquisition,communication and intelligentmultivariable systems. 2ff7e9595c
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