Sciencemadness Discussion Board

DIY rotavap condenser / seal ?

pedant - 6-9-2012 at 21:26

does anyone have any experience with this topic (especially buchi RE-111/12x/14x series with a fixed (KD-22) seal and rotating vapor duct)?

basically, i have a rotavap with intact vapor duct, but i don't have a condenser or the seal stuff (involves a screwcap, a seal, and a compression coil thingy) that connects the condenser to the rotavap.

getting a condenser and the seal kit would realistically run me at least a few hundred bucks, and i don't feel like spending that at this point.

i'm trying to come up with the best way to hook up tubing or something, and then run that into a friedrichs condenser + flask or something like that which i already have.

i don't have a camera handy at the moment, but here are some pics from the internet that basically show what i'm working with

seal1.jpg - 23kB

mine looks very similar to this. the vapor duct rotates. the metal 'condenser coupling' plate, which includes those threads, is stationary. so if you were looking at it dead-on, you would see this plate, the vapor duct in the middle, and a PTFE 'deflector ring' (which is kind of a bearing) stuck on the vapor duct.

seal2.jpg - 69kB

dead-on view of the condenser coupling plate, but the vapor duct and deflector ring are missing.

seal3.jpg - 119kB

dead-on view of the condenser coupling plate, vapor duct (much shorter duct than mine. mine is like the first pic) and PTFE deflector ring visible in the middle. you also see some kind of a black rubber gasket here, but this is absent on mine. i only have a metal surface (coupling plate). normally, the condenser would be inserted onto the vapor duct, and a gasket kind of like you see above would be placed on which seals the plate to the condenser lip.

again, the glass duct and the PTFE ring rotate.


i was thinking of maybe taking a piece of metal pipe larger in diameter than the vapor duct / ptfe ring but smaller in diameter than the threads. the pipe end could be sanded smooth for a metal-on-metal seal to the plate assisted by some vacuum grease.

the other end of the pipe could be capped, and one or more holes could be drilled for hose barbs. some thick polyethylene tubing could then go from here to a condenser or something.

not very elegant, and of course it would all have to be clamped and secured with stands (and the pipe would have to be fiddled with each time while beginning to pull a vacuum until it seals well)...
seal4.jpg - 50kB

thoughts?
any other ideas?

thanks guys

smaerd - 7-9-2012 at 18:29

I like you're idea a lot. PTFE rod can be bought by the foot and machined with simple tools easily(Amazon carries it). Not sure if this thread will help you at all but it has some different design concepts for DIY rotovaps.

http://www.sciencemadness.org/talk/viewthread.php?tid=7128

Wish I had more to offer.

[Edited on 8-9-2012 by smaerd]