[Dsg-halla_ecal] Fw: heating test setup taken apart

[Marc Mcmullen]

Hi,

I'm not sure the picture links from the Hall A test stand worked. Here they are as attachments.

Marc
________________________________
From: Dsg-halla_ecal <dsg-halla_ecal-bounces at jlab.org> on behalf of Marc Mcmullen via Dsg-halla_ecal <dsg-halla_ecal at jlab.org>
Sent: Friday, February 24, 2023 12:02 PM
To: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Cc: Imani Burton <iburton at jlab.org>; Jennifer Williams <jennifer at jlab.org>
Subject: [Dsg-halla_ecal] Fw: heating test setup taken apart

Forwarding for distribution.


Marc

________________________________
From: Donald Jones <jonesdc at jlab.org>
Sent: Friday, February 24, 2023 11:33 AM
To: Marc Mcmullen <mcmullen at jlab.org>; Bogdan Wojtsekhowski <bogdanw at jlab.org>; shahinya at jlab.org <shahinya at jlab.org>; Mark Jones <jones at jlab.org>
Subject: Re: heating test setup taken apart

forgot to attach pictures


Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Donald Jones
Sent: Friday, February 24, 2023 11:30 AM
To: Marc Mcmullen <mcmullen at jlab.org>; Bogdan Wojtsekhowski <bogdanw at jlab.org>; shahinya at jlab.org <shahinya at jlab.org>; Mark Jones <jones at jlab.org>
Subject: heating test setup taken apart

Hi Folks,
I turned off the heater test prototype and after it cooled down I took the front off. Things looked to be in fairly good shape initially, but upon examination I noticed some delamination of the heater pads. At least 1 RTD had fallen off. All the pads are very brittle and easily snap when pulled.
I don't think that this should be surprising given that I wasn't monitoring the heater temperature which is rated only to 250 degC. Even the crystal temperature at one point exceeded this temperature for some time before I caught it (see plot). However, in retrospect, I suspect the damage may have been done during the initial heat up stage when I briefly (a couple of hours) turned the heaters up to 140 VAC (see plot). During this time the oven temperature that I was monitoring was well below 200 degC, but the heater pads may have been much hotter. In fact, during this time I noticed some small wafts of smoke coming from the oven apertures and I didn't know what it was but suspected the aluminum tape adhesive that is rated to 160degC. When I turned the voltage down to 126 VAC the wafts seemed to reduce which I now leads me to believe that the heaters themselves may have been driven well beyond their rated temperatures. It will be interesting to observe the longevity of these same pads when they are kept below their rated 250 degC by careful monitoring as they will be in Marc's system.
The system will not be able to run again until the heater pads are replaced.
On a positive note, the heater tape looks pristine. You wouldn't know it had been baked at 250 degC.
I have attached some pictures.
-Don

[cid:06f7fb1c-db69-4f0e-9ed2-c9f12ab9a581]

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
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