Vacuum pump oil knowledge
The vacuum pump industry simply believes that the function of vacuum pump oil is to lubricate the vacuum pump, which includes base oil plus antiwear and reducing the composition of moshalide. But the fact is not so simple, because to keep the lubrication for a long time, it must make it deteriorate slowly under the action of heat and oxygen, but also have good mobility and no foam. Vacuum pump oil used for vacuum pump lubrication is composed of base oil and additives. The base oil is processed by refining, degreasing and other processes of heavy fraction in petroleum refining, mainly composed of hydrocarbons. There are many kinds of additives, which can respectively improve the performance of the base oil in some aspects, including detergent dispersant, antioxidant, antiwear agent, extreme pressure agent, rust inhibitor, pour point depressant, defoamer, tackifier The technical content of vacuum pump oil lies in its unique additive formula.
In addition to organic compounds such as carbon, hydrogen, nitrogen, and other elements, there are also organic metal salts, mainly calcium, barium and so on. When the metal content in the vacuum pump oil is detected by emission spectrum, the metal content in the additives in the vacuum pump oil is also measured in addition to the metal content in the vacuum pump oil and the pollution metal content. Because of their good solubility in the oil, the detection is very complete.
The technical concentration of additives in vacuum pump oil is much higher than the metal content in the oil from the wear of vacuum pump.
The finished vacuum pump oil has its own classification and specifications of mineral oil, synthetic oil, semi-finished oil and other national and international standards, and some well-known industry standards, including two types of indicators, one is physical and chemical indicators, the other is performance indicators.
No matter what kind of vacuum pump oil, its primary performance is to have good lubrication performance, reduce the friction and wear of moving parts, and make the vacuum pump high efficiency and long life.
vacuum pump oil knowledge:
1. Viscosity index:
Generally, people think that the more viscous the vacuum is, the better. In fact, it is not so. "Thin" and "sticky" are relative visual inspection and hand feeling, and there is no quantitative data. If the viscosity of the two oil products is the same at 40 ℃, when the vacuum pump oil is cooled to room temperature, "dilute" oil is better than "sticky" oil. Because the viscosity index of "thin" oil is higher than "sticky". The viscosity of viscous oil changes greatly with the change of temperature, that is, the viscosity index is low, and the viscosity index is the important index of vacuum pump oil. The viscosity and temperature of high viscosity index pump oil change little. Moreover, the cold pump is easy to operate and has significant consumption saving use. Especially in summer, with the rise of the ambient temperature and the oil temperature in the pump, the oil limit pressure can maintain a good effect.
2. Flash point:
Flash point is also one of the most important quality indexes of vacuum pump oil. It is not only considered from the flammable safety performance. However, the oil content of light components is less when the flash point is high. Therefore, when the oil temperature rises, the light boiling point oil molecules are not easy to volatilize and can effectively maintain the limit pressure.
3. Demulsification resistance:
During the operation of the vacuum pump, the water and air-conditioner in the system will be discharged into the pump oil, and the oil and water will form emulsion, which will not only affect the service life of the pump oil, but also make the ultimate pressure worse. Especially in the vacuum drying process of medicine, food, ceramics and other industrial applications, the demulsibility of pump oil is more important. Good demulsibility and strong oil-water separation ability of pump oil. Part of water vapor will be discharged when water vapor and condensed gas pass through the open gas valve. In addition, the anti emulsification ability of low viscosity pump oil is better than that of high viscosity pump oil. The effect of pump oil with additive is more obvious than that without additive.
During operation, the gas in the vacuum system will be discharged continuously through the sealed vacuum pump oil layer. The discharged gas will generate a large number of bubbles on the oil layer surface and overflow from the pump exhaust hole, resulting in oil loss and equipment pollution. Adding antifoaming agent to pump oil can obviously improve the antifoaming effect.
5. Oxidation stability:
Natural mineral oil has its inevitable leak. Its heat resistance and oxidation resistance are worse than synthetic oil. The composition of vacuum pump oil is oxidized with heat.