sternman318
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Distillation sizes with 14/20
I was looking to get a distillation set-up in 14/20, but have read that it is on the small side is generally used to distill much smaller quantities
than a 24/40 setup, for example. What is the limiting factor here? Is it the actually diameter of the glass, or flask/reaction vessel size?
I am trying to decide between getting a 14/20 or a 24/40 setup. 14/20 seems desirable because of its small size ( seems like it would be easier to
setup/manipulate), but I am scared of it being too small and not being very useful. Also, 14/20 does not seem to be nearly as common as
24/40, which might make it costly/hard to expand the setup. My immediate use for it would be mostly concentrating/distilling acids- would 14/20 be
unable to process useable/significant quantities? Of course, I could probably just run multiple distillations.
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redox
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I have a 14/20 set and a 14/10 set (for 2-3 mL distillation). I have found 14/20 to be very useful and easy to find. You are right, it does
seem to be hard to find, but if you look, you will find it easily. 
14/20 is somewhat limited to large quantities of fluid, which can be frustrating sometimes, but any amount up to ~450 mL is fine. You can't go higher
because the column and condenser will flood really easily at those volumes, and 14/20 has a much smaller diameter that 24/40 (half diameter,
coincidentally). I very rarely need to distill more than 200 mL, though. I don't know what kind of chemistry you want to perform, but the semi-micro
synthetic organic that I practice seldom uses more that 200 mL.
Another problem is powder transfer. If you wanted to put 100g of a flour-like powder into a 14/20 flask, you would find it difficult. Powder funnels
don't work because they don't fit in the neck, so it just gets messy. 
In all, I completely recommend the 14/20 set. The fluid limitations aren't really a problem, and the pieces are much smaller and easier to manipulate
and handle than 24/40.
EDIT:
Have you considered 19/22? I see this size very often, and it seems like a good compromise between these sizes.
[Edited on 10-8-2011 by redox]
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sternman318
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Thanks redox!
450mL is more than plenty, so it sounds like it would work well for me. I would consider 19/22, but I am trying to get some glass from Dr.Bob because
he has some pretty good prices and but hes got only 14/20 and 24/40. And thanks for the tip on the powder! He actually has some glass powder funnels
that fit the 14/20, so I will get sure to grab one of those too 
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ScienceHideout
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I only use 19/22. 24/40 is standard, but too big and expensive for my macrochem purposes. I do have a 14/20 pear shaped flask, but I always have to
use an adapter for it to fit. I agree with redox; 19/22 is small enough for micro chemistry, but large enough for decent experiments if you wish to
do other larger experiments. I personally think a 500 mL flask looks funny with a 14/20 joint, as with a 25 mL flask with a 24/40 joint, but they all
work with my 19/22!
(In fact, it was a professor friend I have that got me into 19/22. He was generous enogh to give me a rbf and it was 19/22, so I just kept buying that
size to go with it, but soon I discovered it is the best size. the keck clips for it aren't too expensive, and you can use all sorts of ring stand
clamps!)
Check out expediglass, they have good ground glassware, top notch, for low price!
hey, if you are reading this, I can't U2U, but you are always welcome to send me an email!
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