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Air Pressure Testing

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  • Air Pressure Testing

    How long do you leave a dial gauge under air pressure when pressure testing your system in a new construction? How much of drop in air pressure over a period of time such as a week is acceptable?

  • #2
    Re: Air Pressure Testing

    15 minutes on a D.W.V system air test. There is no need to keep a test on for any longer than the time needed for a inspector to do his thing and if you have a leak it will show quickly enough.
    ________
    Harley-Davidson Khk
    Last edited by TOPDAWG; 02-24-2011, 06:00 PM.
    Mike

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    • #3
      Re: Air Pressure Testing

      I always blow my system up to 10 psig and leave it for 15 minutes, most inspectors say its way overkill. My thought is codes says 5 psig and I would rather it hold more. Since everything is open if it is going to pop, let pop while it is still easy enough to fix.

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      • #4
        Re: Air Pressure Testing

        5lbs - 15 minutes. Realistically though it should hold forever. I have left gauges on for weeks and still had 5lbs on the system.
        sigpic

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        • #5
          Re: Air Pressure Testing

          you need to be aware of temperature changes. this will affect the reading. depending on the high and the low for the day.

          rick.
          phoebe it is

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          • #6
            Re: Air Pressure Testing

            Originally posted by PLUMBER RICK View Post
            you need to be aware of temperature changes. this will affect the reading. depending on the high and the low for the day.

            rick.
            The piping is pex, the house is 3100 sq ft and there are 2 hot water heaters. How much of a change would be normal due to temp?

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            • #7
              Re: Air Pressure Testing

              for the heating system we need to hydro test at 3 times the working pressure for 30 min and for gas it is 3 times the working pressure for 30 min to .now that is for the inspection . i keep it on for 24 hr or more and with water test 0 pressure drop and gas depending on how much pipe there is and if all inside or not will make the pressure go up and down so i give it 24 hr or more . i will mark the gauge after an hr so the air can cool down first .
              Charlie

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              • #8
                Re: Air Pressure Testing

                Testing of...?
                Copper
                Cast Iron
                Pex
                Pvc/abs...
                Borosilicate glass?!

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                • #9
                  Re: Air Pressure Testing

                  We have to test pex at 200 psi. It doesn't matter what the working pressure is. It is not recommend to test pex with air. You can make a hydrostatic tester with a pressure washer.
                  Buy cheap, buy twice.

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                  • #10
                    Re: Air Pressure Testing

                    Originally posted by gear junkie View Post
                    We have to test pex at 200 psi. It doesn't matter what the working pressure is. It is not recommend to test pex with air. You can make a hydrostatic tester with a pressure washer.
                    That's surprising. Is the PEX stamped/rated for that on the pipe?

                    If not, I would think inspections and the state would be responsible for overstressing the pipe and joints prior to operation.

                    Curious.

                    J.C.

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                    • #11
                      Re: Air Pressure Testing

                      200lbs seems excessive and for that matter dangerous, especially hydrostatically tested.

                      Pressure will rise a lb or 2 and fall a lb or 2 depending on the temperature swing.

                      Gas pipe test is 2 1/2 x working pressure. Should hold forever obviously, as should any piping.
                      sigpic

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                      • #12
                        Re: Air Pressure Testing

                        If you air test a large system, it takes longer for a small leak to drop the pressure. A smaller test (running a short gas line for example) it would drop quicker. If you fill a system with water (pex) and pressurize it, a leak would drop the pressure much quicker. I usually wait a half hour if there's any size to an air test. You get a feel for it after awhile, but it's those dreaded leaky test gauges that get you. You chase a ghost leak and find out it's the ball valve on your test gauge.
                        sigpic3:00, I mean 5:00, and work is done. Time to crack a cold one.

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                        • #13
                          Re: Air Pressure Testing

                          Originally posted by boillerman View Post
                          If you air test a large system, it takes longer for a small leak to drop the pressure. A smaller test (running a short gas line for example) it would drop quicker. If you fill a system with water (pex) and pressurize it, a leak would drop the pressure much quicker. I usually wait a half hour if there's any size to an air test. You get a feel for it after awhile, but it's those dreaded leaky test gauges that get you. You chase a ghost leak and find out it's the ball valve on your test gauge.
                          I think your right with water. I would put as much water as I could from a garden hose then pressurize it with air. If there are leaks they would be easier to find since water is more visible than air.

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