Lubricants_Engineering chemistry.pdf
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May 09, 2023
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About This Presentation
From these slides you can understand basics about Lubricants, types of lubricants, lubrication mechanism, properties of lubricants
Slide Content
Lubricants
➢Introduction
➢Functionsoflubricants
➢Classificationoflubricants
➢Mechanismoflubrication
➢Propertiesoflubricants
➢Selectionoflubricants
Contents
➢Functionsoflubricants
➢Classificationoflubricants
➢Mechanismoflubrication
➢Propertiesoflubricants
➢Selectionoflubricants
Contents
Friction:Aresistantexperiencedbymetaltometalpartsinamachine,duetomovingorslidingsurfaces,
whichretardstheirmovementisknownasfriction.
Frictionalheat:Duetofrictionlargeamountofenergyliberatedintheformofheatwhichreducesthe
efficiencyofmachine.
WearandTearorsurfacedeformation:Appreciabledeformation(wornoutparticlesofsoftermetalbyhard
metal)inductilemetalsduringmotionofthemoving/slidingsurfaces.
whichretardstheirmovementisknownasfriction.
Frictionalheat:Duetofrictionlargeamountofenergyliberatedintheformofheatwhichreducesthe
efficiencyofmachine.
WearandTearorsurfacedeformation:Appreciabledeformation(wornoutparticlesofsoftermetalbyhard
metal)inductilemetalsduringmotionofthemoving/slidingsurfaces.
Seizure:Whentwosurfacestendtobecomeweldedtogetherbytheappreciableheatthatis
generated.
Lubricants:Anysubstanceswhichintroducebetweentwomovingorslidingsurfacewithaviewto
reducefrictionareknownasLubricants.
Lubrication:Theprocessbywhichfrictionbetweentwomovingorslidingsurfaceisreduce,known
asLubrication.
FractionalForce:Theforcerequiredtoovercometheresistancecreatedbytheinterlocking
asperitiesandtoslideoneblocktotheotherisknownasFractionalForce.
Thecoefficientoffriction=
??????��������??????������??????������??????��(??????)
����??????����??????�(�)
generated.
Lubricants:Anysubstanceswhichintroducebetweentwomovingorslidingsurfacewithaviewto
reducefrictionareknownasLubricants.
Lubrication:Theprocessbywhichfrictionbetweentwomovingorslidingsurfaceisreduce,known
asLubrication.
FractionalForce:Theforcerequiredtoovercometheresistancecreatedbytheinterlocking
asperitiesandtoslideoneblocktotheotherisknownasFractionalForce.
Thecoefficientoffriction=
??????��������??????������??????������??????��(??????)
����??????����??????�(�)
➢Thefirstandforemostfunctionofalubricantsisto
reducefriction.
➢Itreducewear,tearandsurfacedeformation.
➢Itactascoolanttocarryawayheat.
➢Itkeepoutdirt.
➢Sometimes,itactasasealingagent
➢Itreducemaintenanceandrunningcostasitprevents
fromrustandcorrosion.
➢Preventsforeignmatter(dirt)fromenteringbearingand
damagingthesmoothsurfaceofthejournalandbearing.
➢Itimprovestheefficiencyofthemachine.
Function of Lubricants
reducefriction.
➢Itreducewear,tearandsurfacedeformation.
➢Itactascoolanttocarryawayheat.
➢Itkeepoutdirt.
➢Sometimes,itactasasealingagent
➢Itreducemaintenanceandrunningcostasitprevents
fromrustandcorrosion.
➢Preventsforeignmatter(dirt)fromenteringbearingand
damagingthesmoothsurfaceofthejournalandbearing.
➢Itimprovestheefficiencyofthemachine.
Function of Lubricants
Classification of
Lubricants
Liquid
Lubricants
Solid
Lubricants
Semi-solid
lubricants
Lubricating Oils
Greases
Lubricants
Liquid
Lubricants
Solid
Lubricants
Semi-solid
lubricants
Lubricating Oils
Greases
❖Propertiesofgoodlubricatingoils
➢Highboilingpoint
➢Lowfreezingpoint
➢Adequateviscosityforproperfunctioninginservice
➢Highresistancetooxidationandheat
➢Non-corrosiveproperties
➢Stabilitytodecompositionattheoperatingtemperature
LiquidLubricants
❖Applicability
➢Mostly used
➢Used in delicate & light machines which works at high speed but under low pressure
➢Highboilingpoint
➢Lowfreezingpoint
➢Adequateviscosityforproperfunctioninginservice
➢Highresistancetooxidationandheat
➢Non-corrosiveproperties
➢Stabilitytodecompositionattheoperatingtemperature
LiquidLubricants
❖Applicability
➢Mostly used
➢Used in delicate & light machines which works at high speed but under low pressure
❖Types of liquid lubricants
❖Lubricating oils are further divided into four categories
1. Animal and vegetable oil
2. Mineral oil
3. Blended oil
4. Synthetic oil
❖Lubricating oils are further divided into four categories
1. Animal and vegetable oil
2. Mineral oil
3. Blended oil
4. Synthetic oil
1. Animal and Vegetable Oil
➢Possess Good oiliness property
➢Extracted directly from nature
➢They are very expensive
➢They can undergo oxidation very easily (gummy and acidic product)
➢With moisture → hydrolysis and with air → Thickened
➢They are used where there is heavy load
➢They are triglycerides of higher fatty acids
➢Examples : Olive Oil, Sunflower Oil, Coconut Oil, Castor oil, Cod-liver oil
➢Possess Good oiliness property
➢Extracted directly from nature
➢They are very expensive
➢They can undergo oxidation very easily (gummy and acidic product)
➢With moisture → hydrolysis and with air → Thickened
➢They are used where there is heavy load
➢They are triglycerides of higher fatty acids
➢Examples : Olive Oil, Sunflower Oil, Coconut Oil, Castor oil, Cod-liver oil
2.Mineral/petroleumOil
➢Obtainedbydistillationofpetroleum
➢Thesearebasicallylowermolecularweighthydrocarbonswith12-50Catoms
➢Shorterchainhavelowerviscosity
➢Mostwidelyused
➢Cheap,availableinabundanceandquitestableunderanyconditions
➢PossessPoorOilinessProperty
➢Oilinesscanbeimprovedbyaddinghighmolecularweightcompoundslikeoleicacid,
stearicacidortriglyceridesofhigherfattyacids
➢Obtainedbydistillationofpetroleum
➢Thesearebasicallylowermolecularweighthydrocarbonswith12-50Catoms
➢Shorterchainhavelowerviscosity
➢Mostwidelyused
➢Cheap,availableinabundanceandquitestableunderanyconditions
➢PossessPoorOilinessProperty
➢Oilinesscanbeimprovedbyaddinghighmolecularweightcompoundslikeoleicacid,
stearicacidortriglyceridesofhigherfattyacids
3.BlendedOil
➢Alsoknownascompoundedoils
➢Additivesareaddedtothelubricatingoilsinordertofurtherimprovetheirpropertiesoftherefined
lubricatingoils.
