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EssOilChem
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Aluminum BBs Vs. Lab Armor
Been lurking on this board for quite some time and have learned alot, thanks for that.
I was wondering if anyone had used aluminum BBs (like the kind you use on BB guns/airsoft guns) for a bath on a hotplate stirrer combo. Would it be
similar to the Lab Armor beads?
Anyone have any positives/negatives they would like to share on using such medium for a high(er) temperature bath? Is there any time when I would not
want to use this due to risk factors?
Is there any cheaper metal beads/BBs that you would recommend? The Lab Armor ones seem to be very overpriced, but then again, I could just be missing
something.
Thanks for your help.
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Bot0nist
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I use copper coated shot (bbs) for heat baths a lot lately. No mess, no scratching, and great thermal conductivity.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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EssOilChem
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Quote: Originally posted by Bot0nist  | | I use copper coated shot (bbs) for heat baths a lot lately. No mess, no scratching, and great thermal conductivity. |
Awesome, thanks for the reply, I may just do that considering those are much cheaper!
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chemrox
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I'm ashamed I hadn't thought of this. What is the practical temperature range? Do you set the flask in the vessel and then stream the BB's in? If
you heat them on a hot plate is there a gradient? I might worry about hot spots depending on the vessel. As with mantles, they might form areas of
focused heat. Have you checked for this? Overall its a really good idea.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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DougTheMapper
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How do you raise/lower the bath to change the flask? Can it push its way into the shot bed without a lot of force?
I'm sick of oil and sand!
Victor Grignard is a methylated spirit.
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MrHomeScientist
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I'm also interested in using BBs for heat baths, seems like a great mess-free idea. It sounds best suited to high temperature baths, but what about
<100C? Water is simple enough to use of course, but it would be convenient to just have one bath for every situation. I'm interested in how this is
done practically, and eager to hear answers to the questions of the other posters as well.
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Bot0nist
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I use water baths for under 100°C needs. I haven't had trouble with the BBs yet, but I haven't ran any tests though. Heats up fast and holds
temp well. Haven't noticed any real issues with localized heating yet. I can't take credit. I saw it in the "p-toluenesulfonic acid" thread, IIRC.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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RonPaul2012
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Are BBs a real practical option to heat RBFs instead of an oil bath ?
I get the principle of it but could someone go into more detail ?
I am looking to equip myself with an oil bath but if BBs are better then finding them is the least of my concern.
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Bot0nist
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Check smuv's "Toluene --> Sodium Tosylate --> p-cresol" thread for pictures of the BBs in use. I just put a few inches in the bottom, put in the
RBF, and fill around the sides. They can also be wiggled in if your careful. They get hot way faster than sand and don't scratch the glass. BBs will
not work for every situation, but I find myself using them more and more. But for most of my work, a boiling brine bath will suffice.
See these threads on heating baths.
http://www.sciencemadness.org/talk/viewthread.php?tid=19089#...
http://www.sciencemadness.org/talk/viewthread.php?tid=17426#...
Here is smuv's thread with a pic.
http://www.sciencemadness.org/talk/viewthread.php?tid=15522
"I don't know if they are copper (probably plated), but they are BB's for airguns. They work much better (and less mess) than sand." ~smuv
[Edited on 6-4-2012 by Bot0nist]
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Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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Funkerman23
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For what it's worth: usually BBs are copper plated steel shot. True copper shot is pricey and while y'all might have a source: I can't point you in
any direction on that.
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RonPaul2012
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Holy hell that lab is filthy 
wouldn't steel shot interface badly with a stir bar ?
I may just go with both an oil and BB bath (not at the same time though).
Damn that Toluene --> Sodium Tosylate --> p-cresol thread gets me so excited , that's one of the things I love about chemistry , it's like this
never ending adventure and I just want more more more 
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Bot0nist
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Yes, no mag stirring with a steel shot bath. I stated that they were copper coated, BTW. Oil and water baths are still necessary in many situations.
Air baths work great too. Use a foil skirt. See the other threads I linked. Many more to be found on TFSE.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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RonPaul2012
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Good to know.
BTW I like your sig 
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peach
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| Quote: Originally posted by Bot0nist | | Oil and water baths are still necessary in many situations. Air baths work great too. Use a foil skirt. See the other threads I linked. Many more to
be found on TFSE. |
I can't imagine they provide the same level of uniformity in the temperature distribution across the glass versus an oil bath, given that they're
making limited point contact (best way to reduce contact area, make it spherical; e.g. balls in ball bearings). But they'll certainly be cleaner than
oil.
The photo isn't that messy, it's just the paint on the wood that's making it look mucky. Same thing set up on one of those snazzy HDPE surfaces
wouldn't look too bad. Provided it gives the same results and is sturdy, no problems. Maybe give the hotplate a wipe.
