Sciencemadness Discussion Board

Thermometer choice

glassplass - 16-3-2016 at 12:08

Hi folks!
I need quick help.
Which thermometer is better to use in distillation aparatus,total or partial immerised?
The thing is little bit confusing.
I thing 76mm partial immerised is good option but i am not sure.
Please help! :D

aga - 16-3-2016 at 12:14

yes, you are right.

arkoma - 16-3-2016 at 12:33

This is a good question. Shit confuses me too, and I don't even KNOW what my chinese thermometers are--no markings. Blogfast, can ya weigh in and enlighten us perhaps?

S.C. Wack - 16-3-2016 at 14:30

Never buy a total immersion thermometer unless you need one.

Check your thermometers for a line aound them at a certain distance from the bulb.

Dr.Bob - 16-3-2016 at 16:23

For most distillations, you typically want a 1-3" immersion thermometer, so the vapors are covering the part from the bulb to the line. Depends on the particular distillation head, and the length of it.

Sulaiman - 17-3-2016 at 04:43

AFAIK if there is no line or text to indicate immersion level then it is a total immersion thermometer.

j_sum1 - 17-3-2016 at 04:52

In practice, how much difference will it make?
The column is a small fraction of the total volume. I can't imagine that it would throw out the reading at a significant level for most applications.

DJF90 - 17-3-2016 at 05:17

There are stem corrections you can apply to a total immersion thermometer that is being used for partial immersion.

See here (at the bottom of the page)
http://www.coleparmer.co.uk/TechLibraryArticle/670

EDIT: Also see attached paper

[Edited on 17-3-2016 by DJF90]

Attachment: A nomograph for emergent stem correction of thermometers.pdf (87kB)
This file has been downloaded 335 times


arkoma - 17-3-2016 at 06:00

Thanx DJF, between the link and the nomograph I can begin to make some sense of this. Vogel's Third was a bit obtuse for me.

DistractionGrating - 17-3-2016 at 07:11

There is this link too: http://www.icllabs.com/thergenlinfo.html

chemrox - 17-3-2016 at 11:13

Thanks DJF90- I printed and posted in my lab.

chemrox - 17-3-2016 at 17:42

I like properly marked Hg thermometers. US or German made..