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Subject: Re: Calibrated Thermometers



"nailer" wrote

> you are right, during phase transition period ,the temperature will
> stay constant (in an isolated setup).

But with Kitchen Kounter Kalibration it isn't.

I STRR that a reasonable setup can be had with distilled water slush,
such that the ice and water are at the same temperature.

Wait for a winter day when the temperature is 32F scoop up some clean
snow in the proverbial styrofoam cup, shake a bit to generate water,
put a cap on it and keep it in the shade.

The ice, the water and the air/water vapor have to be at the same
temperature:
the ice is neither melting nor freezing.

A home made slush of crushed distilled water ice cubes should work.

The NIST/National Bureau of Standards has a publication on 'Practical
Temperature Standards'. Much easier to call Omega and get a triple
point cell.

If you use a glass fever thermometer as the standard be aware they
hold the highest temperature. Look at the thermometer to be tested
and note it's highest temperature. Then look at the reading on the
fever thermometer. The quantity of water needed has to be sufficient
that it's cooling time constant is much greater than heating time
constant of the thermometer. And keep a lid on it. A use for
fast-food litter: the little hole for the straw is the right size for
a thermometer.



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