➢Theyareaddedinamountsupto10%.
❑Therearetwotypesoflubricantadditive
(A)Chemicallyactiveadditives
Chemicallyinteractwithmetalsandwithpolaroxidationanddegradationproducts(rust&corrosion
inhibitor)
(B)Chemicallyinertadditives
Improvesphysicalpropertiesofthelubricants(viscositymodifier)
➢Alsoknownascompoundedoils
➢Additivesareaddedtothelubricatingoilsinordertofurtherimprovetheirpropertiesoftherefined
lubricatingoils.
➢Theyareaddedinamountsupto10%.
❑Therearetwotypesoflubricantadditive
(A)Chemicallyactiveadditives
Chemicallyinteractwithmetalsandwithpolaroxidationanddegradationproducts(rust&corrosion
inhibitor)
(B)Chemicallyinertadditives
Improvesphysicalpropertiesofthelubricants(viscositymodifier)
4. Synthetic Oils
Used in harsh conditions
Highly stable
Temp range: 50 to 250 ℃
Polyglycol, silicon oils, esters
Applications –Engine, piston, gear, hydraulic break, turbine
Used in harsh conditions
Highly stable
Temp range: 50 to 250 ℃
Polyglycol, silicon oils, esters
Applications –Engine, piston, gear, hydraulic break, turbine
Semi-solidlubricantareobtainedbysaponificationoffatwithalkali,followedby
addinghotlubricatingoilunderagitation.
Thepropertiesofgreasedependuponthe
➢thenatureandmountofthickenerused
➢thecharacteristicsofthebaseoilused
➢thewayinwhichthegreaseisprepared
Mostofthecommongreasearemadewithsoapthickener(3%-50%)
Non-soapthickeners:carbonblack,silicagel,bentonite,finelydividedclay
Semi solid lubricants
Usedinconditionwhereoilcannotremaininplaceduetohighload,lowspeed,
suddenjerksetc.
addinghotlubricatingoilunderagitation.
Thepropertiesofgreasedependuponthe
➢thenatureandmountofthickenerused
➢thecharacteristicsofthebaseoilused
➢thewayinwhichthegreaseisprepared
Mostofthecommongreasearemadewithsoapthickener(3%-50%)
Non-soapthickeners:carbonblack,silicagel,bentonite,finelydividedclay
Semi solid lubricants
Usedinconditionwhereoilcannotremaininplaceduetohighload,lowspeed,
suddenjerksetc.
Composition
1.Base oil (75-90%)-Mineral oils, synthetic oil
2.Additives (up to 5%)-solid lubricants, Extreme pressure additives
3.Thickeners (5-20%)
a.Simple soap-Metal salts of fatty acid,
b.Complex soap-Simple soap + complexing agents (adipic acid, boric acid)
c.Non-soap thickeners (polyurea, organic clay, silica, Teflon)
1.Base oil (75-90%)-Mineral oils, synthetic oil
2.Additives (up to 5%)-solid lubricants, Extreme pressure additives
3.Thickeners (5-20%)
a.Simple soap-Metal salts of fatty acid,
b.Complex soap-Simple soap + complexing agents (adipic acid, boric acid)
c.Non-soap thickeners (polyurea, organic clay, silica, Teflon)
Ca-BasedGrease/Cup-Greases
Emulsionofpetroleumoilwithcalciumsoap.
1.Ca(OH)
2(10-30%)inhotoilswhileagitation
2.Insolubleinwater–waterresistant
3.Theyarethecheapest
4.Theycanevenbeusedatlowtemperatures
becauseabove80℃,soapstartstoseparate
USES:usedintractors,waterpumps,etc.
Na-Based
1.Petroleumoils→thickenedbyNasoap
2.Theyarenotwaterresistant.
3.Theycanbeusedupto175℃.
USES:
Theyareusedinballbearings.
Emulsionofpetroleumoilwithcalciumsoap.
1.Ca(OH)
2(10-30%)inhotoilswhileagitation
2.Insolubleinwater–waterresistant
3.Theyarethecheapest
4.Theycanevenbeusedatlowtemperatures
becauseabove80℃,soapstartstoseparate
USES:usedintractors,waterpumps,etc.
Na-Based
1.Petroleumoils→thickenedbyNasoap
2.Theyarenotwaterresistant.
3.Theycanbeusedupto175℃.
USES:
Theyareusedinballbearings.
Li-Based
Theyarepetroleumoilsthickenedby
mixinglithiumsoap
➢WaterResistant
➢Expensive
➢Thermallystable(150℃)
USES:
➢InAircraftApplications.
AxleGrease
➢Theyarecheapresingreasespreparedby
addinglimetoresin&fattyoils.
➢Theyarewater-resistant.
USES:
➢Theyareusedintheequipmentwhich
workunderhighload&lowspeed
Theyarepetroleumoilsthickenedby
mixinglithiumsoap
➢WaterResistant
➢Expensive
➢Thermallystable(150℃)
USES:
➢InAircraftApplications.
AxleGrease
➢Theyarecheapresingreasespreparedby
addinglimetoresin&fattyoils.
➢Theyarewater-resistant.
USES:
➢Theyareusedintheequipmentwhich
workunderhighload&lowspeed
Solid Lubricants
➢Graphite,molybdenumdisulphide(MoS
2),BoronNitride(BN)xarepredominantlyusedas
asolidlubricants.Theyareusedunderhightemperatureandhighpressure.
➢Coefficientoffriction=0.005to0.01
➢Whenlubricatingfilmcannotprotectedbyoilsandgreases
➢Itismostwidelyusedasasolidlubricant.Graphitehaslayer
structure;layersareheldtogetherwiththehelpofweak
VanderWaal’sforceswhichfacilitatetheeasyslidingof
onelayerontheotherlayer.
➢Itisverysoapytotouch,non-flammable.
➢Itisusedathighertemperaturearound450℃.
➢Theyareeitherusedaspowderformormixedwithoil
(oildag)water(aquadag)
➢Cannotworkinvacuum
1. Graphite
➢Graphite,molybdenumdisulphide(MoS
2),BoronNitride(BN)xarepredominantlyusedas
asolidlubricants.Theyareusedunderhightemperatureandhighpressure.
