How Liquid Ring Vacuum Pump works

Liquid Ring Vacuum Pump Working Principle

Liquid ring vacuum pumps are used in the most demanding environments across all sectors from food processing to petrochemical and plastics. Liquid ring vacuum pumps are perfectly suited for wet, humid, and dirty applications with elevated temperatures, extreme vapor loads and even liquid, or solid carryover from the process.

The basic of liquid ring vacuum pump working principle is same as any other positive displacement vacuum pump. The main difference is the operating fluid used in the liquid ring pump.

By design, liquid ring vacuum pumps are capable of handling any contamination which may be present in the gas flow. The attainable pressure at the inlet of the vacuum pump shall be in the region between atmospheric pressure and the vapor pressure of the operating liquid used. For example liquid ring vacuum pumps with the sealant as water at the temperature of 15 °C can attain the operating pressure of 33 mbar.

How do water ring vacuum pumps work?

Let us take a closer look at the water ring vacuum pump working principle:

1. Liquid Ring vacuum pumps are rotary displacement pumps which require an operating liquid. The most common operating liquid used is water. The operating liquid rotates during operation to pump the gases.
2. The impeller wheel in the water ring vacuum pump is arranged eccentrically in a cylindrical casing. When the pump is not in operation half the pump is filled with water.
3. As shown in liquid ring vacuum pump working principle when pump starts operating the impellers, the operating fluid starts rotating . Due to action of centrifugal force a “liquid ring” is created in the cylindrical casing.
4. The fluid is pushed against the cylindrical casing walls creating a void at the center. The void sucks in gases thus trapping them inside the liquid ring. As subsequent gases are sucked in from the chamber the gases trapped gets compressed. This compressed gas or vapor, which is then either discharged direct in case of single stage water ring vacuum pump working or passed on to the next compression stage on a two stage liquid ring vacuum pump design.

The role of operating liquid in liquid ring vacuum pumps is not only to compress the gases but also :
· Removal of heat produced by compression process
· Uptake of liquids and vapors
· Provide a seal between the blade wheel and casing

Typical applications
Liquid ring vacuum pump applications are in a wide range of industries:

o Food Processing:
— Milk evaporation
— Bottling
— Fruit processing
— Poultry and meat evisceration
o Plastic Extrusion
o Drying
o Sterilization
o Evaporation
o Filtration
o Conveying

Atlas Copco manufactures a wide range of single stage and two stage liquid ring vacuum pumps that caters to various industrial applications.
Please reach out to for more information on any liquid ring vacuum pump enquiries.

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