ANSI-ISA-5.4-1991 Instrument Loop Diagrams

InstrumentLoopDiagramsApproved9September1991ANSI/ISA–5.4–1991FormerlyANSI/ISA–S5.4–1991AMERICANNATIONALSTANDARDISATheInstrumentation,Systems,andAutomationSociety–TMCopyright1991bytheInstrumentSocietyofAmerica.Allrightsreserved.PrintedintheUnitedStatesofAmerica.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans(electronic,mechanical,photocopying,recording,orotherwise),withoutthepriorwrittenpermissionofthepublisher.ISA67AlexanderDriveP.O.Box12277ResearchTrianglePark,NorthCarolina27709ANSI/ISA-5.4-1991,InstrumentLoopDiagramsISBN1-55617-227-3ANSI/ISA-S5.4-19913PrefaceTheinformationcontainedinthePrefaceandForwardisforinformationonlyandisnotapartofthestandard.ThisstandardispreparedaspartoftheserviceofISAtowardagoalofuniformityinthefieldofinstrumentation.Tobeofrealvalue,thisdocumentshouldnotbestatic,butmustbesubjecttoperiodicreview.Towardthisend,theSocietywelcomesallcommentsandcriticisms,andrequestthattheybeaddressedtotheSecretary,StandardsandPracticesBoard,ISA,67AlexanderDrive,P.O.Box12277,ResearchTrianglePark,NC27709.Telephone[phone],e-mail:[e-mail]cesDepartmentisawareofthegrowingneedforattentiontothemetricsystemofunitsingeneralandtheInternationalSystemofUnits(SI)inparticular,inthepreparationofinstrumentationstandards.TheDepartmentisfurtherawareofthebenefitstoU.S.A.usersofISAstandardsofincorporatingsuitablereferencestotheSI(andthemetricsystem)intheirbusinessandprofessionaldealingswithothercountries.Towardthisend,thisDepartmentwilltrytointroduceSI-acceptablemetricunitsinallnewandrevisedstandardstothegreatestextentpossible.TheMetricPracticeGuide,publishedbytheInstituteofElectricalandElectronicsEngineersasANSI/IEEEStd.268-1982,andfuturerevisionswillbethereferenceguidefordefinitions,symbols,abbreviations,andconversionfactors.ItisthepolicyofISAtoencourageandwelcometheparticipationofallconcernedindividualsandinterestsinthedevelopmentofISAstandards.ParticipationintheISAstandards-makingprocessbyanindividualinnowayconstitutesendorsementbytheemployersoftheindividual,oftheISA,orofanyofthestandardsthatISAdevelops.Atthetimeitapprovedthisstandardrevision,theISA-S5.4Committeehadthefollowingmembers:NAMECOMPANYW.RichardShawStearnsRoger*GeraldV.BartaDowCorningCorporationWilliamH.ClearyStone&WebsterRichardL.EmersonBechtelPowerCorporationEdwardE.OlinekStearnsRoger*RaymondRobertsonPPGRobertP.LarkinFord,Bacon&DavisJ.SlavinDelmarControlsJohnLorenzLeeds&NorthrupRichardE.TerhuneConsultantMikeWileyLummusCrestThomasC.McAvinewMetropolitanDenverSewageDisposalDistrict*Onevote4ANSI/ISA-S5.4-1991ThisrecommendedpracticewasapprovedforpublicationbytheISAStandardsandPracticesBoardin1989.NAMECOMPANYD.Bishop,Vice-PresidentChevronU.S.A.Inc.N.CongerFisherControlsInt'l.Inc.C.GrossEagleTechnologyH.HopkinsUtilityProductsofArizonaR.JonesDowChemicalCompanyA.McCauleyChagrinValleyControls,Inc.E.NesvigERDCOEngineeringCorp.R.PrescottMooreProductsCompanyD.RapleyRapleyEngineeringServiceR.ReimerAllen-BradleyCompanyJ.RennieFactoryMutualResearchCorporationW.WeidmanGilbert/Commonwealth,Inc.J.WhetstoneNationalInst.ofStandards&TechnologyM.WidmeyerThePowerSupplySystemP.Bliss*ConsultantW.CalderIII*TheFoxboroCompanyB.Christensen*ConsultantL.Combs*ConsultantR.Galley*ConsultantT.Harrison*FloridaStateUniversityR.Jones*PhiladelphiaElectricCompanyR.Keller*ConsultantO.Lovett*ConsultantE.Magison*Honeywell,Inc.R.Marvin*ConsultantW.Miller*MooreProductsCompanyJ.Mock*BechtelWesternPowerCorporationG.Platt*ConsultantJ.Williams*StearnsCatalyticCorporation*DirectorEmeritusANSI/ISA-S5.4-19915ForewordInstrumentloopdiagramsaresuitableforgeneralusethroughoutindustry.Itisimportanttoconsidertheirvaluefordesign,construction,checkout,start-up,operation,maintenance,rearrangement,andreconstruction.Benefitscanincludereductioninengineeringcosts,improvedloopintegrityandpurchasingaccuracy,andeasiermaintenancetroubleshooting.Aninstrumentloopdiagramcanbeeffectiveonanysizeprojectfromoneortwoloopsuptolargeandcomplexinstallations.Itcanpresentononesheetalltheinformationorreferencestotheinformationneededforinstallation,checkout,start-upandmaintenance.Withouttheuseofaninstrumentloopdiagram,thatinformationisspreadamongmanyotherdocumentsandisnotreadilyavailable.Updatingthissinglediagramtoasbuiltstatusismoreeasilyachievedthanupdatingthevarietyofotherdocuments.Thisstandarddoesnotmandatethestyleandcontentofinstrumentloopdiagrams,butratheritisaconsensusconcerningtheirgeneration.Assuch,ithasthesamestrengthsandweaknessesasotherconsensusstandards.Itsprimarystrengthisthattheformatandcontentguidelinesapplytothemajorityofinstrumentationapplications.Itsweaknessisthatitisnotspecificenoughtosatisfythespecialrequirementsofparticularinterestgroups.TheISAStandardsCommitteeonInstrumentLoopDiagramsoperateswithintheISAStandardsandPracticesDepartment.ThiscommitteeisappreciativeoftheworkofpreviousSP5.4committeesandhastriedtotreattheirworkwithrespect.ThiscommitteewouldliketoacknowledgetheworkoftheSP5.1committeeindevelopingISA-S5.1,Instrumentat