Flammable release event tree (process QRA)
A loss-of-containment release branched through detection, isolation, and ignition. The engine computes each outcome frequency — safe shutdown, jet fire, dispersion, vapour-cloud explosion — and flags the dominant one.
For the process-safety engineer
What this shows
The quantitative risk assessment (QRA) event tree a process-safety study runs after a HAZOP flags a credible leak. The initiating event — a flammable release at 0.02 per year — is challenged by three safety functions in order: gas detection, emergency isolation, and the chance of no ignition source. The IGN function reads as a success when there is no ignition (s), so its failure leg f is where the fire or explosion lives.
The value is the computed end-state frequencies. The engine propagates the release frequency through each branch's success/failure probability to size each consequence — safe shutdown, jet fire, large dispersion, vapour-cloud explosion — and accents the dominant sequence in red, the same role the single point of failure plays in a fault tree. That ranked, numeric reading is what turns a forking ladder into an analysis.