Structural features：

Roots screw vacuum unit is an oil-free vacuum unit composed of ordinary roots vacuum pump as the main pump, intermediate pump and screw vacuum pump as the backing pump in series. The working principle and structure of Roots vacuum pump and screw vacuum pump are similar, and the unit composed of Roots vacuum pump and screw vacuum pump has the advantages of screw vacuum pump. At the same time,by connecting Roots vacuum pump with large pumping speed in series,the pump in g speed of screw vacuum pump is doubled,the ultimate vacuum degree is improved, and the pumping system has good energy-saving effect. Roots screw unit has high vacuum and high pumping efficiency in high vacuum area. Through the supporting control system,the unit can be automatically started and stopped, and it has automatic protection functions such as overload,over current and water cut-off. The whole vacuum unit can be subjected to anti-corrosion treatment,so that it can be used for occasions where corrosive gases are pumped out When each vacuum pump of the unit adopts vertical superposition or stepped structure, the unit occupies as mall area, and foreign matters are not easy to accumulate in each pump and intermediate pipeline,which has obvious advantages in pumping out gases containing a small amount of condensable gas or dust. 

According to the size of the pumped system, working pressure and other factors, the vacuum unit is reasonably configured, and the stage ratio (pumping speed ratio) between the pumps of the vacuum unit can be selected between 1:2 and 1: 8. Increasing the stage ratio will reduce the pumping efficiency of the vacuum pump,narrow the working pressure range,slow start-up and prolong the pre-pumping time.

USE：

Roots screw vacuum unit has high vacuum degree, wide working pressure range, high pumping efficiency, and can carry out anti-corrosion treatment, It belongs to oil-free vacuum acquisition equipment and has a wide application range. It can be widely used in various industries such as medicine, chemical industry, aerospace, electronics, solar energy, metallurgy, food, etc. The unit is suitable for high vacuum distillation, vacuum evaporation, dehydration and crystallization in chemical industry and pharmaceutical industry. It can also be used in vacuum impregnation and vacuum drying process in power industry,and it is also an ideal vacuum pumping equipment for vacuum coating, vacuum smelting, vacuum heat treatment,vacuum oil filtering,freeze drying, aviation simulation test and other processes.