The Greek symbol λD represents dangerous failure rates in functional safety, usually expressed in the unit of measurement of FITs, and can be determined through FMEDAs. (FITs (λ) are failures per billion hours, expressed by 10-9 hours).
λD is the number of dangerous failures per…
The Greek symbol λDD is the detectable dangerous failure rate in functional safety expressed in the unit of measurement of FITs which can be determined through FMEDAs. (FITs (λ) are failures per billion hours, expressed by 10-9 hours).
λDD is the number of…
The Greek symbol λDU is the undetectable dangerous failure rate in functional safety expressed in the unit of measurement of FITs which can be determined through FMEDAs. (FITs (λ) are failures per billion hours, expressed by 10-9 hours).
λDU is the number of dangerous undetected failures…
The Greek symbol λS represents safe or spurious failure rates in functional safety expressed in the unit of measurement of FITs which can be determined through FMEDAs. (FITs (λ) are failures per billion hours, expressed by 10-9 hours).
λS is the number of safe…
There are organizations that are small enough to follow an informal or even undocumented process and still produce a product of sufficient quality to meet market needs. When these organizations attempt to develop a safety product, they inevitably fall short of meeting the requirements of IEC 61508. A formalized…
While correcting a CFSP exam, I read a question which went something like this:
If you purchase all IEC 61508 certified equipment for a low demand safety instrumented function, then to meet the requirements of IEC 61511:
A. No other design verification is needed
B.…
exida has discovered yet another forged functional safety certificate. You can read about another occurrence in a previous blog entry.
The company name on the forged certificate is ISP SA DE CV, Cunduacan, Tab., Mex. How could someone…
Functional Safety Assessments (FSA) focus on the relevant functional safety standards that are to be applied to a product in the appropriate industry. These are standards such as IEC 61511 in the process automation industry, or ISO 26262 in the automotive industry. And IEC 61508 is like an umbrella…
I got a copy of the IEC 61508 certificate for a solenoid valve today from an engineer who thought something was wrong. Although the certificate was from a well known certification company, the certificate gave a “Dangerous Failure Rate” of 1.7 FITS (1.7 * 10-9 failures per…
As an engineer responsible for critical industrial processes, we face a variety of challenges:
This makes…
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…
With the appearance of malware and nation state attacks on Industrial Control Systems (ICS), such as the Stuxnet (2010), Industroyer (2016) and TRITON (2017) attacks, the IEC 62433 standards are gaining wider attention.
While the potential targets to attack in an ICS system are many-fold, one plant asset that…
I am told that plagiarism is a compliment. Since exida is the leading company for IEC 61508 certifications I suppose it was bound to happen. Well it did. exida got an email from our sales representative in China. He asked why this certificate was not listed on the…
Thinking about developing a safety product? Use these 3 steps as a starting point:
Do you have documented development processes that govern how you develop a product from start to finish? If not, start by writing down what is actually being done. Interview the people…
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…
When I was a kid, I liked watching the Jetsons. I felt certain that by the year 2000 we’d all be enjoying those flying saucers and futuristic homes. Imagine my disappointment that in 2018 we still drive on 4 wheels… and my home cannot elevate itself above bad weather……
Ehh… If your safety action is stopping flow/closing a valve, how are you going to accomplish this if you consider that the remote actuated valve is not part of your SIF ?
So, what is this myth based on? The title of IEC 61508 reads “Functional safety of electrical/electronic/programmable…
Though this is largely true, I want to discourage people from completely ignoring the good things that IEC 61508 does for the end user.
IEC 61511 is the process industry functional safety standard derived from IEC 61508. In the very first section of IEC 61511 (“Scope”), the standard describes…
Who cares about field failure data? Why are we even here?
The fundamental concepts from our functional safety standards are the probabilistic performance based design. Many of you know that this was terribly controversial when this was first proposed. Even to this day, there…
