Thanks Robert. I'll check mine when I get in tomorrow but I'm pretty sure
that it is set to heat at 100 degrees per minute as well. I'll change that
setting to slow it down in the future.
Thanks to everyone for the responses. In summary of the messages I
received: there are many people who change their own heating elements by
purchasing them from third party vendors. Several EA and TC/EA consummables
suppliers also stock the heating elements and sell them for $550-$650 (US).
Alternatively, the companies that make the heating elements sell them for
about $200 (US) but they are made to order so you have to accept a 3-4 week
lead time. The same thing goes with the ceramic tubes for the TC/EA: if you
can wait (or you have funds to stock up on them), you can get them for
about $50 each from a ceramics supplier, otherwise you will have to pay
$150-$225 to get one right away from one of the consummables suppliers.
For some reason I had developed the impression that the heating element of
the TC/EA would last about 5 years, but the responses I've gotten seems to
indicate that that is not quite right. Ours died after 1.5 years of use. I
now have the impression that that isn't so odd although some people have
had them last several years.
I'm going to opt to order several heating elements at lower cost (and long
lead time) and figure out how to connect them to the terminal plates on the
TC/EA. Given that many people have replaced their heating elements from
scratch it would be very nice to have a section of the isogeochem web page
where one could post this sort of information (suppliers, pictures of the
process, warnings about problems encountered, etc) in the future. I will
certainly document our experience with it and will happily provide that
information.
Anthony
At 06:49 PM 9/6/2006, you wrote:
>Hello Anthony, Bill,
>We took delivery of a TCEA this year and when first switched on it was
>able to reach orange heat before the thermocouple had time to register
>more than a few hundred degrees. I was duly alarmed, the manual
>instructing me to "initially heat at 300 degrees per hour." It turned out
>that the PID controller was set to heat at the unobtaineable rate of 100
>degrees per minute.
>If you are indeed getting over-fast heating (and if your machine is like
>mine) you can choose your ramp rate - refer to the PID controller
>handbook, also available from the Jumo website. Note that there is one
>menu location for setting the numerical value of the ramp rate and one for
>the units - deg per minute or deg per hour.
>I now have mine set to 600 degrees per hour which seems reasonable.
>I'd be interested to know if the TCEAs are getting sent out from the
>factory with that setting wrong?
>Cheers
>Robert
>
>
>----------
>From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
>Behalf Of Bill Showers
>Sent: Thursday, 7 September 2006 1:31
>To: [log in to unmask]
>Subject: Re: [ISOGEOCHEM] TC/EA heating element
>
>Anthony,
>
>We had similar problems with a warped TCEA furnace SiC furnace
>element. These furnaces will ramp up and ramp down way too fast and cause
>the heating element to deform. If they deform enough they will touch the
>side of the ceramic insert and melt the side of the tube and then crack
>the furnace element.
>
>You can prevent this from happening by slowly ramping the temperature of
>the heating element up and down in 200 degree C increments and letting the
>element "heat soak" at each step for 15-20 minutes. We were going through
>furnace elements every 6 -12 months when we first got our TCEA. With the
>slow temperature ramping process our furnace has lasted over three years
>and shows no sign of any problem. Saves a bit on the supply funds. We
>bought a few furnace elements, but had to have our machine shop make
>furnace tops for each element as they were all different diameters. In
>the end the ones from Thermo worked best, so we don't make them
>anymore. It also helps to change the glass carbon inserts frequently as
>they will warp and get material built up on them.
>
>Good luck,
>Bill
>
>At 06:14 PM 9/5/2006, you wrote:
>>The heating element on our TC/EA furnace has cracked and am in the
>>process of trying to get an idea of whether I can purchase just a
>>replacement heating element from Thermo (the catalog only lists a part
>>number for the whole furnace) and for how much.
>>
>>In anticipation of significant markup on the price of the heating element
>>(and the possibility that Thermo only sells the item as part of a more
>>expensive furnace assembly) I am wondering if anyone has found an
>>alternate supplier of these heating elements. I believe it is a silicon
>>carbide heating element.
>>
>>As an aside: I had a sequence of ceramic tubes crack during use or
>>cooling of the furnace. I suspect that that might be a symptom of the
>>ailing heating element. If someone else has had experiences with furnace
>>tubes cracking at an unusually high frequency and found any link to a
>>dying heating element, please let me know. I dont have enough history
>>with the TC/EA to draw on previous experience about this phenomenon.
>>
>
>William J. Showers
>Dept of Marine, Earth & Atm Sciences
>Box 8208
>North Carolina State University
>Raleigh NC 27695
>
>For express mail: 1125 Faucette Dr.
>
>(919) 515 - 7143 Office
>(919) 515 - 7802 Fax
>(919) 515 - 3689 Lab
>(919) 515 - 7911 Field Lab
>[log in to unmask]
------------------------------------------------------
Anthony L. Michaud
W. M. Keck Foundation Laboratory for Environmental Biogeochemistry
School of Earth and Space Exploration
Arizona State University
Tempe, AZ 85287-1404
Web: <http://kfleb.asu.edu>http://kfleb.asu.edu
Tel: 480-727-8033
Fax: 480-965-8102
Mailing address:
Anthony Michaud
PSF-686
Arizona State University
Tempe, AZ 85287-1404
***Windsurf Everywhere***
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