Overview Of Oxidation Laboratory Tests On Industrial .
Overview of oxidation laboratory tests on industrial lubricants - Lubmat ‘16V. Bouillon - BfB Oil Research S.A – IESPM GROUP, Les Isnes, Namur, BelgiumAbstractLubricating oils are very important products without which no equipment or engines can run. This paper focuson a oil key property in industrial systems which is the oxidation resistance and the thermal stability. After ashort review of oil composition and the mechanism of lubricant oxidation, the main normalized laboratorytests designed to evaluate this performance are described with reference to national, international or OEMspecifications.Keywords:Laboratory testing, oil degradation, oxidation, thermal stability, industrial oil, specifications, test,, BfB Oilresearch.1INTRODUCTIONThe technologies and industrial material developmentslead the additives and lubricants manufacturers toelaborate higher performance lubricants. One of the keycharacteristics, besides antiwear and EP resistance, goodsurface properties, anti-corrosion protection is theoxidation and thermal stability. There was a need toevaluate the performance of these oils using laboratorybench tests. The thermal and oxidation characteristics canbe evaluated by many tests which some are detailedbelow. This paper relates to the following applications:-Hydraulic fluids-Turbine oils-Compressor oils-Industrial gear oils2.1 Base oilsLubricating base oils are mixtures of a large number ofchemical compounds and are therefore characterized bythe following physico-chemical properties :Viscosity and VI (indicates viscosity–temperaturerelationship), specific gravity, cloud and pour point –flash, fire and auto-ignition point, aniline point,composition (content of paraffinic, iso-p., naphtenics,aromatics, saturates, sulfur), carbon residue, volatility, airrelease value, water separability, thermal stability, ecotoxicity and biodegradability, API (American Petroleum Institute) has established fivebase oil categories on the basis of percent sulfur, percentsaturates and VI.Even if the control of fluid degradation including physicochemical characteristics of the fluid as well as themonitoring of anti-oxidant depletion, the presence ofdegradation’s products is the key success to detect earlystage of degradation and oxidation in order to avoidproblems are the future, the very high quality andperformance of the formulated new oil remains essential.The aim of this presentation is to give you an overview ofexisting laboratory oxidation tests and a guide to selectthe right test related to the application.2OIL COMPOSITIONIn an industrial lubrication system, the lubricant issubmitted to a lot of constraints like a wide range oftemperature, the presence of hot spots, the evaporationand sometimes several top-up; these severe serviceconditions leads formulators to search for thermo-stablebase oils as well as the most efficient additives.Group I contains oils that have 0.03% sulfur and 90%saturates by mass. These oils have a viscosity index rangeof 80-120. Group II and III Oils, on the other hand, have 0.03% sulfur and 90% saturates by mass. However,they differ from each other in their viscosity index. Theviscosity index for Group II Oils ranges from 80-120 andviscosity index for Group III Oils is 120. In general. GroupII, Group III, and Group IV Oils are low in aromaticstructures and structures with unsaturation. Hence, theyoxidize at a slower rate than Group I Oils that are high insuch structures. This is because such structures morereadily form hydroperoxides and peroxy radicals that areessential to the oxidation process.
