Water ring vacuum pump (referred to as water ring pump) is a rough vacuum pump, it can get the ultimate vacuum of 2000 ~ 4000Pa, series of atmospheric ejectors up to 270 ~ 670Pa. Water ring vacuum 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 vacuum 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 vacuum pump is widely used. Due to the rapid development of vacuum application technology, water ring vacuum pumps have always been valued in rough vacuum acquisition. As the water ring vacuum 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 direction indicated 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 upper part of the water ring is just tangential to the impeller hub and the lower inner surface of the water ring is just in contact with the tip of the blade (in fact there is a certain insertion depth of the blade in the water ring). At this point the impeller hub and the water ring form a crescent-shaped space, and this space has been divided into a number of impeller leaves the same number of small cavities. If the upper part of the impeller 0 ° as a starting point, then the impeller at 180 ° before rotation when the small chamber volume from small to large, and the end of the suction port communicating, when the gas is inhaled, when the end of the inhalation chamber 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 vacuum 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. Water ring pump and other types of mechanical vacuum pump compared to the following advantages: simple structure, low manufacturing precision, easy processing. Compact structure, high pump speed, the general direct connection with the motor, without deceleration. Therefore, with a small structure size, you can get a large displacement, covers an area is small. Compressed gas is basically isothermal, that is, compressed gas process temperature changes very small. Since there is no metallic friction surface in the pump chamber, there is no need to lubricate the pump and the wear is minimal. The seal between the rotor and the retainer can be made directly from the water seal. Inspiratory uniform, stable and reliable, easy to operate, easy maintenance. Water ring vacuum pump also has its drawbacks: low efficiency, generally about 30%, preferably up to 50%. The vacuum is low, not only because of the structural limitations, but more importantly because of the saturated vapor pressure of the working fluid. Water for the working fluid, the ultimate pressure can only reach 2000 ~ 4000Pa. Oil for the working fluid, up to 130Pa. In short, because the water ring vacuum pump gas compression is isothermal, it can be extracted flammable and explosive gases. Because there is no exhaust valve and friction surface, it can be extracted with dust gas, condensable gas and water-air mixture. With these outstanding features, despite its inefficiency, it is still widely used.