Design essentials to achieve a specified SIL

□ The safety function is a cornerstone of functional safety ̃get it wrong and you may have no protection □ The SIL of a safety function is a cornerstone of functional safetỹif it is too low you increase the risk □ The SIL concept was developed as a parameter to determine the rigour of the measures to be applied to combat systematic failure causes □ The SIL is the key parameter for the Architectural Constraints (HFT) and the Systematic Safety Integrity measures (H/W & S/W) □ The mode of operation a key aspect of SIL determination