How to choose vacuum pump oil？

The sealing performance of vacuum pump oil.
Vacuum pump oil needs a suitable viscosity, which can start the vacuum pump quickly at low temperature. The vacuum pump oil has good sealing performance at high temperature, and the temperature rise of the vacuum pump oil in the pump is low. Does not contain light volatile components, reducing the oil return rate of the vacuum pump during use.

Saturation vapor pressure of vacuum pump oil.
Saturation vapor pressure is one of the key indicators of vacuum pump oil. In a sealed container at constant temperature, when the vapor-liquid two-phase reaches dynamic equilibrium, the pressure is called saturated vapor pressure.
The saturated vapor pressure of the oil should be as low as possible. Under the high working temperature of the pump, the saturated vapor pressure should still be low enough, and it should be lower than the limit pressure of the vacuum pump regulation. at a temperature of 60°C
Under the condition of high temperature, at least 6.5x 10-5kPa should be achieved (since every 20°C of temperature increase, the saturated vapor pressure will decrease by an order of magnitude).

The limit total pressure and limit partial pressure of vacuum pump oil.
Ultimate total pressure: Use a Pirani gauge or a thermocouple vacuum gauge to measure the total pressure generated by all substances (gas) in the vacuum pump. At present, foreign countries attach great importance to the full stress test indicators.
Limit partial pressure: The limit air partial pressure of the pump measured by the mercury compaction vacuum gauge (McFootometer) is ≤6x 10-5kPa. The difference between the limit total pressure and the limit partial pressure shall not exceed an order of magnitude. The difference between the more
Larger, the more volatile components in the vacuum pump oil, the worse the properties of the oil.
(Note: Both the ultimate total pressure and the ultimate partial pressure are tested with a two-stage superior vacuum pump)

Smoothness of vacuum pump oil.
The friction and wear of the friction surface, appearance fatigue wear, corrosion wear, etc. are related to the smooth conditions. Good vacuum pump oil helps to inhibit corrosion wear, effectively reduce adhesive wear and appearance fatigue
The wear-resistant fluid lubricant can clean the friction surface and reduce friction and wear. Reduce frictional resistance to save energy, reduce wear and prolong mechanical life.

Cooling performance of vacuum pump oil.
Reducing the temperature of the friction surface is an important function of smoothness. When a friction surface is in motion, it is necessary to restrain the friction force and successfully control the conversion of all functions on the friction force into heat, which will cause friction
Wipe the surface temperature rise. The magnitude of frictional heat is related to the smooth state. High-viscosity heat is very large, low-viscosity heat is minimal, and border friction heat is in between. Therefore, use a suitable

High-strength vacuum pump oil can not only smooth the liquid and reduce the generation of frictional heat, but also remove the frictional heat out of the pump body in time.