Sean: 

It will be interesting to see what responses you get. I have heard others speak
ill of the Pfeiffers, replacing them with Edwards pumps. I did this with the Duo
5 on my Delta+ system, in part because I needed to rebuild the Pfeiffer, and the
Edwards was handy to keep the system up and running. It has given, I think,
better reliability than the Pfeiffer, but it doesn't fit in the box. I rebuild
my Pfeiffers every two years of service, and have not had any issues with shaft
seal leaks or random stops. However, I should also note that, on the Delta+, the
two Duo 2.5's only evacuate parts of the dual-inlet mechanism. I run continuous
flow for 99.9% of everything I do. And I do not run the Duo 2.5's, as I do not
need to evacuate the dual inlet, wear down pumps that are effectively doing
nothing for me or needlessly consume the energy. I have had no issues with doing
this; and I have confirmed with Roger Husted and Jeter Dietrich (if that is the
correct name, I fear I mix it up sometimes) at Finnigan that this practice is
OK. Roger said that there is no need for the dual inlet pumps, as long as the
seal between the dual inlet and the needle valve box that sits on the source is
good. I'm not sure if the arrangement is exactly the same on the V, but I expect
it is similar, and you may not need the pumps.



David R. Vann, Ph.D.
Forest Biogeochemistry and Physiology
Department of Earth and Environmental Science
THE UNIVERSITY of PENNSYLVANIA
240 S. 33rd St.
Philadelphia, PA 19104-6316
[log in to unmask]
office: 215-898-4906
FAX: 215-898-0964


| -----Original Message-----
| From: Stable Isotope Geochemistry 
| [mailto:[log in to unmask]] On Behalf Of Sean Sylva
| Sent: Thursday, October 21, 2010 11:54 AM
| To: [log in to unmask]
| Subject: [ISOGEOCHEM] Pfeiffer Duo 2.5 Problems
| 
| 
|   Dear Community,
| 
| I am writing to ask if anyone has had significant problems 
| with Pfeiffer 
| Duo 2.5 vacuum pumps connected to irms systems? Within the 
| last year, I 
| have had two shaft seals leak and just yesterday, the pump 
| just turned 
| off, with voltage going to the plug. Has anyone had similar, chronic, 
| problems with these pumps? If so did you purchase a new DUO 
| 2.5? If not, 
| what did you replace the pump with? I have the pump on a Delta V plus 
| and I run continuous flow 13C and 2H.
| 
| Any information from the community would be greatly appreciated.
| 
| Sean
| 
| -- 
| Sean P. Sylva
| Woods Hole Oceanographic Institution
| 266 Woods Hole Rd
| Woods Hole, MA 02543
| 
| Ph: 508-289-3546
| Fax: 508-457-2164
| Email: [log in to unmask]
| 
|