➢Coefficientoffriction=0.005to0.01
➢Whenlubricatingfilmcannotprotectedbyoilsandgreases
➢Itismostwidelyusedasasolidlubricant.Graphitehaslayer
structure;layersareheldtogetherwiththehelpofweak
VanderWaal’sforceswhichfacilitatetheeasyslidingof
onelayerontheotherlayer.
➢Itisverysoapytotouch,non-flammable.
➢Itisusedathighertemperaturearound450℃.
➢Theyareeitherusedaspowderformormixedwithoil
(oildag)water(aquadag)
➢Cannotworkinvacuum
1. Graphite
USES:
➢Aslubricantsinair-compressors,lathes,foodstuffsindustry,opengears,chains,railway
track-jointsetc.
➢Graphitemixedwithgrease(graphite-grease)isusedathighertemperatures.
➢Oildagisusedininternalcombustionengines&Aquadagisusedinfoodstuffsindustries.
➢Aslubricantsinair-compressors,lathes,foodstuffsindustry,opengears,chains,railway
track-jointsetc.
➢Graphitemixedwithgrease(graphite-grease)isusedathighertemperatures.
➢Oildagisusedininternalcombustionengines&Aquadagisusedinfoodstuffsindustries.
➢Itissandwichlikestructureinwhichhexagonallayer
ofmolybdenum(Mo)liesbetweenhexagonallayerof
Sulfur(S)atom.
➢MoS
2haveverylowcoefficientoffriction.
➢Likegraphiteeachlayerareheldtogetherwithweak
VanderWaal’sforces.
➢Itisusedathighertemperaturearound400℃.
➢Usedinspacevehicles(70%MoS
2+7%Graphite+
23%silicates)–[email protected].
Nuclearradiation.
2. MoS
2 (Molybdenum disulphide)
ofmolybdenum(Mo)liesbetweenhexagonallayerof
Sulfur(S)atom.
➢MoS
2haveverylowcoefficientoffriction.
➢Likegraphiteeachlayerareheldtogetherwithweak
VanderWaal’sforces.
➢Itisusedathighertemperaturearound400℃.
➢Usedinspacevehicles(70%MoS
2+7%Graphite+
23%silicates)–[email protected].
Nuclearradiation.
2. MoS
2 (Molybdenum disulphide)
1.ThickFilm/Fluidfilm/HydrodynamicLubrication
➢Inthistypeacontinuousfluidfilmexistsbetweentheslidingsurfaces
➢Employedwhentheslidingvelocityismoderateandloadislow
➢Twoslidingsurfacesareseparatedfromeachotherbyathickfilmoffluid
(Hydrocarbonoil).
➢Antioxidants(aminophenol)tobeblendedwithhydrocarbonoiltoavoid
oxidation.
➢Filmthicknessis≥1000ºA
➢Anincreaseinspeedorviscosityincreasesoilfilmthickness.
➢Anincreaseinloaddecreasesoilfilmthickness.
≥1000ºA
Hydro-liquid,
Dynamic-Relativemotion
Mechanism of Lubrication
➢Inthistypeacontinuousfluidfilmexistsbetweentheslidingsurfaces
➢Employedwhentheslidingvelocityismoderateandloadislow
➢Twoslidingsurfacesareseparatedfromeachotherbyathickfilmoffluid
(Hydrocarbonoil).
➢Antioxidants(aminophenol)tobeblendedwithhydrocarbonoiltoavoid
oxidation.
➢Filmthicknessis≥1000ºA
➢Anincreaseinspeedorviscosityincreasesoilfilmthickness.
➢Anincreaseinloaddecreasesoilfilmthickness.
≥1000ºA
Hydro-liquid,
Dynamic-Relativemotion
Mechanism of Lubrication
➢Coefficientoffrictionisaslowas0.001to0.03forthickfilmlubricationincomparisonto0.5to1.5forunlubricated
surfaces
➢Findsapplicationinwatches,clocksandscientificinstrument(stopwatches)
➢Hydrodynamiclubricationoftenoccursincomponentssuchascylinders,gears,andplainbearings
➢Factorswhichaffectthethicknessofhydrodynamicfluidfilmincludelubricantviscosity,rotationspeedorRPM,
oilsupplypressureandcomponentloading.
Viscosity
Toohigh–Lubricantwillcreatefriction
Toolow–Lubricantwillnotbeableto
maintainthicklayer
surfaces
➢Findsapplicationinwatches,clocksandscientificinstrument(stopwatches)
➢Hydrodynamiclubricationoftenoccursincomponentssuchascylinders,gears,andplainbearings
➢Factorswhichaffectthethicknessofhydrodynamicfluidfilmincludelubricantviscosity,rotationspeedorRPM,
oilsupplypressureandcomponentloading.
Viscosity
Toohigh–Lubricantwillcreatefriction
Toolow–Lubricantwillnotbeableto
maintainthicklayer
2.BoundaryLubrication/Thinfilm
➢Boundarylubricationoftenoccursduringthestartupand
shutdownofequipment,orwhenloadingbecomesexcessive.
➢Lowspeed,highload&noncontinuousoperation
➢Thicknessis<700ºA
➢Coefficientoffrictionis0.05–0.15.
➢FilmformationbyeitherPhysisorptionorchemisorption
➢Oilinessshouldbehigh
➢Fattyacidsandtheirsoapsareusedasadditives
➢Usedinautomobilesandheavymachinery
➢Certaintypesofgearsetsthatneedtowithstandslidingpressures
andshockloading,suchashypoidgearsuseboundarylubricants
Adsorbed molecule
Specimen
Active/Polar group
Hydrocarbon chain
Boundary Lubricants-90% Mineral oil
10% Vegetable oil
Graphite, MoS
2
Mineral oil
Vegetable oil and animal oil
Used for boundary lubrication
➢Boundarylubricationoftenoccursduringthestartupand
shutdownofequipment,orwhenloadingbecomesexcessive.
➢Lowspeed,highload&noncontinuousoperation
➢Thicknessis<700ºA
➢Coefficientoffrictionis0.05–0.15.
➢FilmformationbyeitherPhysisorptionorchemisorption
➢Oilinessshouldbehigh
➢Fattyacidsandtheirsoapsareusedasadditives
➢Usedinautomobilesandheavymachinery
➢Certaintypesofgearsetsthatneedtowithstandslidingpressures
andshockloading,suchashypoidgearsuseboundarylubricants
Adsorbed molecule
Specimen
Active/Polar group
Hydrocarbon chain
Boundary Lubricants-90% Mineral oil
10% Vegetable oil
Graphite, MoS
2
Mineral oil
Vegetable oil and animal oil
Used for boundary lubrication
3.ExtremePressureLubricants
➢Extremepressurelubricantsinteractwithmetalsurfacesina
chemicalprocess,atmolecularlevel,tocreateaprotective
compoundwhichincreasesthethermalstabilityofmetal
surfaces.
