Catalog 2010 Technology for Vacuum Systems - Chiron

Choosing vacuum equipment
Fore-vacuum generation for turbo molecular pumps
■ Many analytical applications (such as mass spectrometry, electron microscopy or surface analysis) are carried out in
high vacuum. Turbomolecular pumps are typically used to generate the needed vacuum. Turbo pumps need an auxiliary
backing pump as they cannot compress to atmospheric pressure. Using oil-free diaphragm pumps for fore-vacuum
generation in connection with state-of-the-art turbomolecular pumps (with "molecular drag" stage) decisively improves
the cleanliness of the vacuum generated. In many cases, such an oil-free high vacuum is absolutely necessary.
Process requirements
■ if the high vacuum system is operated without any gas load, the ultimate vacuum of
the diaphragm pump may be assumed as the backing vacuum. The volume flow rate
of the diaphragm pump then only has an impact on the pump-down time.
■ in case of a noticeable gas load, the backing pump has to be appropriately dimensioned
to guarantee the maximum acceptable backing pressure of the high vacuum
pump. For these applications, it is important to select a diaphragm pump with high
flow rates even near ultimate vacuum. All VACUUBRAND diaphragm pumps are excellent
in this regard due to their planar diaphragm design.
Demands made of the vacuum pump
■ sible backing pressure of the high-vacuum pump; VARIO ® diaphragm pumps offer an
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the required ultimate vacuum of the diaphragm pump depends on the maximum permis-
ultimate vacuum up to 0.3 mbar
high volume flow rate even close to the ultimate vacuum
low energy consumption
low back-streaming leakage rate to prevent venting of the application in the event of power failure
continuous-duty rated, 24/7
not sensitive to condensate
high long-term ultimate vacuum stability and diaphragm lifetime
reliable start-up even under vacuum
small size, low weight and very low vibration
Recommended systems
Typical backing pumps for modern wide-range turbo pumps (with molecular drag stage)
down to 4 mbar:
down to 1 mbar:
down to 0.3 mbar:
MZ 2D NT
pg. 92
MD 1 pg. 94 MD 4 NT, MD 4 NT VARIO pg. 96 MD 12 pg. 98
MV 2 NT, MV 2 NT VARIO pg. 100 MV 10, MV 10 VARIO-B pg. 102
Traditional turbomolecular pumps require lower backing pressures. Therefore, they demand single and two-stage rotary
vane pumps:
Rotary vane pumps
pg. 111
Choosing vacuum equipment
Further information at www.vacuubrand.com
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