RogueRose
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Heat gun powered heating plate/mantle
I have 3 1500w heat guns (2 speed) that have bitten the dust after fairly short use (motor went berserk - crazy fast w/ blue sparks at brushes) and am
pretty handy at wiring up new/unique systems. These devices have a thermal fuse so they trip if the temp goes above a certain point.
I think it is possible to run the fans slower and remove the thermal fuse but I must remove the plastic housing which is the most vulnerable in the
device. Running the fan slower should allow for higher temps to be reached.
For many applications 4500 watts is much too much heat but for some, that amount could be very useful for speedy heating.
I also plan on making a voltage controller to allow for adjusting the temp of the coils. The stock units get full power but reducing by 10-15% can
greatly reduce wear on the unit and any danger of damage especially if slowing the fan. The fan will also be controlled like a dimmer switch, so
fully adjustable.
I'm wondering how this type of heating system would best be used to heat beakers or flasks. Has anyone used a hot air system? Is there any reason
that hot air is not good for this (I can think if vapors are an issue - toxic of flammable - so that will be taken into consideration).
Would sinking the coils in sand and making a sand bath be better possibly? Are there any combination setups where air is forced through sand (or
other more porous material)?
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Maroboduus
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On page 7 of the homemade and re-purposed lab gear thread, Nux Vomica shows his hot air mantle.
I've been trying to find my old hot air gun to make something similar, but with an outer shroud to surround the flask and a stillhead so I can use it
for distilling sulphuric acid with a minimal risk of cracking a flask.
I like the idea of heating the entire surface of the flask for high temp applications instead of just wrapping the top in aluminum foil.
I hadn't considered modifying the gun itself, but that sounds like a fine idea. I had a few heat guns burn out on me in the past as well, and I'd be
happy with less than full power for my uses.
I think I've seen a few other references to hot air baths on here, but can't find them.
Other than the kugelrohr apparatus. That thing uses a hot air bath for very sensitive vacuum distillations.
They're supposed to have very even heating.
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ElizabethGreene
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I saw something relevant the other day.
video: https://www.youtube.com/watch?v=QKFC0ke_DOU
It's not forced hot air, but you can cannabalize one of them for the heating element.
Two improvements to this:
1. Use a 50/50 sand/plaster mix for a more durable mantle.
2. Insulate the electrical connections so you don't accidentally die from electrocution or premature detonation when you arc across the terminals and
ignite a fume-hood full of solvent.
Have you tried a patent search for "hot-air heating mantle"?
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