Boiling/Steam Point for temperature verification

[AllTheThings]

I was looking around for a procedure to create some fixed points for temperature verifications.

ASTM E563-11 gives a decent procedure for creating a stable ice point bath. Is there an equivalent for a boiling point of water?

 

[Randy]

For making boiling water? Heat until 212 degrees F or 100 degrees C.

 

[Hendi]

Welcome to the wonderful world of embulliometry.
Basically yes, you can do a steam bath where you have a equilibrium of evaporation and condensation on your thermometer probe.You should use clean water just like with the ice bath. However, the boiling point is pressure-sensitive. You need a barometer to correct for this. Depending on accuracy, remember there is a steam pressure inside your vessel.
(Oh, and if you use historic tables to correct temperature for pressure, e.g. certain NBS monographys - these are old and the °C might possibly have shifted a tiny bit since then.) A reference thermometer makes things easier, of course.

 

[John Predmore]

fixed points for temperature verifications

This video from Fluke Corporation (who sells temperature calibration equipment) explains that atmospheric pressure due to altitude and the presence of ions in water will also affect boiling point. In the video example, the boiling water method was off 4 degrees C from a calibrated dry well calibrator (which is traceable and more accurate). I guess your decision depends on how accurate your 'verifications' have to be.

 

[AllTheThings]

Thank you both for the insights! And teaching me a new word: embuillometry.

I got bit by IPTS-68 vs ITS-90 a decade ago with some used equipment...Won't do that again

I guess I should have clarified: I will be using a higher end calibrated 4 wire industrial PRT as a reference, so creating an exact temperature condition is less important than creating a stable condition. Long-term, I will probably end up with a dry well, but am trying to start with something cheaper.

Sounds like with a steam/boiling bath, I will need to keep an eye on stability, along with immersion depth. Should be interesting to see how stable I can make it.