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Oil Degradation [Varnish]
Degradation products known as “soft contaminants”, are the
precursors of varnish deposits on metal surfaces of machines
and components
CJCTM Fine Filters and CJCTM Filter Separators not onlyremove particles and water from oils - they also remove oildegradation products
C l e a n O i l - B r i g h t I d e a s
Any lubricant in service or in storage will degrate over time, depending onthe type of oil, the operation conditions and the environment. When the oildeteriorates, it will change its composition and functional properties. Duringthe degrading process, a number of unwanted products are formed, whichcan lead to varnish deposits, all of which will result in costly consequencesfor machinery, such as corrosion, sticking valves, varnish, etc.
In this brochure you can read about the consequences of oil deteriorating,as well as finding solutions on how to remove and monitor degradationproducts.
Introduction
[Varnish]
“A thin, insoluble, nonwipeable filmdeposit occurring on interior parts,resulting from the degradation andpolymerization of oil”
(source: Noria)
HDU 15/25 PV HDU 27/27 P PTU2 27-27 PVPTU 15/25 PV
CJC™ Fine Filters and CJC™ Filter Separators
C l e a n O i l - B r i g h t I d e a s2
Baltzer Grafik • Oil Degradation • UK • 03.2010
Oil degrading is a common problem in both lubrication and hydraulic systems
Removal of DegradationProducts from Oil
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The Problem
Oxidation
Hydrolysis
Thermal Degradation
Oil degrading is a common problem both in lubrica-tion and hydraulic systems. The main causes of thisare typically oxidation (oxygen), hydrolysis (water)and thermal degradation (high temperature). In manycases it is a combination of all three.
1Process
Reagent Oxygen
Temperature / Water
Transition metals (wear particles, Cu, Fe, Al)Contaminants (contamination in general, oxidation products)
Pressure
Oxygen / Temperature Water / Oxygen
Water Heat
Process catalysed by:
Oxidation Hydrolysis Thermal degradation
OxidationOxidation is the breakdown of the oil with oxygen as reagent. The oxidationprocess involves a series of reactions forming acid compounds and polyme-rized compounds. Oxidation leads to insoluble products (sludge) that mayprecipitate as a thin film, forming lacquers or varnish deposits on hot orcold metal surfaces.
HydrolysisHydrolysis is the breakdown of the oil with water as reagent. Like oxida-tion, hydrolysis can result in acid compounds and varnish. Oxidation pro-ducts such as: hydroperoxides, carboxylic acids, ketones, aldehydes andothers, usually possess increased solubility in water and therefore oftenaccelerate the hydrolysis process.
Thermal DegradationThermal degradation is the breakdown of the oil activated by heat (hightemperature). Typically thermal degradation occurs in the hot spots of thesystem. It can also result in polymers and insoluble compounds, which leadto varnish formation as occurs in the oxidation process.
Example of varnish formation on steering gear
The degradation process is
catalysed by:
Oxygen
Water
High temperature
Wear particles
Contaminants
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Oil Degradation will Result in:
Formation of acidic compounds: Acid promotes corrosion, for example pitting. This leads to increased wearin the internal surfaces of the machine.
Increase in oil viscosity: The oil´s resistance to flow will increase, which will result in friction, wearand loss in efficiency of equipment.
Decreased additive performance: Additives (antioxidants and detergents) also react with the degrading products.The result is that the additives lose their effect - and instead accelerate thedeterioration process.
Varnish formation:Varnish deposits are “sticky” and will trap hard contaminants, creating a“sandpaper surface”. This “sandpaper” causes accelerated wear in com-ponents. In addition, varnish can result in filters and valves blocking, andorifices clogging. Furthermore varnish acts as an insulator, reducing theeffect of the heat exchangers, resulting in higher temperatures and acce-lerated reaction speeds.
Once the varnish deposits have formed on the metal surfaces, it is very dif-ficult to dissolve them.
Consequences of the Oil Degrading:
Shorter oil lifeAn increase in the level of oil degradationDegradation products act as a catalystA reduction of additive performance
Reduced oil performanceLoss of lubricityValve failureRestricted oil flow
Reduced productivityMonday morning problems: slow start-upsIncreased downtimeReduced machine performance
Higher energy consumptionFriction and wear
Increased maintenance costsIncreased filter change frequency Increased wear of componentsAcidic corrosion in metallic componentsComponent failuresCleaning of the oxidation deposits
Environmental pollution consequencesGreater disposal costs of oil and filter changesLeakages
Oil Degradation andConsequences
Oil reservoir(Plastic MouldingMachine)
Examples of varnish:
Machine components
Steeringgear
Varnish on gas turbine
Varnish on bolts
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The SolutionRemoval of degradation products before they havetime to react further and form insoluble sludge andvarnish deposits
2Oil degradation products cannot be removed with conventional mechanicalfilters because they are submicron particles. It is a fluid in a fluid - like whensugar is dissolved in coffee.