➢Thisisnotafilmorcoatingoverthemetal.Itisapermanent
modificationofthemetalsurface
➢Moleculesintheextremepressurelubricantsarepolarizedand
actuallybondwiththemetalsurface
➢ItisapplicableinHighloadandhighspeedcondition
➢Co-efficientoffriction0.1-0.4
➢Extremepressurelubricantsinteractwithmetalsurfacesina
chemicalprocess,atmolecularlevel,tocreateaprotective
compoundwhichincreasesthethermalstabilityofmetal
surfaces.
➢Thisisnotafilmorcoatingoverthemetal.Itisapermanent
modificationofthemetalsurface
➢Moleculesintheextremepressurelubricantsarepolarizedand
actuallybondwiththemetalsurface
➢ItisapplicableinHighloadandhighspeedcondition
➢Co-efficientoffriction0.1-0.4
➢Metalsurfaceshouldbeactive(Fe,Cuetc.,)
➢Chlorinatedester/Sulphurisedoils/Tricresylphosphateareusedasanextremepressureadditives.
➢Surfacecompoundsisformedduetochemisorption(e.g.sulphurisedoilcontaininglubricantsreactswithIron
andformsIronsulphide(FeS)whosethermalstability(≈1100℃)isbetterthanmereiron)
➢Thethicknessofthesurfacecompoundisafewmoleculelayer
➢Uniquecharacterofthistypeoflubricantsisitsreplenishability/easyofreplacement
➢ItfindsapplicationinAircraftsandspacecrafts
➢Chlorinatedester/Sulphurisedoils/Tricresylphosphateareusedasanextremepressureadditives.
➢Surfacecompoundsisformedduetochemisorption(e.g.sulphurisedoilcontaininglubricantsreactswithIron
andformsIronsulphide(FeS)whosethermalstability(≈1100℃)isbetterthanmereiron)
➢Thethicknessofthesurfacecompoundisafewmoleculelayer
➢Uniquecharacterofthistypeoflubricantsisitsreplenishability/easyofreplacement
➢ItfindsapplicationinAircraftsandspacecrafts
FOR OILS
•Viscosity and Viscosity Index
•Cloud and Pour-Point
•Flash and Fire-Point
•Aniline Point
•Oiliness
•Saponification number
•Steam Emulsion Number (SEN)
•Carbon Residue
FOR GREASE
•Penetration Index
•Drop Point
Properties of Lubricants
•Viscosity and Viscosity Index
•Cloud and Pour-Point
•Flash and Fire-Point
•Aniline Point
•Oiliness
•Saponification number
•Steam Emulsion Number (SEN)
•Carbon Residue
FOR GREASE
•Penetration Index
•Drop Point
Properties of Lubricants
❖Viscosity&ViscosityIndex
➢Propertyofaliquidorfluidbyvirtueofwhichitopposerelativemotionbetweenits
differentlayersisknownasviscosityorinternalfrictionofliquid.
➢Aliquidinastateofsteadyflowonasurfacemaybesupposedtoconsistofaseriesof
parallellayersmovingoneabovetheother.
➢Measureofinternalresistancetoflow
➢ViscositycanbemeasuredbyRedwood/Saybolt/Englerviscometer.
❖TherearetwoTypesofviscosity:
➢–KinematicViscosity
➢–AbsoluteViscosity
Viscosity&ViscosityIndex
➢Propertyofaliquidorfluidbyvirtueofwhichitopposerelativemotionbetweenits
differentlayersisknownasviscosityorinternalfrictionofliquid.
➢Aliquidinastateofsteadyflowonasurfacemaybesupposedtoconsistofaseriesof
parallellayersmovingoneabovetheother.
➢Measureofinternalresistancetoflow
➢ViscositycanbemeasuredbyRedwood/Saybolt/Englerviscometer.
❖TherearetwoTypesofviscosity:
➢–KinematicViscosity
➢–AbsoluteViscosity
Viscosity&ViscosityIndex
➢Any two layers will move with different velocities; top layer moves faster than the next
layer due to internal friction.
➢Newton proved that the backward dragging or viscous force, acting tangentially on any
liquid layer, is directly proportional to its surface area (A), and velocity (ʋ) and inversely
proportional to its distance (x)from the stationary layer.
➢Denoting this force by F, we have
F = -η
??????ʋ
�
η= coefficient of viscosity
➢Now,
ʋ
�
may be put as
�ʋ
��
, which gives the rate of changes of velocity with distance and its
called the velocity gradient.
layer due to internal friction.
➢Newton proved that the backward dragging or viscous force, acting tangentially on any
liquid layer, is directly proportional to its surface area (A), and velocity (ʋ) and inversely
proportional to its distance (x)from the stationary layer.
➢Denoting this force by F, we have
F = -η
??????ʋ
�
η= coefficient of viscosity
➢Now,
ʋ
�
may be put as
�ʋ
��
, which gives the rate of changes of velocity with distance and its
called the velocity gradient.
➢IfA=1,
�ʋ
��
=1thenF=η.Hence,coefficientofviscosity(η)maybedefinedas“the
tangentialforcerequiredperunitareatomaintainaunitvelocitygradientbetweentwo
parallellayers”.ThiscoefficientofviscositymayalsoreferredasaDynamicviscosity.
➢Ontheotherhand,theratio
η
δ
(whereδisdensityoftheliquid)iscalledkinematic
viscosity.
❖Significanceofviscosity
i)Iftheviscosityoftheoilistoolow,aliquidoilfilmcannotbemaintainedbetweentwo
moving/slidingsurfacesassresultofwhichexcessivewearmaytakeplace.
ii)Iftheviscosityoftheoilistoohigh,excessivefrictionwillresult.
�ʋ
��
=1thenF=η.Hence,coefficientofviscosity(η)maybedefinedas“the
tangentialforcerequiredperunitareatomaintainaunitvelocitygradientbetweentwo
parallellayers”.ThiscoefficientofviscositymayalsoreferredasaDynamicviscosity.
➢Ontheotherhand,theratio
η
δ
(whereδisdensityoftheliquid)iscalledkinematic
viscosity.
❖Significanceofviscosity
i)Iftheviscosityoftheoilistoolow,aliquidoilfilmcannotbemaintainedbetweentwo
moving/slidingsurfacesassresultofwhichexcessivewearmaytakeplace.
ii)Iftheviscosityoftheoilistoohigh,excessivefrictionwillresult.
