The typical type of vacuum pump in oil seal vacuum pump is rotary vane vacuum pump. If it is running all the time, the friction heat will lead to the increase of vane wear, which will have a serious impact on the life of the vacuum pump. The temperature of the vacuum pump oil will also increase, which will cause the viscosity to decrease, and the saturated vapor pressure will increase, which will cause the limit vacuum of the vane vacuum pump to decrease, especially the full pressure measured by thermocouple. If ventilation and heat dissipation are strengthened or the performance of pump oil is improved, the limit vacuum can be improved.

Principle and method of replacing and mixing vacuum pump oil

Due to the untimely supply of oil products or the lack of suitable varieties in the market and other factors, the problems of oil substitution and mixed use sometimes occur during the use of vacuum oil, including domestic oil and foreign oil, different types of oil in domestic oil, different manufacturers or brands of the same kind of oil, mixing of new oil with "old" oil in use, etc.

At present, many users are more arbitrary in choosing alternative oil or mixing vacuum pump oil. However, it should be noted that different types of vacuum pump oil have different physical and chemical properties. Its chemical composition, viscosity, acid value and various additives (anti-wear agent, preservative, antioxidant, antirust agent) and other main components and indicators directly affect the operation of the machine parts The performance will change, which not only relates to the service life of the machine parts, but sometimes even causes accidents due to improper lubrication.

Therefore, the following principles should be observed when using substitute oil or mixed oil products, and the selection should be cautious:

1、 Substitution principle of vacuum pump oil

1. Try to use the same kind of vacuum pump oil or pump oil with similar performance and similar additive type.

2. The viscosity of the substitute vacuum pump oil should not exceed ± 25% of the original oil viscosity. In general, priority should be given to the use of pump oil with higher viscosity.

3. The quality should be replaced by high quality vacuum pump oil, that is to say, the vacuum pump oil with high quality should be used instead, which is more reliable for equipment lubrication. At the same time, it can also extend the service life, which is economical.

4. The environment and working temperature of the equipment should also be considered when selecting the substitute pump oil. For the mechanical equipment with large working temperature change, the viscosity temperature property of substitute oil is better; for the machinery working at low temperature, the pour point of substitute oil should be lower than 10 ℃ below the working temperature; for the machinery working at high temperature, the flash point of the substitute oil should be higher, and the oxidation safety should also meet the use requirements.

2、 Mixing principle of vacuum pump oil

1. Different brands, different manufacturers, old and new pump oil should be avoided in general.

2. Vacuum pump oil can be mixed under the following conditions:

(1) Similar products of the same manufacturer with similar quality, or high-quality pump oil mixed with low-quality pump oil are still used for the original machinery and equipment;

(2) The products of the same manufacturer and different brands can be mixed when the viscosity and other physical and chemical properties of pump oil need to be adjusted;

(3) Different types of pump oil, if you know that two kinds of mixed pump oil are not added with additives, or one of them is not added with additives, or both oils are added with additives but do not react with each other, they can be mixed, but the quality of high-quality pump oil will be reduced. When the empty pump oil is exchanged with other synthetic vacuum pump oil, the pump should be disassembled for thorough cleaning. All parts shall be immersed in the oil to prevent contamination.

3. Oil change vacuum pump should try to avoid removing solvent, steam and corrosive gas, such as inhalation of chemical gas and solvent, which will pollute the pump oil and affect the vacuum, it must be cleaned and replaced.

When changing the oil, the used oil in the pump body should be drained. After the new oil is poured into the pump, slowly rotate the pump shaft, clean the pump cavity, drain the residual oil, repeatedly clean it for several times, and then replace the new oil after cleaning.

When the pump is overhauled, all parts of the pump must be cleaned with solvent or cleaning agent and dried. Oiling appliances must be special equipment, and should not be the container pumping pump that contains other oil or solvent.