Won't hold vacuum

So we have a coil, with ball valves on both ends with JIC fittings, and are drawing vacuum from one end.

Suction is being felt at the open JIC end even though that ball valve is closed. From my experience this is indicative of a bad ball valve, but we’ve replaced that once now and are experiencing the same problem.


Pressure test it under water.
Did you install with a verified good valve or the same type?
Its either a bad valve or bad tape job. Unless you have a micro hole somehow

Bad tape job being felt at the end of the JIC fitting… My thought is the JIC fitting is technically isolated from the vacuum if the ball valve is functioning properly, right?

Gonna pressure test it with nitro and hit it with a spray bottle of soapy water in the meantime to verify there aren’t other leaks anyway, but really scratching my head here and kinda leaning towards the new valve being faulty.

It was the new ball valve, just happened to be faulty.

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If the jic fitting is pulling a vacuum with the valve closed, it is 100% the valve. Bad tape jobs, poor/loose fittings aren’t going to bypass the valve straight to the jic. You are on the right track to pressurize and leak test with soap though. If the bubble forms from the jic, the valve is nfg

Edit: sorry you already figured it out. My bad…

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Is this a serviceable valve? Have you tried tightening the packing?

If it’s not holding vacuum, it’s because you have a leak :wink:

Part of the problem was exactly that… non-serviceable valves. Not my purchase, just my headache. My first solution was to tighten the packing nut, which didn’t exist here. Ultimately good valves solved the problem. Moral of the story don’t waste time trying to save money in the wrong places.

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