Foreline pump base pressure degraded

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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Richard Hull
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Re: Foreline pump base pressure degraded

Post by Richard Hull » Tue Jun 05, 2018 8:13 pm

You method is good and how I do it. I valve off the fusor chamber to diff pump inlet. (fusor left under vacuum. I then turn off the boiler in the diff pump and monitor the diff pump boiler temp until it drops to below 80 deg C, then I valve off the diff pump outlet to the mechanical pump inlet. (diff pump left isolated and under vacuum. Last I turn off the mechanical rotary pump and immediately un-clamp the hose to the mechanical pump and foreline. I let the foreline and mechanical pump up to air for 1 second (woosh!) then immediately re-clamp the foreline to pump.

I also have a ball valve on the mechanical pump's outlet. I immediately close this valve so that no air can enter the turned off rotary mechanical pump until the next time I use it.

Naturally, the first action on any restart is to open this ball valve to allow the rotary to exhaust properly while running.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

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