This project will develop the technology employed by an existing fluid level sensor to produce a novel, relatively inexpensive method of measuring the concentration of water in heavy diesel fuel oil. This will enable large diesel engine manufacturers to optimise the removal of nitrogen oxides from exhaust fumes by monitoring the amount of water added to the fuel for this purpose. The present device can determine which of up to three fluids of fixed concentration is present in its flow chamber using an Infra-red interrogation technique. The research programme will expand and develop this process to the point where water in oil concentration can be measured to a satisfactory accuracy. The scientific innovation will incorporate a coherent light source and a position sensitive detection and analysis system. It is anticipated that the subsequently developed instrumentation will find many applications in other areas of industry where concentration levels must be monitored and controlled.