exida explains Blog

Entries tagged with: SIL

  • by Dr. William Goble, CFSE
  • Thursday, January 12, 2012
  • News

2011…A Year in Review

Babies, Bathwater, and Australian Safety Laws

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...

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 11 – How is SIL Used by an End User?

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

Back to Basics 16 - PFDavg

Back to Basics 16 - PFDavg

PFDavg (the average Probability of Failure on Demand) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFDavg can be determined as an average probability or maximum probability over a time period. IEC 61508 and IEC…

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Back to Basics 17 - PFH (Probability of Failure on Demand per Hour)

Back to Basics 17 - PFH (Probability of Failure on Demand per Hour)

PFH (The Probability of Failure on Demand per Hour)  is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFH can be determined as a probability or maximum probability over a time period of an hour. IEC…

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Best Practices in Achieving Functional Safety in Turbine Applications - Part 1

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…

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  • by Chris O'Brien, CFSE
  • Thursday, January 07, 2016
  • Certification

Best Practices in Achieving Functional Safety in Turbine Applications - Part 3

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…

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  • by Dr. William Goble, CFSE
  • Thursday, May 12, 2011
  • Certification

Buy Certified Equipment, Meet the Standard, Right? WRONG!

  • by Iwan van Beurden, CFSE
  • Thursday, March 21, 2013
  • Software

Changing the PVST Interval. Hey, my Architectural Constraints changed!

Close Enough? Not so Much
  • by Denise Chastain Knight, P.E., CFSE, CCPSC
  • Wednesday, May 27, 2015
  • Functional Safety

Close Enough? Not so Much

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.…

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Do you believe the numbers?

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…

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Functional Safety, Cybersecurity, and Alarm Management in 2013
  • by Dr. William Goble, CFSE
  • Friday, January 10, 2014
  • Certification

Functional Safety, Cybersecurity, and Alarm Management in 2013

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…

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Getting Good Proof Test Coverage Numbers

Getting Good Proof Test Coverage Numbers

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

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How can I improve my SIL?

How can I improve my 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…

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How is SIL Used?
  • by Loren Stewart, CFSE
  • Tuesday, September 22, 2015
  • Certification

How is SIL Used?

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:

  1. To establish risk reduction requirements
  2. Probabilistic limits for hardware random failure
  3. Architectural constraints 
  4. Read More...

How to Decode an exida IEC 61508 Certificate: Part 2

Click here to read Part 1

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. …

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IEC 62443: Levels, Levels and More Levels

IEC 62443: Levels, Levels and More Levels

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…

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Is It Possible to Extend Proof Test Intervals?

Is It Possible to Extend Proof Test Intervals?

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…

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Lifecycle Analysis: It’s Worth the Effort