PFDavg (the average Probability of Failure on Demand) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFDavg can be determined as an average probability or maximum probability over a time period. IEC 61508 and IEC…
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Entries tagged with: Dangerous Failure Rate
- by Loren Stewart, CFSE
- Tuesday, November 19, 2019
- Functional Safety
Back to Basics 17 - PFH (Probability of dangerous Failure per Hour)
PFH (Probability of dangerous Failure per Hour) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFH can be determined as a probability or maximum probability over a time period of an hour. IEC 61508 and
- by Chris O'Brien, CFSE
- Friday, April 13, 2012
- Certification
Too Good to be True
A.K.A You’re About to Severely Under-Design your SIF and Put your People at Risk. Twice this week alone, and much more often than I like to remember, I’ve had safety system designers blindly follow certificates that contain data that simply cannot be true. They get a certificate from…