What is the purpose of SIL verification and what activities does it include?

• A. To confirm the SIS meets the required SIL; includes functional testing, proof tests, diagnostics, and reliability calculations.
• B. To document project budgets and resource needs.
• C. To select sensor types.
• D. To train operators.

Answer: (B)

SIL verification aims to confirm that the Safety Instrumented System will meet the required SIL and actually deliver the safety performance planned. It involves activities that validate and quantify how the system will behave in real operation: functional testing shows the SIS responds correctly to credible inputs and conditions; proof testing provides evidence that components and the overall system will perform their safety functions reliably over time; diagnostics monitor the system to detect faults and alert for corrective action; and reliability calculations estimate the probability of failure on demand to verify the SIL claim. These steps ensure the system design, installation, and operation align with the target safety performance. Budgets, sensor selection, and operator training are important parts of project planning and operation, but they are not the purpose of SIL verification.