water in oil what's the big deal

7/26/2019 Water in Oil What's the Big Deal

1/7

www.testoil.com Page1

Water In Oi lWhat's The Big Deal?


2/7

Water In Oil , What's the Big Deal?

Waterrepresentsarealrisktoequipmentand

shouldbe

aggressively

controlled.

Moisture

in

hydraulicfluidsandlubricatingoilshasa

degradingeffectonboththelubricantandthe

machine.Althoughsomeadditivesclingtothe

waterandareremovedwhenthewater

separatesfromtheoil(knownaswater

washing),othersaredestroyedbywater

inducedchemicalreactions(oxidationand

hydrolysis).Wateralsopromotesoxidationof

theoilsbasestock,increasingtheriskofsludge

andvarnish

formation.

Water

also

causes

rust

andcorrosionofmachinesurfacesandreduces

critical,loadbearingfilmstrength.

Watercoexistswithoilinadissolved,

emulsified,orfreestate.Freeandemulsified

waterposethegreatestrisktothemachineand

thelubricant,andtheyshouldbecarefully

monitoredandcontrolled.

Three Forms of Water

1. Dissolvedwater referstowaterthathasbeenchemicallyabsorbedintotheoil.Whiledissolved

waterpossessesnodirectthreattothecomponentbeinglubricated,itspresencecanserveasa

catalystto

oxidation.

Dissolved

water

is

normally

not

visible

in

an

oil.

2. Emulsifiedwateriswaterthatmaintainsitschemicalintegrity,butisheldinsuspensioninthe

oilbyadditivesandcontaminants.Emulsifiedwaterwillseverelyaltertheloadhandlingability

ofanoil.Whentemperatureandpressureareappliedtoacontaminatedfluid,theoxidation

processissignificantlyaccelerated,leadingtoprematuredegradation.Internalcorrosionand

rustwillalsoresultinallareasofthesystem.Whenanoilhasemulsifiedwater,itwilltakeona

hazyormilkyappearance.

3. Freewater describeswaterthatispresentintheoil,butnotheldinsuspension.Sinceoiland

waterdontmix,anoilsbasestockwillbeconstantlytryingtoseparatefromwater.Without

additivesorcontaminantstobondwiththewater,itwillseparaterapidlyandsettletothe

bottomoftheoil.Freewaterwillbevisibleinanoilasaseparatephaseatthebottomoftheoil

reservoir.


3/7


Effects on Lubrication

Ingeneral,waterisapoorlubricant.Proper

lubricationisdependentontheformationofan

oilfilmtoseparateopposingfrictionsurfaces.

Whenpressureisappliedtoanoilfilm,theoils

viscositywillincreaseproportionallytomaintain

protection.Waterdoesnotexhibitthis

tendencyandwillcauseboundarylubricationto

occurwherefullfluidfilmlubricationwould

otherwisebepresent.

AlarmLimits

Waterisconsideredtobeamongthemost

detrimentalofpossiblecontaminants.Studies

haveshownthatwaterpresentatanylevelcan

reducebearinglifefrom10to100times.While

theoveralltoleranceforwatervariesfrom

machinetomachine,agoodgeneralalarmlimit

forwatercontaminationis0.05%(500ppm).

Somesystemsmaybemoretoleranttowater,

whileothersmaybemoresensitive.Some

manufacturershavesetlimitsaslowas30ppm.

Best practicewouldtendtoindicatethatitis

beneficialtokeepwatercontaminationatthe

lowestlevelpossible.

Controlling WaterContamination

Controllingwatercontaminationrequirestwo

individualconsiderations.First,wemust

addresstheissueofkeepingwateroutofthe

system.Watercancontaminateasystemby

condensationwhenmoistairentersthe

componentandachangeintemperaturecauses

thewatertocondenseanddropintotheoil.

Watercanalsoenterasystemthroughnon

dryingbreathers,faultyhatchesandseals,and

internallyfromleakingheatexchangers.

Second,stepsmustbetakentoremovewater

onceithasenteredasystem.Thiscanbe

accomplishedwithphysicalfiltration,vacuum

dehydration

or

centrifuge.

