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, the composition of the two-stage pump. At this time the total compression ratio is borne by two levels, thus increasing the ultimate vacuum.