Addtime： 2020-07-18 Browse times： 3114
As we all know, oil vacuum pump uses oil as medium. If unqualified vacuum pump oil is used, it is like eating gutter oil for people, and the machine will soon be sick. How should we choose high-quality vacuum pump oil?
In the process of using vacuum pump, vacuum equipment suppliers often require vacuum pump users to use regular high-quality vacuum pump oil, and change the oil frequently. At least, customers are required to change the vacuum pump oil every three months. So, what are the requirements and technical indicators of vacuum pump oil selection?
1. Under the working temperature, the vacuum pump oil must have a certain viscosity, and the change with temperature is small to ensure good sealing effect. If the viscosity is too small, the sealing performance is not good, and the viscosity is too high, it will make the pump oil difficult to enter the gap of the rate friction surface, and the lubrication effect will become worse. At the same time, the rotor rotation is difficult, the power consumption is increased, and the pump oil will overheat. It is generally required that the saturated vapor pressure at 20 ℃ shall not be greater than 5.3 * 10-3 Pa; at 50 ℃, the viscosity of pump oil shall be within the range of (47 ~ 57) * 10-6 m2 / s, which can meet the requirements. As the viscosity of the oil decreases with the increase of temperature, the sealing energy of the oil becomes worse, the saturated vapor pressure increases and the vacuum degree decreases. Therefore, the operating temperature of vacuum pump oil should not exceed 70 ℃.
2. The saturated vapor pressure of vacuum pump oil is low, and the volatile light fraction is less. Because the limit vacuum of the pump mainly depends on the vapor pressure of the lightest fraction. The saturated vapor pressure of dalutong vm100 vacuum pump oil at 20 ℃ is 6.5 * 10-5 PA, which is suitable for all kinds of mechanical vacuum pumps. In addition to saturated vapor pressure, it can also be expressed by the ignition temperature (flash point) of the pump oil, that is, at this temperature, the steam accumulated on the oil surface starts to ignite. Therefore, the higher the flash point of the pump oil is, the less volatile light fraction is and the lower the saturated vapor pressure is.
3. The chemical properties of vacuum pump oil are stable, and the contents of water, water-soluble acid, water-soluble alkali and other impurities are less.
In the daily use of vacuum pump, in order to reduce the saponification phenomenon of pump oil in the working process, a dryer can be installed at the pump inlet, which is filled with phosphorus pentoxide (P2O5) ）Or cold trap: it is filled with dry ice (solid CO2) to absorb or freeze the moisture in the gas. Sulfur containing oil should not be used in mechanical vacuum pumps. Corrosive gases and solvents should not be pumped because they will saponify the vacuum pump oil.
In fact, the choice of high-quality vacuum pump oil is not as good as the selection of good vacuum equipment manufacturers. Only powerful manufacturers with physical production plants and professional production technology can produce high-quality vacuum pump oil.
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