Thermometer Sprirt Seperation

[Slartibartfast]

Came across these 2 methods for removing the air gap in the spirit in some of our wonky thermometers:

Heating Method: Holding the thermometer in an upright position and away from your face, heat it suspended in warming liquid or in hot air from a hair dryer just until the separated portion of the column enters the expansion chamber at the top of the thermometer. Be very careful and stop heating as soon as the fluid enters the expansion chambers. Over-filling the expansion chamber will break the thermometer. Now, while keeping the thermometer in an upright position, tap it gently against the surface of a rubber stopper. This should allow the gas separating the column to rise above the column. Allow the thermometer to cool slowly and store it in an upright position.

Cooling Method: Keeping the thermometer upright, place only the thermometer bulb in a solution of shaved ice and salt or dry ice and alcohol. Allow the liquid column to retreat into the bulb, then swing the thermometer in an arc. This should release the trapped gas and permit it to escape above the column. Allow the thermometer to slowly return to room temperature and store it in an upright position.

[Ian]

Richard,
I have used your first method with Mercury thermometers too and had good success. (I like living dangerously!)
Ian

[RosalieM]

Any suggestions on how to fix Max-Min thermometers? We just bought new ones and a few of them arrived with air bubbles. I'm not sure I'm brave enough to try the heated one with the mercury, but the ice one may be difficult because of the casing. I'll go check it out though...

[smiley]

Sometimes you can just shake down Max/Min thermometers, especially if they're mercury ones. If you're old enough you may remember nurses doing the same thing before they took your temperature. Isn't quite as successful with red alcohol ones though.

Cheers, K

[SueH]

The best and safest way I have found to rejoin thermometers is to place the thermometer in a tin of sand and heat. I use an old jam tin and heat it on a hotplate -can do several at a time this way. Wait until the thread joins in the air bubble at the top of the thermometer and remove it to cool.

The beauty of this method is that if the thermometer does break it does so in the sand and the glass and fluid is contained.

The only times I have had thermometers break using this method is if there is no air bubble at the top of the thermometer, hence nowhere for the thread to join.