❑Viscosity-TemperatureRelation
➢Viscosityofliquidsdecreaseswithincreasingtemperature
➢Consequently,thelubricatingoilbecomesthinnerastheoperatingtemperature
increases
➢Hence,viscosityofagoodlubricatingoilshouldnotchangemuchwithchange
intemperature
➢Viscosityofliquidsdecreaseswithincreasingtemperature
➢Consequently,thelubricatingoilbecomesthinnerastheoperatingtemperature
increases
➢Hence,viscosityofagoodlubricatingoilshouldnotchangemuchwithchange
intemperature
❑ViscosityIndex
➢Therateatwhichtheviscosityofanoilchangeswithtemperatureismeasuredby
anarbitraryscale
➢Iftheviscosityofanoilfallsrapidlyasthetemperatureisraised,ithaslow
viscosityindex
➢Iftheviscosityofanoilslightlyaffectedonrisingthetemperature,ithashigh
viscosityindex
➢Foragoodlubricatingoilviscosity-indexshouldbeHIGH
➢Therateatwhichtheviscosityofanoilchangeswithtemperatureismeasuredby
anarbitraryscale
➢Iftheviscosityofanoilfallsrapidlyasthetemperatureisraised,ithaslow
viscosityindex
➢Iftheviscosityofanoilslightlyaffectedonrisingthetemperature,ithashigh
viscosityindex
➢Foragoodlubricatingoilviscosity-indexshouldbeHIGH
❑DeterminationofViscosityIndex
➢Twotypesofstandardoils,Paraffinic-basePennysylvanianoils(VI=100)and
NaphthanicbaseGulfoils(VI=0)areused
➢Againsteachoftheseismarkedtheirviscositiesat100°Fand210°F
➢FormerareknownasH-oilsandlatterasL-oils
➢Followingstepsinvolved:
✓Theviscositiesoftheoilundertestat100°Fandalsoat210°Farefirstfoundout,letthesevaluesbe
UandVrespectively.Thedifferencebetweenthetwovaluesshouldbelow,iftheoilisgood.
✓NowfromthelistofH-oils(VI=100),theoilwhichasthesameviscosityat210°Fastheoilunder-
testisselected,anditscorrespondingviscosityat100°Fisdetermine:sayH
✓Then,fromthelistofL-oils(VI=0),theoilwhichassameviscosityat100°Fisdetermine:sayL
➢Twotypesofstandardoils,Paraffinic-basePennysylvanianoils(VI=100)and
NaphthanicbaseGulfoils(VI=0)areused
➢Againsteachoftheseismarkedtheirviscositiesat100°Fand210°F
➢FormerareknownasH-oilsandlatterasL-oils
➢Followingstepsinvolved:
✓Theviscositiesoftheoilundertestat100°Fandalsoat210°Farefirstfoundout,letthesevaluesbe
UandVrespectively.Thedifferencebetweenthetwovaluesshouldbelow,iftheoilisgood.
✓NowfromthelistofH-oils(VI=100),theoilwhichasthesameviscosityat210°Fastheoilunder-
testisselected,anditscorrespondingviscosityat100°Fisdetermine:sayH
✓Then,fromthelistofL-oils(VI=0),theoilwhichassameviscosityat100°Fisdetermine:sayL
�??????����??????�������=
??????−�
??????−�
���
U: viscosity at 100°F of the test oil (sample)
L: viscosity at 100°F of the low-viscosity standard oil
H: viscosity at 100°F of the high-viscosity standard oil
Graphical sketch of Redwood viscometer
??????−�
??????−�
���
U: viscosity at 100°F of the test oil (sample)
L: viscosity at 100°F of the low-viscosity standard oil
H: viscosity at 100°F of the high-viscosity standard oil
Graphical sketch of Redwood viscometer
Name the three viscometers help in calculating viscosity index.
A lubricating oil has same redwood viscosity of 75s at 210 F as that of standard naphthenic and paraffinic oils.
Their viscosities at 100 F are 462s, 758s and 452s respectively. Find the viscosity index of oil. Comment on a
quality of a sample oil based on the value of viscosity index.
��=
??????−�
??????−�
x100
��=
758−462
758−452
x100= 96.7
758-75= H
452-75= L
462-75= U
AnoilsamplehasEnglerviscosityof123sat210Fand610sat100F.Thehighandlowviscositystdoilshave
Englerviscositiesof123sat210Fand420s&758sat100Frespectively.Calculatetheviscosityindexoftheoil
undertest.
��=
??????−�
??????−�
x100
��=
758−610
758−420
x100= 43.8
DrawthemodeofvariationofviscositywithtemperatureofL,UandHoils.Alubricatingoilhassameviscosity
asstandardnaphthenicandparaffinicoilsat210F.theirviscositiesat100Fare320s,430sand260srespectively.
Findtheviscosityindexoftheoil.
Viscosity and Viscosity Index Numerical
A lubricating oil has same redwood viscosity of 75s at 210 F as that of standard naphthenic and paraffinic oils.
Their viscosities at 100 F are 462s, 758s and 452s respectively. Find the viscosity index of oil. Comment on a
quality of a sample oil based on the value of viscosity index.
��=
??????−�
??????−�
x100
��=
758−462
758−452
x100= 96.7
758-75= H
452-75= L
462-75= U
AnoilsamplehasEnglerviscosityof123sat210Fand610sat100F.Thehighandlowviscositystdoilshave
Englerviscositiesof123sat210Fand420s&758sat100Frespectively.Calculatetheviscosityindexoftheoil
undertest.
��=
??????−�
??????−�
x100
��=
758−610
758−420
x100= 43.8
DrawthemodeofvariationofviscositywithtemperatureofL,UandHoils.Alubricatingoilhassameviscosity
asstandardnaphthenicandparaffinicoilsat210F.theirviscositiesat100Fare320s,430sand260srespectively.
Findtheviscosityindexoftheoil.
Viscosity and Viscosity Index Numerical
➢Whenapetroleumoiliscooled,itbecomescloudyafirstandthensolidifies.
➢WhentheoiliscooledexternallyundertheconditionsprescribedbyASTM,thetemperatureatwhichtheoil
becomescloudyorhazyinappearance,itiscalledcloudpoint.
➢ThePourPointisthelowesttemperatureatwhichtheoilwillpourorflowwhencooledwithoutanydisturbance
totheoil.Ifisalsodefinedasthetemperatureatwhichanoilwillnolongerflowfrom&standardtesttube.
Importance/significance:
➢Cloudandpourpointsgivethesuitabilityoflubricantsincoldenvironments.
➢Pourpointdeterminesthesuitabilityofalubricantorahydraulicoilforlowtemperatureinstallations.For
exampleaircraftenginesandrefrigeratorplants,whichmaybeneeded'tostartandoperateatsubzero
temperatures.
