engleski

Changing the properties of mineral lubricating oils during use

The largest part of modern lubricating oils are mineral oils that are obtained by processing crude oil. Mineral lubricating oils consist of mineral base oil and additives. The primary function of lubricating oil is lubricating the moving parts of machinery in order to reduce friction and prevent wear surface of materials that are in the mutual relative motion. Lubricating oils also slow down corrosion, improves sealing andcooling machine by conducting heat away from moving parts. While using lubricating oil changed its characteristics due to pollution and degradation of the oil. In assessing the condition of lubricating oils are used various methods of analysis that are often applied and effective in a system of monitoring equipment. By spending control of lubricant condition, it is possible to refresh lubricant or replace it before any serious damage to the machine.In this paper were analysed compressor and motor oils taken from the lubrication systems after a certain number of hours of operation. Physical (kinematic viscosity, density, pour point and flash point) and chemical (oxidation, nitration, sulfation, and the presence of soot, fuel, water, antifreeze and additives)characteristics of samples of new and used mineral lubricating oils are determined according to the applicable standards. Chemical characteristics of oils are determined by infrared spectroscopy with Fourier transform (FTIR) and acid numbers are determined by titration method.By using energy dispersive x-ray fluorescence (EDXRF) method of analysis are determined the contents of various metals and non-metals in lubricating oils derived from additives (assessment wear oil), from wear of material surfaces, the coolant or other sources. Based on the overall results of the analysis it can be concluded about the need to replace the used lubricating oil to new one.

EDXRF (Energy dispersive x-ray fluorescence) method ; physical characteristics ; infrared spectroscopy with Fourier transform ; chemical characteristics ; mineral lubricating oils

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