Bleed tubes essentially are glass capillaries with a closed-ish tip right? I'm making the assumption that they made out of borosilicate glass and
flint glass wouldn't sustain? I really only need one for general vacuum distillation needs. Can't find them on-line unless they're in a kit or from
the big name suppliers(aldrich, etc).
Now is there a good reason why 24/40 PTFE bleed-tube/thermometer adapters are $50+? Are there any cheaper alternatives or sources? I'm hoping I've
been looking in the wrong places.
Either way I can't afford either of these items currently but it'd be nice to concoct a game-plan for when I can. Thanks for any advice.DJF90 - 11-3-2011 at 10:44
Use a disposable glass pipette with the tip drawn out a little. You'll notice it fits nicely through a thermometer adaptor. Attach a short length of
rubber tubing and a hofmann clamp to adjust rate of ebulliation.smaerd - 11-3-2011 at 10:46
Excellent suggestion thank you.Magpie - 11-3-2011 at 11:55
If the disposable pipet is not long enough then use a piece of glass tubing that fits your adapter, like 6 or 7mm tubing. Using a bunsen burner draw
out a fine tip then cut off the excess at the tip. Then, cutoff the other end as necessary to give you the exact length you want.
I also use a small piece of rubber tubing with a Hofmann clamp.smaerd - 11-3-2011 at 12:20
Now to find a cheap PTFE adapter.entropy51 - 11-3-2011 at 12:59
If you have a magnetic stirrer, you don't need a bleed tube to prevent bumping during vacuum distillations.
If you don't have a magnetic stirrer, by all means get one. smaerd - 11-3-2011 at 13:07
So you can use stirring only? I thought I read somewhere that you needed stirring and a bleed tube. It must have said 'or'. This changes everything.
Thanks entropy51, I have a nice kick back mag stirrer ready for just the occasion .entropy51 - 11-3-2011 at 13:12
Stirring alone works almost every time. The stirring should be fairly rapid. If the distillation foams so badly that stirring won't work, then a
bleed tube probably won't help either. I posted an article from J Chem Ed about this in another thread not too long ago. Here is the link to it:
.