PID Controller Action : Directing Acting & Reverse Acting
Air to open/close valves and direction of control action Control valves come in two sorts: air to open; and air to close.
Air to open
Different Types of Control Valve Actuators
Fail Open (Spring-to-Open, Air-to-Close) The actuator is spring-to-open, air-to-close type. Operation is via a normally closed 3 way, 2 position