These degradation products can be removed by CJCTM Fine Filters andCJCTM Filter Separators through a combination of adsorption and absorp-tion processes.
Adsorption is the physical or chemical binding of molecules to a surface (likegetting a cake thrown into your face). In contrast with absorption, in whichmolecules are absorbed into the media. See illustrations.
CJCTM Filter Inserts, made of cellulose fibres, have a high surface area andcan be effective as adsorbents and absorbents. In addition, due to theirchemical nature, they are highly suited to pick-up oxygenated organicmolecules, such as oil degrading products.
Absorption Adsorption
Absorptioncan be illustrated by this
drawing: The chemical sub-stances (the cake) is absorbed
by the media (the man)
Adsorptioncan be illustrated by this drawing: The chemical sub-stances (the cake) is binding to a surface (the man)
The CJC™ SolutionFilter Insert consisting of
cellulose fibres treating the oilThis illustration shows the contaminated
oil approaching the cellulose fibres in an almost new Filter Insert
Filter Insert near saturationThis illustration shows that the Filter Insert is still producing clean oil even though the cellulose fibres are nearly saturated
Feed
Oil degradation particles
Fibres
Purified oil
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Before
After
Absorption and Adsorptionby CJC™ Filter Inserts
CJC™ Filter Inserts Remove Contaminants of any Kind and Size
Hard contaminants: Wear particles, debris, dirt
Soft contaminants: Varnish / oxidation
Water
Cross-section of a cellulose fibreEach cellulose fibre consists of millions of cellulose molecules. Each strand of cellulose molecules has a diameter of 10 - 6 cm (0.000001cm)
Degradation products are absorbed and adsorbed into the cellulose material
Film diffusion:Transport from the oil to theboundary of the adsorbent(fibre). The resistance is pictured as a fictitious film
Macropore diffusion: Transport within the adsorbent(fibre). This can be viewedamongst the subfibres
Micropore diffusion:Transport from the pore fluid to the adsorption sites at theadsorbent surfaces. This canbe viewed amongst the molecules
Feed
Oil degradation particles
Fibres
Purified oil
Millipore membrane
Sample taken before offline filtration
Millipore membrane
Sample taken after offline filtration
CJC™ Filter Insert after use
CJC™ Filter Insert before use
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The ResultCJC™ Oil Filtration will maintain both oil and systemcleanliness3Longer oil life
Increased oil performance and lower energy consumption
Increased productivity
Less maintenance
Environmentally friendly
An Oil System Free from Varnish Deposits
ProblemSolution8
Removal of Varnish Depositsfrom Metal SurfacesBy using CJCTM Offline Filters, the amount of varnish deposits on metalsurfaces will be reduced. It is explained by the adsorption equilibriumbehaviour.
There is an equilibrium between the two phases, i.e. the fluid (oil) and var-nish on the surfaces. When the oil becomes cleaner, the deposits from thesystem become unstable because the concentration of oil degradation pro-ducts in the oil has decreased. This will result in a decrease of the amountof adsorbed substance. In other words, this means that the oil degradationproducts on the metal surfaces are released. The oil functions as a systemcleaner.
SummaryProblem:The oil is contaminated byhard contaminants, waterand soft contaminants,which lead to varnish deposits
Solution:Removal of the contami-nants by CJCTM OfflineFilters before they willform sludge and varnishdeposits
Result:Lower levels of contami-nation, which will preventdeposit formation. Futhermore the deposits,once formed, will be redu-ced by using CJC TM OilFiltration
Maintenance:By CJC TM Oil Filtrationyou will maintain both oiland system cleanliness
Result Maintenance 9
Dark colour
Indications of Oil Deterioration
Increase in oil viscosity
Sour and putrid odour indicates oil degradation
Soft contaminants are compounds of molecular sizes,which cannot be measured by conventional particlecounting methods
How to Monitor Oil Degradation?
There are several methods that measure different aspects of the deteriora-ting oil. These methods generally measure the amount of certain degradationproducts from oil or the amount of additives in the oil.
