Safe Failure Fraction (SFF) is defined as the ratio of the average rate of safe failures plus dangerous detected failures of the subsystem to the total average failure rate of the subsystem. It is defined for a single channel (no redundancy, 1oo1).
It is a measurement of the likelihood of…
Route 2H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem.
What exactly is Route 2H…
Route 1H is one of two Architectural constraints options made available in the standards IEC 61508-2 and IEC 61511. Route 1H . Both Route 1H and Route 2H are limitations that impose the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem.
Route 1H is…
We all know that an FMEDA is only as good as the assumptions made regarding typical design engineering practices and the database used for the failure rates. Here is the catch, not all products are designed and manufactured per the same rules! Many manufacturers boast that their…
The question of whether companies follow good site safety practices is an interesting one. Firstly, what do we mean by good site safety practices? I think most companies believe they follow good site safety practices but do they really? Are they really measuring and tracking this?
The basis of having good site…
New reports out now are claiming that an aging, failed elbow pipe appears to be the initial cause of a June 21 fire and subsequent explosions that injured five people at the largest oil refinery on the East Coast, federal investigators said.
The U.S. Chemical Safety and Hazard Investigation…
PFH (The Probability of Failure on Demand 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…
I got a new car. The process was a bit disturbing. It took over an hour to go through the “set-up” menu. And it was suggested that I return for a second training session after spending time studying the manual and testing different settings. I was thinking how different things…
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…
I'm sure you are aware of the preliminary findings of the Philadelphia Energy Solutions (PES) Refinery explosion. If not, have a look at the video below. It is very interesting, but sad. I think we all can learn a lot from it.