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

6

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 4615filter@cjc.dk • 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 29ccjensen.nl@cjc.dkwww.ccjensen.nl

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United Kingdom C.C.JENSEN LTD.Tel.: +44 1 388 420 721filtration@cjcuk.co.ukwww.ccjensen.co.uk

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