Dropped thermometer, irregular mercury?

bobbotron · Sep 25, 2016

I fumbled and dropped my analog thermometer about 6 inches onto a plastic basin. It didn't break, but the mercury (indicator fluid?) got some gaps in it. About two days after, it's still not great. Do any of you fine folks know of some way to fix this?

Sirius Glass · Sep 25, 2016

Shake the thermometer down. Put it hot water and later in the refrigerator.

Andrew O'Neill · Sep 25, 2016

Put it in hot enough water so that the mercury reaches the very top. That's what I do, and it seems to always do the trick.

Bill Burk · Sep 25, 2016

Thankfully, it's not mercury. Many thermometers have instructions to help you re-join the column into one solid bar. Careful, you can break it if you heat too fast (glass stress) or too much (over-expand the liquid creating intense hydraulic forces the tiny extra expansion chamber cannot accommodate).

Gerald C Koch · Sep 25, 2016

You don't want to heat the thermometer. You need to chill it until the alcohol or mercury goes all the way into the bulb.

Agulliver · Sep 26, 2016

That looks like a spirit/alcohol thermometer...one reason why I prefer mercury is that it's less prone to the column breaking in that manner...and it's less poisonous than you probably think. You'd have to inhale a lot of mercury vapour or drink a fair amount of the stuff to do yourself any harm.

Try both techniques mentioned here. First try freezing the thermometer and seeing if that works.

If not, then work out the maximum temperature that will result in the column just reaching the top...and try to gently heat the bulb to that temperature, and the column should reconnect.

Try freezing first as it's less likely to result in breaking the thermometer.

darkroommike · Sep 26, 2016

Someone posted the instructions for the Kodak Process Thermometer here https://www.flickr.com/photos/etr420/9280657696

Gerald C Koch · Sep 26, 2016

Liquid mercury is less poisonous that one might expect. The metal is poorly absorbed by the digestive tract. Mercury vapor on the other hand is very poisonous. However the real danger is from mercury (II) compounds particularly organomercury compounds such as dimethyl mercury. In the 19th century pharmacists would triturate mercury with chalk, licorice root and a bit of honey to make what was called "blue pills." They were prescribed for a number of ailments. Still it's good to limit mercury exposure.

bobbotron · Sep 26, 2016

Thanks for the tips everyone. I have heated it (quite hot), cooled it, refrigerated it, shook it. Success is elusive so far, but I've not flung it across the room yet so I'll keep at it.

DWThomas · Sep 26, 2016

I have dealt with that a couple of times by starting with room temperature water in a pot on the stove. I then turn the burner on to just moderate heat and hold the thermometer in the water. The goal is to raise the temperature at a modest rate, maybe 5 or 6º per minute or so. That way you don't get some nasty run-away. As the colored stuff just gets to the expansion space at the top, lift the thermometer from the water and a quick sideways snap or two with a finger tip will usually consolidate the gaps. Then just let it cool in the air. (This assumes the highest temperature the device reads is well below the boiling point of water!)

bobbotron · Sep 26, 2016

I got it! I put it in a glass with hot water, and then slowly poured a bit of near boiling water into it, letting it adjust for a little bit after every pour until the liquid got right to the expansion space at the top. Thanks!

Dropped thermometer, irregular mercury?

bobbotron

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Dropped thermometer, irregular mercury?

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