Acidification of Gas Engine Oils: Characterisation by Sensors

Recently, a number of sensor principles to measure physical and chemical properties of lubricating oils were investigated. The crucial property of lubricating oils for some applications is the degree of acidification as there is a correlation to corrosive wear of engine components. Corrosiveness is of particular importance for biogas engines due to the fact that bio-fuels are forming more aggressive components during the combustion process as in comparison with conventional fuels. Recent research showed that the corrosiveness of oil cannot be described sufficiently by conventional oil parameters such as total acid number and neutralization number. We propose a sensor concept using the effect of material loss of a thin metal film due to corrosion. The signal of the sensor being immersed in used gas engine oils with corrosive compounds showed good correlation with selected oil properties determined in the laboratory.