sbbspartan
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Can thermometer bulbs burst from too cold of air temperatures?
I was wondering if my thermometers can burst or be damaged from being in too cold of air temperatures?
I ask, because for the past several days and the next several, up here in Duluth, Minnesota the air temp. has been around -20 F (-29 C) with a -40 F
(-40 C) windshield. My lab is out in my garage, so I haven't been heating it the past several days, because it just takes too much fuel.
My thermometers are the mercury ones from Elemental Scientific and only designed to go down to -10 C. I would think that too high of temperatures
would be a lot worse than the temp being too low, but I just wanted to be careful. Would the mercury just pool at the bottom of the thermometer and
not really damage it unless the temps are really, really low?
For now, I am just storing the thermometers inside where it is warm. I am just curious as to when the bulb would burst, if at all... 
[Edited on 23-1-2013 by sbbspartan]
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watson.fawkes
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Quote: Originally posted by sbbspartan  | | For now, I am just storing the thermometers inside where it is warm. I am just curious as to when the bulb would burst, if at all.
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The coefficient of liquid mercury is about an order of magnitude more than that for glass. That means that
as it cools down, you're not going to burst anything. As always, though, rapid and/or uneven heating or cooling are bad for glass.
As long as the mercury doesn't freeze, you'll be fine. That's at -38.8 °C = -37.9 °F. Even if it freezes, the problem would be that
you can get gas trapped between the reservoir and the thermometer might need servicing to get it registering temperature again.
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UnintentionalChaos
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| Quote: Originally posted by watson.fawkes | | Quote: Originally posted by sbbspartan | | For now, I am just storing the thermometers inside where it is warm. I am just curious as to when the bulb would burst, if at all.
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The coefficient of liquid mercury is about an order of magnitude more than that for glass. That means that
as it cools down, you're not going to burst anything. As always, though, rapid and/or uneven heating or cooling are bad for glass.
As long as the mercury doesn't freeze, you'll be fine. That's at -38.8 °C = -37.9 °F. Even if it freezes, the problem would be that
you can get gas trapped between the reservoir and the thermometer might need servicing to get it registering temperature again.
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Interestingly, standard procedure for fixing a broken column (gaps in it) in a mercury thermometer is to cool it in dry ice/acetone so that all the
metal retreats into the bulb, then allow to warm.
[Edited on 1-23-13 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Adas
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Here, in Slovakia, standard procedure when you have gaps between the mercury is to shake the thermometer.  It always works.
Rest In Pieces!
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bfesser
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| Quote: Originally posted by Adas | | Here, in Slovakia, standard procedure when you have gaps between the mercury is to shake the thermometer. It always works. |
With a good chance of loosing your grip and throwing the thermometer into a hard surface and splattering mercury everywhere.
I just had a thermometer bulb shatter in my freezer a few days ago, while I was trying to re-unite the liquid column. It was a non-mercury (<a
href="http://en.wikipedia.org/wiki/Galinstan" target="_blank">Galinstan</a> oral fever thermometer.
For Hg, you'll have no problem with it freezing, but keep it above a collection container as it thaws.
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Endimion17
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| Quote: Originally posted by bfesser | | Quote: Originally posted by Adas | | Here, in Slovakia, standard procedure when you have gaps between the mercury is to shake the thermometer. It always works. |
With a good chance of loosing your grip and throwing the thermometer into a hard surface and splattering mercury everywhere.
I just had a thermometer bulb shatter in my freezer a few days ago, while I was trying to re-unite the liquid column. It was a non-mercury (<a
href="http://en.wikipedia.org/wiki/Galinstan" target="_blank">Galinstan</a> oral fever thermometer.
For Hg, you'll have no problem with it freezing, but keep it above a collection container as it thaws. |
Actually, it's a standard procedure in every weather station for resetting mercury maximum thermometers. You grab it and give it a few firm shakes
towards the ground. That's why kids aren't allowed to work at weather stations.
It is not possible to unite the column just by freezing, unless there's a complete vacuum in the capillary tube, which is never the case.
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