ZHONGNI  Roots vacuum set is an equipment for producing medium and high vacuum. Roots pump is its main pump and rotary vane pump or liquor pump is advance pump.  Whole set is constituted of roots pump, rotary vane pump or liquor pump, pipe (including corrugated pipe), valve and electricity controller.

       The biggest two features of roots vacuum set: one is overtaking two-stage rotary vane pumps’ shortcoming. When pressure is between 103 and 1Pa, its suction speed decreases. The other is comparing with two-stage rotary vane pumps with same suction speed, it saves energy remarkably.
       In common work conditions, series connection set constituted by roots pump and rotary vane pump/liquor pump at most can reach three stages. (2 roots pump and 1 rotary vane pump/liquor pump). Its limit pressure can enlarge by 10 times, i.e. reaching 10-3Pa. But if wanted to product higher limit vacuum, it is not good to add roots pump.
       Comparing with other sets which forehead pump also is mechanic pump, this set makes features of small volume, light mass, low noise and higher vacuum. It is fit for pumping no-corrosion and no-chemical-reaction-with-pump-oil clear gas. In gas ballast condition, it can pump some condensable gases.
       The set can be used not only as main pumping equipment but also as advance pumping equipment ahead of higher vacuum-making equipments like diffusion pump or molecule pump. It is widely used in vacuum smelting, steel liquid degassing, vacuum dryness, vacuum dipping, vacuum heat-insulation, vacuum condensing, vacuum decoloring and deodorization, electric light source and vacuum flask gas discharging.
       According to practical demand, several sets can be designed for parallel connection to improve suction capacity.