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Safety Lifecycle & Management Flashcards

7 cards from real SIL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Safety Lifecycle & Management flashcards as text

  1. In IEC 61511, who is ultimately responsible for ensuring the safety lifecycle is properly implemented for a safety instrumented system?

    Answer: The process owner / asset owner

    IEC 61511 places ultimate responsibility for implementing and maintaining the safety lifecycle on the asset owner/operator.

  2. What is the term for the maximum allowable probability of failure on demand for a SIF operating in low-demand mode at SIL 2?

    Answer: ≥10⁻³ to <10⁻²

    SIL 2 in low-demand mode requires a PFDavg between 10⁻³ (inclusive) and 10⁻² (exclusive).

  3. When a modification is made to a Safety Instrumented System during operation, which lifecycle activity MUST be triggered?

    Answer: Management of change (MOC) process

    Any modification to a SIS must go through a formal Management of Change process to assess impact on functional safety before implementation.

  4. What does 'architectural constraints' refer to in the context of IEC 61511 SIL verification?

    Answer: Hardware fault tolerance requirements based on safe failure fraction and SIL target

    Architectural constraints in IEC 61511 link Safe Failure Fraction (SFF) and Hardware Fault Tolerance (HFT) to determine the maximum achievable SIL for a given hardware configuration.

  5. Which of the following best describes 'demand mode' operation of a Safety Instrumented Function?

    Answer: The SIF is activated only when a hazardous condition is detected

    In demand mode, the SIF remains dormant and activates only when a process demand (hazardous event) occurs.

  6. What IEC 61511 concept describes the requirement that two or more protective layers addressing the same hazard must be independent of each other?

    Answer: Independence of protection layers

    Independence of protection layers ensures that a single failure cannot defeat multiple layers of protection simultaneously.

  7. During SIS decommissioning, which action is MOST critical from a functional safety lifecycle perspective?

    Answer: Ensuring hazards are still adequately controlled by remaining or replacement safeguards

    When decommissioning a SIS, the primary safety concern is verifying that the process hazard is still adequately controlled without that SIF.