Due to the fact that ground glass thermometers are about as expensive as gold plated s**t, I do not own one. I have some thermometer adapters with
o-rings but doubt they would stand up to the acid. Is it workable to use a ground glass thermometer well in the top of the setup to measure the
temperature of the vapors at the three way adapter before coming over?
Or would the lag in readings be too significant?
Method used would be combining the nitrate salt and H2SO4 so the temperature would not be too critical. vmelkon - 6-6-2013 at 20:22
You can try making a O-ring yourself, using silicone. If it gets damaged, no big deal.
If you are going to use a thermometer well, you can fill it with a liquid.Arsole - 7-6-2013 at 12:57
The silicone idea is a good one. yeah baby oil was the plan for the thermometer well. Has any one done this before?Rosco Bodine - 10-6-2013 at 17:28
Silicone won't hold up. Teflon tape can be wound tightly many layers thick in a very gradual "spiral wrap" around the thermometer, and then slowly
carefully jammed firmly with a twist, into the female opening of 10/30 ground glass bushing adapter, the smallest opening of which is 7mm, so a snug
press fit can be made. The same method can be used for inlet tubes. The method can also be applied to a solid teflon stopper which has been drilled
with a slightly oversize hole, even better if a slight taper reamer or countersink is used to slightly throat the opening. Mercedesbenzene - 10-6-2013 at 20:52
Buy some fluoropolymer O-rings! They are super cheap from here.
Click the tab for Viton Fluoroelastomer rings O-rings, they are around 50 cents to a dollar per ring depending on the size.
Chemical resistance chart is here:
It appears to have excellent resistance to concentrated nitric acid.
Not sure if it would hold up to pure nitric acid vapors but the O-ring is less than a dollar! Just in case it fails have the thermometer on a clamp to
hold it.
[Edited on 11-6-2013 by Mercedesbenzene]Arsole - 12-6-2013 at 16:12
I have a ground bushing already and will try the PTFE tape idea to secure the thermometer.
Thanks for the idea about the fluoropolymer o rings I will pick up a pack of these to use as they are not very expensive. Any idea on how to choose
the right size?
I am going to save for a ground glass thermometer but I have a bunch of other things I would like to get that have more uses. Any Idea of where to get
an accurate one at a good price? bfesser - 12-6-2013 at 18:38
Is it workable to use a ground glass thermometer well in the top of the setup to measure the temperature of the vapors at the three way adapter before
coming over? Or would the lag in readings be too significant?
Yes, this would preferred over any gland or o-ring solution. The lag would be acceptable. Don't over-complicate your apparatus, especially with
nitric acid!Mercedesbenzene - 13-6-2013 at 06:40
The average thermometer is around 5-8mm in diameter I think. Best way is to measure your thermometer's diameter and buy an O-ring that is slightly
smaller for a good fit, as they do stretch. Funkerman23 - 14-6-2013 at 20:24
Pardon this but Dr Bob currently has 10/30 jointed thermometers for sale. those would be ideal to try first, Second, while it is Chinese origin, Laboy
does sell 10/18 jointed thermometers as well as the still head/ distillation adapters that use them. accuracy can be off until you learn that
thermometers quirks but I though this might help.if Dr Bob still has the Hg thermometers I'd try him first though. Better accuracy and all. If not
necessary, pardon my intrusion.
