What kind of viscosity oil should be used for all kinds of vacuum pum
In recent decades, China's vacuum technology has developed rapidly and has become an independent basic science. Many industrial sectors are flourishing such as aerospace science, vacuum coating, vacuum smelting, high-energy physics, controlled thermonuclear reaction, surface research and other cutting-edge sciences. Both have direct or even interdependent relationships with the advancement of vacuum technology. Vacuum oil is used as a special lubricant for various types of mechanical vacuum pumps. It is responsible for lubrication, sealing and cooling in the vacuum pump. Although mechanical vacuum pumps are of different types, oils must have suitable viscosity, good oil-water separation, excellent thermal stability and oxidation stability, and as low a saturated vapor pressure as possible, as oil quality directly affects vacuum equipment. The ultimate pressure reached, pumping rate, back pressure and oil return rate. In recent years, with the development of vacuum technology, mechanical vacuum pumps have been developed to high speed, high efficiency, low noise and miniaturization. The surface speed of the friction pair surface in the pump chamber increases, and the oil temperature rises. Therefore, the mechanical vacuum pump oil tends to be low in viscosity, and it is required to maintain a low vapor pressure at the pump operating temperature. According to the working state of the oil during use, the vacuum oil can be divided into mechanical vacuum oil, steam jet pump oil, vacuum mechanical lubricating oil and vacuum sealing oil.
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Vacuum pump oil viscosity is one of the important factors to play the performance of vacuum pump. The viscosity of liquid is the resistance of liquid flow, or the internal friction of liquid. Therefore, the greater the viscosity, the greater the resistance of various moving parts; but the viscosity is too Small, the sealing performance of the pump is deteriorated, causing gas leakage and the vacuum is deteriorated. Therefore, the selection of oil viscosity for all types of vacuum pumps is extremely important.
I. Oil viscosity selection principle
(1) The higher the rotational speed of the pump, the greater the linear velocity of the rotor of the pump, and the lower the viscosity of the selected oil;
(2) The finer the machining precision of the pump parts or the smaller the gap between the friction parts, the lower the viscosity of the selected oil products;
(3) When the vacuum pump is used in high temperature working conditions, the viscosity of the oil is selected to be large;
(4) A vacuum pump with a cooling water circulation, generally using a lower viscosity oil;
(5) The vacuum pump oil used in winter and summer should differ by one viscosity grade.
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2. Selection of oil viscosity range for various vacuum pumps
According to the above principles, the selection of the viscosity range of the vacuum pump oil is recommended as follows:
(1) Piston vacuum pump (W type) generally uses HVI100, HVI150 neutral oil.
(2) Rotary vane vacuum pump (2X type) uses V68, V100 viscosity grade oil.
(3) Direct-coupled (high-speed) rotary vane vacuum pump (2XZ type) uses V46, V68 viscosity grade oil.
(4) Spool type vacuum pump (H type) selects V68, V100 viscosity grade oil.
(5) The trochoidal vacuum pump (YZ, YZR type) uses V100, V150 viscosity grade oil.
(6) Lutz vacuum pump (mechanical booster pump) gear transmission system lubrication, V32, V46 viscosity grade vacuum pump oil can be selected.
(7) Other types of vacuum pumps can be selected according to their speed, processing accuracy, ultimate vacuum, etc.
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In addition, oil must be purchased from regular manufacturers. Because individual manufacturers produce vacuum pump oil, they do not undergo distillation and cutting, directly use base oil, add ordinary antioxidants, and sell as products. The hazards are:
(1) Although the product can be used as vacuum pump oil to a certain extent, it will greatly extend the vacuuming time during use;
(2) Ordinary antioxidants are easily oxidized and decomposed at high temperatures, generating acidic substances, producing odors and polluting the environment. At the same time, oils are also highly susceptible to oxidative deterioration and shortened service life;
(3) The ultimate pressure and saturated vapor pressure do not reach the quality standard, which affects the ultimate vacuum of the vacuum pump.
Mechanical vacuum pump oil is a product that has undergone deep refining, vacuum degassing or molecular distillation, and does not contain light components. The following items must be noted in use:
(1) Storage of oil products. Oil-filled containers must be clean, not exposed to sunlight and stored in the open air. Store in dark, dry and cold places, with water and mechanical impurities.
(2) When taking oil or loading oil, the dust around the lid must be removed to prevent impurities from mixing into the oil, causing the pump to rub.
(3) Different grades, varieties and new and old vacuum pump oils cannot be mixed.
(4) Vacuum pump oil is strictly avoided to mix with other petroleum products, especially light oil products, otherwise it will affect the vacuum performance of the pump.
(5) The vacuum pump should avoid solvent, water vapor and corrosive gas as much as possible. When it is necessary to remove such gas, it is necessary to take necessary remedial measures, and also need to check and change the oil frequently, especially when the oil is emulsified or When diluting to affect the sealing performance of the pump, new oil must be exchanged.
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(6) When changing oil, the old oil must be drained, the new oil should be poured from the suction port of the pump, and the pump shaft should be slowly rotated by hand, the pump cavity should be cleaned and drained, and the pump cavity should be repeatedly cleaned several times, then Wash the residual oil in the pump casing and install new oil.
(7) When the pump is overhauled, the components of the pump must be cleaned with solvent or cleaning agent and the parts dried. When assembling, the components must be immersed in new vacuum pump oil before they can be combined. After assembly, rinse with new oil and then fill in new oil.
(8) The fueling appliance must be a special equipment and cannot be a container filled with other oils or solvents.
(9) For vacuum pumps with high corrosive atmosphere or high purity requirements, fluoropolyether oil may be selected according to equipment requirements.