Tools such as Safety integrity level (SIL) and Layer of Protection Analysis (LOPA) are some of the tools to assess the probability of failure (based on failure rates of individual components) of a functional safety system in time of need. The calculated probability of failure of a safety system acts as a measurement of the level of risk reduction of that system/interlock.

The study provides the calculated reliability of the entire system based on failure of weakest component and not the individual risk reduction measures that comprise them.

The SIL study is performed by certified Functional safety professionals and experts according to an international standard described by the International Electrotechnical Commission (IEC).