# Safety Integrity Level (SIL) #standard #safety #certification Safety Integrity Level (SIL) is a quantitative measure of the reliability of a safety instrumented function, ranging from SIL 1 (lowest) to SIL 4 (highest). ## Definition - Quantitative measure of safety performance - Probability of failure on demand (PFD) - Risk reduction factor - Defined in IEC 61508 and IEC 61511 ## SIL Levels | SIL | PFD Range | Risk Reduction Factor | |-----|-----------|---------------------| | SIL 1 | 10⁻¹ to 10⁻² | 10 to 100 | | SIL 2 | 10⁻² to 10⁻³ | 100 to 1,000 | | SIL 3 | 10⁻³ to 10⁻⁴ | 1,000 to 10,000 | | SIL 4 | 10⁻⁴ to 10⁻⁵ | 10,000 to 100,000 | ## Determination SIL is determined through: - Risk assessment - Hazard analysis - Layer of protection analysis (LOPA) - Risk matrix evaluation ## F&G System Requirements - F&G control systems should be SIL 2 certified minimum - Ensures reliability and safety - Required for worker protection - Critical for asset protection ## Certification - SIL certification guarantees system safety - Ensures compliance with standards - Required for critical safety applications ## Related Concepts - [[IEC 61508]] - [[IEC 61511]] - [[F&G Control Systems]]