Valve Automation, Redundancy and Failsafe Controls

Why Fail Safe?

Since any system or component can suffer a failure that makes it less than 100% operational, where these failures can cause a fault condition that can affect plant or operator safety require strategies to be employed to limit the effect of the failures.

Risk assessments highlight areas which can cause potentially dangerous conditions and corrective measures can be taken to ensure that critical components have additional automation features that cause them to fail to a safe condition or implement inherent redundancy.

In Valve Automation?

Control valves can be critical to safe plant operation and ensuring the risk mitigation for the pneumatic control circuitry to operate the valve actuator requires in depth consideration of independent and consecutive failure modes. This can mean multiple levels of support valves or instruments to ensure that no single or combination of failures can occur that will impact the plant.

In practice this means that the failsafe condition of the valve must be maintained in the event of a failure of the air supply or any component(s) in the control circuit. The valve may need to be closed, opened or remain in position in the event of a failure. Combining components to achieve this can be complicated in order to ensure automatic operation for all failure modes and choice of these components can be critical to the effectiveness of the strategy.

See also Functional Safety, IEC & SIL

Products For Redundancy and Failsafe Operations