Sulaiman - 24-3-2020 at 08:51
I have a 5L flask that gets stuck to its 5L heating mantle when heated and then on cooling.
(If I let the mantle and flask cool then turn the heat on high, the flask usually becomes free)
Given that I cannot reliably separate the flask and mantle when hot
(e.g. during a distillation or reflux)
can anyone suggest an 'emergency' cooling scheme ?
Sigmatropic - 24-3-2020 at 09:02
Applying a vacuum will evaporatively cool the flask and its contents. Cooling through reflux then gets your flask cooler than the mantle and so should
become unstuck.
Although if your reflux is becoming too vigorous that would be the last thing you want to do.
Similarly it will mess with the fractionation during distillation.
I don't think there is a solution to this one other than a mantle without this problem. Maybe you can include some spacers or deform the mantle
slightly?
Also if it becomes snug to the point of not coming apart what's stopping it from stressing and breaking your flask? I would tread carefully with such
a set up.
Sulaiman - 24-3-2020 at 09:23
The flask and mantle were used commercially for testing oils (that's all I know)
there was a lot of carbonised oil when I got them,
I was able to clean the inside of the flask easily,
but there are deposits that I've been unable to remove from the mantle itself, and some around the 'equator' of the rbf, brown 'crystaline tar' (?)
IF things go ballistic I would not care about the product, just safety.
'emergency vacuum' sounds like it could cause catastrophic boiling/bumping
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does an 'emergency siphon' sound viable ?
RedDwarf - 24-3-2020 at 09:42
I use a ptfe spray that has a dry finish on some woodworking tools (planer blades, router cutters) to avoid any buildup when cutting at high speed
(and thus hot). I don't know if that would be an option to spray the mantle with?
RedDwarf - 24-3-2020 at 16:22
Alternatively/additionally you could have an addition funnel charged with chilled water attached to the flask, ready to crash the reaction if
necessary. As you're unlikely to have an addition funnel larger than 1 litre the effect in your 5 litre flask might not be enough, probably worth
looking at.
BromicAcid - 24-3-2020 at 18:14
Connect your distillation setup to lattice work, use a lab jack to hold your mantle to the bottom of your flask. When you need to remove your mantle
just lower/remove your lab jack and pull it out. Use enough clamps to make sure your apparatus can suspend without issue and there will not be a
problem.
RogueRose - 24-3-2020 at 21:40
I second the Teflon spray. Dupont makes a spray like this that leaves a whitish film once it dries and it does a very good job of sticking to what
you spray it on (uses petroleum ether as dispersant IIRC) and stays on nicely.
I never thought about using this on tools, that is a good idea. I'd like to try this on drill & router bits!