I did my homework, purchased certified devices, and specified physical redundancy. I expected an uneventful SIL Verification but the assessor is telling me that I have functions failing Architectural Constraints in the sensor and final element groups. How can that be?
Low demand mode Safety Instrumented Function (SIF)…
This is an intriguing question. One that I often ask my classes when I’m teaching our FSE100 Functional Safety course. Very often, they do not know or do not fully understand what this means and why it is important.
The IEC61511 standard requires that any failures that occur within the…
I’ve been following some discussions from one of the online forums regarding competency and it’s clear from the correspondence that the issue of competency is still very subjective. It made me think about “what is competency?” To me it’s a blend of knowledge and experience and just how well…
The new release of IEC61511:2016 has caused some confusion when it comes to the Functional Safety Assessments (FSAs). Which ones are mandatory?
The confusion comes from the wording in the standard and the clarifications in the notes. The relevant clause in the standard 5.2.6.1.4 states:
A FSA team…
Site audits have shown many differences in how things are done from site to site. This impacts many variables in a safety instrumented system!
A key metric for process industry designs is called average Probability of Failure on Demand (PFDavg). After several studies of many field failure and proof…
It’s interesting to note that with the release of the 2016 edition of IEC61511, there’s more emphasis being placed on the need for better functional safety management. Having taught many courses on Functional Safety over the past few years, I find that most of the…
This is a topic which comes up time and again, especially when reviewing legacy systems. Although IEC61511 doesn’t preclude the use of shared devices, it does however provide guidance under Clause 11 of what the constraints are. Even though the Safety Instrumented System (SIS) and Basic Process Control System (BPCS)…
-Han Solo, Star Wars, Episode V: The Empire Strikes Back, 1980
I have enjoyed watching and reading about the actions of the fictional Star Wars character Han Solo over the years. I recall hearing the above quotation more than once. And as much as I enjoyed watching this character,…
