Click here to read the blog “What is Stiction?”
Stiction is a phenomenon that is beginning to become an accepted theory among engineers. It…
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Entries tagged with: Loren Stewart
- by Loren Stewart, CFSE
- Thursday, February 14, 2013
- Functional Safety
Stiction: Fact or Fiction & Start Time Prediction
- by Loren Stewart, CFSE
- Thursday, May 16, 2013
- Certification
The exida Scheme
Today I was asked: “What is the exida Scheme?” If one person had this question, it is likely that others may be interested as well. Therefore, I decided to take a moment and explain the exida structure. Any Certification Body operates each product certification per a “scheme,” which references…
- by Loren Stewart, CFSE
- Thursday, November 30, 2017
- Functional Safety
The Undetected Detective; PVST
Have you ever wondered why some dangerous failures are classified as undetected and others are classified as detective? Aren’t dangerous failures all dangerous? Why do we classify them differently?
Let's say we have a plant that is running in normal operation mode and the system needs to trip. The…
- by Loren Stewart, CFSE
- Friday, March 01, 2013
- Functional Safety
Welcome to the 2H Initiative
exida has been gathering field failure data for over a decade. At this point we have a total of over 60 billion unit operating hours of field data for process industry devices. This data has been used to create a 2H database for components. exida is using this component…
- by Loren Stewart, CFSE
- Friday, September 18, 2015
- Functional Safety
What is SIL compliance?
The Safety Integrety Level (SIL) of a product is determined by three things:
- The Systematic Capability Rating
- The Architectural Constraints for the element
- The PFDavg Calculation for the product
The Systematic Capability Rating
Systematic Capability is established by having your quality management system audited per IEC 61508.…
- by Loren Stewart, CFSE
- Thursday, February 07, 2013
- Functional Safety
What is Stiction?
Many studies and organizations have defined stiction, or static friction, in different ways. A few examples of the various definitions are as follows:
- According to Entech [1], “stiction is a tendency to stick-slip due to high static friction. The phenomenon causes a limited resolution of the resulting…
- by Loren Stewart, CFSE
- Tuesday, September 01, 2015
- Certification
What is Systematic vs. Random Capability?
There seems to be a bunch of confusion surrounding systematic capability and random capability. I will try to clear up the confusion by explaining what is all considered and what the IEC standard says about both.
Systematic Capability
- Development process/quality system requirements depend on certification SIL level, higher…
- by Loren Stewart, CFSE
- Thursday, February 21, 2019
Where Do You Stand with Functional Safety?
This year, make your New Year’s resolution safety!
Take a moment this year and think about where you currently stand with functional safety. And actually, be honest with yourself. REALLY honest. Do you proof test on time, or does it sometimes get pushed out? Do you pull your devices…
