A SAFETY FUNCTION, within the scope of Industrial Plants Safety, is the description of the actions taken by the Safety System for each hazardous event. Such actions are to be implemented by any combination of hardware, software or external elements, including SIF and SIS.
SAFETY INSTRUMENTED FUNCTION (SIF) is a control equipment intended to reduce the risk due to a specific hazard, to a tolerable level. Is composed of hardware elements such as sensors, logic solvers and actuating instruments, with an assigned SAFETY INTEGRITY LEVEL (SIL).
SAFETY INSTRUMENTED SYSTEM One or more SIF acting as a protection layer between the hazards of process and the public. It is meant to prevent, control or mitigate hazardous events and take the process to a safe state, when defined conditions are violated.
References:
- IEC 61508 Functional Safety of Electrical/Electronic/Programmable Electronic Safety-Related Systems
- IEC 61511 Functional Safety - Safety Instrumented Systems for the process industry sector