Electra - 3-6-2014 at 18:39
I have a few thermometers and thermocouples, some of them are different sizes. My 24/40 thermometer adapter only fits a few of them. Problem is, I am
not sure what the piece is called that allows me to swap the seal so that different sized thermometers can be used..... any ideas? 1/4 inch, 3/8 inch,
etc... oddly I figured most of these glass adapter pieces would be in metric; the thermometers/thermocouples aren't.
I need to put these under a vacuum so the seal is somewhat important and I don't have a thermowell...might look into getting one.
subsecret - 3-6-2014 at 20:16
They probably don't have an "official" name, but Wilmad Labglass describes them as "fitments." Here's a link for that page:
http://www.wilmad-labglass.com/ProductList.aspx?t=579
You can use a sealed-off glass tube with a thermocouple inside as a basic thermowell, though investing in a real one would be a good idea.
FireLion3 - 3-6-2014 at 21:46
Yes, but even with this site you linked, they don't appear to have different sized "fitments". I have thermometers and thermocouples ranging from 1/4
inch, 1/8 inch, and 1/16 inch.
A sealed off glass tube could work, but I would be concerned about it holding under a vacuum. My thermocouples are stainless steel, and thermometers
glass, so I don't really need a thermowell for most non-refluxing reactions. For when I am refluxing, a glass tube may work.... but under a vacuum, an
improper seal might concern me.
If I can find the right sized rubber seals for my thermometer adapters then they should be able to go under vacuum no problem. If I can't find any
good ones I may call my local glass company and see what they think.
Oscilllator - 4-6-2014 at 00:52
I use teflon tape, which held up perfectly well for a vacuum distillation of nitric acid.
Dr.Bob - 4-6-2014 at 05:18
Most adapters are fixed for one diameter, a few could change the O-ring to have a slightly smaller size, but the way that most are made, the O-ring
diameter is the size that defines the size of therm that will work. For smaller thermocouples, the simplest way most people solve the problem is to
put a small hole in a rubber septa and then stick the thermocouple through, like a needle. I used that method many times. Most standard lab therms
are 5-6 mm (~1/4"), so that size adapter is easy to find, smaller diameter adapters are pretty rare, but could be ordered from Ace or similar places.