For

systems

prone

tocontamination,thesetypesofpurification

canbeinstalledinthesystemtoremovewater

continuouslyorondemand.

Systemsthatarepronetowatercontamination

shoulduseanoilthatrapidlyseparatesfrom

water.Anoilsabilitytoseparatefromwateris

knownas

its

demulsibility.

High

detergent

oils

tendtobepoordemulsifiers,whileturbineoils

andmanyindustriallubricantshavebetter

demulsibility.Circulatingsystemsproneto

waterinflux,suchasthosefoundinrollingmills

andpowergenerationplants,cansimplydrain

thewaterfromthereservoirtocontrol

contamination,providedtheoilexhibitsgood

demulsibility.Inthesesituations,theoils

demulsibilityshouldbemonitoredtoensure

thatwatercontaminationdoesnotreachthe

lubricatedcomponents.


4/7


Screening for Moisture: Crackle Test

Oneoftheeasiestwaystomeasurethe

presenceof

free

and

emulsified

water

in

oil

is

withthehotplatecrackletest.Anemulsionis

thestablestateofphysicalcoexistenceof

chemicallyinsolublesubstances,likeoiland

water. Additivesandimpuritiesthatlowerthe

oil'ssurfacetensioncanserveasagentsto

strengthentheemulsion. Waterisinafree

statewhenundissolvedglobulesofwaterare

physicallysuspendedintheoil.

Foryears,oilanalysislaboratorieshave

screenedsampleswiththecrackletest,

performingmoredetailedanalysis,suchasthe

KarlFischertest,onlywhenthecrackletestis

positive.

Inthecrackletest,adropofoilisplacedona

hotplatethathasbeenheatedtoapproximately

400F. Thesamplethenbubbles,spits,crackles,

orpopswhenmoistureispresent.Ifthecrackle

testisnegative,itsimplymeansthatthelevelof

waterpresentinthesampleisbelowthe

detectionlimit;itdoesntnecessarilymeanthe

sampleis

void

of

water.

Sometimesthecrackletestmaynotbe

appropriateandyouwouldneedaKarlFischer

testdoneonallsamplesfromthatmachine.

Thecrackleisnotascientifictestbutan

estimatethat

is

affected

by

oil

type.

KarlFischerorCrackle?

Herearesomequestionstothinkaboutto

helpyoudecidewhichtesttorequest:

Whatisthedetectionlimitforthe

test?

Doesthedetectionlimitchange

dependingonthelubricanttype?

Doyouknowwhatyourlimitsfor

watershouldbe?

Howimportantisittoknowany

watercontamination?

Aredetectionlimitsabovemy

condemnationlimits?

Thefollowingsectionsexplainthesideeffects

ofwaterinoilanddescribeastudyperformed

byTestOilanalyststomeasurethe

effectiveness

of

the

crackle

test.


5/7


Check Out The Limitations of The Crackle Test

Inanefforttocommunicatethelimitationsof

thecrackle

test

in

detecting

water

contamination,TestOilembarkedonalabstudy

touncovercrackledetectionlimits.Atotalof

493samplescomprisedofavarietyoflubricant

typeswererunona400Fhotplate.The

sampleswereassessedforapositiveor

negativecrackle.Thesesamesampleswere

thenanalyzedforwatercontaminationusinga

KarlFischer

titration

(ASTM

D6304

C).

The

waterresultswererecordedinpartspermillion

(ppm).Thetablebelowsummarizestheresults

ofthestudy.Thetablelistsoiltype,thenumber

ofsamplesinthestudy,thedetectionlimit

range,thelowestnegativecracklevalue,and

thehighestpositivecracklevalue.

Thelowestpositivevaluesrepresentthose

samplesthat

exhibited

apositive

crackle

and

theassociatedKarlFischerresultwhilethe

highestnegativevaluesrepresentthose

samplesthatclearlyhadwaterpresent

accordingtotheKarlFischerresults,yetdidnt

crackle. Clearly,thestudydemonstratesthat

quiteabitofvarianceexistsinthewater

detectionlimitofthecrackletest.Youreally

needto

know

your

lubricant

type

before

makingassumptionsonwhatthecracklecan

detect.Insomecases,yourwaterlimitsmayfall

belowcrackledetectionandrunningtheKarl

Fischertestoneverysamplemaybeworththe

cost.