➢Lubricantusedinamachineworkingatlowtemperaturesshouldhavelowpourpoint;otherwisesolidificationof
lubricantwillleadjammingofthemachine.
➢Thepresenceofwaxesinthelubricatingoilincreasesthepourpoint.
➢Polyalkylbenzene,isapourpointdepressant
CLOUD POINT and POUR POINT
➢WhentheoiliscooledexternallyundertheconditionsprescribedbyASTM,thetemperatureatwhichtheoil
becomescloudyorhazyinappearance,itiscalledcloudpoint.
➢ThePourPointisthelowesttemperatureatwhichtheoilwillpourorflowwhencooledwithoutanydisturbance
totheoil.Ifisalsodefinedasthetemperatureatwhichanoilwillnolongerflowfrom&standardtesttube.
Importance/significance:
➢Cloudandpourpointsgivethesuitabilityoflubricantsincoldenvironments.
➢Pourpointdeterminesthesuitabilityofalubricantorahydraulicoilforlowtemperatureinstallations.For
exampleaircraftenginesandrefrigeratorplants,whichmaybeneeded'tostartandoperateatsubzero
temperatures.
➢Lubricantusedinamachineworkingatlowtemperaturesshouldhavelowpourpoint;otherwisesolidificationof
lubricantwillleadjammingofthemachine.
➢Thepresenceofwaxesinthelubricatingoilincreasesthepourpoint.
➢Polyalkylbenzene,isapourpointdepressant
CLOUD POINT and POUR POINT
FlashandFirePoint
➢Theminimumtemperatureatwhichtheoilgivesoff
sufficientvapourstoigniteforamoment(flash),whena
flameisbroughtnearthesurfaceoftheoil,calledits
FLASHPOINT.
➢Thelowestatwhichthevapoursoftheoilburncontinuously
foratleast5seconds,calleditsFIREPOINT.
Goodlubricantshouldhavehigherflashpointw.r.t
workingtemperature
FlashandFirePoint
➢Theminimumtemperatureatwhichtheoilgivesoff
sufficientvapourstoigniteforamoment(flash),whena
flameisbroughtnearthesurfaceoftheoil,calledits
FLASHPOINT.
➢Thelowestatwhichthevapoursoftheoilburncontinuously
foratleast5seconds,calleditsFIREPOINT.
Goodlubricantshouldhavehigherflashpointw.r.t
workingtemperature
FlashandFirePoint
Definition:
Theminimumequilibriumsolutiontemperaturefor
equalvolumesofanilineandoilsample.
Significance:
➢Itgivesanindicationofthepossibletendencyof
deteriorationofanoilwhenitcomeincontactwithrubber
sealing,packingetc.
➢Aromatichydrocarbonshaveatendencytodissolvenatural
andcertainsyntheticrubbers.Ahigheranilinepoint
suggestslowerpercentageofaromatichydrocarbonsand
henceitisdesirable.
Anilinepoint
AnilinepointApparatus
Theminimumequilibriumsolutiontemperaturefor
equalvolumesofanilineandoilsample.
Significance:
➢Itgivesanindicationofthepossibletendencyof
deteriorationofanoilwhenitcomeincontactwithrubber
sealing,packingetc.
➢Aromatichydrocarbonshaveatendencytodissolvenatural
andcertainsyntheticrubbers.Ahigheranilinepoint
suggestslowerpercentageofaromatichydrocarbonsand
henceitisdesirable.
Anilinepoint
AnilinepointApparatus
Working
➢Itisdeterminedbythoroughlymixingmechanicallyequalvolumesofanilineandtheoilsamplein
atesttube.
➢Themixtureisheated,tillhomogeneoussolutionisreached.Then,thetubeisallowedtocoolata
controlledrate.
➢Thetemperaturecorrespondingtotwophases(oilandaniline)separateoutisreportedastheaniline
point.
➢Itisdeterminedbythoroughlymixingmechanicallyequalvolumesofanilineandtheoilsamplein
atesttube.
➢Themixtureisheated,tillhomogeneoussolutionisreached.Then,thetubeisallowedtocoolata
controlledrate.
➢Thetemperaturecorrespondingtotwophases(oilandaniline)separateoutisreportedastheaniline
point.
Saponification value
Definition:ThenumberofmilligramofKOHrequiretoneutralizethefattyacidsresultingfromthe
completehydrolysisof1goffat.
Significance
Itgivestheamountoffattymaterialspresentinoil.
Typesofoilcanbedifferentiated.
Adulterationofoilcanbeidentified.
Alowersaponificationnumberisdesirable.
Definition:ThenumberofmilligramofKOHrequiretoneutralizethefattyacidsresultingfromthe
completehydrolysisof1goffat.
Significance
Itgivestheamountoffattymaterialspresentinoil.
Typesofoilcanbedifferentiated.
Adulterationofoilcanbeidentified.
Alowersaponificationnumberisdesirable.
Procedure
❖Standardizationof0.5NKOHsolution
✓Pipette20mlof0.1Mhydrochloricacidintoflask
✓Dilutewith50mlofwaterandadd0.1mlofphenolphthaleinsolution
✓Titratewiththeethanolicpotassiumhydroxidesolutionuntilapermanentpalepinkcolourisproduced.
❖DeterminationofSaponification
✓Accuratelyweight1gmofsample(fatoroil)Transferintoaroundbottomflask
✓Add25mlof0.5NKOHsolutionandattachedtoarefluxcondenser.
✓Setanotherrefluxcondenserasblankwitheverythingpresentexceptthefat
✓Heatbothflasksonaboilingwaterbathfor30min
✓Leavetocooltoroomtemperatureandtitratewith0.5MHCLandusephenolphthaleinasindicator
✓Untilthepinkcolordisappears
✓Recordyourreadingas(T)mlfortest(B)mlforblank
❖Standardizationof0.5NKOHsolution
✓Pipette20mlof0.1Mhydrochloricacidintoflask
✓Dilutewith50mlofwaterandadd0.1mlofphenolphthaleinsolution
✓Titratewiththeethanolicpotassiumhydroxidesolutionuntilapermanentpalepinkcolourisproduced.
❖DeterminationofSaponification
✓Accuratelyweight1gmofsample(fatoroil)Transferintoaroundbottomflask
✓Add25mlof0.5NKOHsolutionandattachedtoarefluxcondenser.
