Have you ever wondered if you tested your product enough? Either in enough ways or for a long enough time? This assumes that you’d prefer to discover all the problems before your customers do. If you follow a 61508 compliant development process, you should be able to…
Architectural constraints are limitations that are imposed on the hardware selected to implement a safety-instrumented function, regardless of the performance calculated for a subsystem. Architectural constraints are specified (in) according to the required of the subsystem, type of components used, and of the subsystem’s components. (Type A components are simple devices…
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,…
Systematic Capability is achieved when the equipment used to implement any safety function is designed using procedures intended to prevent systematic design errors. The rigor of the required procedure is a function of a Safety Integrity Level (SIL). This is evaluated through an assessment of the quality management system…
Most software developers are familiar with the need for and benefits of change control. Usually change control means one thing to a software developer and that is 'commits' to a source code revision control system. Not only do small and regular commits provide significant advantages to large teams of…
You don’t’ really know what you know until you have to explain it (or teach it) to someone else.
When I’m asked about some of the technical aspects of functional safety, I have to stop and ask myself “What Do I Know About This?” I’m not the kind…
Do you want to know more about IEC 61508 certification, but you’re not sure if you are ready to jump in? Don’t worry, we will make this process as painless as possible.
Here is what to expect:
IEC 61508 and IEC 61511 functional safety standards allow Safety Integrity Levels (SIL) to be used four ways by end users:
IEC 61508 functional safety standard indicates Safety Integrity Levels (SIL) needs to be evaluated by three design barriers:
Systematic Capability is achieved when the equipment…
The IEC 61511 standard recommends the use of a functional safety lifecycle. Any safety lifecycle can be used, but the standard lays out a process which can be divided into three main classifications as an example.
The lifecycle is set up like this:
I have received several calls lately to our Australia / New Zealand office about whether it is acceptable to use published failure rates that seem too good to be true.
The person calling is usually doing a SIL verification calculation for an operating plant or for an…
IEC 61511: 2016 Process Industry Sector
IEC 61511 is a technical standard that sets out practices in the engineering of systems that ensure the safety of an industrial process through the use of instrumentation. It entails requirements for users of process control and instrumentation for component / element or sub-system safety.…
The IEC 61508 standard recommends the use of a functional safety lifecycle. Any safety lifecycle can be used, but the standard does lay out a nominal 16-step process which can be divided into three main classifications as an example.
The Analysis phase of the lifecycle deals with gathering background…
In the following series of blogs, we'll go back to basics and run down everything you need to know to get started in functional safety. We'll start with some more general terms and descriptions and make our way to more advanced material.
IEC 61508: 2010 International Performance-Based Standard
The
A Safety Function is the action of a collection of equipment to implement automatic mitigation of a particular hazard. It is the job of the Safety Instrumented Function (SIF).
Some examples of common Safety Functions: