PNEUMATIC CONTROL FUNDAMENTALS
ENGINEERING MANUAL OF AUTOMATIC CONTROL
58
Controllers ............................................................................................................ 70
General................................................................................................ 70
Temperature Controllers ...................................................................... 71
Humidity Controllers ............................................................................ 71
Pressure Controllers............................................................................ 71
Sensor-Controller Systems ................................................................. 72
Pneumatic Controllers ......................................................................... 72
Proportional-Integral (PI) Controllers .............................................. 72
Controller Adjustments .................................................................... 72
Pneumatic Sensors ............................................................................. 73
Velocity Sensor-Controller ................................................................... 73
Actuators and Final Control Elements ............................................................................................................ 74
Actuators ............................................................................................. 74
General ........................................................................................... 74
Spring Ranges ................................................................................ 74
Control Valves ..................................................................................... 75
Dampers .............................................................................................. 76
Relays and Switches ............................................................................................................ 77
Switching Relay ................................................................................... 77
Snap Acting Relay ............................................................................... 78
Lockout Relay...................................................................................... 78
High-Pressure Selector Relay ............................................................. 79
Low-Pressure Selector Relay .............................................................. 79
Load Analyzer Relay ........................................................................... 79
Capacity Relay .................................................................................... 80
Reversing Relay .................................................................................. 80
Averaging Relay .................................................................................. 80
Positive-Positioning Relay ................................................................... 80
Ratio Relay .......................................................................................... 81
Pneumatic Potentiometer .................................................................... 81
Hesitation Relay .................................................................................. 82
Electrical Interlocking Relays .............................................................. 82
Electric-Pneumatic Relay ................................................................ 82
Pneumatic-Electric Relay ................................................................ 82
Electronic-Pneumatic Transducer ....................................................... 83
Pneumatic Switch ................................................................................ 83
Manual Positioning Switch .................................................................. 84
Pneumatic Control Combinations ............................................................................................................ 84
General................................................................................................ 84
Sequence Control................................................................................ 85
Limit Control ........................................................................................ 85
Manual Switch Control ........................................................................ 86
Changeover Control for Two-Pressure Supply System ....................... 87
Compensated Control System ............................................................ 87
Electric-Pneumatic Relay Control........................................................ 87
Pneumatic-Electric Relay Control........................................................ 88
Pneumatic Recycling Control .............................................................. 88
Pneumatic Centralization ............................................................................................................ 89
Pneumatic Control System Example ............................................................................................................ 90
Start-Stop Control Sequence .............................................................. 90
Supply Fan Control Sequence ............................................................ 92
Return Fan Control Sequence............................................................. 92
Warm-up/Heating Coil Control Sequence ........................................... 92
Mixing Damper Control Sequence ...................................................... 93
Discharge Air Temperature Control Sequence .................................... 94
Off/Failure Mode Control Sequence .................................................... 94
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