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Blog Entry: A 100% Pass Rate!
I recently read a blog comment from an instructor in a well-known functional safety personnel certification program. The instructor bragged that for the last X courses, 100% of the students passed. In this program a course and an exam are developed by independent consultants who give the course, give the…
Blog Entry: Changing the PVST Interval. Hey, my Architectural Constraints changed!
Did you see my Changing the PVST Interval. Hey, my failure rates changed! post? There is more… In addition to impacting the way the Partial Valve Stroke Test (PVST) is addressed in the SIL verification calculation, the PVST frequency can also have a significant impact on the minimum Hardware Fault…
Blog Entry: Changing the PVST Interval. Hey, my failure rates changed!
I’ve been receiving several inquiries lately regarding the impact of the Partial Valve Stroke Test (PVST) interval on the failure rates of a final element. Specifically asking how does exSILentia® deal with this? exSILentia® allows users to specify if partial stroke testing is performed on their final element configuration. In…
Blog Entry: That is impossible! It has never happened before…
A week ago Sunday I was traveling to Baton Rouge, LA. I was flying out of Newark Liberty International Airport (EWR) connecting in Houston (George Bush Intercontinental Airport - IAH) with my final destination as Baton Rouge Metropolitan Airport (BTR). Under normal circumstances I would probably have flown directly to…
Blog Entry: Define the Safety Function for a Better Certification
When a product is getting certified for functional safety, it is essential to have a clear understanding of the safety function. First, let’s be clear what is meant by the safety function. IEC 61508-4 describes a safety function as a “function to be implemented by a safety-related system or other…
Blog Entry: So What’s an Impact Analysis?
It doesn’t take much to remember a time you wish you had “looked before you leaped.” The time you bought furniture that would not fit through the doorway, or the small tree you planted whose roots are now cracking through the sidewalk. Don’t you wish you had given more thought…
Blog Entry: 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 database…
Blog Entry: The Real PFDavg Variables
I was recently asked how the PFDavg value in an exida FMEDA report was calculated. Those PFDavg values are calculated using the exSILentiaTM program. The person who posed the question was using the equations from Part 6 of IEC 61508 and got a different value. Why? exSILentia does a detailed…
Blog Entry: Why Personnel Functional Safety Certification Programs are Needed
The publication of the international functional safety standards IEC 61508 (1999), IEC 61511 / ISA-84 (2004) and IEC 62061 (2005) were significant milestones in the effort to increase equipment and process safety. 1,2,3 Unfortunately, the release of safety standards does not by itself make the world a safer place. Analysis…
Blog Entry: It’s Just a Little Change…
Once there was a laundry room with old, worn-out linoleum floor. It was functional but did not have the look and feel of newer homes. The lady of the house decided to replace the flooring with new ceramic tile. She engaged her husband with the idea, outlining the benefits of…
Blog Entry: Stiction: Fact or Fiction & Start Time Prediction
Click here to read the blog “What is Stiction?” How Does Stiction Affect Me? Stiction is a phenomenon that is beginning to become an accepted theory among engineers. It is no longer a question of is this happening, but how does it happen and when does it start to affect…
News Item: EXIDA CERTIFIES HERO ENGINEERING FUNCTIONAL SAFETY MANAGEMENT SERVICES TO AS/IEC 61508
exida, an accredited global functional safety certification company, has certified the Hero Engineering Functional Safety Management Engineering Services as Safety Integrity Level (SIL) 3 capable per IEC 61508. “This certification was confirmed through an extensive assessment process including a site audit of both Hero’s procedures and projects executed in accordance…
Blog Entry: How Does Stiction Affect Me?
Click here to read the blog “What is Stiction?” In normal operation of a solenoid valve, the O-rings in the valve create a smooth transition while the plunger or spool is in motion. Because the O-rings are in direct contact with the valve chamber walls, in order for the plunger/spool…
Blog Entry: 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 control valve motion.…
Blog Entry: How Do You Handle Interposing Relays?
Many times in the design of a safety instrumented system it is necessary to utilize an interposing relay. Typically there is not a certified relay available. Since no certified product is being used it is important to follow the requirements to justify prior use and also to design the circuit…
Blog Entry: New Working Group (WG7) Formed for Alarm Management
The ISA-18.2 committee on alarm management has launched a new working group (WG7) that is focused on developing a standard, recommended practice, or technical report on the application of alarm management to process plants utilizing multiple packaged equipment systems. The work will be based on and complement the existing ANSI/ISA-18.2…
Blog Entry: Understanding Our Customers – One Step Closer to Excellence
Customer service isn’t about slashing prices or offering great rates. Sure these types of strategies can promote new customers and generate business, but how often do the “new customers” return if the service or product didn’t meet their expectations? It’s always said that a great sales person can sell anything…
Blog Entry: 2012 - Good Progress for Cybersecurity and Functional Safety
I think it is wise for individuals to periodically review things. I like to do my professional review at the end of the year. 2012 was a good year. Product Certification Over 60 new products received functional safety or cybersecurity certification this year. Those products and more can be found…
Blog Entry: Replace Before Failure
The solenoid valve manufacturer provides an FMEDA report that lists “useful life = 12 years.” Useful life is a reliability engineering term that indicates a point in time when the failure rate of a device will begin increasing rather rapidly. Why do we care about this time interval? That means…
News Item: EXIDA CERTIFIES HONEYWELL SMARTLINE ST 800 HART PRESSURE TRANSMITTER FOR FUNCTIONAL SAFETY
exida, an accredited global functional safety certification company, has certified the Honeywell SmartLine ST 800 HART Pressure Transmitter as Safety Integrity Level (SIL) 3 capable per IEC 61508. “This certification was confirmed through an extensive assessment process including a site audit and completion of a Failure Modes, Effects, and Diagnostic…
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