Liquid Ring Vacuum pumps are positive displacement pumps that use centrifugal force to create a ring of fluid inside the casing. Water is the most common fluid that is used. Oil is another alternative but because it has a low vapor pressure, cooling is required. The gas being pumped, usually air, enters through the inlet and travels through the center. The impeller is mounted eccentrically in the casing and rotates to provide suction at the inlet and compression near the exhaust. The outer rim of the impeller is submerged in the fluid creating a cavity near the center. The gas which enters the pump is trapped in this cavity and is then transferred by the rotating motion of the impeller.
Liquid Ring Vacuum pumps are used for heavy duty applications and excel in wet environments where other pumps cannot. Because there is no contact between the vanes and casing, wear and tear is minimized and reduces overall maintenance of the pump. Industries that utilize these pumps include food, paper, fertilizer, and textile. For example, in the food industry, it is used to extract water during the food production process such as drying the cartons used for packaging eggs. Because the gas that enters the pump is in contact with the fluid, liquid rings pumps can handle small impurities, dust and contaminants. Therefore, they are very versatile and can be used in areas that are not well ventilated or have uncontrollable conditions.