
Applied Vacuum Technology
Vacuum for laboratory and industry



Rotary Evaporator Application
Rotary evaporators are typically used to remove solvents following chemical reactions. Combined with gentle heat from the evaporator bath, controlled vacuum is used to bring solvents to boiling or near-boiling. Efficient solvent distillation requires vacuum balanced to achieve sufficient pressure reduction and molecular flow without losing sample or overrunning the condensing capabilities of your rotovap. When selecting a vacuum pump for rotary evaporation:
- Select a chemical resistant dry diaphragm vacuum pump for routine evaporations.
- Buy a vacuum pump capable of quickly evaporating your least volatile solvent. Fast stripping of DMF requires a 2 torr diaphragm pump. See Model Selector.
- The ability to adjust vacuum level and react quickly to bumping / foaming conditions are keys to preserving your sample and using your time efficiently.
- Automated diaphragm vacuum systems can help you save both sample and time.


Aspiration Application
Accumulate your waste solvents with ease using these affordable vacuum pumps. Configure an appropriate collection reservoir to capture liquid prior to pump. Select a Standard Duty WOB-L pump for aqueous vapors or Chemical Duty DryFast pump for organic solvent or harsh acid / base fumes.
For a complete Standard Duty integrated aspiration system , see WOB-L Aspiration Systems, 2511B-75 and 2515B-75.


Vacuum Oven Application
Select a pump for your vacuum oven based on the size of the oven and the nature of the vapors emitted. Select from standard duty pumps for aqueous vapors or choose a PTFE diaphragm vacuum pump for resistance to harsh chemicals. Thorough drying of certain samples requires a deep vacuum, often produced by an oil-seal pump; a cold trap is required to protect the pump. Where sample properties permit, a lesser vacuum dry pump can work well.



Vacuum Filtration Application
Many filtrations require only minimal vacuum to proceed; deep vacuum is not required. Vacuum pump flow required is roughly proportional to the total surface area of filters being used. Filtration of particulate-clogging samples can be improved somewhat with deeper vacuum, but a combination of larger filter surface area, smaller samples, and sequential use of decreasing porosity filter papers may also be required for timely filtration. Choose a standard duty vacuum pump for aqueous vapors; use a PTFE pump for resistance to harsh chemicals.


Vacuum Concentrator Application
Processing multiple samples using a centrifugal concentrator typically requires a chemical resistant diaphragm vacuum pump with special attention to your system setup. Select a pump vacuum deep enough for low volatility solvents and high gas flow at your operating pressure. Trapping solvent vapors using a refrigerated trap is recommended to prevent pump flooding and protect air quality.


Freeze Dryer Application
Lyophilization removes solvent from a sample using vacuum-induced sublimation. Chemical resistance requirements for your freeze dryer vacuum pump depend upon the aggressiveness of your solvent. In all cases, a high gas flow is required at a low operating vacuum level. Collector temperatures and cleanliness must be considered and maintained to protect your pump.
About Welch
Welch is the technology leader for laboratory and light industrial vacuum pumps, systems, and components. Our quality products are sold globally under the Welch name. Welch products are produced by Gardner Denver Thomas, Inc.
Welch® History
Welch has provided quality vacuum pumps for laboratory, industrial and educational applications for over a century. Today, Welch is a leading manufacturer of vacuum pump products for chemical and biological laboratories, high vacuum manufacturing, and air-conditioning/refrigeration.
The Welch product line includes oil lubricated rotary vane vacuum pumps, dry piston and diaphragm vacuum pumps, and specialized vacuum systems, components, and applications. ChemStar Dry, the oil-free deep vacuum system, is the latest technology innovation from Welch
About Gardner Denver
Gardner Denver is a global producer of compressors, vacuum pumps and related equipment.
The durability of our products is measured in decades. Superior designs ensure the most reliable, energy efficient products in the industry.
Gardner Denver provides low-pressure air and vacuum with a complete line of positive displacement and centrifugan blowers and exhausters, as well as rotary vane compressors.






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