Finding and fixing leaks in RotoVape setup

I picked up 2 new chinese rotos and they seem to be running, but I’ve noticed that it really can’t hold vac; and it can’t hold vac because there is a really small leak in one or more of the joints.

I am gonna realign a few of the pieces of glassware, but I was wondering how you guys find the leaks. I’ve seen a few things on this forum about using a balloon, but I’m not sure how one would actually do that with the rotovapes.

What are people doing to make sure they have a proper seal on these chinese rotos? Would one actually use vac grease on these seals? What is the best way to test for a leak? Is there a best way to tighten down the clamps to reduce a chance of small vac leaks? How tight do you actually go with these things?

Any help is appreciated

we use a piece of rubber tubing or polyethylene and run it along all the connection while under vacuum and try to hear the leaks. maybe the seal is no good? did you check your connections where glass hits glass? are all the glass connections clean before you put them together? if there is any dirt or debris that will cause a leak

This is pretty much out of the box from the manufacturer. There really isn’t any glass/glass connections w/o a big PTFE seal in-between with clamp pulling it all together.

Mine leaked at the condenser part

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@Demontrich Were you able to fix it? If so, how?

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I repositioned it for a better fit. I chased my tail for 45 mins before I figured it out.

I think I mentioned it in one of my threads. My migraines kicking back up, I’ll try and link later

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We had the same problem with a Chinese rotovap. We put food safe vacuum grease on the joints and we tested the vacuum after adding each piece as we reassembled it. We put greased mason jar lids over the open connections during the tests.

It’s usually the seal between the flask and the vapor tube. Order extra and hive it just a lil brease, and once again order wxtra while you have them on the line . Just my experience with all my Chinese ones