Please update your browser.

It looks like you are using an old version of the Microsoft Edge browser. To get the best experience with the Busch website, please update your browser.

Contact Pump registration

Vacuum Degassing

Vacuum degassing. A technique for removing dissolved gas from a liquid or paste. By lowering the pressure in a container with the mass.


How does vacuum degassing work?

Degassing of liquid, paste-like and moist products is one of the most important applications of modern vacuum technology.

Gases, vapors and moisture are extracted from the processed material. Under vacuum. The result: higher product quality.

An example: the degassing of plastics during extrusion.
Trapped moisture and gases are extracted directly at the extruder screw zone. Significantly improving the structure and physical properties of the final product.

Busch vacuum technology for degassing

We offer a range of standardized vacuum systems specially designed for extrusion processes. They include separator/filter units to condense the extracted vapors and gases.

Our project engineers will recommend the optimum system. Precisely matched to your extruder throughput and raw material.

Learn more about vacuum degassing

What is vacuum degassing?

Every substance changes according to temperature and pressure. Mixtures of substances can therefore be separated when one substance evaporates at another point than the other. Under vacuum, evaporation is possible at lower temperatures. This technique can be used in degassing processes. To remove dissolved gases from liquids, especially water or aqueous solutions.

According to Henry's law, the amount of dissolved gas in a liquid is proportional to its partial pressure. So, placing a solution under reduced pressure makes the dissolved gas less soluble. Sonication and stirring under reduced pressure can usually enhance process efficiency. This technique is often referred to as vacuum degasification or simply degassing.

How does a vacuum degassing system work?

Vacuum degassing systems are often a combination of a vacuum pump and a trap. The vacuum pump reduces the pressure inside the system. The trap protects the vacuum pump by preventing liquids and particles from reaching it. In the cases of heavy condensable loads, a condenser can be used to collect the valuable compounds. It can be installed upstream or downstream of the vacuum pump, according to the respective process requirements.

Where is vacuum used in the degassing process?

Vacuum is used in degassing installations like extruders, columns, or mixers. Vacuum degassing plays an important role in different applications such as:

  • Sea water deaeration on offshore platforms
  • Degassing of creams and pastes before bottling
  • Degassing of solvents in the chemical industry to avoid side reactions
  • Steel and metal degassing to produce purer grade
  • Degassing of plastics to reduce the odor and improve the transparency and reliability of the product

Degassing under vacuum is only possible if the substances to be separated have different evaporation points.

What are the advantages of vacuum degassing over alternative degassing technologies?

Under vacuum, the evaporation of the gas can take place at a low temperature. This offers several advantages:

  • Energy savings compared to thermal degassing
  • Time and energy savings compared to pump-freeze-thaw cycles
  • Lower investment costs compared to membrane degassing
  • Less consumption of inert gas compared to sparging
  • Protection of the remaining substances against thermal degradation
  • Separation of components at defined physical conditions
  • Controlled handling of the gas portions
  • Control and possible reproduction of the operating conditions

What are the best vacuum pumps for degassing?

An important prerequisite when choosing the right vacuum pump for degassing is that it reaches the expected pressure range for the process step. Moreover, the vacuum pump should be able to handle liquids and small particles.

Typical vacuum pumps for vacuum degassing are liquid ring vacuum pumps, claw vacuum pumps and dry screw vacuum pumps.

Liquid ring vacuum pumps are the perfect choice for vacuum degassing as the vacuum pump often comes in contact with condensable vapors. The condensation of such vapors in the liquid ring is very efficient. Dry screw vacuum pumps are perfectly suited whenever the vapors can be valorized if not contaminated. Oil-lubricated rotary vane vacuum pumps are excellent when accumulation can be avoided in the oil.

What are the best vacuum pumps from Busch for the degassing process?

The choice of the vacuum pump depends on the respective process requirements. The most suitable and proven Busch products for degassing are MINK, COBRA, DOLPHIN, HUCKEPACK and R5.

What are some examples for the use of Busch vacuum technology in degassing applications?

Busch solutions are used in all kinds of degassing applications. DOPHIN vacuum pumps, for example, play an important role in processes like sea water deaeration on offshore platforms or sparkling water degassing. Dry screw vacuum pumps are used in pharma and in the cosmetic industry to degas creams and pastes. Our vacuum technology is also present in plastics degassing in compounding processes, and in water degassing for recycling processes and food applications. Another possible field of application is the degassing of solvents in the chemical industry to avoid adverse side reactions. But also degassing of steel and metal to produce a purer grade.

What are the key points to consider when buying a vacuum degassing system?

You should consider the following in order to find the vacuum degassing solution that best fits your needs:

  • Number of dissolved gases to be removed
  • Mass or volume flow of gases removed
  • Required system pressure
  • System operating temperature
  • System volume
  • Processing time required to achieve the system pressure
  • Leakage rate of air into the system
  • Available steam pressure, temperature, and flow
  • Available cooling water temperature and flow
  • Cost of steam and electricity

Vacuum degassing in practice

  • Modern Vacuum Technology for Melt Degassing During Extrusion

    Modern Vacuum Technology for Melt Degassing During Extrusion

    PolyComp GmbH

    Learn more
  • Complete Vacuum Supply with MINK Claw Vacuum Technology

    Complete Vacuum Supply with MINK Claw Vacuum Technology


    Learn more
When it comes to reliability, maintenance effort and economic efficiency, we made the right choice opting for the PLASTEX degassing system.