Realistic Safety Instrumented System Modeling

Most analysts doing safety instrumented system modeling use either fault trees or Markov models. Both methods provide a clear way to express the reality of multiple failure modes. Both methods, however, require careful modeling and appropriate solution techniques. Realistic levels of detad 

For a gas burner to work without failure, one of two identical fans, the burner, and the controls have to function without failure. The reliability of a fan is 0.9. The reliability of the burner is 0.98. The reliability of the control system is 0.85. The aforementioned reliabilities are for a period of five years. It can be assumed that the failure of each of the listed components is independent of any other failure. 

Calculate the reUabiUty of the furnace system over a five-year period. 

A system has a series reliability block diagram as follows  

What is the failure rate of the system in failures per year  

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