Have you tried wrapping the bottom of the tube with a thin layer of quartz wool
on the outside? I do this, and don't have any fusing issues. Also, if slag is
seeping, the vaccum may not help, as the slits will ultimately become plugged
and flow will suffer. What are your samples? Do they have a high silica content?
I have had some issues with low-C soils (due to the high weight required for the
analysis), and found that frequent ash tube removal and emptying was the only
helpful solution; perhaps this would prevent excess buildup of slag in your
case.

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 Paul Eby
| Sent: Thursday, February 26, 2009 2:03 PM
| To: [log in to unmask]
| Subject: [ISOGEOCHEM] ash tubes
| 
| 
| Listmembers,
| 
| I've been having trouble with ash tubes from our EA breaking lately.
| 
| We use Elemental Microanalysis C1090, which is open both ends and has 
| slits on the bottom half. I have a small bit of quartz wool at the 
| bottom of the tube, and at the top of the reactor. Typically, the 
| tube is stuck when I try to remove it, and breaks near the top of the 
| ash level when I force it. This occurs regardless of whether I am at 
| full temperature or standby temperature, and I have had the same 
| trouble with tubes that are closed at the bottom.
| 
| My best guess is that the slag is seeping through the slits and 
| fusing to the reactor tube. Does anyone have any applicable wisdom?
| 
| I'm considering the vacuum removal method at this point....
| 
| Paul Eby
| University of Victoria
| 
|