[Edited on 6-4-2012 by peach]
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DJF90
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I'd be weary of hot spots using regular BB's - I can imagine the point of contact between them and the glass surface would cause considerable
stresses. I guess you could circumvent this by using smaller spheres of maybe 2-3mm diameter. Pure copper or aluminium shot would be better for heat
conduction, as would silver if you're minted enough!
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EssOilChem
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| Quote: Originally posted by DJF90 | | I'd be weary of hot spots using regular BB's - I can imagine the point of contact between them and the glass surface would cause considerable
stresses. I guess you could circumvent this by using smaller spheres of maybe 2-3mm diameter. Pure copper or aluminium shot would be better for heat
conduction, as would silver if you're minted enough! |
I've never felt or seen the lab armor aluminum baths in person, would that add the same type of stress on the glass in higher temp situations? Any
ideas on what type of consumer (easy to get and cheap) products that are aluminum (for a stirring plate heat bath) would be a viable alternative to
BBs or lab armor?
Edit: Perhaps even regular sized aluminum pellets or BBs, then covering the submerged portion of the flask with thin aluminum foil to evenly
distribute the heat conducted by the spheres? I believe that would solve the heat distribution problem.
[Edited on 6-4-2012 by EssOilChem]
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Moiety
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http://www.ebay.com/itm/1lb-Bag-of-Aluminum-Pretreated-Alumi...
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EssOilChem
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What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it
can be had for like $30 - $40, tiny grain, like 25 lbs.
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Lambda-Eyde
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| Quote: Originally posted by EssOilChem |
What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it
can be had for like $30 - $40, tiny grain, like 25 lbs. |
That would be quite abrasive, wouldn't it? Not good for glassware at all. Also, I think aluminium silicate is the most used sandblasting agent, though
I could be wrong. Neither of them are flammable.
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peach
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I'm sure you could get soft aluminium oxide, but it's also a refractory (insulator). Saying that, sand isn't a great conductor but is common around
mantles. Plus, it's free at your local beach - twigs, biros, tampon applicators and seaweed included. There's even some free medical waste in there if
your beach is close to mine, could be some good stuff mixed in!
Diamond is about five times better than copper in terms of heat conduction, for the ultimately wealthy mantle owner.
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EssOilChem
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| Quote: Originally posted by peach | I'm sure you could get soft aluminium oxide, but it's also a refractory (insulator). Saying that, sand isn't a great conductor but is common around
mantles. Plus, it's free at your local beach - twigs, biros, tampon applicators and seaweed included. There's even some free medical waste in there if
your beach is close to mine, could be some good stuff mixed in!
Diamond is about five times better than copper in terms of heat conduction, for the ultimately wealthy mantle owner. |
haha @ free medical waste.
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RonPaul2012
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| Quote: Originally posted by EssOilChem |
What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it
can be had for like $30 - $40, tiny grain, like 25 lbs. |
I actually use aluminum oxide to sandblast all kinds
of metal , it's is one of the more aggresive medias to use so using it for a bath would be even worse than sand
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peach
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I spent today jet washing someone's garden at 3,000 psi with a 13hp washer. Fun stuff!
The alumina used for blasting is produced by melting oxides, letting it cool, crushing it and then sieving. That method (the bulk fracturing of lumps)
means that the resulting grit has sharp edges to cut away at paint, barnacles, scale, gunk, etc.
There's an interesting video from one of the manufacturers showing the process, here.
Aluminium oxide dust, from grinding through refractory, is kind of soft feeling by comparison.
I remember going to a place that sold refractory when I was about 16, to get some bricks. The place looked like a Columbian coffee factory with guys
in air fed bunny suits walking around, surrounded by clouds of white dust.
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starman
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The tech specs for lab armor only give uasable range to 180C max ,kind of disappoimting. Material is stated as "metal beads",which could be
anythiing,presumably alloy.
Small brass bearings are available and may be suitable for use with magnetic stirring.
Chemistry- The journey from the end of physics to the beginning of life.(starman)
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RonPaul2012
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| Quote: Originally posted by peach | I spent today jet washing someone's garden at 3,000 psi with a 13hp washer. Fun stuff!
The alumina used for blasting is produced by melting oxides, letting it cool, crushing it and then sieving. That method (the bulk fracturing of lumps)
means that the resulting grit has sharp edges to cut away at paint, barnacles, scale, gunk, etc.
There's an interesting video from one of the manufacturers showing the process, here.
Aluminium oxide dust, from grinding through refractory, is kind of soft feeling by comparison.
I remember going to a place that sold refractory when I was about 16, to get some bricks. The place looked like a Columbian coffee factory with guys
in air fed bunny suits walking around, surrounded by clouds of white dust. |
Here is a fun tip (although I
have never tried it) that I have heard people use for large projects.
I'm not sure of the procedure but basically you put sand in your pressure washer and it is supposed to tear paint apart.
I remember a guy who restores school buses tell me this
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