Honeywell AUTOMATIC CONTROL - Pneumatic Control Fundamentals

PNEUMATIC CONTROL FUNDAMENTALS
57
ENGINEERING MANUAL OF AUTOMATIC CONTROL
Contents
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 ........................................................................... 65
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
Pneumatic Control
Fundamentals