Honeywell Pneumatic Controls - Pneumatic Controls Engineering Guide

Humidistats
and
Thermostats Controllers Sensors Relays Switches Actuators Valves Accessories
Engineering
Guide
Cross
Reference
70-6925 123
Pneumatic Controls Engineering Guide
Table of Contents
Introduction.................................................................................................................................. 125
Definitions.................................................................................................................................. 125
Abbreviations.................................................................................................................................. 126
Symbols.................................................................................................................................. 126
Basic Pneumatic Control System.................................................................................................................................. 126
General ................................................................................................................... 126
Air Supply and Operation ....................................................................................... 127
Restrictor ................................................................................................................ 127
Nozzle-Flapper Assembly ...................................................................................... 127
Pilot Bleed System ................................................................................................. 127
Signal Amplifier ...................................................................................................... 128
Feed and Bleed System ......................................................................................... 128
Sensing Elements ................................................................................................... 128
Bimetal ............................................................................................................... 128
Rod And Tube .................................................................................................... 129
Remote Bulb ...................................................................................................... 129
Averaging Element ............................................................................................ 129
Throttling Range Adjustment .................................................................................. 129
Relays and Switches .............................................................................................. 130
Air Supply Equipment.................................................................................................................................. 130
General ................................................................................................................... 130
Air Compressor ...................................................................................................... 130
Air Drying Techniques ............................................................................................ 131
General .............................................................................................................. 131
Dry Air Requirement .......................................................................................... 131
Pressure Reducing Valve Station ........................................................................... 132
Air Filter ............................................................................................................. 133
Pressure Reducing Valves ................................................................................. 133
Thermostats.................................................................................................................................. 133
Controllers.................................................................................................................................. 134
General ................................................................................................................... 134
Temperature Controllers ......................................................................................... 134
Humidity Controllers ............................................................................................... 134
Pressure Controllers ............................................................................................... 135
Sensor-Controller Systems.................................................................................................................................. 135
Pneumatic Controllers ............................................................................................ 135
Proportional-Integral (PI) Controllers ................................................................. 136
Controller Adjustments ...................................................................................... 136
Pneumatic Sensors ................................................................................................ 136
Velocity Sensor-Controller ...................................................................................... 136
Actuators and Final Control Elements.................................................................................................................................. 137
Actuators ................................................................................................................ 138
General .............................................................................................................. 138
Control Valves ........................................................................................................ 138
Dampers ................................................................................................................. 140
Relays and Switches.................................................................................................................................. 140
Switching Relay ...................................................................................................... 141
Snap Acting Relay .................................................................................................. 141
Lockout Relay ......................................................................................................... 141
High-Pressure Selector Relay ................................................................................ 142
Low-Pressure Selector Relay ................................................................................. 142
Load Analyzer Relay .............................................................................................. 142
Capacity Relay ....................................................................................................... 143
Reversing Relay ..................................................................................................... 143
Positive-Positioning Relay ...................................................................................... 143