How come some low-end thermometers are still made in mercuryversion?

>>> I had a thermometer using a red spirit column. It had very slow

Thermomoeters for different purposes sometimes specify immersion
depth for which they have been designed or calibrated. In the
organic lab, you can find "total immersion", "15 mm immersion"
(for a small distillation column), "40 mm immersion", etc.
The black line etched around the circumference is usually the
immersion depth. For organic lab, I don't think I ever needed
to be so precise and if I could get one cm of the bulb of a
"total immersion" thermometer in a crowded oil bath, that was
good enough.

When I was doing p-chem, we had a NIST calibrated thermometer
that was probably a couple hundred dollars (cf., less than
ten bucks for a cheapo thermometer.) Intermediately priced,
there are NIST traceable thermometers.






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[Only registered users see links. ] (Ther Moe) wrote:


Exactly so. It is a little disturbing how few practicing chemists
seem to be aware of immersion length. However, as you mention, there
is often (or usually, in some disciplines) no need for the extra
degree of accuracy that the immersion length criterion provides.

Still, I don't think any of this has any direct bearing on how quickly
the thermometer equilibrates.


And there are traceable thermocouple thermometers available. Those
offer thermal mass which is orders of magnitude smaller, with a
correspondingly faster equilibration time.

Steve Turner

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