Kakati liquid ring vacuum pumps and compressors are rotary machines in which liquid is made to act as piston. This liquid is generally water for most of the applications. Hence these are known as Water Ring, water piston or Liquid Piston rotary pumps and compressors. A balanced rotor with fixed radial blades having slight curvature at the tips and a hollow hub revolves in a circular casing containing the liquid. The axis of rotor is placed eccentric with the axis of casing. At the operating speed the liquid rotates in the casing forming a circular hollow ring whose internal surface is at varying distance from the axis of rotor.
Starting at ‘A’ the liquid ring is nearest to the rotor axis and completely fills the space between the two adjacent rotor blades and the moving liquid ring now acts as piston on its suction stroke. This continues till the rotor chamber moves to the point ‘B’. During their travel from ‘A’ to ‘B’ all the chambers formed by the blades are connected to the inlet branch of the pump through specially designed ports in the cones and end covers (heads).
While traveling from ‘B’ to ‘A’ the chamber formed by any two adjacent blades decrease in volume as the liquid ring is moving towards the centre and acting as piston on its compression stroke. At the end of this part of their travel the chambers are connected to the outlet branch of the pump through the specially designed ports in the end covers and the air is discharged into this branch. This completes one cycle operation and one such cycle is completed by every chamber formed by any two adjacent blades for one revolution of rotor.
Thus during every cycle the air is sucked from inlet branch, compressed and delivered to the outlet branch. Due to more number of vanes, the operation is continuous and the discharge is non-pulsating. Part of the rotating liquid also flows out of the pump along with the discharged air and has to be replenished by supplying fresh liquid to the pump. The continuous flow of this liquid takes away part of the heat of compression from the air / gas handled, there by cooling the pump.
When the inlet is connected to closed system and the outlet to atmosphere the machine will draw air / gases from the system and discharges into the atmosphere and will act as a vacuum pump. When the inlet is connected to the atmosphere and the outlet to a closed system the machine will draw the air from the atmosphere and discharge into the system and will act as compressor.