Synthetic basestocks (Group V Oils) have oxidation ratesthat vary because of varying structures. Alkylaromatics, forexample, contain aromatic rings, and hence oxidize fasterthan ester basestocks, which in turn oxidize faster thanolefin oligomers (PAOs) that belong to Group IV.Vegetable oils oxidize at a fast rate as well because of thepresence of unsaturation. New synthetic fully-saturatedbio-based fluids come into force through recentdevelopments.2.2 AdditivesAlthough base oil quality has considerable impact onformulated oils performance, additives are able toimprove several existing properties of base oils as well asgiven some new.The following properties can be influenced by chemicaladditives:ViscosityVIPour pointRheological properties at low and high temperaturesFriction propertiesDetergencyDispersancyOxidation stabilityAntiwearEPLoad-carrying capacityFoamingWater separation characteristicsRustingCorrosionIndustrial oils generally do not need detergents anddispersants, since these do not come in contact with thefuel combustion products, but need antirust, antifoam,and oxidation inhibitor along with antiwear and EPadditives (wherever these properties are required). Thenature of these additives and dosage vary according tothe equipment requirement and need to be optimized inevery grade. Each lubricant specification has beencarefully defined to meet these requirements. This is onlypossible through the use of suitable chemical additives. Acareful selection of the additive combination is thereforenecessary in a fully formulated lubricant. Additives exhibitboth synergistic and antagonistic effects when used incombination, and this requires careful selection andevaluation.The dosage of each additive in a particular product is ofgreat importance, since this decides the cost andperformance of the product.3 MECHNISM OFDEGRADATIONLUBRICANTOXIDATION&The process of oxidation proceeds in three stages:initiation, propagation, and termination. During theinitiation stage, oxygen reacts with the lubricant to formalkyl radicals. During the propagation stage, these radicalsreact with oxygen and the lubricant to form peroxyradicals and hydroperoxides. As indicated by the oxygenuptake, hydroperoxides are accumulated during theinduction period, after which the autoacceleration ofoxidation occurs. Hydroperoxides, either thermally or inthe presence of metal, decompose to a variety ofadditional radicals and oxygen-containing compounds.The oxygen-containing compounds include alcohols,aldehydes, ketones, and carboxylic acids.From oxidation of lubricants and fuels, ASTM [2]
From these species, polymers, metal carboxylates can beformed; these latter can increase the rate of oxidation dueto their catalytic effect.-The pressure drop as indication for the inductiontimeSome metal salts, at low concentration, can act asoxidation inhibitor; this is the case for some copper salts.Considerable effort has been expended in thedevelopment of better methods to evaluate the oxidationresistance of lubricants.Some parameters affect the oxidation process profoundly:4.2 Base oils-The temperature which is supposed to doublethe rate of oxidation every ten degree centigraderise.-The wear metals-The presence of waterIf oxidation is not controlled, lubricant decomposition willlead to oil thickening, sludge formation, and theformation of varnish, resin, deposits, and corrosive acids.4OVERVIEW OF INDUSTRIAL OILS OXIDATION ANDTHERMAL STABILITY TESTS4.1 General overviewNumbers and various methods are used to evaluate thethermal stability and anti-oxidant properties; some arespecific for a type of lubricants. Nevertheless, all thesemethods attempt to simulate the oxidation phenomena atvarious operating conditions and in various mechanicalcomponents. They are all more or less based on the sameprinciple. The oil ageing depends on :-The thermal stress : temperature higher or lower-The air or oxygen at a flow rate higher or loweror a static pressure of air or oxygen;-The presence or not of metal catalysts; this maybe massive metals or of metals introduced intothe lubricant solution to be tested asnaphtenates;-The presence or not of water;The evaluation of the oxidation stability is determined bythe follow-up of some parameters:-The evolution of the characteristics of the fluid(Viscosity, acidity, additives depletion, metalsconcentration from the catalysts, peak areaincrease (carbonyle peak by IR spectrometry) ;-The volatile acidity;-The evaluation of the corrosion on metalspecimen including the weight loss;-The quantification and appearance of unsolublematerials coming from oxidation (deposits,sludge, varnish);Most of the thermal stability and oxidation tests arededicated to fully formulated lubricants. Nevertheless,taking into account the wide variety of base oils in termsof chemicals structure and performances, some “soft” testscan be carry out to differentiate the base oils :IP-306: Determination of Oxidation Stability of StraightMineral OilsThis method is designed to give an indication of theoxidation stability of straight, unadditized, mineral oilbased lubricants under specific conditions; the test time isreduced to 48 h and no catalyst and solid copper catalystare used. The degree of oxidation is expressed as "totaloxidation products" (TOP) percent.DIN 51554: Test of Susceptibility to Ageing According toBaaderThe Baader ageing test is an accelerated oxidation testenabling the probable in-service behavior of variouslubricants to be predicted. The Baader test was developedto evaluate mineral oil based hydraulic fluids. However,today it has found wide acceptance in predicting theperformance of biodegradable hydraulic fluids. Bothvegetable oil (triglyceride) and synthetic ester based fluidsare evaluated.This is a