Each JZJ2B series roots-liquid ring vacuum system comprising a ZJP series roots vacuum pump as main pump, a SKA(2BV/2BE1) series liquid ring vacuum pump as backing pump and other valve&measure apparatus with pips to consist the unit. The units are applied to exhausting normal gases and gases with water, organic solvents or a little dust. Compared with normal mechanical vacuum pumps, the units resist oil, steam and dust. Compared with normal water ring vacuum pumps, they have high vacuums and high exhaust speeds under high vacuum, which make the unit more fit for drying dehydration and vacuum degassing in textile, food, chemical and industry fields. Comparing with common liquid ring vacuum pump,the capacity to remain high pumping speed under high or ultimate vacuum degree becomes its main advantage. Except for normal gas suction, this system can also pump special gas with small amount of vapor or dust. Additionally, this system is free from oil pollution, as well as vapor and dust. Since the 2BV type of liquid ring pump has been adopted as its fore pump, the JZJ2B series system is more efficient than JZJ2S series (which 2SK type of liquid ring pump has been adopted). And it is compact-designed with no air leakage and high protection level. Besides,our 2BV type is more anti corrosive than 2SK type, because all 2BV impeller are albronze material. Another note, the fore pump can be designed as a closed circulation system so to reduce the environment pollution greatly. JZJ2B series system has become an ideal choice for vacuum drying or dehydration process, and vacuum degassing process in the field of light textile, food industry, chemistry, pharmacy, etc.