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I want to ask for experiences pressure testing fostapex. I am required to do a 100psi hydrostatic test of a system with about 500 feet of fostapex. We charged up the system and saw pressure loss of about 5-8 psi in 1/2 hour. Found a couple weeping threaded connections consisting of very small amounts of water—like so small you hard to touch the fitting and see if the tiniest bit of moisture was on your fingers. One leak was at the factory installed air eliminator on the manifold.
One thing I noticed is that pressure loss was greater the first round and continuously decreased to the point I’m now seeing 1.5psi loss in 1/2 hour. I saw on the fostapex manual that they consider 8psi loss/hour a successful test. I’m assuming there’s some expansion factor.
One other possible culprit is that I inverted my Caleffi manifold which means the end cap is a bit away from the body of the manifold. Caleffi says it should not leak, I see no moisture anywhere but maybe it’s leaking so slowly I can’t see it?
My question is should I be able to stabilize at 100 psi with no loss for a half hour? If so, how long do I need to pressurize it to get all the expansion worked out? Or is no pressure loss just not in the cards with Fostapex? Again, it’s a hydrostatic test so no air.