A comparison of techniques for computing PFD average
Julia V. Bukowski · 2005
This paper compares two techniques for computing PFDavg-the use of Markov models and simplified equations-and applies each to 10 different system configurations. Results show that Markov models, when properly constructed and interpreted, give exactly the same results as those obtained from classical probability techniques. Claims that Markov model results are incorrect as reported in work by others are unfounded. In fact, they provide exact solutions not only for simple models but also for more realistic, complex models that are not covered by the simplified equations. However, Markov models require greater understanding for correct use. Simplified equations are much easier to use for rough estimates but the simplifications required to keep them easy to use may result in significant errors. These errors in the estimates can be quite large for undetected failures.