Rotary vane vacuum pump is an oil-sealed rotary air extractor, also known as Gade pump, which is mainly composed of stator, rotor and sliding vane. The rotor is eccentrically mounted in the stator and is tangent to the apex of the inner wall of the stator. The rotor is equipped with two sliding vanes, which are tightly attached to the stator wall by the action of the spring and centrifugal force during rotation. The rotor and the vanes divide the stator into a suction chamber, a storage chamber and an exhaust chamber. As the rotor rotates and drives the sliding vane, the suction chamber is continuously expanded to inhale. The gas in the exhaust chamber is gradually compressed until the pressure exceeds the atmospheric pressure, the exhaust valve plate is opened, and the gas is discharged into the atmosphere.

In order to prevent the exhaust gas from flowing back into the pump, the exhaust valve is covered and sealed with oil. In addition to the lubrication effect of the vacuum pump oil on the stator, the rotor and the sliding vane, it also has a sealing effect. In addition, the pump oil fills all the harmful spaces in the pump cavity to eliminate their influence on the ultimate vacuum.

Ordinary rotary vane vacuum pumps are mostly used to extract pure and dry gas. If the gas containing a large amount of condensed gas is extracted, a rotary vane gas ballast (valve) vacuum pump should be selected. There is a gas ballast valve installed in the "air storage chamber", it will open to inhale a certain amount of air, and its partial pressure is several times higher than the water vapor pressure in the pumping cavity. When it reaches the exhaust chamber, the partial pressure of water vapor is still low. At the saturated vapor pressure, it will not condense into liquid water droplets, but keep the gaseous state and be discharged out of the pump together with the air.

The rotary vane vacuum pump can be used as an independent equipment to obtain low vacuum, and the ultimate vacuum is about 6.7x10-1Pa. It is widely used in vacuum metallurgy, vacuum transportation, vacuum casting, medical equipment, freeze drying, vacuum impregnation, vacuum heat treatment and other industries. Rotary vane vacuum pump can also be used as backing pump and pre-pumping pump of high vacuum pump, such as oil diffusion pump, Roots pump, oil vapor jet pump, backing pump of turbomolecular pump, pre-pumping pump of sputtering ion pump. It can also constitute an extraction unit for use in various fields of the national economy.