5 tube balancing argument

Pamela Norton pnorton at lac.jci.tju.edu
Wed Oct 16 15:08:50 EST 1996


In article
<Pine.SOL.3.95.961012085307.1026B-100000 at lovelace.infobiogen.fr>, Francois
Coulier <coulier at infobiogen.fr> wrote:

> On 11 Oct 1996, Hiranya Roychowdhury wrote:
> 
> > At 01:52 PM 10/10/96 -0700, Lou Cantolupo wrote:
> > 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


     Not all swinging rotors have 6 buckets, some have 4, can't remember
seeing any with more than 6, though. However, I have spun 3 tubes in 6
place swinging bucket rotors (Beckman) with no apparent ill effects (slots
1, 3 and 5; or 2, 4 and 6). I also do not recall Beckman claiming that all
positions should be filled. They do state that for swinging rotors, all
buckets must be attached, whether full or empty, and the numbers on the
rotor positions and the buckets should be matched up.

     Now that I think about it, I'm not sure what the rationale for filling
all places would be. Weren't the old rotors in the analytical machines
elongated (dating myself)?  Any centrifugal experts out there?

     Pam Norton

-- 
Pamela A. Norton, Ph.D.          Assistant Professor of Medicine
Thomas Jefferson University
Philadelphia, PA 19107           p_norton at lac.jci.tju.edu



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