What Does Safety Integrity Level (SIL) Mean?
A safety integrity level is a measurement of safety system performance. It is related to the probability of failure on demand. There are four safety levels, rated as SIL 1-4, with SIL-4 being the highest. The higher the safety integrity level, the higher the associated safety level and the lower the risk of a safety failure. The assignment of an SIL rating is determined on the basis of risk analysis.
Safeopedia Explains Safety Integrity Level (SIL)
The safety integrity level is assigned according to the risk associated with a specific hazard. It is worked out on the basis of risk matrices, risk graphs and layers of protection analysis. Layers of protection analysis is the method most frequently used by large organizations. SIL ratings allow managers to convey the safety level of a system without having to understand the technicalities of that system. A device or system must meet the requirements for both hardware safety integrity and software safety integrity to meet SIL requirements.