What does the term "fail open" mean in relation to valve actuators?

The term "fail open" in relation to valve actuators refers to the condition where, in the event of a power loss or failure, the actuator ensures that the valve opens. This design feature is critical in specific applications where maintaining an open state is essential for safety, such as in processes requiring the continuous flow of fluids or gases.

When an actuator is designated as "fail open," it has been engineered to move to the open position when it no longer receives electrical power or commands. This ensures that, in cases where power is interrupted, the system will default to a position that minimizes the risk of hazards, such as pressure build-up, which could lead to unsafe conditions.

Understanding this concept is important for instrument technicians, as it affects both the configuration of control systems and the safety considerations of the installations they work on.