How a vacuum pump works A vacuum pump is a device that creates, improves and maintains a vacuum in a confined space in a variety of ways. A vacuum pump can be defined as a device or device that uses a mechanical, physical, chemical or physico-chemical method to evacuate a drawn vessel to obtain a vacuum. As vacuum applications evolve, the variety of vacuum pumps has evolved in many ways, with pumping speeds ranging from a few tenths of a second to hundreds of thousands per second and millions of liters. According to the working principle of vacuum pump, vacuum pump can basically be divided into two types, namely, gas transmission pump and gas trap pump. With the application of vacuum technology in the field of production and scientific research more and more wide range of its application pressure, most of the need to be composed of several vacuum pump vacuum exhaust system together to meet the requirements of production and scientific research process, due to Because of the wide range of working pressures involved in the vacuum application sector, it is not possible for any type of vacuum pump to be perfectly suitable for all working pressure ranges. Different types of vacuum pumps can only be used depending on the pressure range and operating requirements Vacuum pump. In order to facilitate the use and various vacuum process needs, sometimes a variety of vacuum pumps according to their performance requirements combined with the unit type application. Water ring vacuum pump / liquid ring vacuum pump works: Water ring vacuum pump (water ring pump) is a rough vacuum pump, it can get the ultimate vacuum of 2000 ~ 4000Pa, series of air ejector up to 270 ~ 670Pa. Water ring pump can also be used as a compressor, called the water ring compressor, is a low pressure compressor, the pressure range of 1 ~ 2 × 105Pa gauge pressure. Water ring pump was originally used as a self-priming 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 feed, vacuum evaporation, vacuum concentration, vacuum resurgence and vacuum degassing, water ring pump is widely used. Due to the rapid development of vacuum application technology, water ring pumps have gained much attention in the area of ​​rough vacuum. As the water ring pump gas compression is isothermal, it can be extracted flammable and explosive gases, in addition to pumping dust, water-containing gas, therefore, water ring pump applications are increasing. In the pump body with the right amount of water 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 of approximately equal thickness depending on the shape of the pump chamber. The inner surface of the lower part of the water ring is just tangential to the hub of the impeller. The upper inner surface of the water ring is just in contact with the top of the blade (in fact, the blade has a certain insertion depth in the water ring). At this moment, a crescent-shaped space is formed between the impeller hub and the water ring, and the space is divided into a plurality of small cavities equal to the number of the blades by the impeller. If the lower part of the impeller 0 ° as a starting point, then the impeller 180 ° before the rotation of the small chamber volume from small to large, and the end of the suction port communicating, when the gas is inhaled, when the inhalation end of the small cavity When the impeller continues to rotate, the small cavity becomes smaller and the gas is compressed; when the small chamber communicates with the exhaust port, the gas is discharged outside the pump. In summary, the water ring pump is based on changes in the volume of the pump to achieve suction, compression and exhaust, so it belongs to the varactor vacuum pump. Roots vacuum pump works Roots pump in the pump chamber, there are two "8" -shaped rotor perpendicular to each other mounted on a pair of parallel shaft, the transmission ratio of 1 pairs of gear with a reverse direction of synchronization with each other Rotating movement. Between the rotors, between the rotor and the pump housing to maintain a certain gap, you can achieve high-speed operation. As Roots pump is a type of vacuum pump without internal compression, the compression ratio is usually low, so the high and medium vacuum pumps require a foreline pump. Roots pump ultimate vacuum in addition to depend on the pump structure and manufacturing accuracy, but also depends on the foreline pump ultimate vacuum. In order to increase the pump ultimate vacuum, Roots pumps can be used in series. Roots pumps work like Roots blowers. Due to the constant rotation of the rotor, the drawn gas is sucked into the space v0 between the rotor and the pump housing through the air inlet and then discharged through the air outlet. Since inhaled v0 space is completely closed state, so the gas in the pump chamber is not compressed and expanded. However, when the top of the rotor rotates over the edge of the exhaust port, when the v0 space communicates with the exhaust side, part of the gas bounces back into the space v0 due to the higher gas pressure on the exhaust side, causing the gas pressure to suddenly increase. When the rotor continues to rotate, the gas is discharged outside the pump.