OilFlushing-VisualInspectionMediaandCriteriaByLarryBJordanThroughoutmycareerintheflushingindustryIhavebeenaskedcountlesstimeaboutthecriteriaandmaterialsusedfordeemingasystemclean.Whenitcomestimetoperformoilflushingonyourequipmentitisimportanttobuildthecriteriaintoyourflushingplanorprocedure.Therearetwoaspectstokeepinmindwhendeemingaflushclean.Firstisthematerialsyoucannotseewithanakedeye.Anaveragehumanhairwidthisaround40-micronbutparticulatecancausedamagetoyoursystemassmallas2-micron.Sohowcanyoujudgeyoursystemcleanifyoucannotseethematerial.Thereareafewoptionsforyouatthispoint.

• Option1–Usealaboratorytotestyouroilandverifyresults.Theprosforusingalabarecontrolled,certifiedresults.Consforutilizationofalaboratoryaretimeandcontrol.Forexample,theflushhasbecomethecontrollingfactorofyouroutageandyouarereadytomoveforwardwithfinaltestingtoverifytheflush.Ifthishappenstobeat5pmonaFriday,doesyourlabrunovertheweekend?Whereistheclosestlab?Doyouhavetowaitforshipping,processing,thenpostingofresults?Havingworkedinsomeruralareasthetimingcanbeanywherefrom2-4dayswaitingforexpeditedresults.

• Option2–Usingapatchkit.Whilepatchkitshavecomealongwayfromtheoldmicroscopeandcountingparticles,(Newerversionsallowforattachmenttocomputerandmeasurementofactualparticles)Patchkitsstillallowforhumanerror.Theyaremoreofaquick“downanddirty”methodandshouldalwaysbebackedbysendingasampletoalaboratory.

• Option3–PortableParticleCounters.Usingaparticlecounteronsiteisthequickestmostreliablemethodforverificationofmicroscopicparticles.Therearemultipletypesandshouldberesearchedbasedonapplication.Wherelightrefractingunitsaregreatforturbineandhydraulicfluidstheycangivefalsereadingswithdarkeroilsandoilswithmoisturecontamination.Poreblockageunitswillworkwithdarkeroilsandmoisturebutwillrequiremorecarewithhandlingandcalibration.ThepreferredunitswillgiveyouparticlecountsinbothISOandNASbasedonmanufacturerrequirements.Alwaysverifycalibrationonunitbeforestakingthesuccessoftheflushonthereadings.

So,whataboutmaterialyoucansee?Thematerialshouldshowupontheparticlecount….right?Notalways.Picturethefollowing.YouhaveaverifiedoilsampleatanISOCodeof18/16/14.Youtakeaballbearingthesizeofamarble,cleanitoffwithdenaturedalcoholanddropitintothesample.Youthenrunthesamplethroughyourportableparticlecounter.Thesamplecomesbackat18/16/14.Why?Simple,thebearingistoolargetorunthroughtheparticlecounter.Thatiswhyitisvitaltohavebothparticlecountandvisualinspectionaspartofyourcleanlinesscriteria.Thisbringmetothesecondpartaroundinspectionmedia.Themostcommonmediausedis100meshscreen.Thiscancomeindifferentformsrequiredbyequipmentmanufacturers.

• WyeStrainer- TheWyestrainerusesacylindricalor“barrel”screenforinspections.Whilethescreensarequicktochangeandfairlycommontheyarenotapreferredmethodbymostflushingexperts.Thescreenshaveatendencytogetcrushedfromrepeatedremovalandinstallation.Nottomentioncontaminationcandropoutintothescreencoverandgivefalsepositive.

• BasketStrainer- Basketstrainerareutilizedinmanyflushestoday.Theyacceptfullflowandhasasealedbottomtocatchallmaterialsduringtheinspection.Ifutilizingbasketstrainers,itisadvisabletopurchaseunitswithquickreleasehandlesontopandadrainvalveonbottom.Thisallowsforeaseofinspection.Downsidetobasketstrainersareavailabilityandcost.Thereisno1standardbasketorhousing.Ifabasketisdamagedduringyourflushingactivityyoushouldalwaysstockspares.Thiswillkeepyourflushfromhavingneedlessdelays.

• WitchesHat- Thewitcheshatstrainerisnotcommonlyusedfromflushingexperts,howevertherearemanufacturerswhorequirethestrainertobeplacesinthereturnheaderpreventingcontaminationfromgettingbackintothereservoir.Thewitcheshatshouldonlybeusedforgrosscontaminationandinspectedoften.Thesurfaceareaofthescreenleavestheunitwithatendencytotearorblowout.Otheritemstoconsiderareaccessibility.Thewitcheshatrequiresapipespoolpiecetoallowremovalandinstallation.

• BagFilters- Bagfiltersarecommonlyusedinmanyturbineandcompressorflushestoday.Theprosofbagfiltersarecostandavailability.Bagfilterscanbepurchasesinmanymicronsizestomeetyourneedsaswellasbeingproducedanddistributedglobally.A36”1-micronbagfiltercanbepurchasedforaslittleas$3U.S.Theconswithbagfiltersarethatthehousingtoutilizethebagfilterscanbecostly,bulkyandthefiltersarenominal.Whichistosaytheydonotcaptureallofthecontamination.Bagfiltercanbedifficulttoinspectaswell.Mosttimesnecessitatingcuttingthefilteropenandcountingparticles.

• FlangeScreens- Flangescreensor“slipscreens”astheyarebetterknowninthefieldareapreferredmethodtooilflushsubjectmatterexperts,myselfincluded.Theslipscreencanbeeasilydroppedbetweentwoflangesinplaceoftheexistinggasketmaterial.Thisallowsforeaseofplacementwithoutdisturbingthelubeoilpipinganymorethannecessary.Thescreenscanbecleanedandusedmultipletimesthroughoutaflushifbuiltcorrectly.Itisbestpracticetoutilizealayeredapproachwhenusingslipscreens.Meaning,usinggasketmaterial,a40-meshscreenforarigidback,100-meshscreenontopof40-mesh,thenanotherlayerofgasketmaterial.Allgluedtogetherwithasilicone.Asseeninthepictureabove,ahandleforeasyinstallationandremovalcanbeadded.Theslipscreenallowsforfullflowcaptureofparticulateduringinspectionphase.Theconsofusingtheslipscreencomeintoplayiftheyarenotproperlybuiltorbecomefullycoatedwithdebris.Thiscouldcauseeitheraback-upoffluidupstreamofthescreenorthescreentotear.

Withalloftheinspectionmediaitisrecommendedtoinsertvalvesonbothsidesoftheinspectionlocation.Thisallowsforsegregatingthemediafromthesystem.Preventingoilspillsastheinspectionisexecuted.Alwaysuseatwo-partinspectioncriteria.Particlecountforthematerialsyoucannotseeandinspectionmediaforthematerialyoucan.