Page 3 - Instrumentation and Measurement
P. 3
Contents
1. INTRODUCTION 6
1.1 Historical……………………………………………………………………………….6
1.2 Economy……………………………………………………………………………….6
1.3 Safety…………………………………………………………………………………..7
1.4 Terminology……………………………………………………………………………8
1.5 Control Loops…………………………………………………………………………..9
1.6 System…………………………………………………………………………………10
1.7 Analogue………………………………………………………………………………10
1.8 Digital………………………………………………………………………………….11
1.9 Computers……………………………………………………………………………...11
1.10 Microprocessors and Microcomputers…………………………………………………11
2. MEASUREMENT OF PROCESS VALUE 8
2.1 Introduction…………………………………………………………………………….12
2.2 Pressure Measurement………………………………………………………………….12
2.2.1 Manometers…………………………………………………………………….13
2.2.2 Diaphragms, capsules, and bellows…………………………………………….14
2.2.3 Bourdon Tube…………………………………………………………………..16
2.2.4 Piezoelectric Sensor…………………………………………………………….17
2.3 Temperature Measurement……………………………………………………………..18
2.3.1 Mechanical Thermometry………………………………………………………18
2.3.1.1 Liquid in Glass Thermometers………………………………………..18
2.3.1.2 Filled-System Thermometers …………………………………………18
2.3.1.3 Bimetallic Thermometers……………………………………………..19
2.3.2 Electrical Thermometry…………………………………………………………20
2.3.2.1 Resistance Temperature Detectors (RTDs)…………………………...20
2.3.2.2 Thermistors (Thermally sensitive resistor)……………………………21
2.3.2.3 Thermocouples………………………………………………………..22
2.3.3 Radiation Pyrometers……………………………………………………………23
2.4 Level Measurement……………………………………………………………………...25
2.4.1 Floats…………………………………………………………………………….25
2.4.2 Displacer Gauge ………………………………………………………………...26
2.4.3 Electrical Conductivity Level Indicator…………………………………………26
2.4.4 Capacitive Level Indicator………………………………………………………27
2.4.5 Ultrasonic Level Gauge………………………………………………………….28
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