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Valves - Normally Closed (NC)

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The term Normally Closed (NC) applies to manual valves or dampers which the operator must leave closed in normal operation.

A control valve that should go to a closed position on a control signal failure should be labeled FC, i.e. Fail-Closed. The control signal may be pneumatic, hydraulic or electric.

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Related Topics

Control Valves

Control Valve terminology, bodies, trim, flow characteristics, Cv and Kv sizing, noise, actuators and positioners

Related Documents

Valves - Fail-Closed (FC)

A control valve that goes to closed position if control signal or air fails.

Valves - Fail-Last (FL)

A control valve that should stay put if control signal or air fails.

Valves - Fail-Open (FO)

A control valve that goes to open position if control signal or air fails.

Valves - Normally Open (NO)

Valves and the term Normally Open.

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