What are the basic working principles of centrifugal pumps? (below)

2. vacuum pump

Working principle of zero water ring vacuum pump

Vacuum refers to the state of a gas below standard atmospheric pressure in a given space.

A machine or instrument that uses mechanical, physical, chemical, or physical and chemical methods to pump the container to obtain a vacuum is called a vacuum pump.

There are many types of vacuum pumps, which can generally be divided into three categories: volumetric vacuum pumps, jet vacuum pumps, and other types of vacuum pumps. Among them, volumetric vacuum pumps are widely used.

Water ring vacuum pump (referred to as water ring pump) is a kind of rough vacuum pump, it can obtain the ultimate vacuum of 2000~4000Pa, series atmospheric ejector up to 270~670Pa. The water ring pump can also be used as a compressor, called a water ring compressor, which is a low-pressure compressor with a pressure range of 1~2 × 105Pa gauge pressure.

The water ring pump was initially used as a self-priming pump, and then gradually used in many industrial sectors such as petroleum, chemical, machinery, mining, light industry, medicine and food. In many industrial processes, such as vacuum filtration, vacuum water diversion, vacuum feeding, vacuum evaporation, vacuum concentration, vacuum moisture and vacuum degassing, water ring pump has been widely used. Due to the rapid development of vacuum application technology, the water ring pump has been paid attention to in the rough vacuum. Since the gas compression in the water ring pump is isothermal, it can pump out flammable and explosive gases, and in addition to dust and water-bearing gases, the application of water ring pumps is increasing.

The working principle of the water ring vacuum pump is as follows: the pump body is equipped with an appropriate 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 with equal thickness determined by the shape of the pump cavity. The inner surface of the upper part of the water ring is just tangent to the impeller hub, and the inner surface of the lower part 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 small cavities with equal number of blades by the impeller. If the upper 0 ° of the impeller is taken as the starting point, the volume of the small cavity will increase from small to large when the impeller rotates 180 ° before, and it will communicate with the suction port on the end face. At this time, the gas will be sucked in. When the suction ends, the small cavity will be isolated from the suction port. When the impeller continues to rotate, the small cavity changes from large to small, making the gas compressed; when the small cavity communicates with the exhaust port, the gas is discharged out of the pump.

In short, the water ring pump is to achieve suction, compression and exhaust by the change of the volume of the pump chamber, so it belongs to the positive displacement vacuum pump.