Working principle of various vacuum pumps, vacuum pump principle Water ring vacuum pump / liquid ring vacuum pump Working principle Water ring vacuum pump (hereinafter referred to as water ring pump) is a rough vacuum pump, it can get the ultimate vacuum of 2000 ~ 4000Pa, 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 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 gear ratio of 1 by a pair of gear with the reverse action of each other in sync 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. Rotary vane vacuum pump Rotary vane vacuum pump (referred to as rotary vane pump) is a kind of oil-sealed mechanical vacuum pump. The working pressure range of 101325 ~ 1.33 × 10-2 (Pa) belongs to the low vacuum pump. It can be used alone or as a foreline pump for other high-vacuum or ultra-high vacuum pumps. It has been widely used in metallurgy, machinery, military, electronics, chemicals, light industry, petroleum and pharmaceutical production and research departments. Rotary vane pump can be sealed off the sealed container of dry gas, if accompanied by gas-town device, you can also pump a certain amount of condensable gas. However, it is not suitable for the extraction of gases that are highly oxygenated, corrosive to metals, react chemically to pump oils and contain particulate dust. Rotary vane pumps are one of the most basic vacuum acquisition devices in vacuum technology. Rotary vane pump for small and medium-sized pump. Rotary vane pump has a single-stage and two-stage. The so-called two-stage, is the structure of two single-stage pump in series. Generally made more double-stage, in order to obtain a higher degree of vacuum. The relation between pumping speed and inlet pressure of rotary vane pump is as follows: under the inlet pressure of 1333Pa, 1.33Pa and 1.33 × 10-1 (Pa), the pumping speed shall not be lower than 95% of the nominal pumping speed of the pump respectively, 50% and 20%. Rotary vane pump mainly by the pump body, rotor, rotary vane, end caps, springs and other components. A rotator is eccentrically mounted in the cavity of the rotary vane pump, the outer circumference of the rotor is tangent to the inner surface of the pump cavity (both have a small gap), and two rotary vanes with springs are arranged in the rotor slot. Rotation, by centrifugal force and the tension of the spring so that the top of the rotary vane and the inner wall of the pump chamber to maintain contact with the rotor rotation of the rotary vane slide along the wall. The two vanes separate the crescent-shaped space enclosed by the rotor, the pump chamber and the two end caps into three sections A, B and C. When the rotor rotates in the direction of the arrow, the volume of the space A communicating with the suction port is Increasingly, is in the process of breathing. While the volume of the space C communicating with the exhaust port is gradually reduced and is in the process of exhausting. The volume of the central space B is also gradually reduced, is in the process of compression. Since the volume of space A is gradually increased (ie, expanded), the pressure of the gas is decreased and the pressure of the external gas at the inlet of the pump is greater than the pressure in space A, so gas is drawn in. When the space A and the suction port isolated, that is, to the space B position, the gas began to be compressed, the volume gradually reduced, and finally connected to the exhaust port. When the compressed gas exceeds the pressure of the exhaust gas, the exhaust valve is pushed by the compressed gas and the gas is discharged into the atmosphere through the oil layer in the fuel tank. By the continuous operation of the pump, to achieve the purpose of continuous extraction. If the discharge of gas through the airway and into another level (low vacuum level), from the low vacuum stage pumped away, and then by the low vacuum stage after the discharge to the atmosphere, that constitutes a two-stage pump. At this time the total compression ratio is borne by two levels, thus increasing the ultimate vacuum. 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.
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