Petri-net models for comprehensive hazard analysis of MOCVD processes

Reducing contamination level is of primary importance for the safety and efficiency of a MOCVD process. Off-line fault identification is one of the basic tasks that must be performed in hazard analysis to identify potential operational problems. For illustration convenience, the scope of present study is limited to the purge-gas purifier of the process. A systematic step-by-step procedure is proposed in this paper to construct Petri nets for modeling the purification system. Efficient hazard assessment studies have been performed by simulating the fault propagation behaviors on the basis of the system model. A comprehensive list of possible fault origins has been thoroughly examined to demonstrate the effectiveness of the proposed approach.