[RASMB] Elevated temperature operation with a turbomoledcular pump.

[John E Harlan]

Sounds like a pretty nice improvement.  Depending on cost, I would be 
interested.

John E. Harlan
Advanced Technology
Abbott Laboratories
Dept. R46Y AP10-2
100 Abbott Park Road, 
Abbott Park IL  60064-6100

(847) 938-4278   Tel. 
(847) 935-4994   Fax
john.e.harlan at abbott.com




Walter Stafford <stafford at bbri.org>
Sent by: rasmb-admin at server1.bbri.org
03/11/2005 11:18 AM

 
        To:     rasmb at server1.bbri.org
        cc: 
        Subject:        [RASMB] Elevated temperature operation with a turbomoledcular pump.


Dear RASMB-ers

        I have been testing a turbomolecular pump as a replacement for the 
standard diffusion pump on the XL-I. I am writing to report the results of 
that experiment.

On my machine, with the standard diffusion pump installed, I have not been 
able to run above about 23 degrees without having serious fogging of the 
interference condensing lens after about 15 minutes, making it impossible 
to take data.

About a month ago, with the help of the Beckman Serviceman and folks from 
the Axiden Division of Alcatel Vacuum Technology {http://www.adixen-usa.com/}, we installed an ATP80 TMP in place of the diffusion pump. Other than a 
flange that had to be machined to mate the TMP to the diffusion pump 
flange, it was a direct replacement. The original rough pump was used to 
back up the TMP.  see: 
{http://www.adixen.com/all/dyn/products/products.php?id_prod=20&lg=us}

So far the results have been quite remarkable. After the first test of 
running for 4 days at 40 degrees, the optics were clean. The chamber was 
actually cleaner after the run than before. The TMP seemed to have removed 
all the residual oil that we were unable to remove after replacing the 
diffusion pump. It pumps down to 3-5 micons in less than 5 minutes and 
ultimately to about 1-2 microns. The fringe patterns seem to be more 
stable (not sure exactly why, but I was informed that the regular 
diffusion pump heater normally cycles on and off; the flexing associated 
with that may explain it).

We use it routinely now for all runs and couldn't be happier with it.

Several labs have expressed an interest in installing one on their 
machines.

However, Beckman will not support the pump or provide one as standard 
equipment unless there is sufficient interest. A proper, Murphy-proof 
installation would require a firmware change and field service support to 
allow it to be included under the service contract and warranty.

I would like to take a survey of those who might be interested, so that we 
can convey that expression of interest to Beckman.

If you have an interest and think that running at higher than 20 degrees 
or higher precision might be useful to you, please respond to this email 
by replying to the RASMB. I'll collect the responses and comments and 
forward them to the folks at Beckman.

It has opened new vistas for our research.

Thanks
Walter
-- 

########################################################################
Walter F. Stafford III, Ph.D.
Analytical Ultracentrifugation Research Laboratory
Senior Scientist
Boston Biomedical Research Institute
64 Grove Street
Watertown, MA  02472-2829

main:(617) 926-8040
tel: (617) 658-7808
fax: (617) 972-1753

mailto:stafford at bbri.org
http://www.bbri.org/faculty/stafford/Stafford.html
#################################################################

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