Sciencemadness Discussion Board

Thermometer question

demorol - 13-2-2005 at 11:44

I have recently aquired new thermometer for the distillation setup and I realized I have probably bought the wrong one. On the back of it says "total immersion", so I suppose it must be immersed in the liquid you are heating, which means it is useless for distilling purposes. Then I looked in the glassware catalog and realized there's no such thing as "distillation thermometer". All I could see was a variety of different thermometers with immersion depth ranging from 50 to 108 mm. I'm puzzled, because I don't know which one to get, and I certainly don't want to be spending any more money on useless "total immersion" thermometers. Should I get the one with the lowest immersion depth? I'd be very grateful if anyone can help me with anykind of answer.

I don't know if said it already, but the thermometer is needed for distillation.


[Edited on 13-2-2005 by demorol]

Magpie - 13-2-2005 at 11:49

I think 75mm immersion is pretty standard. It's what we used at school and what I bought for home use.

mycoguy - 14-2-2005 at 16:55

yup, you need a PI thermo. 76mm immersion is common.

demorol - 15-2-2005 at 00:33

Originally posted by mycoguy
yup, you need a PI thermo. 76mm immersion is common.

Thank you all. Just one more question, as I'm new here. What does PI mean?

neutrino - 15-2-2005 at 05:07

Partial immersion. It’s the type that only needs to be immersed to a certain line on the thermometer.

demorol - 15-2-2005 at 05:17

I still don't get it. So "76 mm immersion" means that you actually have to immerse the thermometer into liquid for 76 mm? If so, how are you gonna read the distillation temperature?


Magpie - 15-2-2005 at 10:21

76mm is the immersion to which the thermometer is calibrated. That's the optimum immersion. It will still give useful readings with other immersions. But the closer to 76mm the more accuracy you get.