Summarization JZH series rotary piston vacuum pump set is made up with the Roots pump and rotary piston vacuum pump. Rotary piston vacuum pump is used as the pre-vacuum pump and the backing vacuum pump of the roots vacuum pump. The selection of displacement ratio between the Roots vacuum pump, is mainly referred to the pump under long term running; when working in low vacuum, it is advisedto select small displacement ratio(2:1 to 4:1); if working in medium or high vacuum, the bigger displacement ratio(4:1 to 10:1) should be preferred. Features ● High vacuum,high exhausting efficiency in medium or high vacuum,wide working range,obvious energy-saving; ● Integrated rack,compact structure,small required space; ● High automation,simple operation,easy maintenance,safe,reliable and durable running. Applications Widely used in vacuum metallurgy, vacuum heat treatment, vacuum dry, vacuum impregnation, vacuum strainer, poly-silicon production, aerospace simulation and so on..