Abstract: Affected by corrosion, aging, blockage and other cumulative factors, the wet alarm valve group of the automatic sprinkler fire extinguishing system in case of fire has a probability that it cannot operate on demand. In order to scientifically evaluate the ability of the wet alarm valve bank to perform predetermined functions, the safety failure modes and dangerous failure modes of the valve bank are analyzed. Through the introduction of functional safety evaluation methods, the distribution of interval deleted failure data is simulated by JMP relevant software. Example analysis showed that the failure rate function of the wet alarm valve conforms to the Weibull distribution, and then the average probability of failure on demand (PFD_avg) is calculated, and the SIL level of the valve pack is evaluated. The research method can provide references for the functional safety evaluation of other fixed fire-fighting facilities and help to improve the safety management level of fire-fighting system.

Key words: wet system alarm valves, Weibull distribution, safety integrity level, average probability of dangerous failure on demand