✓Setanotherrefluxcondenserasblankwitheverythingpresentexceptthefat
✓Heatbothflasksonaboilingwaterbathfor30min
✓Leavetocooltoroomtemperatureandtitratewith0.5MHCLandusephenolphthaleinasindicator
✓Untilthepinkcolordisappears
✓Recordyourreadingas(T)mlfortest(B)mlforblank
Saponificationvalue=
(���������??????��−����������??????��)x������??????����??????????????????x56.1
��??????�ℎ����??????�������(��)
�??????���??????�??????�??????�??????���??????���=�−�×??????×56.1/��.���??????�
(���������??????��−����������??????��)x������??????����??????????????????x56.1
��??????�ℎ����??????�������(��)
�??????���??????�??????�??????�??????���??????���=�−�×??????×56.1/��.���??????�
Definethesaponificationnumber.3.0gofoilwassaponifiedwith75mlN/10alcoholicKOHsolution.
Afterrefluxingforonehourthemixturewastitratedby15mlof0.1NHCl.Ablankexperimentwas
takingtheoilandonrepeatingthesameproceduregaveatitrevalueof70ml.Calthesaponificationvalue
oftheoilsample.Howcanwesuggestthattheoilisvegetableoilormineraloilonthebasisofthis
number?
�??????���??????�??????�??????�??????���??????���=�−�×??????×56.1/��.���??????�
�??????���??????�??????�??????�??????���??????���=70−15×0.1×56.1/3
�??????���??????�??????�??????�??????���??????���=���.�
Definethesaponificationnumber.8.0gmofanoilwassaponifiedusingexcessof0.5alcoholicKOH
solution.Themixturerequired50mlof0.5HCl.Afterrefluxingforonehourthemixturewastitratedby
25mlofN/2HCl.Calculatethesaponificationvalueoftheoilsample.
�??????���??????�??????�??????�??????���??????���=��.��
Saponification value numerical
Afterrefluxingforonehourthemixturewastitratedby15mlof0.1NHCl.Ablankexperimentwas
takingtheoilandonrepeatingthesameproceduregaveatitrevalueof70ml.Calthesaponificationvalue
oftheoilsample.Howcanwesuggestthattheoilisvegetableoilormineraloilonthebasisofthis
number?
�??????���??????�??????�??????�??????���??????���=�−�×??????×56.1/��.���??????�
�??????���??????�??????�??????�??????���??????���=70−15×0.1×56.1/3
�??????���??????�??????�??????�??????���??????���=���.�
Definethesaponificationnumber.8.0gmofanoilwassaponifiedusingexcessof0.5alcoholicKOH
solution.Themixturerequired50mlof0.5HCl.Afterrefluxingforonehourthemixturewastitratedby
25mlofN/2HCl.Calculatethesaponificationvalueoftheoilsample.
�??????���??????�??????�??????�??????���??????���=��.��
Saponification value numerical
➢Oilinessofalubricantisameasureofitscapacitytostickontothesurfacesofmachineparts,under
conditionsofheavypressureorload.
➢Whenalubricatingoilofpooroilinessissubjectedtohighpressure,ithasatendencytobesqueezedout
ofthelubricatedmachineparts,therebyitslubricationactionstops.
➢Ontheotherhand,lubricants,whichhavegoodoilinessstayin-betweenthelubricatedsurfaces,when
theyaresubjectedtohighpressure.
➢Oilinessisveryimportantpropertyoflubricants,particularlyforextreme-pressurelubrication.
➢Mineraloilshavegotverypooroiliness;whilevegetableoilshavegoodoiliness.So,inorderto
improvetheoilinessofmineraloils,additiveslikevegetableoilsandhigherfattyacids(suchasoleicand
stearicacids)areaddedtothem.
➢Nodirecttestisavailableformeasuringoiliness.
Oiliness
conditionsofheavypressureorload.
➢Whenalubricatingoilofpooroilinessissubjectedtohighpressure,ithasatendencytobesqueezedout
ofthelubricatedmachineparts,therebyitslubricationactionstops.
➢Ontheotherhand,lubricants,whichhavegoodoilinessstayin-betweenthelubricatedsurfaces,when
theyaresubjectedtohighpressure.
➢Oilinessisveryimportantpropertyoflubricants,particularlyforextreme-pressurelubrication.
➢Mineraloilshavegotverypooroiliness;whilevegetableoilshavegoodoiliness.So,inorderto
improvetheoilinessofmineraloils,additiveslikevegetableoilsandhigherfattyacids(suchasoleicand
stearicacids)areaddedtothem.
➢Nodirecttestisavailableformeasuringoiliness.
Oiliness
✓Thepropertyofoilstogetmixedwithwaterknownasemulsification.Emulsionspronetoattractdirt,grit,
foreignmatteretc,asaresultofwhichabrasionandwearingoutofthelubricatedpartsofthemachinery
maytakeplace.
✓Therefore,itisessentialthatthelubricatingoilshouldformsuchanemulsionwithwaterthatbreaksoff
easilyi.e.demulsified.
✓ThecapacityoflubricatingoiltodetachfromwateriscalledDemulsibility.
✓Thenumberofsecondsrequiredforoiltoseparatewhenitisemulsifiedandseparatedunderspecified
conditionsisrecordedassteamemulsionnumber(SEN).
✓Unit:seconds
✓Forgoodlubricantitshouldbeless
✓Toindicatestheformationofstableemulsionornot
✓Goodlubricatingoilsneverformstableemulsion
SteamEmulsionNumber(SEN)
foreignmatteretc,asaresultofwhichabrasionandwearingoutofthelubricatedpartsofthemachinery
maytakeplace.
✓Therefore,itisessentialthatthelubricatingoilshouldformsuchanemulsionwithwaterthatbreaksoff
easilyi.e.demulsified.
✓ThecapacityoflubricatingoiltodetachfromwateriscalledDemulsibility.
✓Thenumberofsecondsrequiredforoiltoseparatewhenitisemulsifiedandseparatedunderspecified
conditionsisrecordedassteamemulsionnumber(SEN).
✓Unit:seconds
✓Forgoodlubricantitshouldbeless
✓Toindicatestheformationofstableemulsionornot
✓Goodlubricatingoilsneverformstableemulsion
SteamEmulsionNumber(SEN)
❑Processtocalculatesteamemulsionnumber
➢Firstofall20mlofoilistakenintesttube.
➢Thensteamof100Cispassedthroughitsothat
temperaturerisesto90Candvolumebecome40ml.
➢Thentubeisplacedinabathtomaintainitstemp.at90C
andthentimeinsecisnoted,whenlayerofwaterandoil
aredistinctlyseparated.
➢Firstofall20mlofoilistakenintesttube.
➢Thensteamof100Cispassedthroughitsothat
temperaturerisesto90Candvolumebecome40ml.
➢Thentubeisplacedinabathtomaintainitstemp.at90C
andthentimeinsecisnoted,whenlayerofwaterandoil
aredistinctlyseparated.