non-severe oxidation test in which a copper coilentertain air inside the lubricant at a rate of 25 cycles/minThe test conditions are 140 h at 110 C for insulating oilsand synthetic ester hydraulic fluids. For mineral oilhydraulic fluids and vegetable based hydraulic fluids; theconditions are 72 h at 95 C; these can also be apply tobases oils. At the end of the ageing period, the viscosity ofthe aged fluid is determined and compared to the originalfluid viscosity. Percent viscosity increase at 40 C isreported.4.3 Turbine oilsOxidation is the most important property of turbine oils,and high oxidation stability means longer lubricant life.Base oils as produced in the refinery do not have sufficientoxidation stability to support turbine oil performance. Thisproperty is therefore obtained by the incorporation of anantioxidant molecule that functions by interaction with thefree radicals produced during the process of hydrocarbon
oxidation. Different base oils respond differently toantioxidants and need to be investigated thoroughlybefore arriving at the turbine oil composition. Oxidationstability of turbine oils is evaluated by the main followingmethods:ASTM D 943: Oxidation Characteristics of Inhibited MineralOilsThis method was developed for and is used to determinethe oxidation life of inhibited turbine oils. It is now widelyused for predicting the oxidation life of anti-wearhydraulic oils, and R&O oils, as well as turbine oils. Thetest is designed to simulate the conditions found in atypical steam turbine system. The test oil is heated in thepresence of copper and iron catalysts, which are typical ofthe metallurgy found in a steam turbine. Water is addedto simulate steam condensate and finally, oxygen isintroduced to accelerate the oxidation process. Thedegree of oxidation is determined by an increase in theacid number of the lubricant oil. The test is conducted inthe following manner: 300 mL of test oil, along withcatalyst coils of copper and steel are placed into a largeglass test tube and placed into a heated bath, maintainedat 95 C. 60 millilitres of distilled water is introduced intothe test tube. A water-cooled condenser is used toprevent the loss of water vapour during the test. Oxygenis bubbled through the oil sample at a rate of 3 l/h.Periodic samples of the oil are taken and the acid numberis determined. The test is usually concluded when thetotal acid number (TAN) reaches or increases of 2.0 mgKOH/g. The number of hours needed is considered to bethe "oxidation lifetime" of the oil.This test method is widely used for specification purposeslike in ISO 8068, DIN 51515 part 1 L-TD, Siemens TLV901304, Mitsubishi MS4 – MA – CL 001 002 003, GeneralElectric GEK 107395A, and is considered useful inestimating the oxidation stability of lubricants.Uninhibited oils will usually fail within 200 h, while highquality oils can exceed 5000 h – 10.000 h. However, itshould be recognized that the correlation between thistest and actual field performance can vary markedly. It isassumed that the longer the oxidation life is in the D 943test, the longer the lubricant will perform in the field.It should be noted that the D 943 has an upper life limit of10 000 h. Values higher than 10 000 h are considered tobe nonstandard extensions of the methodD 4310: Determination of the Sludging and CorrosionTendencies of Inhibited Mineral Oils.This method is a modified alternate to the ASTM D 943test method, and is used to determine the tendencies ofinhibited mineral oils, especially turbine oils, to formsludge during oxidation.The test conditions described under ASTM D 943 are used.After 1000 h, the test is stopped. The oil and water layersare separated and filtered. The weight of insolublematerial is determined gravimetrically by filtration of thecontents of the oxidation test tube through a 5 micronpore size filter. The amount of copper in the oil, water, andsludge phases can be determined according to anysuitable methods.This method is used primarily for specification purposes.Formation of oil insolubles or metal corrosion productsduring this test may indicate that oil will form insolubles orcorrode metals, or both, during field service. However,correlation with field service has not been established.D 2272: Oxidation Stability of Steam Turbine Oils byRotating Pressure Vessel Oxidation Test (RPVOT)The RPVOT is a rapid method of comparing the oxidationlife of lubricants in similar formulations, in the presence ofwater and a copper catalyst. This method can be used toevaluate the oxidation characteristics of turbine oils,hydraulic oils, and transformer oils. The test apparatusconsists of a pressurized vessel axially rotating at 100 rpm,at an angle of 30 from the horizontal, in a bathmaintained at 150 C. Fifty grams of test oil, 5 g of distilledwater, and a freshly polished copper coil are placed into aglass liner, and inserted into the vessel. The vessel isinitially pressurized to 600 kPa at room temperature.The 150 C bath temperature causes the pressure in thevessel to increase to approximately 1400 kPa. As oxidationoccurs, the pressure drops, and the usual failure point istaken at 175 kPa from the maximum pressure obtained at150 C. The results are reported as the induction timewhich is the number of minutes to reach 175 kPa loss.The RPVOT is favored as a quality control test because it israpid. The RPVOT result is useful in controlling thecontinuity of this property for batch-to batch acceptanceof production lots, having the same composition. TheRPVOT is also useful in determining the remainingoxidation life of in-service systems by charting the originalRPVOT value versus subsequent samples of that system. Itshould be noted that the D 2272 test method isdependent on additive chemistry.
