It is a rotary positive displacement vacuum pump. The two 8-shaped rotors maintain a certain gap with the pump chamber. Through a pair of synchronously counter-rotating high-precision gears, the two rotors do not contact each other and maintain a certain gap when rotating in the pump chamber.

Its advantage is that it still has a large pumping rate at a lower inlet pressure, but ordinary Roots vacuum pumps cannot be used alone and must be used in conjunction with a fore-stage vacuum pump. The Roots vacuum pump can only be started after the fore-stage vacuum pump has pumped the pressure in the system to the pressure allowed by the Roots vacuum pump.

According to different working pressures and process conditions, the fore-stage vacuum pump of Roots vacuum pumps can use oil-sealed mechanical vacuum pumps, liquid ring vacuum pumps, oil-free screw dry vacuum pumps, etc. After being equipped with different types of fore-stage vacuum pumps, the performance indicators of Roots vacuum pumps are different. Roots vacuum pumps are mainly used in any vacuum system that requires a large pumping speed and rough and medium vacuum (10°~10-Pa.), such as: vacuum coating, vacuum welding furnaces, vacuum heat treatment furnaces, large-scale space simulation tests, microelectronics and integrated circuits, lamp and bulb manufacturing, laser manufacturing, vacuum packaging, centralized exhaust systems, various chemical treatments, vacuum degassing, vacuum dehydration, vacuum freeze drying, and vacuum distillation.