www.SILSafeData.com is a complimentary resource that contains the upper and lower bounds failure rates for many categories of automation equipment, as well as the methodology used by exida to derive the numbers.
Many of you have asked how to…
www.SILSafeData.com is a complimentary resource that contains the upper and lower bounds failure rates for many categories of automation equipment, as well as the methodology used by exida to derive the numbers.
Many of you have asked how to…
I heard about a “safety certified” PLC in the late 1980s at an ISA SP84 standard committee meeting. The “logic solver” (as they later called it) was the focus of attention in the field of functional safety back then. Many engineers even said, “My system is safe because I…
There’s a lot that exida does behind the scenes to advance the industry and benefit you. We try to make sense of data that we collect and put it to good use. One thing we found is that human activities play a role in functional safety, often causing the intended safety performance…
In this blog series, I will cover the emerging trends in the valve assembly market, how these trends relate to the IEC 61511 requirements, and what's in a final element. When you look at the different devices that go into some of these safety systems, the final element becomes…
Some organizations complain about the ‘high bar’ to comply with 61508. They complain that there is too much overhead in documentation and testing, and it all costs too much. Other organizations actually benefit from this ‘high bar’ as a barrier to entry for competitors. This is a differentiation factor…
I get an email that includes a “certificate” of some sort most every week. The sender asks “Can I accept this certificate?” Or the sender might ask “Are these failure rates valid for the process industries?”
At exida we have some specific criteria we use when performing third party…
There have been passionate debates in email and meetings about “Proven In Use” versus IEC 61508 certification. Most debates characterize these evaluation techniques as competing methods. In 2000 when IEC 61511 was being written there were few IEC 61508 certified products on the market. The…
There was a joke I heard many years ago that went like this…
3 workers were hired to run telephone lines. The first part of their job was to install the poles on which the wires would run. Each day, the foreman would ask the workers how many poles…
The IEC 61508 standard states that automatic diagnostics can only lower the dangerous undetected failure rate if those diagnostics execute 100 times faster than the expected demand rate. That requirement has always seemed excessive to many of us here at exida. As an accredited Certification Body we…
Have you even wondered, been involved, or WERE the little kid that didn’t listen to your parents, but always listened to a teacher? This is called the “Third party effect.” In business, it is well known that the power of persuasion can be the most effective by a third…
Sure, you might think I’ve got it made… sitting here on my perch telling you what you need to do to meet IEC 61508, while you sit there with all the work to do. Well, it wasn’t always that way. I was in your shoes, responsible for achieving functional…
The FMEDA technique is performed on a specific device (e.g., ball valve, pressure transmitter, temperature sensor, electronic module, etc.) specified down to the manufacturer and series/model. Based on the specifics of the design, the parts used to execute the design, the design margins, any automatic diagnostics, the…
When I start working with new customers for IEC 61508 certification projects, it’s easy to understand why they might not have a compliant development process for functional safety: they’ve never done it before! They understand their market and their products, but they need help to understand the…
I was told by an end user engineer that he considers all field devices to be simple Type A devices. In IEC 61508, Type A is defined as a device with well-defined failure modes, well known failure rates, and behavior under fault conditions that can be completely determined. Type…
In several of our technical papers over the years, we have noticed that failure rates for the manufacturer, model number are different at different sites, even when the processes were quite similar. When I have mentioned this to end users and manufacturers, often the response is “Yes, I have…