1. Sealing property of vacuum pump oil

The vacuum pump oil needs to have suitable viscosity, which can make the vacuum pump start quickly at low temperature, good sealing performance at high temperature and low temperature rise in the pump. It does not contain light volatile components and reduces the return oil rate of vacuum pump during operation.

2. Saturated vapor pressure of vacuum pump oil

Saturated vapor pressure is one of the key indexes of vacuum pump oil. In a closed vessel with constant temperature, when the vapor-liquid two phases reach dynamic equilibrium, the pressure is called saturated vapor pressure.

The saturated vapor pressure of oil products should be as low as possible. Under the highest working temperature of the pump, the saturated vapor pressure should be low enough and lower than the limit pressure of vacuum pump rules. At least 6.5 × 10-5 kPa should be reached at 60 ℃ (the saturated vapor pressure will drop about one order of magnitude for every 20 ℃ temperature rise).

3. Limiting total pressure and limiting partial pressure of vacuum pump oil

Limit total pressure: the total pressure of all substances (gases) in vacuum pump measured by Pirani meter or thermocouple vacuum gauge. At present, foreign countries pay attention to the test index of full pressure.

Limit partial pressure: the limit air partial pressure of the pump measured by mercury contraction vacuum gauge (Maxwell's meter), and the partial pressure of double-stage rotary vane pump shall be ≤ 6 × 10-5 kPa. The difference request between the limit full pressure and the limit partial pressure is not more than one order of magnitude. The greater the difference between the two, the more volatile components contained in vacuum pump oil, the worse the properties of the oil.

4. Smoothness of vacuum pump oil

The friction wear, surface fatigue wear and corrosion wear of the friction surface are all related to the smooth condition. The results show that the good performance of vacuum pump oil is beneficial to prevent corrosion and wear; it can effectively reduce adhesive wear and external fatigue wear; fluid lubricant can clean the friction surface and reduce friction and wear. Reduce friction resistance to save energy, reduce wear and prolong mechanical life.

5. Cooling performance of vacuum pump oil

Reducing the temperature of friction surface is an important function of smoothness. When the friction surface moves, it is necessary to work against the friction force, and all the work consumed in restraining the friction force is converted into heat, which will cause the temperature of the friction surface to rise. The heat of friction is related to the smooth state, the heat of high viscosity is the largest, the heat of low viscosity is the least, and the heat of boundary friction is between the two. It can be seen that the vacuum pump oil with suitable viscosity can not only smooth the liquid and reduce the generation of friction heat, but also take the friction heat out of the pump body in time.

6. Detergency of vacuum pump oil

Friction pairs can not be prevented from contacting with the surrounding media, causing corrosion, corrosion and damage. The vacuum pump oil with excellent performance shall be cleaned and cleaned as far as possible; anti-corrosion and rust prevention shall be conducted and the friction surface shall not be subject to oil degeneration or external corrosion.