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Liquid ring vacuum pumps
and compressors

3d_animation_liquid_ring_inlet

Types of liquid ring vacuum pumps

Liquid ring pumps are available in single- and two-stage versions. In single-stage versions, compression is carried out once. In two-stage versions, the pumped medium is compressed again to allow higher vacuum levels to be achieved. Operation as a compressor is also possible with some models of liquid ring vacuum pumps.

Depending on the pumped medium, liquid ring vacuum pumps can be operated as a simple continuous flow system or as a partial or total recirculation system.

The operating fluid is usually water, but other liquids may be used if required to suit the process conditions.

Product series
Ultimate pressure / Overpressure
Version
DOLPHIN LX
33 hPa (mbar)
single-stage (valved) vacuum pump
DOLPHIN LT
33 hPa (mbar)
two-stage
DOLPHIN VL
33/130 hPa (mbar)
single- or two-stage
DOLPHIN LM
130 hPa (mbar)
single-stage
DOLPHIN LR
33 hPa (mbar)
single-stage (valved)
DOLPHIN LB
33 hPa (mbar)
two-stage vacuum pump / compressor
DOLPHIN LA
130 hPa (mbar)
single-stage
DOLPHIN LG
160 hPa (mbar)
single-stage (valved)
DOLPHIN LN
9 bar(g)
single- or two-stage compressor

Robust and compact. Ideal for demanding applications.

Applications

Liquid ring vacuum pumps and compressors are used in various industries. They are suitable for applications ranging from flare gas recovery to wood drying.

Each industry and application has different needs. To find out which vacuum solution fits your needs best, get in touch with our Busch experts.

Find out more about how liquid ring technology is used in different applications.

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FAQ

What is a liquid ring vacuum pump?

A liquid ring vacuum pump is a positive displacement pump that uses a liquid as a sealant. The liquid, also referred to as operating fluid, is usually water. Other fluids can also be used if required to suit the process conditions.

The housing is partially filled with operating fluid, and the blades of an eccentrically mounted impeller dip into it. As the impeller rotates, a liquid ring is created due to the centrifugal force. Chambers are formed between the impeller and the liquid ring, and the rotation of the impeller alters their volume. The pumped medium is transported in these chambers, where it is compressed and expelled via the outlet. Liquid ring vacuum pumps are available in single- and two-stage versions. Compression is carried out once in single-stage versions. Two-stage versions compress the pumped medium twice to achieve higher vacuum levels.

The operating fluid creates a barrier that prevents contamination from entering the pump. Liquid ring vacuum pumps are often used in processes where a liquid is already present that can be used as the operating fluid. They are particularly well suited for industries such as hospitals and healthcare facilities, vapor recovery, and biogas handling.

How does a liquid ring vacuum pump work?

Liquid ring technology is synonymous with robust construction and a well-proven, highly reliable design.

An eccentrically mounted impeller rotates in a housing partially filled with operating fluid. The impeller blades dip into the fluid, and the centrifugal force exerted by their rotation forms a so-called liquid ring within the housing.

The pumped medium is transported in the spaces between the blades and the liquid ring. The eccentric rotation of the impeller alters the volume of these spaces. Thereby, the gas is drawn in, compressed and expelled.

Vacuum generation in liquid ring vacuum pumps explained in three steps

1. Inlet

  • The pumped medium enters via the inlet port.
  • Operating fluid partially fills the cylindrical housing.
  • The blades of an eccentrically mounted impeller dip into the fluid.
  • As the impeller continuously turns, it exerts a centrifugal force that forms a liquid ring within the housing.

2. Compression

  • Spaces are formed between the impeller blades and the liquid ring.
  • The eccentric rotation of the impeller alters the volume of each space.
  • The pumped medium is suctioned into the spaces and compressed.
  • Compression is carried out once in single-stage versions and twice in two-stage versions to achieve higher vacuum levels.

3. Outlet

  • After compression, the pumped medium is released via the outlet.
  • Exhaust is a mixture of compressed gases and operating fluid.

What is the difference between a liquid ring vacuum pump and compressor?

Compressors produce overpressure while vacuum pumps produce vacuum.

Basically, a liquid ring compressor is built the same way as a liquid ring vacuum pump, only the inlet and outlet are connected the other way around.

What are the advantages and disadvantages of liquid ring vacuum pumps and compressors?

Liquid ring vacuum pumps and compressors from Busch are robust, reliable, and cost-efficient. They have several benefits:

  • Suitable for demanding applications such as evacuating saturated gases and vapors
  • Operating fluid can be chosen according to process demands
  • Wide range of housing materials and shaft seals
  • Virtually isothermal compression
  • Low noise and vibration levels

Vacuum pumps and compressors using this technology are not suitable for processes in which vapors should not come in contact with the operating fluid.

What is the difference between a water ring vacuum pump and a liquid ring vacuum pump?

There is no difference. These are just two different names used to refer to the same technology. However, the name liquid ring indicates that other liquids besides water can be used as an operating fluid.

How do I select the appropriate liquid ring vacuum pump?

Several factors should be considered when selecting the appropriate liquid ring vacuum pump type.
To find out which vacuum pump fits your needs best, get in touch with our Busch experts.

What makes Busch one of the leading manufacturers of liquid ring vacuum pumps and compressors?

Busch has over 40 years of experience in manufacturing liquid ring pumps.

Our DOLPHIN LA/LB and LG/LR ranges come in a large variety of housing metals.