Rotary Vane Vacuum Pumps

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Example The vacuum system of non-benchtop mass spectrometers consists of one to three rotary vane pumps and two or three turbo pumps. Rotary vane pumps are used for the inlet system(s) and as backing pumps for the turbo pumps. One turbo pump is mounted to the ion source housing, another one or two are operated at the analyzer. Thereby, a differentially pumped system is provided where local changes in pressure, e.g., from reagent gas in Cl or collision gas in CID, do not have a noteworthy effect on the whole vacuum chamber. 

Important note Particularly in rough vacuum technology, partial pressure in a mix of gas and vapor is often understood to be the sum of the partial pressures for all the non-condensable components present in the mix - in case of the partial ultimate pressure at a rotary vane pump, for example. 

Instead of rotary pumps, large water jet, steam ejector, or water ring pumps can be used. For batch evacuation, and the production of hydrocarbon-free fore vacuum for sputter-ion pumps, adsorption pumps (see Section 2.1.8.1) are suitable. If the use of oil-sealed rotary vane pumps cannot be avoided, basically two-stage rotary vane pumps should be used. The small amount of oil vapor that backstreams out of the Inlet ports of these pumps can be almost completely removed by a sorption trap (see Section 2.1.4) Inserted In the pumping line. 

For the pumping of large quantities of gas in this pressure region, vapor ejector pumps are by far the most suitable. With mercury vapor ejector pumps, completely oil-free vacua can be produced. As a precaution, the insertion of a cold trap chilled with liquid nitrogen is recommended so that the harmful mercury vapor does not enter the vessel. With the medium vacuum sorption traps described under a), it is possible with two-stage rotary vane pumps to produce almost oil-free vacua down to below 10" mbar. 

Backing a rotary vane pump with a Cole pump (evacuating the oil box of the rotary vane pump) provides a combination which can achieve the high ultimate vacuum of a rotary vane pump combined with the vapour handling capability of a Cole pump. 

A single-stage rotary vane pump ( S0 = 25m3h ) is used to remove residual water from a vacuum vessel which has been cleaned, washed with demineralised water and drained. The pump is fitted with an oil-mist filter. If the exhaust temperature is 75 °C and ambient air ( T= 20 °C, RH = 50%, p0 = 1013 mbar) is used as the ballast gas, calculate the maximum amount of water that can be handled by the pump. (Assume that the pump is directly connected to the chamber.)... 

A UHV chamber for LEED studies is evacuated to ultra-high vacuum with a combination of pumps consisting of a turbomolecular pump (backed with an oil-sealed rotary vane pump) and a titanium sublimation pump (TSP). When the chamber is evacuated by both pumps, a total pressure of 4 x 10 9mbar is achieved and residual gas analysis shows that this consists of 50% Ar + 50% H2. 

Mechanical pumps are used directly to produce a low and medium vacuum, as well as extensively to back Roots vacuum, turbomolecular and diffusion pumps. These pumps are also called oil-sealed rotary vane pumps as they rely on the use of vanes or blades to compress gases. 

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