This is not necessarily true. While a higher SIL level corresponds to a lower probability of failure on demand, a SIL 2 SUITABLE product may be perfectly acceptable for use in a SIL 3 ENVIRONMENT if, for example, the PROOF testing interval is increased or if redundancy is used. It is very important for an end-user to understand the operating requirements of the products within a given SIL environment to ensure that once installed, the products maintain their SIL suitability levels. Incorrect installation, proof testing, or configuration of the products could make the SIL suitability level inaccurate.

This is not necessarily true. While a higher SIL level corresponds to a lower probability of failure on demand, a SIL 2 suitable product may be perfectly acceptable for use in a SIL 3 environment if, for example, the proof testing interval is increased or if redundancy is used. It is very important for an end-user to understand the operating requirements of the products within a given SIL environment to ensure that once installed, the products maintain their SIL suitability levels. Incorrect installation, proof testing, or configuration of the products could make the SIL suitability level inaccurate.