Oil Viscosity Monitoring

This chapter is devoted to monitoring the oil viscosity as one of the major physicochemical factors of quality and efficiency of oil. The review of methods of monitoring the oil viscosity presented in the chapter shows that at present, portable viscometers requiring periodic sampling of oil are widely applied; however real-time on-line monitoring is necessary for the reliable operation of machines. Among the devices mounted directly into the oil circulation lines and, particularly, into the lubrication systems of vehicles, acoustic devices are the most promising. In parallel with solid-state sensors based on acoustic waves, magnetoelastic viscosity sensors are considered; they operate at lower frequencies. Both piezoelectric and magnetoelastic types of the on-line acoustic viscometers have proved to be promising in the real-time monitoring of lubricating oils.