vacuum pump

What is a Liquid Ring Vacuum Pump?

These pumps are robust and steady pieces of equipment for industrial use. If properly maintained, these. units can last and produce well for many years. If you require a very large unit or a small one, a good industrial liquid ring vacuum pump can provide months of service between each inspection.

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3 Main Functions of a Liquid Ring Pump

The Function of Intake:

The intake component of the liquid ring pump is where air or gas is drawn into the device. The air is drawn into an opening and taken through a rotor ring, where the compression occurs.

The Function of Compression:

The liquid-filled rotors that spin within the ring pressurize the air. The blades catch and hold air as the rotors pass through the intake port, increasing pressure as the rotors continue to turn.

The Function of Discharge:

The trapped, newly pressurized gas is carried to the discharge port via the turning liquid-filled rotors.

Vacuum pumps are used in various industrial processes like packaging, drying, bottling, etc. A liquid ring vacuum pump is one of the types of vacuum pumps at which we will have a look. The use of an industrial vacuum pump is to create, improve and maintain a vacuum in the above-mentioned processes.

Technology has been developed in industrial vacuum pumps to decrease 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 on the market.

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Liquid Ring Vacuum Pumps are rotary machines. The working of these liquid ring 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 kinds of machines, liquid acts like a piston.

In most cases, usually water is used, and therefore, this machine is also called a water ring or water piston rotary pump. Apart from water, such machines utilize sealant or any other liquid which is compatible with the industrial processes.

Vacuum pump system

The obvious question that arises in the mind of everyone is why are they called liquid ring pumps? 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 ring. These pumps are simple to operate and they are also a reliable and safe choice.

Many times these are the best choice for industries where dirty or hazardous gases are used. They are also good for industries that require a high tolerance for carryover of liquids like food production and the dairy industries. They also function well in industries involving molded paper pulp products.

Performance of the Liquid Ring Vacuum System

These pumps consist of an inlet connection through which the gases are sucked and taken to the pump motor unit. The cylindrical housing is the area where the impeller blades are located. Apart from the impeller, it also contains liquid. This operating liquid port is the port through which this liquid enters and at the end, both the liquid and the gas get discharged through the discharge connection.

Two Basic Types

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 released back into the atmosphere in 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 pumps are more efficient and have the ability to handle solvents at a very high level of vacuum.


Basic Parts

Inlet ports-

The intake port or inlet feeds the air or gas into the vacuum pump’s internal inlet port. The inlet port is a passageway that opens to the outside of the vacuum and leads to the inner ring of the cylinder, where gas is released into the liquid-filled rotors.


The gas or air is drawn into the rotor chambers by the liquid ring. This happens to be similar to the concept of the suction of a piston within a cylinder. The liquid ring functions in a similar way as a piston, and the chambers of the rotor would play the part of cylinders.

The rotor component is made up of a ring of impeller blades that continuously spin around in circles inside the cylinder. The liquid is contained by the rotor and will produce a vacuum level that pressurizes the incoming gas. It only takes half a revolution for the gas molecules to complete the cycle.


The entire gas vacuuming operation is contained and takes place within the cylindrical casing. The gas becomes compressed when the liquid ring converges with the cone. The liquid moves along the upper circumference as the rotors revolve inside the cylinder, resulting in vacuum levels that draw gas in from the inlet port.

Discharge of Gas:

The discharge valve for the newly pressurized gas is located on the central component that swivels the rotor. The moment that the gas molecules enter the cylinder, the stream is expelled through this valve after half a revolution.

Discharge Port:

The freshly pressurized stream is then dismissed through the discharge port, where it is sent out for its intended purpose. The discharge port is 90 degrees removed from the inlet port on the outside of the device.


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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 were noisy but with development in technology, there has been a significant development in these pumps. They do not produce as much noise while operating and it is relatively quieter than other machines.

  • Easy maintenance- Liquid Ring Vacuum Pumps do not consist of a lot of parts. Moreover, it just has a single part that moves i.e., its motor. Therefore, maintaining a Liquid Ring Vacuum Pump becomes a lot easier.

  • Works for a long duration. The pump has fewer fixtures or joints which makes it work for a long duration without an extreme amount of maintenance. They also do not break down as frequently and provide continuous work for long periods of time.

  • Environment-friendly- These pumps are environment-friendly as they do not require oil changes and filter changes at many 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 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 Pumps from other types of vacuum pumps?

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

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

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 kinds of gases than any other vacuum pump. 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 types of gases.

Many within the industries that use these pumps take advantage of Rebuilt Vacuum Pumps and Vacuum Pump Repairs which can save a company thousands of dollars.

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Simplified Operation

Liquid Ring Vacuum Pumps have a simplified operation and also, and the operation cost is a lot less compared to other vacuums. Many other pumps have complex mechanisms and become difficult for everyone to understand them. Also, its operation cost is less than other vacuum pumps.

Moving on, if we talk about maintenance, then Liquid Ring Vacuum Pumps do not have many parts and just have one single moving part which limits the amount of maintenance. On the contrary, all other vacuum pumps require maintenance depending upon the number of hours they have operated. Also, these types of pumps have very little wear and tear as the surface of the pump cavity doesn’t have any metal friction.

Another great thing about this style of pump is that it can be used not only for vacuum tasks but also for compressor jobs. 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.

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 the Carburetor and are 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 food spoilage.

Gas specialties– Liquid Ring Vacuum Pumps help to dry oxygen cylinders with the help of a vacuum and also help in evacuating the old gas cylinders before filling the gas in the new cylinders.

Petroleum industry– Similar to its usage in gas specialties, 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 one of the most reliable and safest vacuum pumps which can be used for compressing harmful gases. Other vacuum pump performs the function of vacuum creation and pumping but these pumps have much more to offer. If you are planning to install a vacuum pump in your industry, then this could be a great option for you to consider. This video gives details on the Nash Liquid Ring Pump.