Vacuum Greese

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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Alex Peterson
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Real name: Alex Peterson

Vacuum Greese

Post by Alex Peterson »

I Have a few gas and vacuum gauge connections with NPT fittings. I know to use the gas teflon tape and to apply it in a counterclockwise direction around the connection. But, how much vacuum greese do you use. I sometimes hear just dabbing a little on a gasket then wiping off the excess wilol give you a good seal. But sometimes i see people usng huge globs of greese. I found this video of a guy applying vacuum greese to some brass fittings. Is he using too much greese? Is this the correct way?


https://www.youtube.com/watch?v=kiGQr4hI91k
Jack Puntawong
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Re: Vacuum Greese

Post by Jack Puntawong »

I've never used the npt fittings before but I can give you advice about vacuum grease in general. Think of vacuum grease the same way as the thermal compound you applied between the CPU and the heat sink. The thermal compound is design to filled up the microscopic holes on the surfaces, thus improving grease surface area and thermal conductivity. No manufacturer can produce something that is perfectly flat so, the vacuum grease is also designed to "fill up" this microscopic holes to reduce leak. My advice is that you should only apply a minuscule amount to your fittings such that you can see a thing layer on the fittings. Also, wear a dust free gloves while applying this substance. (It's very nasty to clean off)

ps. the guy on the video put about 3-4 times the amount of grease you required. Also, buy a dust free glove!

Jack Puntawong
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Dennis P Brown
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Re: Vacuum Greese

Post by Dennis P Brown »

Your statement
dabbing a little on a gasket then wiping off the excess
is how many professionals suggest using (if you must) vacuum grease for high vac systems and I have had great success with that technique. That said, if one use a good bit and/or does not wipe off the excess the vacuum quality of the seal should still be fine (assuming the leakage isn't due to a bad O-ring or poor seating surfaces) but one will have to deal with a lot of out gassing from the extra grease every time the system is opened to air. Also, if a little vacuum grease that is then wiped off does not seal an O-ring, then the leakage issue isn't going to be solved by adding even more grease(lol.)
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