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gsd bahamuth - 19-11-2010 at 08:28
Very good indeed, but the vertical ones are not the easiest/handiest to use IMO.
But if you get it for less than 200 EUR ~ $270 US you be lucky, have been looking on ebay.de for a year now, and those tend to go for as much as
400-500 EUR.
Büchi and Heidolph are the only usable rotavapors at least for hobby chemists as parts are widely available, and they the ones with most experience
producing them. Would myself go for a Büchi as the "most" older/newer models have interchangeable glass parts...Lambda-Eyde - 19-11-2010 at 13:39
Very good indeed, but the vertical ones are not the easiest/handiest to use IMO.
Why is that? What's the practical difference? I thought the only real difference was that the vertical ones occupied less space.bahamuth - 19-11-2010 at 15:40
If one tilt the vertical to much, say with a small small flask to reach the water bath the condensed solvents will drip from the condensers (almost)
back into the vapour tube and onto the rotary seal.
The vertical ones does not have the possibility for a long vapour tube either. These limits the use I feel, might only be my preferences but I've
heard a couple other agreeing on that..
Depending on where you have the vacuum outlet, (most models have two, depending on long or short vapour tube situated in the start or the top of the
condenser, but the vertical ones I've seen has only one in top of course) one might improve solvent recovery and evaporation rates. Had really good
"yields" with a long vapour tube and horizontal setup, with vacuum drawn from the start of the condenser with the vapour tube extending beyond the
vacuum outlet.
All this might be in my head but do not like the feeling when I bath my rotating seal in solvents, especially when when salts/compounds which have
travelled with the vapours crystallize on the seal...
Does any of these make sense to others?
But on the contrary, the vertical ones take a little bit less bench space..Panache - 25-11-2010 at 13:24
there's more to it than that, the vertical ones are by far superior, in terms of space, flexibility and efficiency of use.
For small flasks the angled ones are tedious as the long vapour duct acts as a condenser, theres no chance of return down the vapour duct from the
vertical dripping condenser, especially if you have it setup such that the drip feed/angled bit on the condenser after the ground glass joint is
positioned correctly.
i often use it to steam distill by inserting teflon tube down through the vapour duct into the flask and running steam through this, it can be down
with the longer vapour duct but is trickier and far less efficient.
Also with the vertical you have a excellent condenser you can use in other setups as it has a ggj, the angled one have the seal on the end and are not
useable'
btw the price is at 700 euro now lol 8, about AUS$120 given current exchange rates (just kidding)
