🔒 Please log in to use tool features (fill sample / analyze / AI interpretation / export document)
📊 PFD Availability / MTBF
Dangerous failure rate × diagnostic coverage × test interval → PFDavg / availability / MTBF and SIL
Input parameters
Notes
· Simplified model (IEC 61508 approach): λDU = λD·(1−DC); 1oo1 → PFDavg=λDU·TI/2; 1oo2 → (λDU·TI)²/3; 2oo3 → (λDU·TI)². Availability = 1 − PFDavg; MTBF = 1/λD.
· Results are approximate estimates. For full SIL verification, perform detailed hardware failure rate and common-cause failure analysis per IEC 61508/61511.
About PFD / Availability (MTBF)
Compute availability from MTBF and MTTR, estimate the average probability of failure on demand (PFDavg) for safety instrumented functions, and check SIL.
Learn more about this tool →
SIL Safety Integrity Level
LOPA Layer of Protection Analysis
Reliability Calculator
RBI Risk-Based Inspection
Weibull Analysis
← Back to all quality tools