A Novel Approach to on Line Oil Quality Sensing Through Side- Polished Optical Fiber

The availability of sensors able to determine on-line the ageing (the evolution in the condition) of oils would be of great interest in many industries. Oil finds applications mainly in three areas: (i) food processing (mainly frying) both in industrial and home environments, (ii) engines lubrication (cars, planes, boats) and (iii) insulation in transformers (and other power devices). In all cases the oils, complex mixtures of many chemical compounds, evolve with time and use, leading eventually to a significant loss of its properties becoming necessary its replacement. In this paper we present a novel procedure to obtain physical information on the condition of oils in situ and in a relatively simple manner. Sensing procedure clearly distinguishes between different samples of fresh oils (olive, sunflower, etc.) and their mixtures and assesses the evolution with use of a particular oil. The proposed procedure is based on the combined measurement of the transmitted optical power through a small polished zone of a single mode optical fiber immersed in the oil and its temperature