How to distinguish vacuum pump oil advantages and disadvantages
Vacuum pump oil, as the name implies, is vacuum pump lubricating oil. Vacuum pump oil in addition to the conventional lubricating oil, lubrication It is more important that under low pressure, light components are less. Generally speaking, when you are vacuuming, oil and gas will not be pumped out, so that your vacuum pump will soon achieve the vacuum effect. Otherwise, if you pump it away, the vacuum will always fail to come up, which requires a higher degree of refining of the oil.
Vacuum pump oil has high requirements for base oil. It needs to use white base oil with high refining degree, which forms the unique color of vacuum pump oil. The vacuum pump oil meeting the requirements of national standard is colorless and transparent or light yellow. The deep color indicates that ordinary or inferior base oil is used, which can save production cost.
Mainly through the following aspects to distinguish the quality of vacuum pump oil:
1. Extremely low vapor pressure: This is the most important performance index of vacuum pump oil. The lower the vapor pressure is, the higher the vacuum degree will be. Because the vacuum degree of rotary vane vacuum pump is required to reach 0.06pa and the high requirement is below 1.33 × 10-4Pa, the evaporation of vacuum pump oil is extremely low. Generally, paraffin based narrow fraction lubricating oil is used, and for diffusion vacuum pump, silicone oil with low vapor pressure or other synthetic oil can be used.
2. Proper viscosity, good viscosity temperature characteristics: the vacuum system uses the constant change of the pump cavity volume to form exhaust effect, which requires that the lubricating oil should have appropriate viscosity and good viscosity temperature characteristics. (viscosity temperature characteristic means that the viscosity of vacuum oil will change with the increase or decrease of temperature in the pump. For vacuum oil with good viscosity temperature characteristics, the viscosity changes with temperature
3. Good thermal oxidation stability: the vacuum pump is developing to high speed. The high-speed friction between the sliding vane and the pump body makes the oil temperature rise, so the heat and oxidation of the oil are intensified. The diffusion pump often works at high ambient temperature, and the poor thermal oxidation will cause the vacuum pump oil to oxidize and deteriorate. The vacuum degree is low, so the vacuum pump oil is required to have good thermal oxidation stability.
4. Good corrosion resistance and emulsification resistance: if the vacuum pump inhales corrosive gas, it will corrode the metal parts in the pump and cause chemical changes to the oil. In addition, there is often water vapor in the air, which causes the emulsification of vacuum pump oil, so it is required to have good corrosion resistance and demulsibility. The emulsification of vacuum pump oil used in vacuum dehydration process is more prominent.
5. Higher flash point: the vacuum pump is required not to carry light components, so as not to affect the saturated vapor pressure of oil. (when the volatile vapor of combustible liquid is mixed with air to a certain concentration, it will flash and burn in case of open fire, or when the combustible solid is heated to a certain temperature, it will flash and ignite in case of open fire. The minimum temperature of the solid at which flashover occurs is called the flash point.)
Good vacuum pump oil has the following advantages:
1、 Good viscosity temperature property, that is, high viscosity index lubricating oil, can give better lubrication protection to vacuum pump.
2、 Good oxidation resistance, lubricating oil in high temperature operation is not easy to deteriorate.
3、 The most important thing is that it is not easy to volatilize, that is, the flash point of lubricating oil should be high, so it is not easy to extract oil gas during vacuum pumping, and the loss of vacuum pump oil will also be reduced.