15.4 The Evapanator DIY Rotary Thin Film Evaporator

Rotary evaporators are a keen thing to have if you're running much alcohol, but alas the good ones are handsomely priced and finished material is not easily removed from the boiling flasks without leaving a film behind or again resorting to a solvent.

Here is the design for a "double barrel" DIY rotary evaporator, made from 6" X 6" stainless sanitary, which are easily opened and cleaned.

I modified the lids to accommodate shafts, one hollow, to which I attached a Deublin 17-051-045 rotary vacuum union.   That allows rotating the two drums on a horizontal axis in a hot water bath, which in this case I provide using a Wyott W-3Vi 1200W countertop food warmer.

I supported the shafts on both sides in a vee rest, comprising two 1 1/2" roller bearings.  The drive end of the assembly has a #35, 2" X 15 tooth sprocket on the shaft, which rests on a moving #35 roller chain, driven by a variable speed (about `2 rpm) gear motor.

At that speed, each drum provides about 1.6 square feet of thin film per minute, and the rotary vacuum union allows us to hold a -28" Hg vacuum on it while doing so.

Because the drive sprocket just sits on the drive chain and the shaft bearings are vee rest, when finished you can lift the whole assembly up out of the bath without disconnecting anything but the vacuum hose.

Here is the design.  I never built it because I was busy with other things and after taking one look at the plans Siskayou Sam got so excited that he designed and built a rotary evaporator design of his own, which is posted here as 6.7.4  Siskayou Sam's Rotary Evaporator.

 

 


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