Schlenk line
A vacuum pump with an ultimate vacuum in the range of 10-3 mbar is required for working in the absence of oxygen and humidity or for residual drying. This pump must often also be suitable for aggressive media.
Vacuum for Schlenk lines
Low ultimate vacuum and protection against corrosion
The aim of evacuating the Schlenk line is to work as completely as possible in the absence of oxygen and humidity. A low ultimate vacuum of the vacuum pump is crucial for this. We therefore recommend our pumps with an ultimate vacuum in the range of 10-3 mbar.
Two-stage rotary vane pumps and the chemistry-HYBRID pump meet these requirements. However, the use of a cold trap is required to protect against corrosion caused by aggressive media.
The chemically resistant VACUU·PURE 10C screw pump generally does not require a cold trap. Another advantage over other pumps is the 100 % oil-free operation. As neither oil nor cooling medium need to be changed, it is perfect for uninterrupted processes and can be used overnight.
Important questions on vacuum technology
The aim of evacuating the Schlenk line is to work as completely as possible in the absence of oxygen and humidity. A low ultimate vacuum of the vacuum pump is crucial for this. We therefore recommend our pumps with an ultimate vacuum in the range of 10-3 mbar.
These requirements are met by two-stage rotary vane pumps, the chemistry-HYBRID pump and the VACUU·PURE screw pump. For use with aggressive media, the chemistry-HYBRID pump offers better protection against corrosion than a rotary vane pump. The intervals for oil changes are also significantly longer. However, in order to provide effective protection against corrosion, the use of a cold trap is generally required for both pump types on the Schlenk line.
The best chemically resistant pump is the VACUU·PURE 10C chemistry screw pump. It usually does not require a cold trap. The screw pump is also 100 % oil-free and has no wear parts. There is no need to change the cooling medium, oil or wear parts. It is therefore perfect for uninterrupted processes and can be used overnight.
The low ultimate vacuum is advantageous for applications on the Schlenk line. We therefore recommend our pumps with an ultimate vacuum in the range of 10-3 mbar.
The pumping speed of 2.3 m3/h of our smallest two-stage rotary vane pump RZ 2.5 is already sufficient for evacuating the Schlenk line. Larger pumps such as the RZ 6 or the RC 6 have a higher pumping speed and can therefore evacuate the Schlenk line more quickly.
At 9 m3/h, the oil-free VACUU·PURE 10C chemistry screw pump has the highest pumping speed of all the pumps mentioned.
In our Vacuum Pump Selection Guide you will find suitable product suggestions for your Schlenk Line requirements:
find pumpYes, the pump type can be replaced at any time.
The need for a cold trap depends on the media used and the pump type. The chemically resistant VACUU·PURE 10C screw pump generally does not require a cold trap.
If corrosive media are used, the use of a cold trap is generally advisable for rotary vane pumps. As many wetted parts are made of metal, this type of pump is prone to corrosion. Better protection against corrosion and extended oil change intervals are offered by the combination of rotary vane pump and chemistry diaphragm pump - the chemistry-HYBRID pump. In most cases, however, the use of a cold trap is also advisable here.
You can use cold traps with dry ice or liquid nitrogen. Suitable models are available from laboratory equipment dealers.
For optimum performance, rotary vane pumps, chemistry-HYBRID pumps and screw pumps should warm up for approx. 30 minutes before starting the process. After operation, rotary vane pumps and chemistry-HYBRID pumps should run for a further 30 minutes with the gas ballast open in order to remove any condensate. The VACUU-PURE screw pump has an integrated regeneration mode for self-cleaning.
All useful tips for operating your vacuum pump are summarized here:
learn moreThe vacuum connection on the Schlenk line is usually a hose nozzle connection for attaching a tubing. The vacuum pumps we recommend all have a small flange connection. In our online store you will find suitable adapters with a hose nozzle connection for attaching the rhose to the pump.
Dr. Andryj Borys - Author of the “Schlenk Line Survival Guide”
This webinar is for chemists of all stages and research areas, who are interested in learning more about Schlenk line chemistry, from basic understanding and techniques, to advanced equipment options to improve your day-to-day setups.
VACUU·PURE® supplies several chemical synthesis hoods at the Max Planck Institute
LMU Munich test report on our new VACUU·PURE® vacuum pump
Chemically resistant and oil-free vacuum down to 10-3 mbar