The Following are Indications of Oil Deteriorating:
Dark colour
Sour and putrid odour
Increase in oil viscosity
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Methods to Monitor Oil Degradation
Methods to Monitor the Level of Degradation in the Oil:
Ultra-centrifuge
test
Colourimetric/millipore
membrane analysis
Gravimetricanalysis
RULERtest
Infraredspectroscopy
QSAtest
Viscositytest
TAN analysis
Ultracentrifuge Test: This test uses the gravitatory for-ces to extract and settle the con-taminants of the oil. The sedi-ments are compared with a sedi-mentation rating system to deter-mine the degradation of the oil.
Colourimetric/MilliporeMembrane Analysis:This analysis is an indication thatthe oil contains degradation pro-ducts. The varnish is captured inthe white millipore membrane(0.45 micron cellulose membrane),and shows as a yellow, brownishor dark colour depending on theamount of varnish present in theoil. A microscopic magnificationshows if the colour comes fromvarnish or hard particles.
Gravimetric Analysis:This analysis can determine thelevel of oil degradation by mea-suring the weight of residualcomponents.
RULER TestIndicates the amount of anti-oxi-dants (oil additives). When the ad-ditives get depleted due to incipientdegradation of the oil the RULERnumber decreases. This effect isevident before varnish starts pre-cipitating, which makes the testproactive.
Infrared Spectroscopy: (FTIR Analysis - Fourier Transfor-mation Infrared Spectroscopy)This analysis is based on the prin-ciples of molecular spectroscopy. Itcan verify the level of oil degrada-tion by the identification of thefunctional groups (e.g. ketones,carboxylic acids) in molecules.
QSA Test:This method identifies the varnishpotential rating, and is based oncolorimetric analysis.By comparing the result to a largedatabase of QSA tests, a 1 to 100severity rating scale indicates thepropensity of the lubricant to formsludge and varnish
Viscosity Test: This test measures the oil resi-stance to flow. It can be used as anindicator of oil degradation.
TAN (Total Acid Number): This analysis measures the level ofacid compounds. It can also beused as an indicator of oil degra-dation, since acid is a product ofdegradation.
Methods to Monitor the Consumption of Additives:
FTIR Analysis (Fourier Transformation Infrared Spectroscopy)It can monitor the additive depletion.
RULER Test (Remaining Useful Life Evaluation Routine)It measures the remaining antioxidants by voltammetric analysis.
RBOT Test (Rotating Bomb Oxidation Test)It measures the oil’s resistence to oxidation under prescribed conditions.
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C.C.JENSEN all over the WorldThe CJC™ Offline Filters are distributed by our own inter-national sales organisation and designated distributors
Manufacturer & Headquarters
C.C.JENSEN A/SDenmark • Løvholmen 13 • DK 5700 SvendborgTel. +45 6321 2014 • Fax: +45 6222 [email protected] • www.cjc.dk
Your Local CJCTM Distributor We are represented all over the world by distributors.
Find your nearest distributor on our website: www.cjc.dk
- or give us a call.
Benelux C.C.JENSEN Benelux B.V.Tel.: +31 182 37 90 [email protected]
Chile C.C.JENSEN S.L. LimitadaTel.: +56 2 739 2910 [email protected] www.ccjensen.cl
ChinaC.C.JENSEN A/S ChinaTel: +86 10 6436 [email protected]
DenmarkC.C.JENSEN DanmarkTel: +45 72 28 22 [email protected]
FranceC.C.JENSEN FranceTel: +33 3 59 56 16 [email protected]
GermanyKARBERG & HENNEMANN GmbH & Co. KGTel: +49 (0)40 855 04 79 [email protected]
Greece C.C.JENSEN Greece LTD.Tel.: +30 210 42 81 [email protected]
Ireland C.C.JENSEN IrelandTel.: +353 61 374 [email protected]
ItalyKARBERG & HENNEMANN srlTel: +39 059 29 29 [email protected]
Poland C.C.JENSEN Polska Sp. z o.o.Tel.: +48 22 648 83 [email protected]
Spain C.C.JENSEN Ibérica, S. L.Tel.: +34 93 590 63 [email protected]
United Arab Emirates C.C.JENSEN Middle EastTel: +971 4 447 [email protected]
United Kingdom C.C.JENSEN LTD.Tel.: +44 1 388 420 [email protected]
USA C.C.JENSEN INC.Tel.: +1 770 692 [email protected]
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