This pump is an oil-sealed mechanical rotary pump. Pumps such as rotary-vane, rotary-piston and mechanical booster are all positive displacement types. They reduce the pressure in a system by repeatedly taking samples of gas into the pump. The pump mechanism isolates the gas from the inlet, compresses it and then expels it through an outlet. This type of pump is the one most generally adopted in the vacuum industry today for the production of pressures down to 10-2 to 10-3 mbar.