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Commentator

Join Date: Nov 2008
Posts: 91

SIL reduction by Increasing the testing frequency

03/04/2009 5:13 AM

we all know that one of the method to mitigate harm and reduce risk is increasing the testing frequency of critical components

this understood very but the how this affect the SIL of the SIS ?

Is that becouse increasing the frequency of test will decrease the the dangrous undetect fault which will and this will affect on PFD

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Anonymous Poster
#1

Re: SIL reduction by Increasing the testing frequency

03/04/2009 8:48 AM

What do the acronyms you refer to mean?

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Commentator

Join Date: Nov 2008
Posts: 91
#2
In reply to #1

Re: SIL reduction by Increasing the testing frequency

03/04/2009 9:02 AM

SIL =Safety Integrity Level

SIS =Safety Instrumented System

PFD = Probability of Failure on Demand

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Power-User

Join Date: Mar 2008
Location: Mumbai
Posts: 250
Good Answers: 2
#3

Re: SIL reduction by Increasing the testing frequency

03/05/2009 2:04 AM

Nope

Mathematically PFD is defined as

PFD=(LAMDA Du+ Lamda DD) tce

( Lamda dangerous) tce

By reducuing Test Interval ,Channel equivalent downtime is reduced which in turn reduces PFD Thereby Increasing The SIL level

For Further Info Ref DIN 19250 .

BTW thanks for PTC 19.3

Regards

Jose John

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