Does anyone know if electrothermal heating mantles in general can be run without a flask in them, or do they require a "load" to work properly?
I have a 1000ml mantle but I want to use a 100ml flask with it... Would that be OK, or would the mantle suffer damage since it was meant for a larger
flask?
Thanks a lot!entropy51 - 4-11-2009 at 13:37
I have a 1000 mL Glascol mantle that I use as a sandbath for smaller flasks, as small as 250 mL and it has withstood that abuse for several years.
But it really is abuse, and I would not recommend running it for very long at more than 50% input voltage.
Some mantles are said to work fine for smaller flasks, even without sand, but I wouldn't push that envelope too far. It's not hard to make an oil
bath for smaller flasks. I heat my baths with a coil of immersed heating wire connected to a variac.cds333 - 4-11-2009 at 15:52
The glascol is a fabric blanket type right?
The one I have looks like this:
Does that make any difference? It has a built in temp control, so it is obviously designed to work at less than 100% power, but IDK what would happen
if only ~20% of it's surface was in contact with the glass (as would be the case with a 100ml flask)...
And I probably wouldn't want to use this kind as a sand bath right? I imagine the sand would get stuck all up in the base and mess it up...
Thanks
[Edited on 2009-11-4 by cds333]entropy51 - 4-11-2009 at 16:06
Yes that's the Glascol. I don't have experience with the electrothermal mantle, but that's what I had in mind when I said they're claimed to be
useable without sand. No, I don't think I would use sand in that one. Someone here who knows this beast will have to give his experience. You might
look for the manufacturer's literature, which is probably online.
But my gut feeling is that heating a 100 mL flask in a 1000 mL mantle is just overkill. If you apply much heat, you will superheat the glass of the
small flask and carbonize liquids that boil up onto that hot glass, and perhaps break the flask.
I would really use an oil (or water, if possible) bath for a flask that small.
[Edited on 5-11-2009 by entropy51]1281371269 - 8-11-2009 at 10:49
I had an idea on this, though it would require some bravery - for a sand bath, find a dirty old 1L RBF on eBay going cheap and cut it in half. That
way it would be a perfect fit and there would be no more risk to the mantle than if you were using a flask of the correct size.entropy51 - 8-11-2009 at 11:43
Quote:
That way it would be a perfect fit and there would be no more risk to the mantle than if you were using a flask of the correct size.
Not a bad idea, except for the low thermal conductivity of sand, but it would be OK if you didn't crank the
heat too high. Finding a steel mixing bowl of the proper size is waaaay easier than cutting a pyrex flask, though, since I don't think you could use
mag stirring with this mantle anyhow.
