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Vacuum mixing – special process for efficiently mixing various materials

November 21, 2013

Vacuum is a space in which its pressure is lower compared to atmospheric pressure. In the blending of a number of products, vacuum mixing is performed to take away the oxygen component. Vacuum is also applied to prevent the process of decaying of sensitive materials. This particular mixing is effective in hindering unnecessary chemical reactions as well as microbial growth. It is a vital procedure in the production of beverages since it minimizes oxygen content in the product. Removing oxygen is in fact important in ensuring the quality and shelf life of many manufactured products.


The application of vacuum during the mixing process helps in the improvement of product manufacture. For instance, specific pastes, gels, and similar fluids are blended under vacuum condition to eliminate any defects during syringe printing or filling.

Such process also promotes a faster and highly successful drying while maintaining a low temperature. Actually, this type of mixing is the choice procedure when blending dry and heat-sensitive substances without worrying about thermal degradation.

Indeed, mixing via vacuum presents a number of advantages. These include the removal of unwanted voids within any finished product, enhancement of the overall quality of dispersion, degassing, and improved drying at low temperatures, as well as sub-surface addition of raw ingredients. Put simply, fine-tuned mixing procedures via vacuum result in the maximization of such advantages.

Operating vacuum mixers

Most batch mixers are built for vacuum operation, from one-shaft machines like high capacity saw-tooth disperser and stator/rotor mixers that are utilized to make low level viscosity formulations to multiple agitators and planetary mixers utilized in batch-mixing highly viscous and dense compounds. Even blending machines that are used for drying operations, like the vertical screw blenders or horizontal ribbon-type blenders are capable of this type of mixing. Such machines have built in vacuum pumps that are pre-wired to their control panels.

Proper techniques in using vacuum mixers

When operating a vacuum mixer, the worker must see to it that the machine possesses the appropriate pump that will accommodate the vacuum level as well as the operational conditions that the process requires.

For instance, rotary vane pumps allow the operator to draw a much deeper vacuum than if a liquid pump is used. However, the latter is more capable of accommodating condensate from the mix. The worker must utilize the right condenser and filter before the pump for protection against contaminants. He should also visually monitor the materials in the mix vessel while applying vacuum to prevent any formation of bubbles or alteration in volume.

Separate break valve must be included in the design of the mixing vessel. This allows the operator to pull in the vacuum, begin with the mixing process, and close the chamber as soon as the desired level is achieved within the mixture.

As the operator isolates the mix chamber and turns the pump off at this point, he avoids drawing out any volatile constituent and altering the formulation. As the vacuum mixing process is complete, he can allow inert gas back into the chamber.

vacuum mixing

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