The Evaluation And Optimization Of Lubricants’ Demulsibility Property

Excellent demulsibility property is of critical importance for the application of lubricants. As the main detection methods of oil demulsibility property, GB/T7305has some deficiencies in the practical application.Using an improved and more practical mothod, this paper evaluated three hydraulic oils and PAO from a more comprehensive angle. To simulate the actual working condition, several influencing factors such as different oil-water ratio、 industrial water and oxidation product were also studied. Besides, through the commercial demulsifier choosing, the demulsibility performance of hydraulic oils were optimized, which was of practical application value on better using lubricants.Combined with the examination of several specifications such as dewatering speed, dewatering ratio, the quality of the separated oil and water, the appearance of oil-water interface and the concentration of oil in the separated water, the demulsification performance of A, B and C hydraulic oils were evaluated by the continuous demulsification performance testing methods. The experimental results showed that C had the best demulsibility property. The dewatering speed and dewatering ratio of A hydraulic oil was slightly lower than C, but its oil contained in separated water was high. B hydraulic oil had slow dewatering speed and bad continuous demulsification performance.The oil-water ratio made a big difference on demulsibility property. When the oil-water ratio got bigger, the continuous demulsification performance of hydraulic oils deteriorated and there was a big difference of demulsification performance among different oils. The three hydraulic oils were different in the stability of the emulsion, interfacial film strength and water droplets particle size distribution, thus showing different demulsibility properties. At the low oil-water ratio, the existence of Ca2-in industrial water slowed down dewatering speed while at the high oil-water ratio, dewatering speed was quicken. The adding of DL32could improve hydraulic oil demulsification performance at oil-water ratio of7:1and for B hydraulic oil, there was an optimal concentration as0.05%-0.06%. A number of commodities demulsifier was dissolved with PAO To further improve its water separation property. After demulsification experiments and one month’s storage, C20and AE8O51were choosed to be the best demulsifiers which could improve the water separability property of PAO greatly. Besides, the add of diisopropyl adipate improved the solubility of C20and AE8051in the PAO.