While discussing functional safety certification of an integrated valve assembly with a manufacturer, exida stated that all devices (actuator, pneumatic parts, valve, etc.) must be IEC 61508 certified. The manufacturer said this was no problem, and provided a set of exida and TÜV certificates.
Of…
I recently studied the design changes made on the T series of old British cars (a hobby) made by the MG Company in England from 1936-1955. Models progressed over that time period including the TA, TB, TC, TD, and TF. I noted a strange looking two position switch on the dash…
An owner-operator engineer compared the failure rates for two similar products from an exida certificate with those from a TÜV Italia certificate. exida numbers were an order of magnitude higher. Who is right?
There are some relevant fundamental facts in the field of Reliability Engineering:
Reliability Engineering experts know there are many variables that impact operational failure rates. These variables even include how operations and maintenance are done at a specific site. Sometimes it feels like there are so many variables that no realistic failure rate can ever be predicted without a few hundred hours of…
I find YouTube to be a good source of information on many subjects. Want to know how to fix a widget? There are probably a few videos on that exact subject. Technical subjects are also there. I was searching on “FMEA” and found an interesting looking video on the “Read More...
IEC 61508 functional safety certification began in the 1990s. As I recall, the only organizations doing this work in those days were TÜV Rheinland and TÜV Product Services (now TÜV Sud). These two companies remain competitors.
Functional safety certification started with logic solvers. Some engineers and regulators at the…
After careful planning and development of your system, the last thing you want to worry about is the credibility of your certification. Although it may seem like a given for your certification to be well accepted by your customers, it is never a bad idea to dig a little…
I got a new car. The process was a bit disturbing. It took over an hour to go through the “set-up” menu. And it was suggested that I return for a second training session after spending time studying the manual and testing different settings. I was thinking how different things…
It is tough to receive an email with this message from a prospective CFSE candidate. I know that when I have failed exams, I want to understand what was wrong so I can study those areas of knowledge more deeply and try again. Given the recognition and prestige…
We want our system to work. We're going to do everything we can to make it work properly. If it doesn't work, we want it to fail in a predictable and hopefully safe manner. If the failure modes are predictable, we can design the equipment to be fail safe.…
I got an email saying that the exida's www.SILSafeData.com minimum failure rates were way too high. The email went on to say that his REAL field failure data showed a result of 150 FITS for a remote actuated valve assembly. The lowest SILSafeData limits for clean service, Class IV leakage,…
I learned about the Failure Modes and Effects Analysis (FMEA) process for designs some decades ago. I was Supervisor of an Embedded System development group. There seemed to be a lot of evidence that an FMEA on a design was a really good way to identify issues (problems) early…
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…
The term SIL is rapidly spreading to Request for Proposals (RFP) and purchase requirements in many industries. But in many of those industries, few have heard about SIL and fewer have a grasp of the fundamental concepts of SIL. SIL is a term that means Safety Integrity Level. It is used…
At exida, we just finished a Failure Modes and Effects Analysis (FMEA) on a medical ventilator. This was done for a new manufacturer who needed independent design verification. It was a fascinating job. We found lots of pneumatic devices very similar if not identical to the kind used in…
SILSafeData contains upper and lower bound ranges of dangerous undetected failure rates for many automation devices. It was created by exida using statistical analysis of FMEDA failure rate predictions. The component database used in the FMEDAx tool is based on…
I had an engineer from a European Certification Body ask me why exida would bother paying any attention to these failure rate numbers, especially on mechanical devices? He said that he does not know anyone who actually uses them! To answer why exida pays attention to failure rates, we…