Sciencemadness Discussion Board

Removal of vapor duct Büchi R-114

Panzerkemie - 15-11-2020 at 10:16

Hello, new to this forum and i've got an old R-114 rotovap, which i'm in the processe of dismantling and renewing a bit. I've already got a new KD-22 seals from Sigma but i'm stuck at removing the vapor duct, anybody has experience on how to get it out and remove the metal ring retainer that's on the distilling flask side ? i think that's what is keeping it stuck with some rust in that point, and i would like to change the bearing or clean it and grease it when i get it out, because it's not perfectly silent anymore when turning and has some rust formation there at the bearing site, combi-clip side. The pin under seems to not unlock anything when i push it in, so i stopped before breaking the vapor duct :(

Any help would be appreciated, thanks to all and looking forward to chat with the amazing users of this forum :)

[Edited on 15-11-2020 by Panzerkemie]

elapid - 15-11-2020 at 12:38

Assuming by vapour duct you are referring to the central glass joint, be prepared to replace it. I have had two rotovapors that despite heat, WD40, other solvents etc the joint was fused in the steel fitting. In both cases I ended up breaking the joint to get it out. You can get a glass blower to make up a new joint though if they are discontinued or expensive, not sure about Buchi, but bibby used a very strange joint size that meant that whilst it fitted it was 1mm too long to get the retaining clip in so have to rely on vacuum to keep it in place.

Heptylene - 16-11-2020 at 06:55

If you can sacrifice the metal part, I would dissolve it in HCl to avoid breaking the glass.

Dr.Bob - 16-11-2020 at 12:38

The metal part holding the duct is integral to the rotovap.

The safest way to remove the steam duct is to remove the condenser, make sure the rotovap is well anchored, and then put a block of wood (2 x 4 works well) against the condenser end of the steam duct, then tap that with a mallet, hammer, or something heavy, using increasingly heavy blows, until it comes out. The joint is far easier to replace without breaking it than with, although sometimes that happens. The retaining clip on the flask end of the steam duct is a spring clip that will let the duct out when it comes out fast enough, I don't think it can come out intact, so don't try to remove it, just pop the steam duct out, and it will release it.

For people in the US, I have some spare parts, including ducts and a few KD-22 seals left. But they are going fast. If the rotovap does not turn easily, it not likely the seal, as they get loose with age, it is much more common that the grease inside the motor has leaked out or been dissolved, and that the parts inside are corroded by the horrible chemicals people put on rotovaps (I do it often) like acid chlorides, TFA, DCM, and many other things that corrode metal and plastics. They can handle it a long time, but eventually wear down some.

Panzerkemie - 17-11-2020 at 04:12

Quote: Originally posted by Dr.Bob  
The metal part holding the duct is integral to the rotovap.

The safest way to remove the steam duct is to remove the condenser, make sure the rotovap is well anchored, and then put a block of wood (2 x 4 works well) against the condenser end of the steam duct, then tap that with a mallet, hammer, or something heavy, using increasingly heavy blows, until it comes out. The joint is far easier to replace without breaking it than with, although sometimes that happens. The retaining clip on the flask end of the steam duct is a spring clip that will let the duct out when it comes out fast enough, I don't think it can come out intact, so don't try to remove it, just pop the steam duct out, and it will release it.

For people in the US, I have some spare parts, including ducts and a few KD-22 seals left. But they are going fast. If the rotovap does not turn easily, it not likely the seal, as they get loose with age, it is much more common that the grease inside the motor has leaked out or been dissolved, and that the parts inside are corroded by the horrible chemicals people put on rotovaps (I do it often) like acid chlorides, TFA, DCM, and many other things that corrode metal and plastics. They can handle it a long time, but eventually wear down some.


Im in the Eu, but eventually do you ship parts over the pond ? if so send me a parts list with prices and i'll gladly do some shopping for new ones !