Satan - 9-3-2010 at 12:43
What kind of fractionating column is good for vacuum distillation? Is there some risk of implosion(pressure in range of 10-20mm)?
Aqua-regia1 - 9-3-2010 at 15:28
Commonly: Vigreaux column
not_important - 9-3-2010 at 17:40
To expand on that a bit. You are talking about working within a pressure range where traditional packed columns, such as glass beads or steel wool,
have enough resistance to the flow of vapour that the pressure drop through the column is a significant percent of the desired vacuum, and may even
exceed the target pressure. The Vigreux, concentric tube, and spinning band columns offer less resistance and lower pressure drops, as does some
specially designed packing.
Note that vacuum fractionation columns generally require _good_ insulation, the low pressure vapour just doesn't carry a lot of heat per unit volume,
and in many cases may require a heated jacket.
The risk of implosion is similar to that of flasks and so on. check for cracks and chips beforehand, don't use any such damaged glassware for vacuum
work.
mr.crow - 9-3-2010 at 18:45
I would imagine a packed column would be safer. All those little 'pokes' in a vigreaux column look like they would be a weak spot!