A Safety Function is the action of a collection of equipment to implement automatic mitigation of a particular hazard. It is the job of the Safety Instrumented Function (SIF).
Some examples of common Safety Functions:
- Car brake stop
- ESD valve – Shutdown process
- Sprinkler system
- High pressure in a vessel opens a vent valve
- Guard sensing/speed sensing functions
- Coolent valve - Open
- Overflow sensing functions
An example of a safety function is shown below. Note: The Basic Process Control System (BPCS) is also shown in green, where the safety function is highlighted in orange.