Cg-17 glass three-stage high vacuum oil diffusion pump GG-17 has low glass expansion coefficient and can better withstand high temperature difference. Therefore, compared with the same type of pump, the pump can withstand high temperature and has a longer service life. The pump is suitable for electronic industry, such as electronic tube. Picture tube. X-ray tube, as well as semiconductor monocrystalline silicon smelting and purification, high boiling point oil distillation, purification and separation, fluorescent lamp, thermos, high vacuum exhaust instrument. Working principle: firstly, the system is pumped to 10 ~ 2PA by rotating vacuum pump, and the diffusion pump oil is heated and boiled. Then, the gas molecules in the system are continuously carried to the elbow ball bubble of the pump side arm by the high-speed steam flow from the oil, and the gas molecules are extracted when the gas density reaches the working range of the mechanical vacuum pump, The working principle of water ring vacuum pump / liquid ring vacuum pump is a kind of coarse vacuum pump, which can obtain the limit vacuum of 2000 ~ 4000Pa and the series atmospheric ejector can reach 270 ~ 670pa. Water ring pump can also be used as a compressor, called water ring compressor, is a low-pressure compressor, its pressure range is 1 ~ 2 × 105Pa gauge pressure.

Water ring pump was initially used as self suction pump, and then gradually used in petroleum, chemical, machinery, mining, light industry, medicine and food and many other industrial sectors. In many industrial processes, such as vacuum filtration, vacuum water diversion, vacuum feeding, vacuum evaporation, vacuum concentration, vacuum moisture regain and vacuum degassing, water ring pump has been widely used. Due to the rapid development of vacuum application technology, water ring pump has been paid attention to in the aspect of obtaining rough vacuum. Because the gas compression in the water ring pump is isothermal, it can extract flammable and explosive gas, in addition to the gas containing dust and water. Therefore, the application of water ring pump is increasing day by day. A proper amount of water is installed in the pump body as the working fluid. When the impeller rotates clockwise in the figure, the water is thrown around by the impeller. Due to the centrifugal force, the water forms a closed ring approximately equal to the thickness determined by the shape of the pump chamber. The inner surface of the lower part of the water ring is just tangent to the impeller hub, and the upper inner surface of the water ring is just in contact with the tip of the blade (in fact, the blade has a certain insertion depth in the water ring). At this time, a crescent shaped space is formed between the impeller hub and the water ring, and this space is divided into several cavities equal to the number of blades by the impeller. If the lower 0 ° of the impeller is taken as the starting point, then the volume of the small cavity changes from small to large when the impeller is 180 ° before rotation, and it is connected with the suction port on the end face. At this time, the gas is inhaled, and when the suction end, the small cavity is isolated from the suction port; when the impeller continues to rotate, the small cavity becomes smaller and the gas is compressed; when the small cavity is connected with the exhaust port, the gas is discharged from the pump. To sum up, water ring pump is to achieve suction, compression and exhaust by the change of pump chamber volume, so it belongs to variable volume vacuum pump.

The working principle of roots pump: Roots pump in the pump cavity, there are two "8" shaped rotors installed vertically on a pair of parallel shafts, driven by a pair of gear belts with a transmission ratio of 1 to move in reverse synchronous rotation. There is a certain gap between the rotors and the inner wall of the pump shell, which can realize high speed operation. Because roots pump is a kind of vacuum pump without internal compression, the compression ratio is usually very low, so the high and medium vacuum pumps need the front stage pump. The limit vacuum of roots pump depends not only on the structure and manufacturing accuracy of the pump itself, but also on the limit vacuum of the previous stage pump. In order to improve the limit vacuum degree of the pump, roots pump can be used in series. The working principle of roots pump is similar to roots blower. Due to the continuous rotation of the rotor, the extracted gas is drawn into the space V0 between the rotor and the pump shell from the air inlet, and then discharged through the exhaust port. Because the V0 space is completely closed after suction, there is no compression and expansion in the pump chamber. However, when the top of the rotor turns around the edge of the exhaust port and the V0 space is connected with the exhaust side, a part of the gas will recoil into the space V0 due to the high gas pressure on the exhaust side, which makes the gas pressure suddenly increase. When the rotor continues to rotate, the gas is discharged from the pump.

Working principle of rotary vane vacuum pump (referred to as rotary vane pump) is an oil sealed mechanical vacuum pump. Its working pressure range is 101325 ~ 1.33 × 10-2 (PA), which belongs to low vacuum pump. It can be used alone, and can also be used as the front stage pump of other high vacuum pumps or ultra-high vacuum pumps. It has been widely used in metallurgy, machinery, military industry, electronics, chemical industry, light industry, petroleum and medicine and other production and research departments. The rotary vane pump can pump out the dry gas in the sealed container, and a certain amount of condensable gas can also be pumped out if there is a gas stabilizer. However, it is not suitable for the removal of gases with high oxygen content, corrosive to metal, chemical reaction to pump oil and dust particles. Rotary vane pump is one of the most basic vacuum equipment in vacuum technology.

Rotary vane pump is mostly small and medium-sized pump. Rotary vane pump has single-stage and two-stage. The so-called two-stage, is in the structure of two single-stage pumps in series. Generally, it is made of two stages to obtain higher vacuum. The relationship between the pumping speed and the inlet pressure of the vane pump is specified as follows: when the inlet pressure is 1333pa, 1.33pa and 1.33 × 10-1 (PA), the pumping speed value shall not be lower than 95%, 50% and 20% of the nominal pumping speed of the pump respectively. Rotary vane pump is mainly composed of pump body, rotor, rotating blade, end cover, spring, etc. A rotor is eccentrically installed in the cavity of the vane pump. The outer circle of the rotor is tangent to the surface of the pump cavity (there is a small gap between them). Two rotors with springs are installed in the rotor groove. When rotating, centrifugal force and spring tension keep the top of the vane in contact with the inner wall of the pump chamber, and the rotating rotor drives the vane to slide along the inner wall of the pump chamber. The crescent shaped space surrounded by the rotor, pump chamber and two end covers is divided into three parts a, B and C by two rotating blades. When the rotor rotates in the direction of arrow, the volume of space a connected with the suction port is gradually increased and is in the process of suction. The volume of space C connected with the exhaust port is gradually reduced and is in the process of exhaust. The volume of space B in the middle is also gradually decreasing and is in the process of compression. As the volume of space a is gradually increasing (that is, expansion), the gas pressure is reduced, and the external gas pressure at the pump inlet is greater than that in space a, so the gas is inhaled. When space a is isolated from the suction port, i.e. to the position of space B, the gas begins to be compressed, the volume gradually reduces, and finally communicates with the exhaust port. When the compressed gas exceeds the exhaust pressure, the exhaust valve is pushed open by the compressed gas, and the gas is discharged into the atmosphere through the oil layer in the oil tank. By the continuous operation of the pump, the purpose of continuous pumping is achieved. If the discharged gas is transferred to another stage (low vacuum stage) through the airway, it is pumped out by the low vacuum stage, and then compressed by the low vacuum stage and discharged into the atmosphere, which is a two-stage pump. In this case, the total compression ratio is borne by two stages, thus increasing the limit vacuum degree.