Characterization of Lubricating Oil Using Ultrasound

this paper presents an ultrasonic method to measure small concentrations of water in lubricating oil. it uses an ultrasonic measurement cell composed by a piezoceramic emitter (5 and 10 mhz), and a large aperture pvdf receiver that eliminates diffraction effects. the propagation velocity, attenuation coefficient and density of several samples of water-in-oil emulsion were measured. the concentrations of water of the samples were in the range of 0 to 5% in volume, and the results showed that these low concentrations can be discriminated within a resolution of 0.2% in the studied range, using the measurement of the propagation velocity.