Quince
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Can I use 1 L mantle for smaller flasks?
I got an Electrothermal 1 L round-bottom flask heating mantle off eBay, and I want to know if I can use it for a 500 mL flask (I don't have a 1 L
flask anyway). I didn't realize it while buying, but the mantle inside is shaped by a hard metal mesh so it cannot be adjusted to different size
flasks. I'm worried about all the pressure being at the bottom point of the small flask, as well as the lack of equidistance from heat to all points
on the flask's heat-exposed surface. Or can I just pad around it with mineral wool?
BTW, the seller is an idiot. On the customs declaration form, he put value for duty the retail price of the item, instead of what I paid him. So I
paid ludicrous customs charges. I'm still thinking if I should defame his eBay account name around here.
[Edited on 20-10-2006 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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SecretSquirrel
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I've read somewhere that if you have smaller flask than your mantle you can fill the gap between them with quartz sand.
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not_important
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The sand trick works, but it effectively makes a small sand bath out of the mantle, with all of the drawback of a sand bath - lower heat transfer
rates and slower tracking of changes in power input.
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Quince
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Hmm...the problem is the sand will be stuck all over the glass weave afterward. And where do I get quartz sand locally? Ordering sand on the
internet seems dumb. (I'm in Canada)
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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SecretSquirrel
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| Quote: | Originally posted by not_important
The sand trick works, but it effectively makes a small sand bath out of the mantle, with all of the drawback of a sand bath - lower heat transfer
rates and slower tracking of changes in power input. |
I'm aware of that, but it's the cheapest solution if one wants to use the mantle that is too big for his flask. I personaly would rather go for oil
bath, but that's just me.
| Quote: | | And where do I get quartz sand locally? |
Pet stores (for aquariums/terrariums), gardening stores...
I even saw quartz sand being sold at some stores that are selling products for painters, sculpturers and other artists. I don't know the situation in
Canada as I come from EU.
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not_important
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Quartz sand? Just get white sand, as can be found in garden sections of stores, or from pottery supply places. But even ordinary sand should be OK,
the colour is from other minerals along with the quartz and is mostly iron and managanese oxides. Does not affect this use. just wash the sand - stir
in bucket with running water to remove any lightweight trash, let it dry, and 'fry' it once outdoors to remove any remaining organics.
Small iron or steel shot is another alternative. It transfers heat faster, is large enough that it shouldn't stick to the glass weave. Used for
preparing metal surfaces, similar to sand blasting. Small ball bearing or 'BBs' almost work, but they are a little too large and don't have enough
contact area in my experience.
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BeerChloride
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Good idea, not_important, I was going to suggest some kind of metal. Quince, don't stuff the gap with mineral wool or fiberglass. That would act as an
insulator. I would probably try a molded form out of Al foil. It could be removed and put back easily.
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Magpie
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When in school we had those big Electrothermal mantles. IIRC they were conical and in that way would adjust to the size of the smaller RBFs. We used
them for much smaller RBFs than 1L all the time. It wasn't ideal but it worked OK.
Then the school switched to bird's nest type mantles and they had the proper size for the RBF, which was better.
I bought 100mL and 500mL bird's nest mantles for my home lab. I use these for 25, 50, 100, 250, and 500 mL RBFs. I like this setup and have had no
problems.
I use no sand or such. I think much of the heating is by radiant transfer anyway. Try it out without sand.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Quince
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The mantle I have has a hemispherical shape, I guess the same as what you call bird's nest. So when I put a 1000 mL flask, it has perfect contact all
around, but if I put a smaller one in, it only touches the bottom and one point on the side it's leaning on.
The metal shot idea is interesting, I may try that. For the fiberglass, I was just thinking of having some at the bottom spot for cushioning, and
draped over the top in a ring for insulation.
[Edited on 20-10-2006 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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demax
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I have used a 500ml flask in a 2000ml electrothermal mantle before without problems. Sand it seems would be a horrible idea with regards to cleaning
at least to me anyway.
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Sauron
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Mantles are cheap, often available used, so I really don't see much need to muck around with ethiopean engineering as proposed here.
Just use correct flask size for mantle and scale reaction up or down as required.
I have 250ml, 1L, 3L, and 5 L mantles I would like to add 12L and 22L but have not done so yet. Also have a pair og huge 72 L mantles that I bought
new and have never used.
I used to buy used mantles off LabX and eBay and honestly never had any trouble, except once a 12 L soft mantle was ruined in shipment. Not the fault
of the seller, but of my re-shipper, who dumped something heavy into it rather stupidly trying to save on freight.
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