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5 tube balancing argument

Gene Huh gshuh at garnet.berkeley.edu
Fri Oct 11 16:21:16 EST 1996

In article <325DFF19.1903 at bbsrc.ac.uk>, Andy Phillips
<andy.phillips at bbsrc.ac.uk> wrote:

# Lou Cantolupo wrote:
# > HOWEVER.  In an ultra centrifuge, where you routinely approach speeds in
# > excess of 80,000 rpm (as in CsCl grad's), it is imperetive that you fill
# > all slots with equal weights.  In ultra, where the rotor tolerance is
# > 5/10,000 of an inch in the eliptical orbit, equal vector forces prove
# > not to be so equal unless they are 100% equal.  In otherwords, when you
# > go fast, the rules can't be bent as easily; you have to optimize your
# > orbit.
# If Beckman feel that it's imperative that you fill all 8 slots of an 
# ultracentrifuge rotor, it's a pity they don't mention this in their 
# manuals. I have several Beckman rotor manuals and catalogues that 
# specifically descibe how to arrange tubes symmetrically if not all the 
# slots are to be used.

My two cents:  I got the impression that the rotor can actually deform
significantly at ultra speeds.  Hence it might not be safe to do a 2+3
balancing act, since the resulting deformation may not be radially

Or something like that. :)
Gene Huh
gshuh at garnet.berkeley.edu

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