Air pressure test

ugabulldog · Oct 27, 2010

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???

Jimbo · Oct 27, 2010

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.

Sponsor · 2022-01-29T12:20:58-0800

ugabulldog · Oct 27, 2010

can't do that yet, no water to house, ...why is it dangerous?

Zorka · Oct 27, 2010

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.

Asktom · Oct 27, 2010

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.

ugabulldog · Oct 27, 2010

ok, i understand the dangers....how about my question though, thanks

Thatguy · Oct 27, 2010

ugabulldog said:
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.

Here's some specs more or less applicable to your situation
http://www.contractorsunlimited.co.uk/toolbox/valve-leakage.shtml
I think anybody claiming zero leakage didn't wait long enough. Almost everything is permeable.

Jimbo · Oct 27, 2010

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?

Thatguy · Oct 28, 2010

jimbo said:
One drop of leakage, anywhere, is unacceptable

If the water leaked out at a rate less than the rate at which it evaporates, isn't this acceptable?

ugabulldog · Oct 28, 2010

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???

Thatguy · Oct 28, 2010

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???

So it's the valve stem packing? Sometimes just tightening the valve stem nut fixes this.

ugabulldog · Oct 28, 2010

Thatguy said:
So it's the valve stem packing? Sometimes just tightening the valve stem nut fixes this.

It is leaking where you add the air

Air pressure test

Users who are viewing this thread

ugabulldog

Member

Jimbo

Plumber

Sponsor

Paid Advertisement

ugabulldog

Member

Zorka

New Member

Asktom

Member

ugabulldog

Member

Thatguy

Homeowner

Jimbo

Plumber

Thatguy

Homeowner

ugabulldog

Member

Thatguy

Homeowner

ugabulldog

Member

Similar threads