[RASMB] Elevated temperature operation with a turbomoledcular pump.

[Kristian Schilling]

Dear Walter,

thank you for going into this. The fogging problem has been an issue here 
as well. If we have not been confronted with this problem for some time 
it's mainly due to the fact that we have been sticking to 20 degrees most 
of the time.

Our serviceman had always stressed his own attempts to have Beckman resolve 
this issue; I think his suggestion was to introduce a cooling trap. 
However, I feel that your solution should be somewhat easier to handle.

I would be definitely interested in implementing this improvement; as the 
others, I would also be eager to learn what costs would be connected with this.

Regards,
Kristian

At 12:18 11.03.2005 -0500, you wrote:
>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
>#################################################################



=================================
Nanolytics
Gesellschaft fuer Kolloidanalytik mbH
Dr. Kristian Schilling

Hauptstr. 20
D-14624 Dallgow

Tel.:           +49 3322 24200-5
Fax:            +49 3322 24200-6
e-mail: schilling at nanolytics.de
Internet:       www.nanolytics.de
   
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