The circulating water vacuum pump, also known as the water-ring vacuum pump (laboratory type) or suction filtration pump, is a device that generates low-pressure air using fluid dynamics principles, with tap water (or cooling fluid) as the working medium.

  It utilizes the high-speed rotation of the impeller within the pump chamber to create a rotating liquid ring around the working water. This liquid ring is used to facilitate the intake, compression, and expulsion of gases by taking advantage of the periodic changes in volume between the liquid ring and the blades of the impeller. Due to its simple structure, low cost, corrosion resistance, lack of oil contamination, and ability to extract water vapor-containing gases, the circulating water vacuum pump has become one of the most widely used vacuum sources in chemical laboratories, pharmaceutical pilot production, food analysis, and small-scale industrial production. It is an ideal companion for rotary evaporators, vacuum drying chambers, and filtration devices.