[RASMB] XLA run at 37 degrees

[David Hayes]

Hi Dean,

I wanted to mention that we have done runs up to 40 C also and have 
installed a turbomolecular pump as a replacement to the diffusion pump to 
help alleviate oil problems.  I believe that at least one other lab has 
had  a Beckman service person install the turbomolecular pump also.  With 
the turbopump, we have no long term oil problems during a run at 40 
degrees:  it actually seems to clean the chamber of oil.  But we do have an 
initial oil condensation problem during the initial heating up for the 40 
degree run and have basically adopted the rotor preheat regimen that 
Barbara outlined in her email.  Using the centrifuges heaters to heat up 
the rotor is very inefficient and definitely puts the can temperature much 
too high and may affect the drive.  It seems that some of the oil comes 
from the drive at very high temperatures and not only from the notoriously 
messy diffusion pump because we see oil with no diffusion pump 
installed.  As a maintenance issue for the drive and to limit the amount of 
oil splattered into your system, I strongly recommend you follow Barbara's 
advice about pre-heating, though I have not had the fogging problem when 
preheating the rotor with the full cells installed (Maybe because our 
pre-heat oven is 5 feet from the centrifuge?)  If this one run turns into a 
long series of studies, you may want to look into purchasing a 
turbo-molecular pump.

David Hayes
(Walter Stafford's lab, Boston Biomedical Research Institute)
64 Grove St.
Watertown, MA  02472
617-658-7738


At 12:57 PM 5/12/2006, you wrote:
>Dean,
>
>I've done runs at 30 and 40C. The main problem that I've encountered is 
>the presence of oil in the chamber and the fact that there are two 
>temperature controls. when you first start equilibrating you'll notice 
>that the temperature that you read is the temperature of the 'air' in the 
>chamber but once the vacuum goes below 100micron then you'll start reading 
>the temperature of the rotor. So, if the rotor is at less than 37C the 
>machine will heat up and the actual temperature in the chamber might go as 
>high as 80C and you'll start having trouble with oil. I have the following 
>suggestions:
>
>1) incubate your rotor at 37C in a cell culture oven.
>2)but don't incubate the cells with the sample because when you take them 
>out of the 37C oven the windows will fog up!
>3) when you start adjusting the temperature, do it step by step. Set the 
>machine at 30C and as soon as the vacuum goes below 100 micron, look at 
>which temperatre the rotor is and slowly increase the machine setting from 
>that temperature, so it won't go too hot in the chamber.
>4) At the end of the run before releasing the vacuum make sure to 
>re-equilibrate the instrumet at 20C. that way you'll have less oil problem
>4)After the run, clean the windows and do a small run at 20C and then 
>clean the windows again. you'll find that the second run after a high 
>temperature run will have a lot of oil drops in the chamber/windows.
>
>good luck
>barbara
>
>PS I don't think there's a difference if it's a velocity of equilibrium 
>run, just remember to adjust the parameters when you fit the data 
>(like  density etc.)
>
>
>-----Original Message-----
>
> > Date: Fri May 12 09:27:39 PDT 2006
> > From: "Dean Malencik" <malencid at ucs.orst.edu>
> > Subject: [RASMB] XLA run at 37 degrees
> > To: RASMB at server1.bbri.org
> >
> > Hello,
> >
> > I have been asked to do a run at 37 degrees on the XLA analytical 
> centrifuge.  Does anyone have any pitfalls to anticipate or is it even 
> feasible to do a run at this temperature?  Any differences if the run is 
> a velocity or equilibrium run?
> >
> > Thanks.
> >
> > Dean Malencik
> >
>--
>Barbara Lelj Garolla Di Bard
>Dr. Mauk's Lab
>Dept. of Biochemistry and Molecular Biology
>University of British Columbia
>Life Sciences Building, Center for Blood Research
>2350 Health Sciences Mall
>Vancouver, B.C. V6T 1Z3
>Phone: (604) 822-2526
>
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