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Author Topic: vacuum dist. thermo adapter  (Read 68 times)

akcom

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vacuum dist. thermo adapter
« on: October 13, 2010, 03:12:15 PM »
So I'm having a bit of trouble doing a vacuum distillation.  I've got a 3CFM pump which should be just fine, but my setup is leaking air and I can hear it coming from my thermometer adapter.  The adapter looks like this:
hxxp://imgur.com/YsuEN.png
The two pieces simply screw together with a plastic o ring around the thermometer.  I already broke down and just got a ground glass thermometer + 10/30 thermometer adapter but I have trouble believing everyone does this.  What kind of thermometer adapter are you guys using for vac. distillation and how do you keep it air tight?  Thanks!

Tungsten.

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Re: vacuum dist. thermo adapter
« Reply #1 on: October 13, 2010, 03:26:17 PM »
You greased your joints right? If so, I can't think of why it might be leaking. Maybe your thermometer adapter's o-ring is sitting wrong, or maybe you tightened it too much.

Hope this help. If not then I would think it would have to be the pump. Good luck.
-W

NeilPatrickHarris

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Re: vacuum dist. thermo adapter
« Reply #2 on: October 13, 2010, 03:51:09 PM »
i use this type it goes into a 3-way adapter.  i grease not only the glass ground joints but where the plastic/glass threading is also as well as the o-ring.  overkill i know but i've felt the leak come from the thermometer adapter before and no longer leaks now that i grease each and every component.  in the past i've also had to use a couple layers of ptfe tape just above the o-ring because it didn't seem to be quite thick enough and there was a tiny bit of airflow

h**p://images2.labplanet.com/180-180-ffffff/opplanet-chemglass-adapter-thermometer-inlet-2-cg-1042-01.png

« Last Edit: October 13, 2010, 04:28:39 PM by NeilPatrickHarris »

akcom

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Re: vacuum dist. thermo adapter
« Reply #3 on: October 13, 2010, 10:47:13 PM »
I rigged mine up the same way with ptfe tape but I just wasn't happy with the results.  Perhaps I should have greased the oring joint as well.  Regardless, the o-ring later broke (it lost its elasticity, probably the solvent?) and I'm chugging away happily now with a ground glass thermomemeter.  I think I'll look into getting the kind you've got NPH.  Looks like it might do me some good.
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