Safety Integrity Level (SIL) and Performance Level (PL)

Safety Integrity Level (SIL) and Performance Level (PL). This short article provides an overview of the standards and methodologies applied to achieve a ... LogicandNormicomtogethertoincreasetheproductionplantsafety June24,2020 NEWTONS.r.l.NewofficialdistributorfortheTrivenetoarea July28,2020 Showall SafetyIntegrityLevel(SIL)andPerformanceLevel(PL) Thisshortarticleprovidesanoverviewofthestandardsandmethodologiesappliedtoachieveasafeoperatingstateofplantsandmachines,basedontheconceptsofSafetyIntegrityLevel–SILandPerformanceLevel–PL. Somerisksfortheoperators’safetymaybecausedbytheuseofdevicesinproductionplants,suchastheuseofautomatedsystemsinATEXclassifiedareasorthepresenceofroboticsystemintheworkingenvironment.Suchrisksneedtobecarefullyassessedandoftenitisnecessarytomeasureandquantifytheriskreductionfactor.   SafetyIntegrityLevel–SIL:    TheIECStandard61508–FunctionalsafetydefinestheSafetyIntegrityLevelSILasthereliabilityofacomponent,equipmentandsystemusedinsafetyapplications. Thesafetysystemsusuallyconsistof: Sensorsandtransducers Controlsystems(withpossiblesafetysoftware) Finalelements(actuators/safetyfunctionactuators) Withinthestandard,theriskreductionfactorsarespecifiedthroughthedefinitionofthreeparameters: PFDavg:Averageprobabilityoffailureondemand PFH:Probabilityoffailureperhour RRF:Riskreductionfactor TheseparametersarerelatedwiththeSILlevelasshowedinthefollowingtable:   SILLevel PFDavg PFH RRF SIL1 10-2≤PFD<10-1 10-5≤PFH<10-6 10 ≤RRF<100 SIL2 10-3≤PFD<10-2 10-6≤PFH<10-7 100 ≤RRF<1.000 SIL3 10-4≤PFD<10-3 10-7≤PFH<10-8 1.000 ≤RRF<10.000 SIL4 10-5≤PFD<10-4 10-8≤PFH<10-9 10.000 ≤RRF<100.000   ItcanbeseenthatahigherSILlevelimpliesahigherriskreduction,that’swhytheSILlevelrequiredbythehazardandoperabilitystudy(HAZOP)dependsontheriskfactorthatneedstobereduced.   PerformanceLevel–PL:  ThePerformanceLevel–PLstandsforthediscretelevelusedtospecifythecapabilityofsafetyrelatedpartsofcontrolsystems–SRP/CS. Therefore,5differentperformancelevelsoftheprotectionsystemaredefined,linkedtotheprobabilityofdangerousfailureofthesystemitself.DangerousfailuremeansafailurethatmayleadtheSRP/CSintoadangerousorincapacitatedstate. The5levelsofPLareindifiedbytheuseofletters:a,b,c,d,e;whereletteraindicatesthelowerPL(thereforerelatedtolowerrisks),whileletter e representsthehigherPL(thereforerelatedtohigherrisks).    LogicS.r.l. isanATEXcertifiedmanufacturer,whosesystemsareguaranteedintermsofSafetyIntegrityLevel–SILandthankstotheknowledgeandexperiencegainedovertheyears,isabletooffersystemsbasedonyourneeds.     Relatedposts January17,2022 BELSATEXnewofficialdistributorforSpainandPortugal Readmore