Development of an artificial olfactory system for lubricant degradation monitoring

Off-line strategies are commonly used to evaluate lubricant aging. These methods are expensive, time consuming and often require skilled personnel. Online detection of lubricant degradation would eliminate some of these issues. Lubricant degradation is principally due to oxidation, additive depletion and contamination by water, acid, fuel, sulphur, and insoluble content which happens gradually through different phases of the lubricant lifetime. The by-products and final products of this chemical process characterise the different evolutive phases of oil aging and are reflected in the volatile compounds emitted by the lubricant while degrading. Hence, the lubricant headspace contains a significant amount of information about oil degradation. This paper reports the development of an artificial olfactory system for real-time oil condition evaluation by headspace analysis. The instrument has been optimised to exhibit high discriminatory power and high sensitivity towards the vapours characterising the oil aging process, while the device costs have been kept low. Preliminary measurements have been carried out on water samples, new engine oil and aged engine oil to evaluate the ability of the system to generate sensor patterns distinctive of the samples under test and to discriminate between new engine oil and relatively aged engine oil. The results of these measurements are presented and discussed in the paper