Vacuum pump oil is a special lubricating oil for vacuum acquisition equipment. It is one of the important materials of vacuum pump, oil quality directly affects the equipment to achieve the ultimate pressure, pumping rate, back pressure and oil return rate. In the vacuum pump, the vacuum pump oil is not only used as a medium to obtain vacuum, but also plays a role in lubricating, cooling and sealing the mechanical friction points. According to the working condition of the oil in the use process, vacuum pump oil can be divided into mechanical vacuum pump oil, steam jet pump oil, vacuum seal oil and so on.


Vacuum pump oil performance requirements:
(1) Very low vapor pressure
This is the most important performance of vacuum pump oil. Since the vacuum pump requires a vacuum degree below 0.000133Pa, the evaporation of the vacuum pump oil is required to be extremely low. General vacuum pump oil with paraffin-based narrow distillate oil, for diffusion vacuum pumps, can also use very low vapor pressure silicone oil or other synthetic oil. The saturated vapor pressure should be lower than the limit pressure indicated on the pump nameplate.


(2) Viscosity and viscosity-temperature characteristics
The vacuum pump cavity content is constantly changing to form the exhaust effect, which requires that the lubricating oil should have appropriate viscosity and viscosity temperature characteristics.


(3) Thermal oxidation stability
The vacuum pump continues to develop to a high speed, due to the high-speed friction of the slide and the pump body, the oil temperature rises, and the oil is easy to oxidize and decompose, especially the diffusion pump is often in a very high temperature environment, so that the vapor pressure in the system is increased, and the vacuum degree is reduced. Therefore, the vacuum pump oil is required to have good thermal oxidation stability.


(4) Corrosion resistance
If the vacuum pump is inhaled corrosive gas, it will react with the oil to corrode the parts in the pump. On the other hand, the inhaled air often contains water vapor condensate, which will cause the emulsification of the vacuum pump oil and corrosion of the metal. Therefore, the oil is required to have good corrosion resistance and emulsification resistance.


(5) Resistance to emulsification
During the operation of the vacuum pump, the water and cold air in the system will be discharged into the pump oil, and the oil and water will form emulsion, which not only affects the service life of the pump oil but also makes the limit pressure worse. Especially in the process of vacuum drying for industrial applications such as medicine, food and ceramics, the emulsification resistance of vacuum pump oil is more important. Good anti-emulsification, strong oil-water separation ability of pump oil, water vapor and condensed gas discharge through the needle valve.


(6) Flash point
Not only should flammable safety be considered, but the main requirement is that the vacuum pump does not carry light components, so as not to affect the saturated vapor pressure of the oil.


(7) Water separability
The moisture contained in the oil can be quickly separated to achieve the required vacuum degree.

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