OILTYPE SamplesTested DetectionLimit(ppm)Lowest

Positive(ppm)

Highest

Negative(ppm)

Turbine 111 110610 110 610

MineralGear 62 2401190 240 1190

SyntheticGear 86 100460 100 460

AWHydraulic 86 320750 320 750

PolyolEster 36 3401830 340 1830

PhosphateEster 37 4501140 450 1140

Engine

40

320580

320

580

WindTurbine

(Optigear) 35 7801070 780 1070

Combined 493 1001830 100 1830

Make sure you understand the detection l imits for thecrackle test and know your lubricants tolerance for water.


6/7


Quanti fying the Amount of Water: Karl Fischer Water Test

Ifacrackletest(seetheprecedingsection)is

positive,furthertestingisneededintheformof

theKarlFischerWaterTest.TheKarlFischer

coulometricmoisturetestisaseriesofchemical

reactionsdiscoveredin1935bytheGerman

chemistKarlFischer.Thismethodanalyzes

waterinthemicrogramorpartpermillion

range.Thistestisveryaccurate,to.001%.

WaterdeterminationbyKarlFischerisdefined

inASTM

D

6304.

Forthistest,asampleofoilisintroducedintoa

titrationvesselinknownmassorvolume.Any

waterpresentinthesamplewillreactwith

iodineinthetitrationvessel.Theamountof

iodinerequiredtoreactwiththewaterandthe

knownmassorvolumeofthesampleareused

tocalculate

the

amount

of

water

present

in

the

sample.Resultscanbeclearlyexpressedin

percentorpartspermillion.

Anelectriccurrentpassesthroughagenerator

containingaKarlFischersolution.Iodineis

producedattheanodethatconsumesthe

waterintheintroducedsample.Whenan

excessofiodineisdetected,theanalysisis

complete.Inchoosingthismethod,makesure

thattestspecimensarecompatiblewiththe

chosenreagentandthatnosidereactions

occur.Thismethodistypicallyusedtoanalyze

hydrocarbons,alcohols,andethers.Note:

AnalysisofketonesmustemployaKarlFischer

solutionthatisspecificallyformulatedfor

ketoneanalysis.

Lowlevelsofwater(lessthan2percent)are

typicallytheresultofcondensation.Higher

levelscanindicateasourceofwateringress.

Watercanenterasystemthroughseals,

breathers,hatches,

and

fill

caps.

Internal

leaks

fromheatexchangersandwaterjacketsare

otherpotentialsources.

Remember This...

Whenfreewaterispresentinoil,itposesa

seriousthreattotheequipment.Waterisavery

poorlubricantandpromotesrustandcorrosion

tothecomponents.Dissolvedwaterinanoil

promotesoiloxidationandreducestheload

handlingabilityoftheoil.Watercontamination

canalsocausetheoilsadditivepackageto

precipitate.Waterinanyformcauses

acceleratedwear,increasedfriction,andhigh

operatingtemperatures.Ifleftunchecked,

water

can

lead

to

premature

component

failure.


7/7

About TestOil

TestOilisafullserviceoiltestinglaboratory

ownedbyInsightServices. Since1988the

laboratoryhasbeenprovidingfastandreliable

oilanalysisresultsacrossallindustries

throughouttheAmericas.

Thefirmscomprehensiverangeofoilanalysis

servicesassistsreliabilityengineerswith

conditionmonitoringandidentificationof

machinewear.

TestOilemploysasophisticateddiagnostic

technologythatassiststheirMachineCondition

Analystsinmakingequipmentandlubrication

conditionassessments.

ContactUs

Call:2162512510

Email:[email protected]

Visitourwebsite:www.testoil.com

Visitourblog:http://oilanalysis.testoil.com/

Tweetusat:@testoil1

water in oil what's the big deal

Documents