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Tandem Use of Turbopumps

IP.com Disclosure Number: IPCOM000107789D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 37K

Publishing Venue

IBM

Related People

Rabe, G: AUTHOR

Abstract

In spite of the versatility of turbopumps, their application may have less favorable characteristics or prerequisites. o The compression factor of hydrogen of about 2000 is rather low and leads to a high residual hydrogen partial gas pressure. o They require rather high pumping speeds on the prevacuum side (20 l/sec. - 100 l/sec. at about 10-1 mbar). These speeds necessitate roughing lines with large cross-sections. In addition, booster pumps and large oil-sealed mechanical roughing pumps are required (60 to 80 m3/h).

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Tandem Use of Turbopumps

       In spite of the versatility of turbopumps, their
application may have less favorable characteristics or prerequisites.
      o    The compression factor of hydrogen of  about  2000 is
rather  low  and  leads  to  a  high  residual hydrogen partial gas
pressure.
      o    They require rather high  pumping  speeds  on  the
prevacuum  side  (20  l/sec. - 100 l/sec. at about 10-1 mbar).
These  speeds  necessitate  roughing lines  with  large
cross-sections.   In addition, booster  pumps  and  large  oil-sealed
mechanical roughing pumps are required (60 to 80 m3/h).

      These  disadvantages  are overcome by the tandem use of
turbopumps, such  that  there  is,  for  instance,  a  first
turbomolecular  twin-rotor-  type  pump with a speed of 2200 l/sec.
The backup flange is connected  to  a  second  wire range
turbomolecular pump with a speed of 180 l/sec.  and an integrated
spiral compressor stage.

      Such an arrangement yields hydrogen compressions of 108 mbar
and  is  suitable  for  gas  loads of up to < 3.5 mbar l/sec.

      On the backup side of the spiral  compressor  stage,  a
roughing  vacuum  of  5 - 6 mbar should be provided which is obtained
by a pump having a speed of 0.4 - 0.6 l/sec.    The roughing  line
only requires a cross-section of about 5 cm2 over a several-meter
length.

      The prevacuum may be provided by  a  chemistry ...