Honeywell AUTOMATIC CONTROL SI Edition

PNEUMATIC CONTROL FUNDAMENTALS
ENGINEERING MANUAL OF AUTOMATIC CONTROL
57
CONTENTS
Pneumatic Control Fundamentals
ENGINEERING MANUAL OF AUTOMATIC CONTROL
Introduction ............................................................................................................ 59
Definitions ............................................................................................................ 59
Abbreviations ............................................................................................................ 60
Symbols ............................................................................................................ 61
Basic Pneumatic Control System ............................................................................................................ 61
General................................................................................................ 61
Air Supply and Operation .................................................................... 61
Restrictor ............................................................................................. 62
Nozzle-Flapper Assembly ................................................................... 62
Pilot Bleed System .............................................................................. 62
Signal Amplifier ................................................................................... 63
Feed and Bleed System ...................................................................... 63
Sensing Elements ............................................................................... 63
Bimetal ............................................................................................ 63
Rod and Tube .................................................................................. 64
Remote Bulb ................................................................................... 64
Averaging Element .......................................................................... 64
Throttling Range Adjustment............................................................... 64
Relays and Switches ........................................................................... 64
Air Supply Equipment ............................................................................................................ 65
General................................................................................................ 65
Air Compressor ................................................................................... 65
Air Drying Techniques ......................................................................... 66
General ........................................................................................... 66
Dry Air Requirement ....................................................................... 66
Condensing Drying ......................................................................... 67
High-Pressure Drying ................................................................. 67
Refrigerant Drying ...................................................................... 67
Desiccant Drying............................................................................. 67
Pressure Reducing Valve Station ........................................................ 68
Air Filter........................................................................................... 68
Pressure Reducing Valves .............................................................. 69
Single-Pressure Reducing Valve ................................................ 69
Two-Pressure Reducing Valve .................................................... 69
Thermostats ............................................................................................................ 69
Controllers ............................................................................................................ 70
General................................................................................................ 70
Temperature Controllers ...................................................................... 71
Humidity Controllers ............................................................................ 71
Pressure Controllers............................................................................ 71