抗燃液压油技术.docx

抗燃液压油技术.docx

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抗燃液压油技术

Tableofcontents

Clickonthelinksbelow.Section1BackgroundtofireresistanthydraulicfluidsSection2FireratingmethodsforfireresistanthydraulicfluidsandfluidselectionSection3HydraulicsystemsoverviewSection4TechnicalcomparisonbetweenCastrolAnvolSWXpropertiesandawell-knowncompetitorSection5ChangeoverproceduresandcompatibilitydataSection6TrialproceduresandoilconditionmonitoringSection7Casestudies

Background

Hydraulicsystemsareoneofthemostcommonsourcesofpowertransmissionfoundinsteelmills.Theyareusedintheoperationofmeltshops,rollingmills,reheatfurnaces,temperingfurnaces,heat-treatfurnacesandannealingfurnaces.Thefluidofchoiceformostengineersisonebasedonmineraloil.Itisinexpensiveandprovidesgoodsystemreliability.However,hydraulicsystemsleakandifhosesarebrokentheycansprayhydraulicfluidthroughoutthesteelplant.

Infactthissituationworsenswiththeageofthesystem.Inthiscase,itislikelythatthehydraulicsystemislocatedneareitheranakedflameorahotormoltenmetal.High-pressuremineralhydraulicfluidcancomeincontactwiththoseignitionsourcesandthepotentialforafireisthenpresent.

Fire-resistanthydraulicfluidsarethereforeessentialforthesafe,cost-effectiveoperationofmajorcomponentsofsteelproduction.Thistechnicalsupportmanualisprimarilyfocusedonpolyolesterhydraulicfluids,suchasCastrolAnvolSWX,butalsodoesreferenceotherfireresistanthydraulicfluids.

Thepurposeofthistechnicalsupportmanualistoallowsteelengineerstomakequalifieddecisionsaboutthefireresistanthydraulicfluidtheyuseandassisttheminconsideringotherfactorssuchassystemcompatibility,fluidconditionmonitoringandfluidtrialing,plusappropriatefluidchangeoverprocedures.

Theaimistoprovideyouwithabest-in-classfireresistanthydraulicfluidwhichoffersoptimumfireprotection,premiumsystemprotectionandextendedsystemlife.

Backgroundcontinued

Firesinmetalmanufacturingplantsarenotathingofthepast.Infact,accordingtoFactoryMutual（seeSection2）,astudyoflossesintheUnitedStatesbetween1981and1990showedthat134firesoccurredinvolvinghydraulicfluids,resultinginmillionsofdollarsinlosses.Nearlyhalfoftheselossesoccurredinmetalworkingprocesses,suchasmachineshops,rollingmills,orheat-treatmentshops.

Primemotivatorsfortheuseoffire-resistanthydraulicfluidsaresafetyconsiderationsandinsuranceguidelines.Firesafetypoliciesandproceduresprotectbothpeopleandequipment.Insurancecompaniesprovideincentivesintheformofreducedpolicycostsforcompaniesthatmeetsetstandards.

ThisisstillarealissuewithmanyofoursteelcustomersandneedstobeincorporatedintodiscussionswehavewhenwetalkaboutHealth,Safety,SecurityandtheEnvironment（HSSE）.

Changestothewayproductsareevaluatedforfireresistancehaveoccurredoverthelastfewyears.FactoryMutual,theprimaryinsuranceunderwriterthattests,certifiesandsetsstandardsforsafeuseofequipmentandproducts,hasadjusteditsfire-resistancefluidsrankingscale,makingitmorerestrictive.EffectiveJuly1,2003,twonewproductclassifications–Group0andGroup1–willbeinsertedintotheclassificationtableinthenewstandard#6930.ThiswillbediscussedinfullwithinSection2.

Customershaveanumberofwaystominimizeriskswhentacklingtheissueoffiresemanatingfromhydraulicfluids.TheycaneitherstaywithlowperformingfireresistanthydraulicfluidssuchasGroup2（seeSection2fordetails）andinstallexpensivefiresuppressionequipmentortheycanelecttouseanappropriatefireresistanthydraulicfluidfromtheGroup0orGroup1category.WhichfluidtochooseforyourspecificapplicationcanbefoundinSection2.Generallythereisatrade-offbetweenfireresistanceperformanceandhydraulicsystemperformance.Anextremeexampleofthisistheuseofwater.Ithasexcellentfireresistanceproperties,howeveritsabilitytoprotectconventionalpumpsagainstwearisextremelypoor.

Thereisnotonlyatrade-offbetweenfireprotectionandsystemperformanceamongdifferentfamiliesofhydraulicfluids,（e.g.HFAversusHFDU）butalsowithinfamilies.Notallpolyolestersperformequallyinhydraulicsystems.Infacttherehasbeenalonghistoryofheavysludgeandvarnishformationwithinsomebrandsofproducts.Itisessentialwhendesigningtheseproductsthattheyareformulatedtomeetthehigheststandardsexpectedbyconventionalcirculatoryoils.Manyinternationalstandardshavebeenwrittentoobjectivelyandquantitativelyevaluateaproductforitssuitabilityinahydraulicsystem.AnexampleofthisisAmericanSocietyofTestingMethodD943.Effectivelyratingcomparativeperformanceofhydraulicfluidsinsystems,thismethodallowsengineerstocompareoneproductagainstanothertodeterminetheeffecttheywillhaveoncriticalcomponentssuchasvalves,withregardtovarnishingand,importantlyhowlong,comparatively,theproductwilllastinasystem.

