Penny,
If one of the wires to the heating element was loose, that explains why
the reactor wouldn't heat up and your wires are fried. I would replace
the wires, maybe some can be salvaged, and check the resistance of the
element. In the manual there are specs for what is normal, then you
could gauge if moving the jumper is even necessary. Also don't forget
the temperature offset stamped on the front of your oven. Mine for
example, reads about 50C lower than it really is. It is good to avoid
heating higher than you need to.
Under the right side panel there is an adjustable pressure safety switch
for the carrier. If the pressure drops below a certain point, power to
the reactor is cut. You might want to check to see that its set point
is well below the pressure you use for stand by service.
On a related note to help the tubes last longer, you can easily adjust
the temperature ramp rate (rA.Sd) in the jumo control. This number
equates to degrees C/minute. Out of the factory the setting is 100,
which means 6000C/hr heating or cooling! If you want to heat or cool
the reactor at a safe rate of 300C/hr, change this to 5.
After your rewiring and potential parts replacement there are a couple
fuses on the back that might have blown.
Hope this helps,
Ben
Benjamin Harlow
Manager, Stable Isotope Core Laboratory
Washington State University
School of Biological Sciences
G-81 Eastlick
Pullman, WA 99164-4236
Office: 509-335-6161
Lab: 509-335-6154
Fax: 509-335-3184
Laboratory for Biotechnology and Bioanalysis (LBB2) Stable Isotope Core
http://www.isotopes.wsu.edu
-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
Behalf Of Penny Higgins
Sent: Monday, December 01, 2008 9:46 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] TC/EA Troubles
Hi all,
I'm working hard to promote my deep, deep dislike of the TC/EA. So I
have a new problem I'd like to have your help with.
The background:
Probably more than a month ago now we most recently shut down the
TC/EA after a series of analyses of water for hydrogen isotopes.
Alas, I was not present during the power down (that'll never happen
again!), but am told that at about 500 degrees C the system cooled
rapidly, and the student in the lab simply shut off the power and
stopped helium flow to the TC/EA. This I suspect is related to a
crack that developed in the ceramic reactor tube that I discovered
later when taking the TC/EA apart. This has happened before with no
long-term ill effect to the TC/EA.
This morning I tried to power up again for another set of water
analyses. There's a brand new reactor in the TC/EA and everything is
leak-tight. Ordinarily at this point, I just turn on the TC/EA and
warm it slowly to the full temperature that we use to water analyses:
1450 degrees C.
I did recently shift the jumper on the transformer to higher voltage,
because the TC/EA was having difficulty getting all the way to 1450.
The problem:
The furnace is not warming up. The CG oven is warming fine. I've
switched on and off the system and rechecked for leaks with no
change. I moved the jumper back to where it had been with no effect.
The trouble-shooting guide only offers the further suggestion that it
could be a bad thermo-element switch. I took the aluminum cover off
the furnace to see what I could see.
The questions:
1) Is there a visual way to tell if this thermo-element switch is
bad? Or do I just order a new one and hope for the best?
2) Is it possible that the heating element itself is broken? Is there
a simple way I can determine that? Where/who is a good supplier for
an element should I need to buy another?
3) This is what I saw when I took the cover off (see photo at:
http://www.earth.rochester.edu/SIREAL/Files/TC_EA_Hell.html). The
insulation crumbles if I so much as look at it and the blue wire was
not fully seated in the screw holder. Could this be the source of my
trouble? Obviously, a repair is needing and I don't want to do a bad
repair here. Any suggestions?
Thanks for all your help, everyone!
~Penny
*******************************************************************
Dr. Pennilyn Higgins
Research Associate
"SIREAL"
Stable Isotope Ratios in the Environment Analytical Laboratory
Department of Earth and Environmental Sciences
University of Rochester
227 Hutchison Hall
Rochester, NY 14627
[log in to unmask]
Office: 209b Hutchison Hall Lab: 209 Hutchison Hall
Voice : (585) 275-0601 Outer lab: (585) 273-1405
FAX : (585) 244-5689 Inner lab: (585) 273-1397
http://www.earth.rochester.edu/SIREAL/index.html
*******************************************************************
|