A rotary vane vacuum pump (or simply rotary vane pump) is an oil-sealed mechanical vacuum pump. Its operating pressure range is 101325~1.33×10⁻² (Pa), classifying it as a low-vacuum pump. It can be used independently or as a backing pump for other high-vacuum or ultra-high-vacuum pumps. It is widely used in production and research departments in metallurgy, machinery, military, electronics, chemical, light industry, petroleum, and pharmaceutical industries.
Rotary Vane Vacuum Pump Working PrincipleA rotary vane vacuum pump (referred to as a rotary vane pump) is an oil-sealed mechanical vacuum pump. Its operating pressure range is 101325~1.33×10⁻² (Pa), classifying it as a low-vacuum pump. It can be used independently or as a backing pump for other high-vacuum or ultra-high-vacuum pumps. It is widely used in metallurgy, machinery, military, electronics, chemical, light industry, petroleum, and pharmaceutical production and research departments.
Rotary vane pumps can evacuate dry gases from sealed containers. With a gas ballast device, they can also evacuate a certain amount of condensable gases. However, they are not suitable for pumping gases with excessively high oxygen content, gases that are corrosive to metals, gases that chemically react with pump oil, or gases containing particulate dust.Rotary vane pumps are one of the most fundamental vacuum-generating devices in vacuum technology. Most rotary vane pumps are small to medium-sized. They come in single-stage and two-stage types. A two-stage pump is essentially two single-stage pumps connected in series. Two-stage pumps are generally preferred to achieve higher vacuum levels.
The pumping speed of a rotary vane pump is related to the inlet pressure as follows: at inlet pressures of 1333 Pa, 1.33 Pa, and 1.33 × 10⁻¹ Pa, the pumping speed must not be less than 95%, 50%, and 20% of the pump's nominal pumping speed, respectively.A rotary vane pump mainly consists of a pump body, rotor, vanes, end covers, and springs. An eccentric rotor is mounted inside the pump's cavity, its outer circumference tangent to the inner surface of the pump cavity (with a very small gap). Two spring-loaded vanes are installed in the rotor slots. During rotation, centrifugal force and spring tension keep the vane tips in contact with the inner wall of the pump cavity, and the rotor's rotation causes the vanes to slide along the inner wall. The two vanes divide the crescent-shaped space formed by the rotor, pump cavity, and two end covers into three parts: A, B, and C. When the rotor rotates in the direction of the arrow, the volume of space A, which communicates with the suction port, gradually increases, indicating the suction process. The volume of space C, which communicates with the exhaust port, gradually decreases, indicating the exhaust process. The volume of space B, in the center, also gradually decreases, indicating the compression process. Because the volume of space A gradually increases (i.e., expands), the gas pressure decreases. The external gas pressure at the pump inlet is greater than the pressure inside space A, thus drawing in gas. When space A is isolated from the intake port, i.e., when the pump moves to space B, the gas begins to be compressed, its volume gradually decreases, and finally it connects to 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 through the oil layer in the tank and is discharged into the atmosphere. Continuous pumping achieves continuous evacuation. If the discharged gas passes through the air passage and enters another stage (low vacuum stage), is drawn away by the low vacuum stage, and then compressed again before being discharged into the atmosphere, this constitutes a two-stage pump. In this case, the overall compression ratio is borne by both stages, thus increasing the ultimate vacuum.
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