AdetailedanalysisispresentedinSection4comparingthesystemreliabilityofCastrolAnvolSWXversusawell-knowncompetitor.

Ratingmethodsforfireresistanthydraulicfluidsandfluidselection

Therearemanyinternationallyrecognizedstandardsthatratehydraulicfluidsfortheirpotentialtoresistburning.Thetwomostcommonmethodsarethe7thLuxembourgReportandthosedesignedbyFactoryMutual.Inthesteelandmanufacturingindustries,FactoryMutualisarguablythemostwell-known.

FactoryMutual

FactoryMutualisalargeprimaryinsuranceunderwriter,basedinNorwoodMAnearBostonUSA.Theyhavehadalongassociationwithinsuringheavyindustrystartingwithtextileplantsandmovingintometalmanufacturingsuchassteel.ForfurtherinformationonFactoryMutual,visittheirwebsiteat.

Theyrealizedearly-onthatalargenumberoftheirclaimswerecomingfromfiresthatinvolvedhydraulicfluidleakage.Tohelpminimizetheriskattheplantandhencethepropensityformakinginsuranceclaims,FactoryMutualdidtwothings.First,theywouldadvisecustomersonstepstotaketoreducetherisksoffiredamageandthenauditthemtoensurethosestepsweretaken.Second,theirengineeringdepartmentdevisedawayofevaluatingfluidsforacategorycalled“LessHazardousFluids”.Thesefluidswereconsideredsufficientlyfireresistanttouseinhazardousmanufacturingenvironments.

Thiswasaqualitativemethodfordeterminingproductsthatcouldpasstwovisualtestswhichwere:

1）SprayFlammabilitytest

2）HotManifoldtest

Thesetwotestsweredesignedtosimulatethetwomostcommoncausesoffire.First,whenhigh-pressurehydraulicfluidescapesfromahoseandhitsaflameorignitionsource（SprayFlammabilitytest）andsecondwhenhydraulicfluidpoolsontoahotsurface（HotManifoldtest）.

Ratingmethodscontinued

Inordertosuccessfullypassthesprayflammabilitytest,fluidsupplierswouldcommonlyresorttoaddingpolymertotheirpolyolesterfluidstohelpincreasethesizeofthefluiddroplets（reclassify）asthefluidbecameatomizedafterleavingthespraynozzle.Theideabehindthatwaswhentheatomizedfluidhittheignitionflameinthetest,theflamegeneratedbythepolyolesterwouldstandabetterchanceofselfextinguishingaftertheignitionflamewasremovedifitsatomizeddropletswerelargenotsmall.Thefluidalsohadtopassthehotchanneltestandonceithaddonethisitwasgivenapassorfail.A“pass”wasconsideredtobea“LessHazardousFluid”.

Theonlydraw-backtothatwasthatthepolymerscommonlyusedforthis,sheardowninuseandeffectivelylosetheirabilitytoreclassifythepolyolesterdroplets.Thenetresultofthiswasthatafterashortperiodoftimeinthehydraulicsystem,thefluidwouldnolongerpassthestandardFactoryMutualtest.Notonlythat,theviscosityoftheproductdecreasedbyasmuchas15%asdemonstratedinFigure1.

CastrolAnvolSWX

Section2

Forinternaluseonly

Figure1

Thisfactanddatacollectedovertheperiodof1981to1990showedthattherewerestillmanyfluidsinvolvedinfires.Infact,manyfluidstestedfromthefieldshowedenormousvariabilityintheirfireprotectionproperties.ThispromptedthemtodeviseanewmethodofevaluationunderthenewFactoryMutualclassificationstandard#6930.CastrolAnvolSWXwasspecificallydesignedtoconformtothisnewstandard,providingsteelengineerswithasaferoptionwhenselectingtheirfireresistanthydraulicfluid.

NewFactoryMutualstandard-#6930

Thenewstandardwasfirstpublishedforreviewin1991.Ittakesadifferentapproachtothepreviousmethodbyassessingafluidthroughaquantitativemeansandnotaqualitativeone.Thereforefluidscanberatedandcategorizedintogroups.Theyhavedonethisbyusingathermodynamiccalculationtoeffectivelyratefluidsontheirabilitytobothcatchfireandsustainafire.

ThevaluethattheycalculateiscalledtheSprayFlammabilityParameterrepresentedbythefollowingcalculation:

SFP=8.31X106XQch/（pfqcrmf）

Where:

Qch=ChemicalHeatReleaseRate

pf=densityofthefluid

=CriticalHeatFluxforIgnition

qcr

BasicallytheChemicalHeatReleaseRatedeterminestheamountofheatreleasedwhenthefluidisburnt.Thisisimportantasitdetermineshowlikelyafluidistosustainafireoncethefluidhasbeenignited.ThepieceofequipmentthatisusedtomeasurethisheatreleaserateisillustratedinFigure2.

Figure2

NewFactoryMutualstandardcontinued

TheCriticalHeatFlux