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The working principle of self-priming pump
Water pumpIt is a device that uses various methods to generate, improve and maintain vacuum in a closed space.Vacuum pumpIt can be defined as: a device or equipment that uses mechanical, physical, chemical or physical chemical methods to pump air from the pumped container to obtain a vacuum. With the development of vacuum applications, many types of vacuum pumps have developed, with pumping speeds ranging from a few tenths of a liter per second to hundreds of thousands and millions of liters per second. According to the working principle of vacuum pumps, vacuum pumps can basically be divided into two types, namely gas transmission pumps and gas capture pumps. As vacuum application technology has wider and wider requirements for its application pressure range in the field of production and scientific research, most of them require a vacuum pumping system composed of several electric diaphragm pumps to pump together to meet the requirements of the production and scientific research process. , Due to the wide range of working pressure involved in the vacuum application department, it is impossible for any type of vacuum pump to be completely suitable for all working pressure ranges. It can only be used according to different working pressure ranges and different working requirements. Type of vacuum pump. In order to facilitate the use and the needs of various vacuum processes, sometimes various vacuum pumps are combined according to their performance requirements and applied in unit type. Related Reading:carKnowledge: Introduction to Automobile Exhaust System EngineCarburetorWorking principle
The working principle of various vacuum pumps
Working principle of water ring vacuum pump/liquid ring vacuum pump
Water ring vacuum pump (abbreviated as water ring pump) is a kind of rough vacuum pump, which can obtain the ultimate vacuum of 2000~4000Pa, and the series air ejector can reach 270~670Pa.Water ring pump can also be used ascompressor, Called the water ringcompressor, It is low pressurecompressor, Its pressure range is 1~2×105Pa gauge pressure.
Water ring pumps were originally used as self-priming water pumps, and then gradually used in many industrial sectors such as petroleum, chemical, machinery, mining, light industry, medicine and food. In many processes of industrial production, such as vacuum filtration, vacuum water diversion, vacuum feeding, vacuum evaporation, vacuum concentration, vacuum rehydration and vacuum degassing, water ring pumps are widely used. Due to the rapid development of vacuum application technology, water ring pumps have always been valued in terms of obtaining rough vacuum. Because the gas compression in the water ring pump is isothermal, it can pump out flammable and explosive gases, and also dust and water-containing gases. Therefore, the application of water ring pumps is increasing.
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 of approximately equal thickness determined by the shape of the pump cavity.The inner surface of the lower part of the water ring coincides with the impellerWheel hubTangent, the upper inner surface of the water ring just touches the top of the blade (actually, 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 by the impeller into several small cavities equal to the number of blades. If the lower part of the impeller is 0° as the starting point, the volume of the small cavity becomes larger when the impeller rotates 180° before, and it communicates with the suction port on the end face. At this time, the gas is sucked in. When the suction ends, the small cavity It is isolated from the suction port; when the impeller continues to rotate, the small cavity changes from large to small, so that the gas is compressed; when the small cavity communicates with the exhaust port, the gas is discharged out of the pump.
In summary, the water ring pump relies on the change of the pump cavity volume to achieve suction, compression and exhaust, so it is a variable volume vacuum pump.
The working principle of self-priming pump
In the pump cavity of the Roots pump, there are two "8"-shaped rotors mounted on a pair of parallel shafts perpendicular to each other, and a pair of gears with a transmission ratio of 1 drive synchronous rotational movement in opposite directions to each other.There is a certain gap between the rotors, between the rotors and the inner wall of the pump casing, which can achieve highRotating speedrun. Since the Roots pump is a vacuum pump without internal compression, the compression ratio is usually very low, so high and medium vacuum pumps need a fore pump. The ultimate vacuum of a roots pump not only depends on the structure and manufacturing accuracy of the pump itself, but also depends on the ultimate vacuum of the backing pump. In order to improve the ultimate vacuum of the pump, Roots pumps can be used in series.
The working principle of a Roots pump is similar to that of a Roots blower. Due to the continuous rotation of the rotor, the pumped gas is sucked from the air inlet into the space v0 between the rotor and the pump casing, and then discharged through the air outlet. Since the v0 space is fully enclosed after inhalation, there is no compression and expansion of the gas in the pump cavity.
However, when the top of the rotor turns over the edge of the exhaust port and the v0 space communicates with the exhaust side, due to the higher gas pressure on the exhaust side, a part of the gas rushes back into the space v0, causing the gas pressure to suddenly increase. When the rotor continues to rotate, the gas is discharged out of the pump.
Working principle of rotary vane vacuum pump
Rotary vane centrifugal pump for short) is a kind ofOil sealType mechanical vacuum pump. Its working pressure range is 101325~1.33×10-2 (Pa), which belongs to the rough vacuum pump. It can be used alone or as a backing pump for other high vacuum pumps or ultra-high vacuum pumps. It has been widely used in the production and scientific research departments of metallurgy, machinery, military industry, electronics, chemical industry, light industry, petroleum and medicine.
The rotary vane pump can pump out the dry gas in the sealed container, and if it is equipped with a gas ballast device, it can also pump out a certain amount of condensable gas. But it is not suitable for pumping gas with high oxygen content, corrosive to metal, chemical reaction to pump oil, and particulate dust.
Rotary vane pump is one of the most basic vacuum obtaining equipment in vacuum technology. Rotary vane pumps are mostly small and medium-sized pumps. There are two types of magnetic pumps, single-stage and double-stage. The so-called two-stage is to connect two single-stage pumps in series in structure. Generally, it is made into two-stage to obtain a higher degree of vacuum.
The relationship between the pumping speed of the rotary vane pump and the inlet pressure is stipulated as follows: When the inlet pressure is 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%.
The screw pump is mainly composed of a pump body, a rotor, a rotary vane, an end cover, and a spring. A rotor is installed eccentrically in the cavity of the rotary vane pump. The outer circle of the rotor is tangent to the inner surface of the pump cavity (there is a small gap between the two). Two rotary vanes with springs are installed in the rotor slot. During rotation, centrifugal force and spring tension keep the top of the rotary vane in contact with the inner wall of the pump cavity, and the rotation of the rotor drives the rotary vane to slide along the inner wall of the pump cavity.
The two rotary vanes separate the crescent-shaped space enclosed by the rotor, the pump cavity and the two end caps into three parts 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 Gradually increasing, it is in the process of inhalation. The volume of the space C communicating with the exhaust port is gradually reduced, and it is in the exhausting process. The volume of the centered space B is also gradually decreasing, and it is in the process of compression. Since the volume of the space A is gradually increasing (that is, expanding), the gas pressure decreases, and the external gas pressure at the inlet of the chemical pump is stronger than the pressure in the space A, so the gas is sucked in. When the space A is isolated from the suction port, that is, when it is turned to the position of the space B, the gas begins to be compressed, the volume gradually decreases, and finally it 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 passes throughtankThe oil layer inside is discharged into the atmosphere. The continuous operation of the pump achieves the purpose of continuous pumping. If the discharged gas is transferred to another stage (low vacuum stage) through the air passage, it is pumped away by the low vacuum stage, and then compressed by the low vacuum stage and discharged to the atmosphere, forming a two-stage pump. At this time, the total compression ratio is borne by two stages, thus increasing the ultimate vacuum.
