5 tube balancing argument

Francois Coulier coulier at infobiogen.fr
Sat Oct 12 01:55:17 EST 1996


On 11 Oct 1996, Hiranya Roychowdhury wrote:

> At 01:52 PM 10/10/96 -0700, Lou Cantolupo wrote:
> 
> (snip)...
> >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.  
> (snip)...
> 
> It is true that ultraspeed machines need to be balanced far more precisely
> than the regular tabletop microfuges or even the superspeed machines. The
> simple reason is the rcf achieved in the ultra. However, balancing can not
> be ignored even in the smallest of the clinical low speed machines. The
> origininal issue was about balancing and not its precision. Correct me if
> I'm wrong, but I think the rotors designed for ultras only carry
> even-numbered slots/buckets. So, the odd-numbered balancing dilemma is a

Most (if not all) swinging bucket rotor hold 6 tubes; you can therefore
balance 3 tubes, as advised by some manufacturers (at least Kontron, I was
lazy to check Beckman).

Francois Coulier
INSERM Unite 119
27 bd Lei Roure
13009 Marseille
France

tel (33) 91 75 84 11 (October 18, 1996=> 33 (0) 4 91 75 84 11)
fax (33) 91 26 03 64 (October 18, 1996=> 33 (0) 4 91 26 03 64)
email: coulier at infobiogen.fr




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