No correlation has been established between RPVOT andASTM D 943 methods neither between actual field service.Mitsubishi specification for heavy-duty turbine oilsrequires RPVOT (ASTM D 2272) retention value in additionto the ASTM D-943 test.ASTM D 7873: Determination of oxidation stability andinsolubles formation of inhibited turbine oils at 120 Cwithout the inclusion of water (Dry TOST Method)A total of six to eight tubes containing 360 mL of samplewithout water are heated at 120 C with oxygen in thepresence of an iron-copper catalyst. Each tube is removedover time and the sample is analyzed by Test MethodD2272 and the insoluble are measured until the RPVOTresidual ratio reaches below 25 %.The criteria is to maintain less than 100 mg/kg of sludgeat a RPVOT value 25 percent of new oil. The 100 mg/kglimit was determined by MHI based on field experiencewith their turbines and hydraulic control systems.IP-280: Determination of Oxidation Stability of InhibitedMineral Turbine Oils.This method is commonly used for Europeanspecifications relating to turbine oils and other hydraulicfluids. This method is technically identical to the CIGREmethod "Turbine Oil Oxidation Stability Test." The testapparatus consists of a suitable size test tube containing25 g of test oil, plus copper naphthenate and ironnaphthenate as soluble catalysts. The sample test tube isplaced in a heated bath, 120 C for 164 h. During the testperiod, oxygen is bubbled through the oil sample at a rateof 1.0 l/h. Both the test temperature and the oxygen flowrate must be carefully maintained throughout the testperiod. The volatile acids, soluble acids, and the sludgeare used to calculate the "Total Oxidation Products" (TOP).Because of the relatively short test time, this method issometimes used as a replacement for the longer runningASTM D 943. However, no correlation between this testand the D 943 exists. Oils showing good results in D-943test could fail in IP 280 test. Both the tests are antioxidantspecific. Hindered phenols in adequate amount wouldshow good result in D-943 test at 95 C but would sublimeat 120 C in the IP 280 test and show poor result. The IP280 test, therefore, require high-temperature antioxidants.It is, however, possible to design turbine oil by usingcomplex mixtures of antioxidants, which will show upgood results in both ASTM and IP tests.FTM 791A – 3462 Panel Coker TestThe Panel Coker Test is a method for determining therelative stability of lubricants in contact with hot metalsurfaces. The test apparatus consists of a rectangularstainless steel reservoir, inclined 25 from horizontal. Thetest panel (95 mm by 45 mm) is held in place by a heatingelement, which is fitted with thermocouple probes tocontrol the temperature of the aluminium or steel testpanel. A horizontal shaft, fitted with a series of tines, ispositioned above the oil and is rotated at 1000 rpm.During rotating of the shaft, the tines sweep through thetest lubricant and lubricant droplets are thrown onto theheated test panelThe test panel is reweighed and the amount of deposit isdetermined. Weight gain of test panel and the amount oftest lubricant consumed during the test are an indicationof the lubricant's performance under high temperatureconditions.Many other test methods are dedicated to the evaluationof oxidation stability performance of gas and steamturbine oils as ASTM D 5846, D 6514, 4.3.1 Aicraft Turbine engine oilsThe aviation environment offers a very tough condition forthe lubricants such as high temperatures, low pressure,very low temperatures, high load, etc. Therefore, specialproducts are required for these applications. Synthetic oilsare usually preferred for severe application. The testmethod ASTM D4636 is used to give the resistance tooxidation and corrosion tendencies of hydraulic oils,aircraft