Proceedings of SerbiaTrib '13

analytical tests. The analytical tests are classicaland instrumental. Instrumental technical have theadvantages in small quantity of the sample andrapid analyze. As a part of the common proactivestrategy of the hydraulic systems maintenance,concept of on-line monitoring is introduce inpractice, recently [2], [3], [4], [5], [6]. It is acombination of the measurement procedures, bywhich sample of fluid is to be analyzed is takendirectly from the system and the results of themeasurements are continuously. On-line monitoringconsidering, first of all, control of cleanlinessclasses (according to ISO, NAS, SAE), control ofhumidity, viscosity, permittivity (acid),temperature…The following tests are the most used incondition monitoring: Spectrometric analysis,Analytical Ferrography, Rotrode FilterSpectroscopy (RFS), Infrared Analysis (FT-IR),Viscosity, Total Acid Number (TAN), Total BaseNumber, Water and Particle Count.Spectrometric analysis is a technique fordetecting and quantifying metallic particulates inused oil arising from wear, contamination andadditive packages. The oil sample is energized tomake each element emit or absorb a quantifiableamount of energy, which indicates the element’sconcentration in the oil. The results represent theconcentration of all dissolved metals and particles.The equipment for spectrometric analysis is thestandard equipment for oil analysis laboratoriestoday. It provides information on technical system,contamination and wears condition relativelyquickly and accurately. Spectroscopy is more-orlessblind to the larger particles in an oil sample,more precisely, to particles greater than 10 µm indiameter, which are more indicative of an abnormalwear mode [7].Analytical ferrography is a technique whichseparates magnetic wear particles from oil. Thoseparticles settle on a glass slide known as aferrogram. Microscopic examination enables todetermine the wear mode and probable sources ofwear in the technical system. Analyticalferrography is an exceptional indicator of abnormalferrous wear and it is inadequate for nonferrouswear.Rotrode Filter Spectroscopy (RFS) was firstintroduced in 1992. This spectrometric techniquedetects coarse wear metals and contaminants in aused oil sample. Diameter of those particles is upto 25 µm, but it excludes all additives. The coarseparticles are especially important. They are the firstindicators of abnormal wear situations.Fourier-Transform Infra-Red Spectroscopy is aspectrometric technique for detecting organiccontaminants, water and oil degradation products ina used oil sample. It monitors lubricant degradation(oxidation, nitration, sulfation, additive depletion)and liquid contaminants (water, glycol, fueldilution).Viscosity is the resistance of a fluid to flow andthe most important lubricant physical property. Thefluid is placed in a "viscometer" (a calibratedcapillary tube for precise flow measurementbetween two pre-marked points on the tube) andpre-heated to a given temperature in a "viscositybath" (which is usually oil-filled). After the oilreaches the desired viscosity temperature, gravityinfluencedflow of the oil is initiated in theviscometer and timed between two calibratedpoints. This time becomes the determinant for theresult.Total Acid Number (TAN) is a neutralizationnumber intended for measuring all acidic and acidactingmaterials in the lubricant, including strongand weak acids. It is a titration method designed toindicate the relative acidity in a lubricant. The TANis calculated from the amount of KOH consumed.The acid number is used as a guide to follow theoxidative degeneration of oil in service.Total Base Number (TBN) is a neutralizationnumber intended for measuring all basic (alkaline)materials in the lube (acid-neutralizing componentsin the lubricant additive package). The converse ofthe TAN, this titration is used to determine thereserve alkalinity of a lubricant. The TBN is highestwhen oil is new and decreases with its use. LowTBN normally indicates that the oil has reached theend of its useful life.Water can be detected visually if grosscontamination is present. Excessive water in asystem destroys a lubricant's ability to separateopposing moving parts, allowing severe wear tooccur with resulting high frictional heat. There areseveral methods used for testing the moisturecontamination (crackle, FT-IR water, centrifuge,Karl Fischer) each with a different level ofdetection (1000 ppm or 0.1 % for first threemethods and 10 ppm or 0.001 % for Karl Fischermethod).Particle Count is a method used to count andclassify particulate in a fluid according to acceptedsize ranges, usually to ISO 4406 and NAS 1638 [8].There are several different types of instrumentationon the market, utilizing a variety of measurementmechanisms, from optical laser counters to poreblockage monitors.3. THE RESULTS OF OIL ANALYSIS ANDDISCUSSIONIn this part are presented the results of oilanalysis examination during application in four-13 th International Conference on Tribology – Serbiatrib’13 241