Air pressure test

ugabulldog

ugabulldog

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How many psi should I blow into cpvc supply lines to test??? I blew 40 psi and it leaks slowly over an hour or so. The universal tub valves shouldn't allow air to escape should they....I am going to try a new pressure gauge to make sure it is ok, as well.



UPDATE: ,....it is leaking at about 1 psi per hour, ...I used soapy water and found a leak in the valve stem,........At that rate should I just conclude that is only leak or buy new valve stem and retest???
 
Last edited:
plastic pipe should NEVER be pressurized with air. It is dangerous. Pressurize with system water pressure.

An air test on copper can be up to 50 PSI
No air testing for plastic pipes.
 
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Air is compressible and water is not (well, not significantly compared to air). If something fails under air pressure, 'stuff' (fittings, pipe segments, etc.) can get shot out at a high velocity.

This is why pressure vessels are tested using pressurized liquid, not gas.
 
If the plastic pipe is broken under air pressure it can throw nasty shards of plastic schrapnel. There is also a remote chance that glue fumes in the pipe could diesel and blow the pipe up, more shards.
 
The problem with air test....you will get fluctuation due to changes in temperature, and natural expansion/contraction of components. With a water test, there are two results....either ALL the water stays inside the pipe, or it doesn't! One drop of leakage, anywhere, is unacceptable, and also immediately apparent. Air test is "iffy".


Can you bring in a couple gallons of water, and a pump?
 
Ok,....it is leaking at about 1 psi per hour, ...I used soapy water and found a leak in the valve stem,........At that rate should I just conclude that is only leak or buy new valve stem and retest???
 
ugabulldog said:
Ok,....it is leaking at about 1 psi per hour, ...I used soapy water and found a leak in the valve stem,........At that rate should I just conclude that is only leak or buy new valve stem and retest???
Click to expand...
So it's the valve stem packing? Sometimes just tightening the valve stem nut fixes this.
 
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