exida explains Blog

How Much Testing Is Enough?

How Much Testing Is Enough?

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…

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Back to Basics 15 - Architectural Constraints

Back to Basics 15 - Architectural Constraints

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…

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My Final Element Field Failure Data says 150 FITS and OREDA is 2000 FITS

My Final Element Field Failure Data says 150 FITS and OREDA is 2000 FITS

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,…

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Back to Basics 14 - Systematic Capability

Back to Basics 14 - Systematic Capability

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…

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Let’s Talk About Configuration Management and ISO 26262

Let’s Talk About Configuration Management and ISO 26262

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…

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Do You Really Know What You Know (When it Comes to Functional Safety)?

Do You Really Know What You Know (When it Comes to Functional Safety)?

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…

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Back to Basics 13 - How Do I Start IEC 61508 Certification?

Back to Basics 13 - How Do I Start IEC 61508 Certification?

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:

  1. Introduce Scope
  2. Kickoff Meeting
  3. Perform FMEDA on Product
  4. Creation of…

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Back to Basics 11 – How is SIL Used by an End User?

Back to Basics 11 – How is SIL Used by an End User?

Back to Basics 10 – How Does a Product Get a SIL?

Back to Basics 10 – How Does a Product Get a SIL?

IEC 61508 functional safety standard indicates Safety Integrity Levels (SIL) needs to be evaluated by three design barriers:

  • The Systematic Capability Rating
  • The Architectural Constraints for the Element
  • The Probability of Failure for the Product

What Makes a SIL?

Systematic Capability is achieved when the equipment…

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Back to Basics 09 – Safety Lifecycle – IEC 61511

Back to Basics 09 – Safety Lifecycle – IEC 61511

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: 

  1. Analyze the situation and document…

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Duty of Care (Too Good to Be True Failure Rate Data)

Duty of Care (Too Good to Be True Failure Rate Data)

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…

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Back to Basics 08 – IEC 61511

Back to Basics 08 – IEC 61511

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.…

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Back to Basics 07– Safety Lifecycle – IEC 61508

Back to Basics 07– Safety Lifecycle – IEC 61508

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…

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Back to Basics 06 – IEC 61508

Back to Basics 06 – IEC 61508

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 

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Back to Basics 05 – What is a Safety Function?

Back to Basics 05 – What is a Safety Function?

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: 

  • Car brake stop
  • ESD valve – Shutdown process
  • Sprinkler system 
  • High…

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