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Author: Subject: Alcohol burner usefulness? Also, some glassware heating questions.
The Mad Plater
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[*] posted on 15-11-2016 at 08:52
Alcohol burner usefulness? Also, some glassware heating questions.


I'm currently in the process of compiling a "wishlist" of lab equipment to add to my next online order.

I've been wondering about the alcohol burners.
They are dirt cheap, pretty much a dime a dozen. I also maintain a large stock of denatured alcohol, mostly for car windshield deicing (cheap, rapid AND effective!).

The problem isn't the cost - it's the terminal lack of storage space. I don't want to buy any crap that I won't ever use, and have it waste my extremely valuable space.

Now, here's the deal: many of my "reactions" (metal plating and surface treatment stuff) require heating.
Obviously, I'm not even going to try heating eg. my 5L beaker with a wimpy little alcohol burner, that would be totally nuts.
For that, I'll be using an electric hotplate of some sort.

No, what I have in mind, is preheating the makeup water and bath replenishment solutions, to keep the bath temperature from swinging all over the place from the additions of cold liquids.
We're talking about quantities of a few tens to a few hundreds of mL's, in suitably sized beakers, that need to be heated to ~70-80C (close temperature control not important, just "in the ballpark").
Due to the process requirements, this might involve as many as 3-4 such beakers being preheated at the same time.
Each beaker would get on average maybe 15-30 minutes of "cooking time" before being emptied.

Is this even remotely feasible to do with alcohol burners, without requiring some form of constant micromanagement?
I've never used an alcohol burner of that type before, and my previous experiences with DIY "coke can stoves" of various types were mostly rather disappointing.


A couple other related questions:
- are the wickless burners any good? Is there any way to adjust the flame size?
- what approximate values of burn times per 1 filling can I expect?
- I presume that even the relatively "cool" alcohol flame is still not safe to heat borosilicate glassware directly (no mesh)?
- would it be OK to heat the (big) beakers directly on a ceramic cooktop (infrared, NOT induction)?
- as above, but directly on an ancient "cast iron disc" type electric stove plate?

Finally, an unrelated question: I've recently read somewhere that hot phosphoric acid attacks glassware, but unfortunately no further specifics.
Should I be worried about heating an aqueous solution containing ~1-3% phosphoric acid to ~100C for a total of several hours? (again, in borosolicate glassware.)
I tried that in an old "chinese stainless" pot before, and it etched the "stainless" quite significantly after only a few hours...
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[*] posted on 15-11-2016 at 11:00


I use a small alcohol burner for test tube scale experiments,
but a large hotplate sounds more suitable for your needs,
possibly a microwave oven ?

A shallow pan with sand on a hotplate provides a softer 'landing' for glassware than solid steel ;)




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The Mad Plater
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[*] posted on 15-11-2016 at 11:42


Hmm, let me clarify a few points:

Yes, a hotplate will most certainly be needed for the main bath, no if's, and's, or but(t)'s about that.
Preferably with PID control, we'll see about that.

The spirit burners would be used only for preheating the bath makeup solutions (~1/10th to 1/20th of the actual bath volume).

If the burners worked as intended, that would be very convenient, at least when compared to the other alternatives.

Also, they would be very handy for running small scale (50-200mL) test runs. Again, assuming that they would actually work for that purpose.

It might sound crazy, but even the smallest gas stove burner, on the weakest setting, is much too hot for the small scale tests.
I had to resort to moving the beaker well away from the burner axis, just to prevent the mixture from overheating. And then the whole rig is poorly supported by the pot support rods, and wants to fall to its side at the slightest provocation.

A microwave is out of the question - there's already barely enough space for the ridiculously tiny "food use only" microwave; placing another one reserved for chemical use just ain't gonna happen, there simply isn't anyplace to put it.

Also, I'm "working" at 2 different locations (small scale tests at home, full scale runs in the workshop), several km's away, and thus it is vital to minimize the size and weight of all the crap that has to be shuffled around - there's far too much of it already.

The burners are cheap enough, that I could keep a set of them at each location, plus the tripods and mesh screens, and some jugs of denatured alcohol. No need to waste time (and thus $$$$$) shunting that cheap stuff around.

Gas burners of any kind are not acceptable, for various reasons.

Using a second hotplate (or a 2 "burner" portable electric cooktop) is a possibility, but one I would preferably avoid.
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[*] posted on 15-11-2016 at 12:02


A Spirit Burner is an excellent piece of equipment.

Would not be without one, ever.




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[*] posted on 16-11-2016 at 07:43


As aga said, they are super useful and mobile.
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[*] posted on 16-11-2016 at 08:37


They are useful, but you should really only have one at a time. Having multiple open flames in a lab is just generally a bad idea. Especially since alcohol burners can do this thing where the air heats up inside them, building up pressure, which forces more fuel out through the wick, until the alcohol in the burner starts to boil, increasing the pressure further, etc. Granted, a properly designed lamp shouldn't do this, but a malfunctioning one could.

If you need to heat something to about 60-80C, these things are extremely cheap, and work quite well:

www.ebay.com/itm/371514177628

You can insulate your flask if you want to make it warmer.
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[*] posted on 16-11-2016 at 09:58


Quote: Originally posted by Melgar  
They are useful, but you should really only have one at a time. Having multiple open flames in a lab is just generally a bad idea. Especially since alcohol burners can do this thing where the air heats up inside them, building up pressure, which forces more fuel out through the wick, until the alcohol in the burner starts to boil, increasing the pressure further, etc. Granted, a properly designed lamp shouldn't do this, but a malfunctioning one could.

If you need to heat something to about 60-80C, these things are extremely cheap, and work quite well:

www.ebay.com/itm/371514177628

You can insulate your flask if you want to make it warmer.


In that case, add some water to your alcohol. I use methanol and I add 30% by volume of water. The flame will be cooler which is fine for test tube heating and slow heating of glassware.




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[*] posted on 20-11-2016 at 04:09


Spirit lamps are immensely useful. I own one and use it all the time when I need an open flame.



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[*] posted on 20-11-2016 at 09:58


Mine works perfectly with a cotton wick poking through the ceramic top part.

No alcohol boiling, just a nice hot flame for about an hour.

The time-limit is sometimes reassuring, as the heat will stop when the ethanol is exhausted.

The Burner came from www.oxfordchemserve.com aka blogfast25 and has seen plenty of action over the past 2~3 years.

The Wick came from an old-style mop on the suggestion of arkoma.

Buy a decent sprit burner and you got reliable Heat forever.

Buy one cotton mop, you get enough wicks to last forever !




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[*] posted on 22-11-2016 at 03:11


Nice idea about mops, aga! I have always been using wicks from kerosene lamps. The mops must be immensely cheaper.



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[*] posted on 22-11-2016 at 09:14


Big thumbs up to arky - it was him who suggested it, and it works perfectly.

I bought just one cotton mop-head about two years ago and pulled all the threads out.

The remaining cotton threads will last me approximately 2.4 lifetimes !

(they only burn up quickly if the alcohol runs out)




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