A control valve which should stay put on the position on control signal failure should be labeled
- FL - Fail-Last
The control signal may be pneumatic, hydraulic or electric.
Control Valve terminology, bodies, trim, flow characteristics, Cv and Kv sizing, noise, actuators and positioners
A control valve that goes to closed position if control signal or air fails.
A control valve that goes to open position if control signal or air fails.
Valves and the term Normally Closed.
Valves and the term Normally Open.