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Author: Subject: Need Help Fixing Separated Thermometer
Oncorhynchus
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[*] posted on 19-9-2022 at 04:32
Need Help Fixing Separated Thermometer


I have an alcohol thermometer (max temp 250 C) that has a few mm of separated liquid near the top. I've already tried rejoining it with an EtOH/dry ice bath with no luck. Think the heating method would do the trick? If so, open flame or sand bath on a hot plate?
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Endo
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[*] posted on 19-9-2022 at 05:17


If you have access to a centrifuge with deep wells you may consider padding the bottom of the well with cotton and making a tube with water to counterweight it (use a scale).

It should only take a few seconds after spin-up.
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Sulaiman
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[*] posted on 19-9-2022 at 06:24


Heating worked for me but you have to be careful : if the bubble fills, the internal pressure will pop the bulb :(
The internal pressure will in any case be high for alcohol at 260C
I held the thermometer with the bulb a few inches above a candle flame.
(360C mercury thermometer)
A high bp liquid bath would have been more controllable but I had no suitable liquid,
in your case conc. sulphuric acid is one option.




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Gammatron
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[*] posted on 19-9-2022 at 07:42


Coincidentally I just noticed my alcohol thermometer had the same problem last night and was wondering if there's a way to fix it.



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Oncorhynchus
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[*] posted on 19-9-2022 at 18:06


Follow up...

Is anyone looking to get rid of a 10/30 alcohol thermometer?
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unionised
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[*] posted on 20-9-2022 at 01:27


Quote: Originally posted by Sulaiman  
Heating worked for me but you have to be careful : if the bubble fills, the internal pressure will pop the bulb :(
The internal pressure will in any case be high for alcohol at 260C
I held the thermometer with the bulb a few inches above a candle flame.
(360C mercury thermometer)
A high bp liquid bath would have been more controllable but I had no suitable liquid,
in your case conc. sulphuric acid is one option.

While 260 C is pushing it, cooking oil may be safer than sulphuric acid...
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Sulaiman
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[*] posted on 20-9-2022 at 05:37



Whatever the maximum of the temperature scale is,
a higher temperature will be required to get the liquid up to the bubble,
consider it as a linear extension of the scale
Plus
Some of the liquid is already in the bubble so an even higher temperature will be required,
so I doubt that cooking oil will be suitable,
temperatures above smoke point and flash point will be required.

There will be an inert gas in the thermometer, usually nitrogen,
to increase the internal pressure hence prevent the alcohol from boiling,
which is why it will be necessary to force the alcohol all the way up to the bubble.

Good luck




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Dr.Bob
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[*] posted on 20-9-2022 at 11:17


If anyone is good at this, I have a few therms with this feature. I have not listed them, but would be happy to sell cheap to anyone who wants to try to fix them. Most are lower range alcohol therms with red liquid.
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Rainwater
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[*] posted on 15-1-2023 at 16:50


Just duck taped mine to a box fan, gonna let it spin for the night
Edit: its almost there, running it more.
Edit. Seems to work, all the red is in the same place now.
Need to check its accuracy
[Edited on 16-1-2023 by Rainwater]

[Edited on 16-1-2023 by Rainwater]




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Dr.Bob
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[*] posted on 16-1-2023 at 14:50


Did you tape it to the outside to shake it or to the blade to spin it around? I am willing to try a lot to fix the 4 or 5 ones I have that are separated now. Tried cooling, no luck, and tried heating one or two, but most have a very small bubble at the top. The ones that were lower or had a large bubble at the top were easy to heat and fix, but some are not that easy.
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Rainwater
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[*] posted on 16-1-2023 at 18:10


I taped to the blade, red part away from center.
It started dancing so i weighed the thermometer and cut some wire to match.
tapped the weights (copper wire) to the center of each blade to stop the dancing.




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Sir_Gawain
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[*] posted on 16-1-2023 at 19:31


The same thing happened to me; I found an effective method is to drop it repeatedly from waist height (onto carpet).



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Rainwater
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[*] posted on 18-1-2023 at 14:16


Soo after testing, my thermometer is kept precision but
not its accuracy.
Ice now melts at 1c and boils at 101c.
Better than nothing




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