AFAIK the way to stop the pooling is to make sure that gravity is
working for you. Introduced back into the column, the condensed
liquid will fall back down the column before turning back into vapour
and rising back up again.
Pressure release - yes, that's the reason for the open ended design
on a 100% reflux system.
How do you kow you're not losing loads of good stuff to the air? You
over-engineer your condensor to make sure that all the liquid is
taken out of the expanded gas well before releasing it into the open.
> Additionally, since this unit is an external loop, isn't there
going to be a
> problem with column vapor rising up through its outlet as well as
That's exactly the problem that I had with my modified still. The
Nixon / Stone design has the inlet and back-flow pipes sharing the
same tube - vapour rises to the top of the tube, liquid flows back on
the bottom. This seems like the best design, other than playing with
a non-return valve on the flow-back pipe, which is my next project.
Watch this space!
> Finally, wouldn't increasing the flow rate through the coil in the
> my still accomplish the same thing as either of the above?
Yes, if your head returns the distillate back down the column. You'd
not get as fine a level of control doing this, but it'd more or less