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How does a liquid ring vacuum pump work?

Author: Site Editor     Publish Time: 2021-05-16      Origin: Site


Liquid ring vacuum pump working principle

The water ring pump relies on the change of the pump cavity volume to achieve suction, compression and exhaust, so it is a variable volume vacuum pump. The water ring vacuum pump is a kind of rough vacuum pump. The ultimate vacuum it can obtain is 2000~4000Pa, and the series air ejector can reach 270~670Pa. Water ring pumps can also be used as compressors, called water ring compressors, which are low-pressure compressors with a pressure range of 1~2×105Pa gauge pressure.

The operation of the liquid ring vacuum pump requires an appropriate amount of water as the working fluid in the pump body. After starting, when the impeller rotates clockwise, the water is thrown around by the impeller. Due to the centrifugal force, the water forms a closed ring of approximately equal thickness determined by the shape of the pump cavity, forming a circle of liquid. The liquid forms a liquid ring concentric with the stator. The liquid ring and the rotor blades together constitute a variable volume rotary variable volume vacuum pump.

The liquid ring vacuum pump is different from other pumps in that the impeller of liquid ring vacuum pump systems deviates from the center of the pump. Therefore, compared with the vanes on the side of the pump and the vanes on the bottom of the pump, the vanes on the top of the pump are closer to the outer wall, the space is enlarged, and the process gas is sucked in through the suction port. As the impeller rotates further, the space is reduced, so that the gas is compressed and discharged through the discharge groove. The vacuum pump can be operated by water circulation, open loop or closed loop loop. As the impeller rotates further, the space is reduced, so that the gas is compressed and discharged through the discharge groove. The vacuum pump can be operated by water circulation, open loop or closed loop loop.

The inner surface of the upper part of the water ring is just tangent to the impeller, and the lower inner surface of the water ring just touches the top of the blade. In fact, the blade has a certain insertion depth in the water ring. A crescent-shaped space is formed between the impeller and the water ring, and this space is divided into several small cavities with the same number of blades by the impeller. If the upper part of the impeller is 0° as the starting point, the volume of the small cavity becomes larger when the impeller rotates 180° before the rotation, and it is connected to the suction port on the end surface. At this time, the gas is sucked in. When the suction ends, the small cavity It is isolated from the suction port; when the impeller continues to rotate, the small cavity changes from large to small, so that the gas is compressed. When the battery is discharged, the compression is too high. When the small cavity communicates with the exhaust port, the gas and some sealant The gas is discharged through the discharge port and the gas is discharged out of the pump.

The fluid at the suction port of the pump has a lower pressure value, and after each pump impeller stage, the fluid will be discharged from the discharge port of the pump at a higher pressure. Liquid ring vacuum pump systems are used to extract air from a low-pressure container, so that the pressure of the container drops below atmospheric pressure and creates a vacuum condition.

Liquid ring vacuum pump operation

The operator must standardize the use, and the start of the equipment is very important, the operation steps:

  1. We need to close the gate valve on the intake pipe.

  2. Start the motor. From the perspective of the drive, the motor rotates in a clockwise direction. The right side is the suction port, and the left side is the exhaust port. The pump is a mechanical seal. Water should be added to the mechanical seal before starting the motor.

  3. Open the valve on the water supply pipe, or directly use tap water to gradually increase the water supply to the water supply squeegee in the pump until the water supply meets the specified requirements.

  4. When the water ring vacuum pump reaches the limit vacuum or the limit pressure, open the valve on the intake pipe and the pump starts to work normally.

  5. Adjust the packing gland so that the water drips out.

  6. The valve adjusts the amount of water supplied by the gas-water separator to the pump in order to operate under the required technical conditions, so that the power consumption is small, the performance index is reached, and the work requirements are met.

  7. Adjust the amount of water supplied by the water supply pipe to the gas-water separator so that a small water consumption can be used to ensure the required technical specifications in the water ring vacuum pump.

  8. When the pump is working under the limited pressure, explosion sound may occur in the pump due to physical effects, but the power consumption is not increased. The valve on the intake pipe can be opened to make it enter a small amount of gas, and the explosion sound will disappear. If the explosion sound does not disappear and the assistance rate consumption increases, it indicates that the pump has failed and should be shut down for maintenance.

Liquid ring vacuum pump installation

If you want to play a good performance of the water ring vacuum pump, you must master the correct installation method. When installing, you should first confirm the delivery time of the pump.

Before installing the water ring vacuum pump, you should turn the coupling by hand to confirm whether the pump is stuck or damaged. If the pump motor and reducer are packaged separately for easy transportation, the coaxiality of the pump reducer and motor should be corrected before the pump and motor anchor bolts are hardened during the installation process.

The calibration method of the water ring vacuum pump is also: put the ruler on the coupling in parallel, and the ruler will be close to the outer circle of the coupling at any position on the entire circumference (check with a feeler gauge). The axial clearance between the couplings (pump coupling and reducer coupling) should be equal. A gate valve should be installed on the inlet pipe of the pump so that when it is stopped, the valve should be closed first to prevent water from flowing back into the system under the pressure acting in the exhaust pipe. In addition, a vacuum gauge should be installed between the inlet of the pump and the valve to check whether the vacuum pump is working properly at any time.

At the same time, pay attention to the following points during the installation process:

  • Be sure to select qualified lifting equipment based on the weight of the equipment, and the operator should have relevant knowledge and operating certificates.

  • The coaxiality between the motor and the water ring vacuum pump will be affected during transportation and lifting, and should be recalibrated.

  • The tension of the tape should be moderate, too loose will affect the transmission of shaft power, and the tape will be easily damaged; too tight will increase the shaft power, and the bearing life of the tape, motor and vacuum pump will also be affected.

After a long period of use, it needs to be cooled because the equipment will generate some heat during operation. In order to ensure the stable operation of the vacuum pump equipment and prevent the pump body from overheating, it needs to be cooled but the water ring vacuum pump is cooled. Certain conditions are required.


If it is a medium with a temperature lower than 120℃, it is generally not equipped with a special cooling system. Generally, the medium that comes with the water ring vacuum pump itself is used for lubrication and cooling. You can choose to use a suspension structure to achieve the upper temperature limit. A certain temperature.

Regarding the medium above 120°C and within 300°C, a cooling chamber must be provided on the cover of the water ring vacuum pump, and the sealed chamber should also be connected with coolant. When the coolant is not allowed to penetrate into the medium, it can be adopted after cooling the medium itself. The reconnection is completed through a simple heat exchanger.