What is a Liquid Ring Vacuum Pump?

Vacuum pumps are used in various industrial processes like packaging, drying, bottling, etc. The use of an industrial vacuum pump is to create, improve and maintain a vacuum in the above-mentioned processes. In the past, industrial vacuum pumps were popular for their loud operation and large energy costs. But with the development in technology industrial vacuum pumps have significantly developed and now they are popular for their reliability and performance. There has been developed in industrial vacuum pumps to decreases the loud noises made by them by maintaining a level of noise that can be produced by them. Moving on, let us read about the different types of industrial vacuum pumps that are available in the market.

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Various types of industrial vacuum pump available in the market

There are various types of industrial vacuum pumps available in the market. These are:

  • Rotary Claw– It is also a type of industrial vacuum pump which generates a contact-free vacuum economically and efficiently. This is because the rotary claw design is based on the principle of internal compression. This type of pump consists of two motors that work in opposite directions.
  • Liquid Ring Pumps– These types of pumps are powered typically by an induction motor and they have a low-friction design as the rotor is the only part which is moving in the whole pump.
  • Rotary Screw Pumps– This vacuum pump comprises two parallel rotors that are screw-shaped and these two screws help to turn in the compressor without any friction. These screws rotate at the opposite direction so that the chamber attached with the screw enlarges and the gas gets transported into the compressor chamber.
  • Side Channel Blowers– These types of vacuum pumps have an impeller which is mounted on the motor shaft and this leads to a contact-free compression. The gas gets in through tan inlet in the system. As the gas travels through the inlet and enter the side channel, the impeller which is mounted on the motor shafts rotates and this rotation gives velocity to the gas and makes the gas move in the direction in which the impeller is rotating.

In this article, we shall be discussing Liquid Ring Vacuum Pump which, as discussed above, is a type of industrial vacuum pump having many uses especially in food processing and poultry industries. Before delving into the details, let us first understand what Liquid Ring Vacuum Pumps are and what is the working mechanism of such pumps.

What are Liquid Ring Vacuum Pumps?

Liquid Ring Vacuum Pumps are rotary machines. The working of Liquid Ring Vacuum Pumps is based on the principle of positive displacement. It provides process vacuum in several industrial applications like chemical, environmental, electric power, food processing, beverage packaging, marine, mining, etc. In such kind of machines, liquid acts like a piston. In most of the cases, the liquid used is water and therefore, this machine is also called a water ring or water piston rotary pumps. Apart from water, such machines utilize sealant or any other liquid which is compatible with the industrial processes. As already mentioned above, these machines are powered typically by an induction motor and they have a low-friction design as the rotor is the only part which is moving in the whole pump.

The obvious question that arises in the mind of everyone is that why is it called a liquid ring? The reason for this is that as the impeller of this pump rotates, the liquid which is used is thrown out and it forms a literal liquid rings. Liquid Ring Vacuum Pumps are very simple to operate and they are also a reliable and very safe choice. This is the best choice for industries where dirty or hazardous gases are used. They are also best for industries that require a high tolerance for carryover of liquids like food production and the dairy industries.

How do they perform?

A Liquid Ring Vacuum Pump consists of an inlet connection through which the gases are sucked and is taken to the pump motor unit. The cylindrical housing is the area where the impeller is located. Apart from the impeller, it also contains the liquid. This operating liquid port is the port through which this liquid enters and at the end, both the liquid and the gas gets discharged through the discharge connection.

There are two basic types of Liquid Ring Vacuum Pumps: the single-stage liquid ring vacuum pump and the two-stage liquid ring vacuum pump. In a single-stage pump, in one single revolution, the suction and compression take place. This means that the vacuum is pulled and is released back in the atmosphere at one single revolution. Whereas, a two-stage liquid ring vacuum pump is a pump in which two single-stage activities take place one after the other. In this case, the first pump discharges to the port from where the air is sucked off the second pump. The two-stage liquid ring vacuum pumps are more efficient and have the ability to handle solvents at a very high level of vacuum.

Characteristics of Liquid Ring Vacuum Pumps

The characteristics of Liquid Ring Vacuum Pumps are:

  • Noiseless operation- As we discussed above, in earlier times, vacuum pumps meant to be noisy but with development in technology, there has been a significant development in these pumps and Liquid Ring Vacuum Pumps are the best example. They do not produce much noise while operating and it is relatively quieter than other machines. They maintain a decent level of noise which is not more than 85 dBA.
  • Easy maintenance- Liquid Ring Vacuum Pumps do not consist of a lot of parts. Moreover, it just has a single part which moves i.e., its motor. Therefore, maintaining a Liquid Ring Vacuum Pump becomes a lot easier.\
  • Works for a long duration. The pump has only one moving part and therefore, has very fewer fixtures or joints which makes it work for a long duration without maintaining it much. They also do not breakdown as much frequencies and continuously work for a long period.
  • Environment-friendly- Liquid Ring Vacuum Pumps are environment-friendly as they do not require oil changes and filter changes at much frequencies. This is the reason why the room in which such machines are installed is clean and there is no oil contamination.
  • Safe and reliable- Liquid Ring Vacuum Pumps are safe and reliable especially if you working with dirty and hazardous gases. Such gases are very dangerous for the environment and for human health and also if these gases are mishandled they may take the lives of several people.


