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Safety Analysis

1 tool in the Reliability area.

Hazard and Safety Analysis

Three system-safety calculations under one select. A hazard log assessed by MIL-STD-882E: each hazard's severity category (1 to 4) and probability level (A to F, or a quantitative probability placed in the standard's Table A-II bands) give its risk assessment code and the High / Serious / Medium / Low risk level of Table III before and after mitigation, with the counts, the risk acceptance authority of DoDI 5000.88 and a drawing of the matrix with the hazards placed in it. A layer of protection analysis: the initiating-event frequency multiplied by the probabilities of failure on demand of the independent protection layers and by the conditional modifiers and enabling conditions, compared with a target frequency; the risk reduction still required and the PFD and safety integrity level of a safety instrumented function that would close the gap. A SIL verification of a safety instrumented function made of sensor, logic-solver and final-element subsystems in 1oo1, 1oo2, 2oo2, 2oo3, 1oo3 or 1oo2D architecture: the average probability of failure on demand of each subsystem by the IEC 61508-6 simplified equations with β-factor common cause, an exact periodic Markov model beside them with PFD(t) over the proof-test interval, the safe failure fraction and hardware fault tolerance rule, and the SIL achieved. The default case is an illustrative six-hazard log, a LOPA with an initiating frequency of 0.1 per year, two protection layers of PFD 0.1, an ignition probability of 0.5 and a target of 10⁻⁵ per year (required PFD 0.02, SIL 1), and a function with 1oo2 pressure transmitters, a 1oo1 logic solver and a 1oo1 valve proof-tested yearly (PFD 8.8 × 10⁻³, SIL 2).

1 worked example reproduced, listed on the tool page.

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