turbine engine lubricants, and other highly refinedoils used in military aircraft and equipment.D 4636: Standard Test Method for Corrosiveness andOxidation Stability of Hydraulic Oils, Aircraft TurbineEngine Lubricants and Other Highly Refined Oils.This method is the result of combining Federal testmethods 5307.2 and 5308.7.The test method can be used to evaluate mineral oils aswell as synthetic fluids. It can be run using dry or moist air,as well as with or without the metal test specimens. Thereare two basic versions of this test method. Procedure 1uses "washer" type metal specimens, which includetitanium, magnesium, steel, bronze, silver, and aluminum.Procedure 2 uses "square-shaped" metal specimens, whichinclude copper, steel, aluminium, magnesium, andcadmium. The test is conducted in the following manner:The specified amount of test oil, 100 mL or 200 mL, isplaced into a large test tube along with the polished andweighed test specimens. The assembled apparatus isweighed and placed into the constant temperatur
thermal stability and anti-oxidant properties; some are specific for a type of lubricants. Nevertheless, all these methods attempt to simulate the oxidation phenomena at various operating conditions and in various mechanical components. They are all more or less based on the same principle. The oil ageing depends on :
NFP121 5 Sommaire 1) Tests et tests unitaires - Outil : junit www.junit.org une présentation Tests d'une application - Une pile et son IHM Tests unitaires de la pile Tests de plusieurs implémentations de piles Tests d'une IHM Tests de sources java Invariant et fonction d'abstraction comme tests - Tests en boîte noire - Tests en boîte blanche
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Anti oxidation, Anti aging Anti oxidation, Anti aging Anti oxidation, Anti aging Skin regeneration, Nutrition, Anti wrinkle Anti oxidation, Anti aging Anti oxidation Whitening Whitening Effects Skin Whitening, Anti oxidant Anti inflammatory, Acne Anti oxidant, Anti inflammatory Skin smooth and glowing Anti oxidant, Anti inflammatory Anti ageing .
Oxidation-reduction reactions are those which take place with a change in the oxidation state of atoms through the redistribution of electrons between them. or Biological oxidation is catalysed by enzymes which function in combination with coenzymes and/or electron carrier proteins. The differences between biological oxidation and combustion
Oxidation states were defined in Chapter 7. The oxidation number assigned to an element in a molecule is based on the distribution of elec-trons in that molecule.The rules by which oxidation numbers are assigned were given in Chapter 7.These rules are summarized in Table 19-1. OXIDATION-REDUCTION REACTIONS 591 SECTION 19-1 O BJECTIVES Assign .
Oxidation Numbers Worksheet . Directions: Use the . Rules for Assigning Oxidation Numbers. to determine the oxidation number assigned to each element in each of the given chemical formulas. Formula Element and Oxidation Number Formula Element and Oxidation Number . 1. Cl. 2. Cl 16. Na. 2. O. 2. Na O 2. Cl-Cl 17. SiO. 2. Si O 3. Na Na 18. CaCl .
This can not only reduce the cost but also simplify the process. The microstructure characterization of the composite coating was investigated. The high temperature oxidation tests at 650 C and at 850 C were carried out to study the high temperature oxidation behaviors of the composite coatings, and the oxidation mechanisms were explained. 2.
-2) is a polyatomic ion, and the sum of all oxidation numbers in a polyatomic ion equals the charge of the polyatomic ion. The charge for (SO 4-2) is -2, so ALL elements in (SO 4-2) will add to a -2 oxidation number. c. Oxygen as stated will have an oxidation number of -2, so the four oxygen atoms will have a total of -8 oxidation number. d. As .
