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I set up about 12 vacuum manifold in a teaching lab. Regular grease on the stopcocks. Put everything up, then tested the glass stopcocks for leaks. No leaks, bubbler stops when stopcock open and vacuum works well, all is well. I go and check on that shit now months later and little to no change in the bubblers when the stopcocks are open to gas. Any clue? Only thing I can think of is the grease has thickened up in cold weather and clogs things but that sounds wrong. When I plug the bubbler it forces the gas out the open stopcock but when I stop the flow stops. Also jammed a pipe cleaner up the stopcock and that fixes it until I turn the stopcock again. The bubblers have mineral oil, mercury is not an option and the Univ Dept is too cheap to go with the nice setups of the telfon stopcocks with the black handle. Any ideas?
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>>7801447
>Also jammed a pipe cleaner up the stopcock and that fixes it until I turn the stopcock again.
That was going to be my first suggestion.
There's probably a bunch of solvents and shit in the old grease from months of use and this could change the viscosity.
Just begin anew, wash away all the old grease with hexanes and apply fresh.
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>>7801465
I thought that too until I set up a crippled manifold today that I had to plug up a port because somebody stole the stopcock. Cleaned it, greased it and sometimes the stopcocks work and sometimes not. Though reading your reply reminded me that I have some thin brushes that might do better than pipecleaners if the don't bend to shit before they do anything. I also want to trouble shoot things a bit better before I redo 48 stopcocks and end up where I started again.
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>>7801486
Are the stopcocks mated?
Often each port and stopcock are labeled with a number and for best results you need to match the numbers on the port to the number on the stopcock.
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>>7801491
Most are anyway. Four manifolds were fresh from the box. The rest are mostly matched. The unmatched ports have fallen prey to students breaking theirs and taking them from unused manifolds in the room or research students wandering in to replace what they broke. I have a manifold I don't have the heart to throw away that had all of its stopcocks stolen.
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>>7801502
time to start dating the glassblower's daughter
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