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currious 04-06-2007 11:04 AM

Pressure testing methods
When a new home or building is plumbed what method/s are used to test the system for leaks? Air/water? How much psi? Etc.

handy man88 04-06-2007 11:35 AM

Definitely water. If you're pumping air into the system, you would kill ourself spraying snoop solution at every joint and valve and that's assuming you have time to find the leak before pressure is lost. Water is the quickest way to see if there's a leak. Pressure is probably 1.5x city pressure giving you roughly 100psi.

Generally speaking, all valves are shut off and openings capped and a pressure gauge is installed. Test is to see if pressure holds steady for x amount of time, probably 5 minutes.

currious 04-06-2007 12:36 PM

If you are using 100psi (1.5x city) are you pumping it up with a hydrostatic (air/water) hand pump?

handy man88 04-06-2007 01:07 PM

Let me take that back. My initial answer was based on testing of hydraulic systems.

City water comes in at about 70psi, but generally speaking, new homes have a pressure reducing valve that dials down the pressure (30-40 psi) because house plumbing can not handle the high pressure of city water. After shutting all valves, capping openings, and installed a pressure gage, the main valve is turned on and the required pressure is set by adjusting the pressure reducing valve. No need to use hand or powered pumps.

currious 04-06-2007 08:01 PM

Pressure test methods
Thanks handy man88.

I need to know because an ex-plumber turned sales engineer is trying to tell me that new plumbing systems (especially apartment buildings) are tested using 125 psi air. My argument is just as you stated: most components in a sytem cannot withstand that kind of air pressure. I figure that using 35-45 psi air is equivalent to approximately 3x that of water (105-135 psi in this scenario) due to the molecular structure difference. Possibly the manufacturers of diverter , shower and even faucet valves should state so in their documents.

handy man88 04-06-2007 10:27 PM

It'd be proper to test with air if this was a pneumatic system, but it's not. It's a plumbing system where the medium is water.

It's almost impossible to have zero leakage if you're pressure testing using air for a sophisticated pneumatic system, nevermind a simple plumbing system. Could have been a scam where you definitely would have had air leakage, and thus your plumber turned "sales" engineer would have made a sweet commission.

Air is obviously composed of several gases (nitrogen, oxygen, etc.), which has a density much lower than water. That's essentially why it's harder to hold pressure with air compared to a liquid, with water in this case.

If your sales engineer used air for testing, and your plumbing system couldn't hold water, it'd be interesting how he proposes to find this leak besides just recommending tearing everything out.

Ron The Plumber 04-07-2007 10:37 AM

Most codes require a static test or air on DWV, water filled though the roof, or 10' head of water, this comes out to be 1/2 psi per foot of water, 10' head would make that 5 psi, so in reality to air test a line per code, you would only air test dwv at 5 psi on the guage.

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