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Topic Title: ISO 13849
Topic Summary: Performance Levels and Risk Graph
Created On: 07 December 2012 12:00 PM
Status: Read Only
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 07 December 2012 12:00 PM
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01967834

Posts: 24
Joined: 21 September 2003

I am undertaking a risk assessment with regards to Machine safety and the associated E/E/PE systems used in protecting people. The use of ISO 13849 is the relevant standard (same as EN 61508 but for machine safety).

My problem is that in my experience with IEC 61508, the use of a risk graph in ISO 13849 is not the normal practice for High demand mode. Secondly in all the information i have seen there has been no mention as to the calibration procedure required for the risk graph.

Has anyone got any thoughts on this matter.

Regards

Paul Karslake
 09 December 2012 08:33 PM
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dougflorence

Posts: 74
Joined: 25 July 2008

Hi Paul,

There has been a lot of discussion about the EN 13849 risk graph on Linked In discussion group "IEC 62061 and ISO 13849 machinery functional safety".

IMHO (and that of many others) the risk graph is a very blunt tool and is frequently misapplied.
 09 December 2012 11:36 PM
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01967834

Posts: 24
Joined: 21 September 2003

Doug,

Thanks for the information, I will have a look at the discussions on linkedIN.

One other thought is that the risk graph on ISO 13849 appears linear, but in reality the mathematics of this would not be linear.

Regards

Paul
 10 December 2012 08:14 AM
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dougflorence

Posts: 74
Joined: 25 July 2008

The EN 13849 risk graph is really very unsatisfactory. Have you considered using EN 62061 which is designed for machinery rather than process plants but is closer in its approach to EN61508?

What sort of machinery are you dealing with. If there is a C type standard for something similar the writers of that standard may already have made a decision about appropriate PL/SIL.
 14 December 2012 11:40 AM
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01967834

Posts: 24
Joined: 21 September 2003

Doug,

The machinery is mechanical handling, hoists skips etc.

I will look into the 62061 risk graph.

Thanks

Paul
 14 December 2012 12:21 PM
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Avatar for dougflorence                                      .
dougflorence

Posts: 74
Joined: 25 July 2008

There may be a relevant C type standard which will give you guidance on a suitable PL for your safety related control systems. Call me on 07788 751 911 or mail doug@safemech.net if you want more advice.
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