Definition:
A final element is the device in a Safety Instrumented Function (SIF) that directly implements the corrective action to achieve or maintain a safe state. It is usually an automated valve but could be things like a contactor, VFD (with safety torque off – STO), or various other items.
Also called the Final Control Element (FCE).
Key Points:
- Final Element is the last device in the chain of the safety system.
- Includes valves, breakers, relays, STO, and actuators.
- Often the largest contributor to the SIF’s PFDavg.
Example:
An automated valve closing upon high pressure detection is a final element.
See Also: instrument, logic solver, SIF, STO, hazardous areas
Cited Source:
- IEC 61511-1:2016, Clause 3.2.22
- IEC 61508-4:2010, Section 3.2.68