What distinguishes Liquid Ring Vacuum Pumps from other type vacuum pumps?

Unlike other kinds of industrial vacuum pumps, which are only used for vacuum creation and pumping activities, Liquid Ring Vacuum Pumps can also be used as gas compressors. This machine has the ability to compress gas with the help of impellers rotating mechanism.

This next point which distinguishes a Liquid Ring Vacuum Pumps from other types of industrial vacuum pumps is the way its working mechanism. In case of Liquid Ring Vacuum Pumps, the rotor which contains multiple blades is located in the cylindrical housing area eccentrically. With the rotation of the impeller, the liquid which is used is thrown out and form a liquid ring. Whereas in other types of industrial vacuum pumps like a screw vacuum pump, the working mechanism is completely different.

The next distinguishing feature which Liquid Ring Vacuum Pumps have as compared to other vacuum pumps is that the former allows the pumped gases to contain a large quantity of water vapor and a very small quantity of solid particles and this gives Liquid Ring Vacuum Pumps an unparallel advantage over other types of vacuums. While selecting a good vacuum pump, one of the most important things is the vapor pressure of the liquid as it directly affects the capacity of the pump.

The next distinguishing feature is that with Liquid Ring Vacuum Pumps you can rely on them for hazardous gases. They are safer and more reliable for such kind of gases than any other vacuum pumps. They are the most desired for pumping such gases while it might be a little risky to use any other type of vacuum for pumping such type of gases.

Liquid Ring Vacuum Pumps have a simplified operation and also, the operation cost is very less as compared to other vacuums. Most of the vacuum pumps have a complex mechanism and it becomes difficult for everyone to understand it. Also, its operation cost is way too less than other vacuum pumps. Like, the operation cost of a screw vacuum pump is almost thirty times more than the cost of a liquid ring.

Moving on, if we talk about maintenance, then Liquid Ring Vacuum Pumps does not have many parts and just have one single moving part, so, it is not required to maintain it for around 3-4 years. On the contrary, all other vacuum pumps require maintenance depending upon the number of hours they have operated. Also, Liquid Ring Vacuum Pumps have very little wear and tear as with the surface of the pump cavity, it doesn’t have any metal friction.

The Liquid Ring Vacuum Pumps are the most desired for handling extreme vapor loads as compared to others and this makes it perfect for application in various industries. They are used in several industries including the food processing industries and also in poultry. These pumps can easily take care of the condensable vapor. It can also handle various kinds of fluids without hampering the performance of the pump. The performance efficiency of the pump does not get affected no matter which fluid is used in it.

The best thing about Liquid Ring Vacuum Pumps is that they can be used for not only vacuum tasks but also for compressor jobs and this makes them useful at various points or stages of activities and this gives the users the benefit of several functionalities in a single machine.

Industrial uses of Liquid Ring Vacuum Pumps

Liquid Ring Vacuum Pumps are used in the following industries:

  • Aircraft industry- Liquid Ring Vacuum Pumps are used at various stages in the aircraft industry. They are used for testing of the Carburetor and is also used for altitude chamber work.
  • Automobile industry- Similar to the aircraft industry, Liquid Ring Vacuum Pumps are used for testing of the Carburetor and also for engine testing.
  • Chemical industry- Liquid Ring Vacuum Pumps are used for vacuum on chemical reactors and on resin kettles. They are also used for vacuum filtration and the distillation of fatty acids and synthetic resins.
  • Dairy products and poultry- In this industry, Liquid Ring Vacuum Pumps are used to deodorize and flash cool milk. These pumps are also used for aeration and agitation in this industry.
  • Food processing industry- In the food processing industry, Liquid Ring Vacuum Pumps are used to inhibit the growth of bacteria and thereby, reduce the food spoilage.
  • Gas specialities- Liquid Ring Vacuum Pumps helps to dry oxygen cylinders with the help of vacuum and also helps in evacuating the old gas cylinders before filling the gas in the new cylinders.
  • Petroleum industry- Similar to its usage in gas specialities, Liquid Ring Vacuum Pumps help in vacuum cleaning and then filling of barrels. They also help to recover vapors from the storage tanks.



A Liquid Ring Vacuum Pump is the pump developed keeping in mind the needs of the present. It is one of the most reliable and safest vacuum pumps which can be used for compressing harmful gases. Every other vacuum pump performs the function of vacuum creation and pumping but Liquid Ring Vacuum Pump has much more to offer. It can also be used as gas compressors and this makes it far better than others. It is easy to maintain and is used in many industries especially food processing and poultry industries. If you are planning to install a vacuum pump in your industry, then this could be a great option for you to consider.