nas-1683and-iso4406[1]清洁度标准

Particlecontaminationinoilisspecifiedfromparticlecount.TwobasicstandardstheISOandNASsystemsarecom-monlyusedascontaminationreference.Thetwocleanlinessstandardscannotbedirectlycomparedorconverted,asthebasicprincipleswithinthetwosystemsdiffertomuch.Thisisexplainedinthenextpages.However,thefollowingtablesgivessomeroughguidelinesofcommonpracticeforsettingtargetsofcleanlinesslevelsindifferentsystems.AsseenbothISO4406andNAS1638arerepresented.Theseguidelinesareminimumfluidcleanlinesslevelsrequiredforanacceptablelifetimeofequipmentandcomponents.Manyfactorsinfluencelifetimeanddemandstofluidquality.Highreliabilitysystemsenhancedemandstoquality,andhighpressuresystemsandheavybearingloadincreasede-mands.ThelastthreecolumnsofthetablesindicatetherangeoftheGreenOilfiltersystem.Althoughthefiltersmaybeputintoserviceinmanyapplication,parametersasfluidvolumeandviscosityshouldbetakenintoconsiderationbeforeexpecta-tionstocontaminationlimitsareset.WorkingwithISO4406andNAS1638GreenOilStandardDate:15-12-2005TechnicalPaper004ParticleContaminationISO4406andNAS1638Page1af3Savedas:TechnicalPaper004HydraulicEquipmentandComponentsPressureRangeGreenOilFilterInsertsISO4406NAS1638HTMSiltsensitive,aerospace,robots,Highpressure250-400bar14/12/94ISO10/6NAS3Servosystems,injectionmoulding,Highpressure250-400bar16/14/115Proportionalandflowvalves,Highpressure250-400bar17/15/126Pistonpumpsandmotors,Normalpressure150-250bar18/16/137Typicalnewhydraulicoil18/16/137Gearpumpandmotors,Mediumpressure50-150bar19/17/148CylindersandFlowControlLowpressure0-50bar20/18/159LubricationOilEquipmentandComponentsBallbearings,turbineoils,Smallandmediumgearboxes14/12/94RollerbearingsTransmissiongearboxes16/14/115ISO14/11NAS5JournalbearingsIndustrialgearboxes17/15/126MobileequipmentandgearboxesPapermill18/16/137ISO16/12NAS7Dieselenginelubrication19/17/148Heavydutygearboxes20/18/159Typicalnewlubricationoil20/18/159Typicalin-linefiltration21/19/1510MinimumClassRequirementPage2TechnicalPaper004IntroductionContaminationinoilisspecifiedfromparticlecount.Twobasicmethodsareused:Laserbasedparticlecountanalysisequipmentgivesdirectlyinformationonparticlesizes(micron=u)andfigureswithinspecifiedsizeranges.Theothermethodutilizefilteringanoilsamplethroughanveryfinemeshfilterpaper.Theparticlesonthesurfaceofthefilterpaperisthenmonitoredinamicroscopeandcom-paredtostandardcontaminationpicturestoindicatethede-greeofcontamination.ContaminationclassesInsteadofspecifyingparticlecountscontaminationissepa-ratedintoclassesdefinedintwomajorsystemsISO(InternationalStandardOrganisation)andNAS(NationalAir-spaceStandard).Eachclassdefinesarangeofcountswithinanexponentialscale.Unfortunately,thetwosystemsarenotidenticalandcannotbeconvertedinsimplemathematics.However,somesimpleguidelinescanbegiven.Firstofalllet’slookatthetwosys-tems.NAS1638TheNASsystemdividesparticlesin5ranges.Furthermore,theNASsystemspecifydifferentcountswithineachparticlerangetoscoreaspecificclass.InpracticeoilsampleswillshowuptogainalmostsameNASclassratingwithinthedifferentparticleranges.Thesystemisdesignedtomatchthemostcommonfoundcon-taminationwhichhasreallymanysmallparticlesandfeverbigparticles.Thesidebarexampleshowsatypicaloilanaly-siswithcountsdividedinthe5classes.Asseentheclassesrangesfrom3to6,however,theresultingNASclassisde-finedastheparticlecountwiththehighest(worse)score,andonlythisclassisspecified.Thesidebarexamplewillbeclassifiedas“NAS1638class6”.Classes5to1515to2525to5050to1001000012522410025044820150089163121,000178326132,0003566311244,00071212622458,0001,425253458616,0002,8505069016732,0005,7001,01218032864,00011,4002,025360649128,00022,8004,05072012810256,00045,6008,1001,44025611512,00091,20016,2002,880512121,024,000182,40032,4005,7601024ParticleClassesSizeRangeper100mlNAS1638ParticlerangeCountsClass5-15u8450615-25u11982525-50u312650-100u466100u23Resultingclass6NASanalysisexampleISO4406TheISOsystemisnotaspracticalorientatedastheNASsys-tem.Firstofallitconsistsof2or3figures.Eachfigurede-fineaclasswithinasizerange.AtypicalISO4406oiltestwillbeindicatedas:17/15/12Particles2uParticles5uParticles15uAsseenparticleslessthan2uareomitted.TheoriginalISO4406operatedwithonlytwodigitsomittingcountsbelow5u.Thisstandardisstillwidelyaccepted,thoughitdoesnotrelievethesameinformationasthenewer3digitISOversion.15/12Particles5uParticles15uThecleanlinesslevelsrepresenttheparticlecountsasshowninthetable.(Nottogetstuckinmathematics:theclassrepresentspowersofthenumeral2.Acleanlinesslevel15indicatescountsbe-tween214(16,383)and215(32,768)forasampleof100mlfluid).Thesidebarexamplewillbeclassified“ISO440617/15/12”NASandISOToconclude:NASandISOcannotbecompareddirectly.AsseenbothNASandISOoperatesexponentially.Inbothsystems,theparticlecountsmustbehalvedtoreducetheclassorcleanlinesslevelonedigit.InpracticethegreatadvantageoftheNASsystemisthatcon-taminationisidentifiedbyonlyoneclassnumber.Foridenti-fyingcontaminationsourcesthiscouldbealimitationwhichdoesnotapplyasmuchfortheISOsystemwhichismoreopenyetcomplicated.TheNASandISO2-digitsystemsdoesnottake