Rotary Vane Pump is an oil-based vacuum pump, that can be used to obtain #prevacuum or even medium vacuum (depending on the system). In this device the rotor and vane(s) are in the housing, that is filled with oil. When the gas enters the chamber through the inlet, it gets trapped in the oil and is transported through the working chamber with the help of the rotor and vane(s) to the outlet, where the gas exits the system. The oil acts as a lubricant and also allows the pumping of some corrosive gases, as it protects the metal to some degree. Although this pump is quite fast and efficient for obtaining pre vacuum, it also may contaminate the vacuum system with oil. Therefore the use of oil traps is highly recommended.