Carbonresidue
➢Lubricatingoilscontainhighpercentageofcarbonincombinedform.Onheating,theydecompose
depositingacertainamountofcarbon.
➢Thedepositionofsuchcarboninmachineisintolerable,particularlyininternalcombustionengines
andair-compressors.
➢Agoodlubricantshoulddepositleastamountofthecarboninuse.
➢ThedeterminationofcarbonresidueiscarriedoutbyConradsonandRamsbottommethods.Aknown
weightoftheoilisallowedtoevaporateandundergopyrolysisunderaprescribedsetofconditions.
Thecarbonaceousresidueisreportedaspercentagebyweightofthesample.
➢Thesetestspredictthecarbon-depositingtendenciesofoils,underconstantconditionsofoperationand
oilconsumptions.
Carbonresidue
➢Lubricatingoilscontainhighpercentageofcarbonincombinedform.Onheating,theydecompose
depositingacertainamountofcarbon.
➢Thedepositionofsuchcarboninmachineisintolerable,particularlyininternalcombustionengines
andair-compressors.
➢Agoodlubricantshoulddepositleastamountofthecarboninuse.
➢ThedeterminationofcarbonresidueiscarriedoutbyConradsonandRamsbottommethods.Aknown
weightoftheoilisallowedtoevaporateandundergopyrolysisunderaprescribedsetofconditions.
Thecarbonaceousresidueisreportedaspercentagebyweightofthesample.
➢Thesetestspredictthecarbon-depositingtendenciesofoils,underconstantconditionsofoperationand
oilconsumptions.
Carbonresidue
1.DropPoint
➢Definedasthetemperatureatwhichgreasepassesfromthesemi-solidtotheliquidstate
➢Upperlimittempfortheapplicabilityofthegrease
Droppingpointofagreaseisthe
temperatureatwhichadropof
greasefallsfromtheorificeof
thetestthimblesizecupundera
prescribedrampedtemperature
Properties of lubricating grease
➢Definedasthetemperatureatwhichgreasepassesfromthesemi-solidtotheliquidstate
➢Upperlimittempfortheapplicabilityofthegrease
Droppingpointofagreaseisthe
temperatureatwhichadropof
greasefallsfromtheorificeof
thetestthimblesizecupundera
prescribedrampedtemperature
Properties of lubricating grease
2.PenetrationIndex
Consistencyoryieldvalueisexpressedintermsofpenetration,whichis
definedas"thedistanceintenthofmillimeterthatastandardcone
penetratesverticallyintothesample,underthestandardconditionsofload,
temperatureandtime"'.Thevalueofload,temperatureandtimearetaken
respectivelyas150g,25°C,and5seconds.Consistencyofagrease
dependsonthestructureandinteractionofthegellingelementsinitandto
someextentontheviscosityofoilused.Theconsistencyisdeterminedby
using"Penetrometer'showninFig.
Theapparatusconsistsof:
(i)Heavybase,whichisprovidedwithspiritlevel,levellingscrewsanda
plaintable,overwhichaboxcontainingthegreaseunder-testisplaced.
Consistencyoryieldvalueisexpressedintermsofpenetration,whichis
definedas"thedistanceintenthofmillimeterthatastandardcone
penetratesverticallyintothesample,underthestandardconditionsofload,
temperatureandtime"'.Thevalueofload,temperatureandtimearetaken
respectivelyas150g,25°C,and5seconds.Consistencyofagrease
dependsonthestructureandinteractionofthegellingelementsinitandto
someextentontheviscosityofoilused.Theconsistencyisdeterminedby
using"Penetrometer'showninFig.
Theapparatusconsistsof:
(i)Heavybase,whichisprovidedwithspiritlevel,levellingscrewsanda
plaintable,overwhichaboxcontainingthegreaseunder-testisplaced.
(i)Verticalsupportisaniron-rodfittedtothebase.Onthisareslottedmarks,aroundwhichaholdercanbemovedup
anddown.
(ii)Circulardial:Theholdercarriesacirculardialgauge,whichisgraduated
(iii)Movingdialrodisarrangedbehindthedialbyamechanicalmechanism.Therodisprovidedwithaclutch
arrangementfordisconnectingorconnectingittothecirculardial.
(iv)Amirror:Verticalrodisprovidedwithanadjustablemirrorforremovingparallaxwhilepositioningtheconein
contactwithgreasesamplesurface.
❖Working:Theapparatusislevelled,theconecleanedandthesampleofgreaseunder-test,inabox,isplacedbelowthe
cone.Theheightoftheconeisso-adjusted,withthehelpofmirror,thattipoftheconejusttouchesthesample.Initial
dialreadingisnoted.Theconeisthenreleasedforexact5seconds,bypressingabuttonprovidedforthispurpose.
After5seconds,thepressbuttonisreleasedandfinaldialreadingisnoted.Thedifferenceofthetwodialreadings
givesthepenetration.
anddown.
(ii)Circulardial:Theholdercarriesacirculardialgauge,whichisgraduated
(iii)Movingdialrodisarrangedbehindthedialbyamechanicalmechanism.Therodisprovidedwithaclutch
arrangementfordisconnectingorconnectingittothecirculardial.
(iv)Amirror:Verticalrodisprovidedwithanadjustablemirrorforremovingparallaxwhilepositioningtheconein
contactwithgreasesamplesurface.
❖Working:Theapparatusislevelled,theconecleanedandthesampleofgreaseunder-test,inabox,isplacedbelowthe
cone.Theheightoftheconeisso-adjusted,withthehelpofmirror,thattipoftheconejusttouchesthesample.Initial
dialreadingisnoted.Theconeisthenreleasedforexact5seconds,bypressingabuttonprovidedforthispurpose.
After5seconds,thepressbuttonisreleasedandfinaldialreadingisnoted.Thedifferenceofthetwodialreadings
givesthepenetration.
Selection of Lubricants
1.Internal Combustion Engines
2.Lubricants for gears
3.For delicate instruments
4.For very high pressure and low speed
5.For high pressure and low speed
6.For transformer
7.For spindles in textile industries oxidation and rust inhibitors
8.For refrigeration system
1.Internal Combustion Engines
2.Lubricants for gears
3.For delicate instruments
4.For very high pressure and low speed
5.For high pressure and low speed
6.For transformer
7.For spindles in textile industries oxidation and rust inhibitors
8.For refrigeration system
References
❖Engineering Chemistry by Jain and Jain
❖A text book of Chemistry in Engineering by S. G. Pillai
❖Engineering Chemistry by Jain and Jain
❖A text book of Chemistry in Engineering by S. G. Pillai
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