Liquid ring vacuum pump by offset impeller rotary motion within the pump chamber to periodically change the working chamber volume in order to achieve vacuum pump. Its studio consists of a rotating liquid ring and impeller, its structure and working principle and liquid ring compressor is similar. Inhalation port work was evacuated vacuum container. The pump cavity filled with water is called water ring vacuum pump Water ring vacuum pump is simple in structure, easy to manufacture, reliable, easy to use, durable, can be extracted from corrosive, dusty gas and water mixture. Exhaled gas temperature to 0 ~ 40 ℃ is appropriate. Circulating water should not contain impurities. Water ring vacuum pump suction rate range of 0.25 to 500 meters (/ h; ultimate pressure: unipolar pump 8 × 10 (~ 2 × 10 (Pa, two-stage pump 2 × 10 (~ 1 × 10 (Pa. Water ring vacuum pump is mainly used for vacuum distillation, vacuum drying and pump water diversion, etc .. Liquid ring vacuum pump has single-stage, two-stage, as well as the single role and double-action difference.The single-stage and two-stage vacuum pump refers to the impeller of the series; The single / double action refers to the form of impeller / shell. The impeller of the single-action impeller vacuum pump undergoes one inhalation / discharge once a week. The double acting liquid ring vacuum pump experiences two inhalations and expels of gas once a week.