Addtime： 2020-07-18 Browse times： 1961
Do you know the characteristics of vacuum pump oil, matters needing attention and oil change method?
1、 Characteristics of vacuum pump oil
If the gas inhaled by the vacuum pump is corrosive, it will react with oil and corrode the parts inside the pump; the water vapor condensate often exists in the air inhaled, which causes the emulsification of vacuum pump oil and corrosion of metal, so it is required to have good corrosion resistance and demulsification resistance.
2、 Performance requirements of vacuum pump oil
Main performance requirements:
1. Very low vapor pressure
This is the most important performance of vacuum pump oil. Because vacuum pump requires high vacuum degree, paraffin based narrow distillate lubricating oil is generally used. For diffusion vacuum pump, silicone oil with low vapor pressure or other synthetic oil can also be used.
2. Suitable viscosity and good viscosity temperature characteristics
The volume of the vacuum pump cavity changes constantly and forms the exhaust effect, which requires that the lubricating oil should have appropriate viscosity and viscosity temperature characteristics.
3. Good thermal oxidation stability
The vacuum pump is developing to a high speed. Due to the high-speed friction between the sliding vane and the pump body, the oil temperature rises, and the oil is easy to be oxidized and decomposed. Especially, the diffusion pump often works in a very high temperature environment, which increases the vapor pressure in the system and reduces the vacuum degree. Therefore, the vacuum pump oil is required to have good thermal oxidation stability.
4. In vacuum pump, vacuum pump oil is not only used as the medium to obtain vacuum, but also plays the role of lubrication, cooling and sealing for mechanical friction points.
5. High flash point
The main requirement of vacuum pump is not to carry light components, so as not to affect the saturated vapor pressure of oil.
6. Lower limit pressure
Limit pressure is an important performance index of vacuum pump oil to understand the limit pressure of vacuum pump under the lowest vacuum limit pressure.
3、 Precautions for using vacuum pump oil
1. The shelf life of vacuum equipment oil can reach three years under sealed condition;
2. Oil should be stored in a cool and dry place;
3. After the oil barrel is opened for use, the remaining oil should be covered with a sealing cap. At the same time, use up the remaining part as soon as possible. Do not mix other powder and liquid impurities;
4. Environmental tools should be kept clean. If they are cleaned with solvent, they should be dried for use;
5. According to the structure accuracy and service environment of vacuum pump, the oil with corresponding precision and quality should be selected.
4、 Oil change method of vacuum pump
1. Remove the pump from the system and connect it with a clean square plate under the oil drain hole. Screw off the oil filling plug and oil drain plug to drain the dirty oil. Start motor 4 ~ 6 intermittently to discharge all oil in each vacuum chamber. Then add 200 ~ 300cc clean vacuum pump oil from each suction pipe. Start the motor intermittently and clean each vacuum chamber again. After repeated cleaning for 2 ~ 3 times, the oil used for cleaning is released and the oil drain plug is screwed on. Add clean vacuum pump oil from the oil filling plug to the center of the viewing window, and tighten the oil filling plug to prevent air leakage.
2. It is better to change the oil after the oil temperature rises. It is strictly forbidden to use kerosene, gasoline, alcohol, etc. to clean the pump. At ordinary times, we should also pay attention to protect the air inlet and check the filter screen to prevent dust and impurities from entering the pump, contaminating the pump oil and damaging the vacuum chamber.
Troubleshooting of vacuum pump after oil change
1. There is a phenomenon of oil injection at the pump outlet: too much oil is added to reduce the amount of oil added; the air intake for a long time should be avoided.
2. There is fog at the air outlet of the pump: check whether there is air leakage at the air inlet and other parts.
3. The vacuum degree is low: whether the pump cavity and oil are mixed with other light liquids. After the oil is replaced, the pump should be operated properly for a period of time to check whether there is air leakage in the sealing parts of the pump.
4. Check the instrument.
5、 Common problems and solutions of vacuum pump oil
Return oil in vacuum pipeline or system
1. The oil vapor flows back to the vacuum pipeline or system
2. The steam pressure of oil is not correct
3. When the pump is stopped, the oil flows back
4. The seal on the shut-off valve plate is damaged
5. The seal at the bottom of the exhaust pipe is corroded or damaged
resolvent:
1. Clean the vacuum pump and replace it with oil that meets the requirements
2. Check and replace the shut-off valve
3. Replace the shut-off valve
4. Replace the exhaust pipe and repair the seal
Return oil in vacuum pipeline or system
1. Lack of oil
2. Wrong connection between air outlet and exhaust port
3. The oil supply pipeline is blocked
4. There is a problem with the vacuum pump
5. Foreign matters in the vacuum pump are blocked
6. The ambient temperature reaches or exceeds the oil vapor pressure
7. The steam pressure is lower than the target
8. The working gas temperature is too high
resolvent:
1. Come on
2. Connect the air extraction pipeline with the air extraction port
3. Disconnect the pump, clean and replace the required oil
4. Replace vacuum pump oil for repair goods
5. Clean the vacuum pump
6. Reduce ambient temperature and pay attention to air circulation
7. Replace the vacuum pump oil that meets the requirements
8. Change process or add cooling system
Vacuum pump oil, as its name implies, is the lubricating oil used in vacuum pump. In addition to the so-called lubrication, cooling, anti-oxidation, oil-water separation and other characteristics of general lubricating oil, it is more emphasized that in the low-pressure state, the light components are much less than the conventional oil products. Generally speaking, when you vacuum, you will not pump oil and gas, so your vacuum pump will be very fast To achieve the effect of vacuum, but not to pump, vacuum always can not come up, this requires a high degree of oil refining, when necessary to choose synthetic oil!
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