Testing water lines with air

Originally Posted By: bking
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Anyone know about testing water lines with air ?


Where do you connect the compressor? What pressure?


I was told it was done by an inspection company working for HUD, the rest was a "drive by" that missed every single problem (about 20).


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Originally Posted By: Mark Dudley
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A fitting with a gauge is attached to the line and pressurized to a given PSI (say, 100). It is then checked at 5 minutes and 15 minutes. No loss in pressure, then the lines are good. Air will leak before water, as it’s molecules are smaller.



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Originally Posted By: bking
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How would an inspector connect it without disconnecting anything? Use an exterior faucet?


I realize this is done during construction and before any fixtures are installed. Could 100 psi damage a fixture valve ? If air leaks quicker than water then why use a higher pressure to test with?


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Originally Posted By: Mark Dudley
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There is no practical way to test this with air once the system is charged with water.


You could use one of the screw on gauges ($15 or so at Home Depot in near the sprinkler pumps) on an exterior faucet, and then rely on the static water pressure, but you'd also have to turn off the water main (to keep it's pressure from screwing up the test).

Then you have to consider the hot water heater, as it creates pressure when heating, and loses pressure when cooling.

Most water systems never go over 100 psi and most newer homes have pressure regulators, sometimes required by code, set at maybe 40-60 psi.

I guess the theory is if it doesn't break at 100 psi, it won't break at 60 psi As best I recall, PVC/CCVC is rated for 150 and 125 psi for the thick wall type.


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Originally Posted By: dedwards
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never mind…


Originally Posted By: Mark Dudley
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50 PSI is the minimum according to code, so you could just check it a that.


My home (built new last year) was tested at 100 psi, and all homes built by this builder were tested at 100 psi.

Not sure what would get damaged at 100 psi, certainly not the piping, as it's rated for more than that. Although I can see where an attached fixure such as a ref. water line might not be rated for it.


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Originally Posted By: Kyle Kubs
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This is typically done to test the rough plumbing, long before the fixtures are put in… The test is normally done at around 90 - 100 PSI. I’ve seen areas where you had to pressurize the system and leave it over night - it still had to be holding when you came back the next morning… You just make a rig with a female fitting holding a schrader valve(car tire valve) and a pressure gauge on a Tee. Sweat it onto a nipple somewhere and your in business…


javascript:emoticon('![icon_eek.gif](upload://yuxgmvDDEGIQPAyP9sRnK0D0CCY.gif)')If your on a job sight where there isn't a compressor that will hit over 100 PSI. you need to get out of Mr. Rogers neighborhood... Also it can't damage the pipes at all. I had an industrial shop that I plumbed the air compressor to different stations throughout the shop with copper. The system was charged every day for four years with 140 psi. Never a leak...


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Originally Posted By: Mark Dudley
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Kyle Kubs wrote:
This is typically done to test the rough plumbing, long before the fixtures are put in... The test is normally done at around 90 - 100 PSI. I've seen areas where you had to pressurize the system and leave it over night - it still had to be holding when you came back the next morning... You just make a rig with a female fitting holding a schrader valve(car tire valve) and a pressure gauge on a Tee. Sweat it onto a nipple somewhere and your in business...

javascript:emoticon('![icon_eek.gif](upload://yuxgmvDDEGIQPAyP9sRnK0D0CCY.gif)')If your on a job sight where there isn't a compressor that will hit over 100 PSI. you need to get out of Mr. Rogers neighborhood... Also it can't damage the pipes at all. I had an industrial shop that I plumbed the air compressor to different stations throughout the shop with copper. The system was charged every day for four years with 140 psi. Never a leak...


Mine was tested, complete with fixtures installed.

I've had my shop plumbed with PVC for air for years at 100 PSI (that is the 'low' of my compressor, so it seemed the logical choice). If the system is tested beyond what it would normally see, you can be pretty confident that it won't fail under normal usage. As far as I can tell, pretty much all products and assemblies are tested this way, not so that it's 'just good enough', bet better than needed.

That being said, on an existing site, it wouldn't be a bad idea to stick to the code lingo of 50 psi or average working pressure. That way if something does fail, you have an 'out' of you were only testing it to minimum of code requirements.


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