Properties of water-contaminated lubricating oil: variation with temperature and small water content

Water contamination is one of the most critical factors in industrial applications since if the water content exceeds a certain level that the lubricating oil cannot accept it may shorten the service of lubricating oil and damage machines gradually. Dynamic viscosity and permittivity were used as performance indexes to investigate the effects of water contamination on lubricating oil. Temperature and water content were examined simultaneously to obtain the correlation with the viscosity and permittivity of lubricating oil separately. The Vogel’s law was employed to express theoretical relationship between temperature and dynamic viscosity. The extended models are proposed to give good correlations with the viscosity and permittivity of water-contaminated lubricating oil as a function of temperature and water content. The dynamic viscosity and permittivity of lubricating oil have an approximate linear relationship with water content within small water content and a certain temperature span. The variations of used oil properties under different temperatures at a certain water content follow the same relationship as those of pure oil.