2011 was a good year in many ways for Functional Safety and Cyber Security. Several instrumentation products achieved IEC 61508 certification. exida Certification alone issued 64 product certifications (http://www.sael-onine.com). With most certification projects, improvements to the design and quality are made. Some manufacturers…
The old saying goes, “Don’t throw the baby out with the bathwater.” But it looks like a number of people in Australia may be in danger of doing just that with their response to the country’s newly harmonized health and safety laws.
Australia’s new Read More...
The adoption of the functional safety standards continues to gain momentum in turbine applications. Both industrial and power turbine sites are now requiring compliance to IEC 61511. This blog will review both technical requirements and market trends related to functional safety system design. Market trends will cover which standards…
The adoption of the functional safety standards continues to gain momentum in turbine applications. Both industrial and power turbine sites are now requiring compliance to IEC 61511. This blog will review both technical requirements and market trends related to functional safety system design. Market trends will cover which standards…
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.…
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…
Performing a SIL Verification calculation on preliminary design information can be a very useful tool to dial in the Safety Instrumented Function (SIF), Safety Requirements Specification (SRS) content , and define critical elements for the field component purchase specifications. Conceptual verification is typically performed quickly with general design information.…
In a couple of recent projects and discussions, I have come across something extremely concerning. Engineers are very good at performing accurate calculations, and the PFDavg and PFH computations for SIL performance verification are improving in precision all the time. Unfortunately, there is often such a focus…
2013 was a good year for functional safety progress. exida Certification issued a record number of new product functional safety certifications in mostly every product category - valves, actuators, solenoid valves, PLCs, fire and gas sensors, process sensors, and components. The component category is one of the most…
Several years ago we recognized that proof test coverage was an important variable that must be considered when doing PFDavg calculations. We ran some models and discovered that the difference between “perfect” proof test coverage (100%) and a very good 90% could mean a whole SIL…
Click here to read the first entry in this blog series (What is SIL compliance?)
Click here to read the second entry in this blog series (How is SIL Used?)
As we now know, a Safety Integrity Level (SIL) can only be given to a…
Click here to read the first entry in this blog series
Once the Safety Integrety Level (SIL) of a product is found, it will be used FOUR ways:
Now that you know the step-by-step process of product certification, now let’s take a look at the actual information on the certificate.
In the left panel (gray background) you will find an exida certification logo. …
By now we’ve all become familiar with safety integrity levels (SIL), as they have become part of our everyday lives. However, with the recent release of several cybersecurity standards in the IEC 62443 series, things are getting more complicated. This series of standards introduces two more levels…
I am often asked whether extending proof test intervals will be a problem.
This is a tricky question. The design and engineering SIL calculations for the Safety Instrumented Functions (SIFs) are taking credit for a specific proof test interval with a defined level of coverage, as defined within the…
Performing a risk analysis as part of an IEC61508 / 61511 / ISA 84.01 safety lifecycle process can be quite challenging. How can you be sure you get what you need within budget and how can your team provide the best value for money?…
It’s an interesting question and one I asked myself. For any engineer and/or professional working in the controls business or process industries where safety-related equipment is required, it is essential (per IEC61511-1 Clause 5.2.2: Organization and Resources) to prove competency to carry out any safety-lifecycle activities. So what does…
In some cases the screening methods will indicate that a SIF is needed. These screening methods can be designed to determine how many orders of magnitude risk reduction is needed, allowing a required SIL to be documented for a particular SIF. The screening…
I saw and responded to a LinkedIn discussion on this very issue, where someone had asked “if I have a misaligned limit switch that fails dangerously, then is it random or systematic? “. This is an intriguing question because many view human error as being systematic and, whereas, this…
An Interference-Free component, either as an interface or a defined functional area, is a system component that is neither safety critical (C3) nor safety relevant (C2), but interfaces with such subsystems.
If a component has been shown to be interference free (C1), then it has been demonstrated that no…