From: Claus Urbanke <Urbanke.Claus@MH-Hannover.DE>
  To  : rasmb@bbri.harvard.edu
  Date: Tue, 9 Jun 1998 14:49:48 +0100

Problems with aluminium centerpieces

Hi Virgil and  RASMBer's,

you might use the epon centerpieces at higher speeds. Beckman doesn't recommend this but 
in the instructions for the An60 rotor they say something about beeing very careful when 
going up to higher speeds than 48000 rpm. The problem is the wall between the sectors. 
As long as both sectors are filled to almost the same height nothing happens. If one 
sector leaks out completely the wall will break. Thus, if you watch your cells 
while starting the run and during thre first scans and nothing leaks you re safe. I run 
aluminum filled epon double sector centerpieces with this procedure up to 6ss000 rpm and 
it has only been once that a septum broke because we did not watch the cells at the 
begining of a run. I admit, though, that I do not use the charcoal filled epon 
centerpieces regularily with this method because they are a bit too expensive. 
By the way, be very careful with Kel-F centerpieces. They will be very 
sensitive to unequal filling heights. They contain an aluminum core and this core will 
not break but  slightly (and irreversibly) bend.

Best wishes
Claus


        Claus Urbanke
        Medizinische Hochschule
        Biophysikalisch-Biochemische Verfahren
        OE 8830 
        Carl-Neuberg-Str. 1
D-30623 Hannover
        Germany

Tel.:(+49) 511 532 3707 (2928)
FAX :(+49) 511 532 5966

Urbanke@bpc.MH-Hannover.de