[RASMB] Elevated temperature operation with a turbomoledcular pump.

[Mary Barkley]

Hi Walter!
	I would buy this pump upgrade in a 
heartbeat!  We badly need to measure protein 
association constants at 25-37 °C, and do so only 
with great difficulty, if at all, now.  Please 
put me on the list.
Mary



>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
>#################################################################

-- 
Mary D. Barkley
M. Roger Clapp University Professor of Arts & Sciences
Department of Chemistry
Case Western Reserve University
10900 Euclid Avenue
Cleveland, OH 44106-7078
(216) 368-0602		(216) 397-3349 home
(216) 368-0604 fax		(216) 409-8839 cell