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Thread: Hose Testing

  1. #1
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    Question Hose Testing

    COULD SOMEONE TELL ME WHY THE MAX. LENGTH OF HOSE FOR HOSE TESTING IS 300'. I'M WONDERING BECAUSE SINCE I'M DEALING WITH STATIC PRESSURE, I SHOULD BE ABLE TO GO AS LONG AS I NEED. THE ONLY AWNSER I GOT WAS BECAUSE THATS THE WAY WE ALWAYS DONE IT & THATS WHAT THE N.F.P.A. STANDARD SAYS.


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    Yes the water should be at the same pressure in the entire length.
    Longer then the 300' makes it a lot harder to get all the air out of the line, and since the air will compress the test won't be accurate.
    On a less scientific side it is a pain in the butt to try to set up a longer test the way it should be per NFPA. The lines should be straight, not crossing, and when you come across a leak you have to take that line out and start over, in a long test it just takes forever. We have LDH and only use a hose tester so a single test takes a half hour just to get up to pressure. One bad year we got one test in for the entire morning.

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    Default HOSE TESTING

    ADSNWFLD THANKS FOT YOUR RESPONSE. I THOUGHT ABOUT THE AIR IN THE LINE ALSO, BUT WE'RE USING AN ENGINE HOOKED UP TO A HYDRANT, AND THE LINES ARE BLEED OFF FOR APROX 30 SEC AFTER THE LAST POP OF AIR IS HEARD LEAVING THE LINE. I WAS JUST LOOKING FOR A "SCIENTIFIC" EXPALNATION, COULDN'T LIVE WITH "ITS THE WAY WE ALWAYS DONE IT"

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    MembersZone Subscriber ullrichk's Avatar
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    As you bring up pressure on the hose it stretches. In doing do it develops quite a bit of potential energy (even though no water is moving). If you experience a catastrophic hose failure, the hose will whip and release all that potential energy at once. The longer the hose, the more stored energy.

    For what it's worth, I hope you have a drilled gate valve to limit flow in case of a failure as well. Going from 250 psi and zero flow to max flow in the blink of an eye is a recipe for disaster as well.

    Hose testing is much more serious business than most people think. There was even a hose testing LODD a few years ago. If I recall correctly, the victim was struck in the head by a coupling that was flailing around.
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    [ The longer the hose, the more stored energy. ]

    MY QUESTION IS THIS, IF YOU CANNOT COMPRESS WATER, AND THE WATER IS SATIC, THE PRESSURE (STORED ENERGY) SHOULD BE THE SAME ANYWHERE IN THE LINE, BEGINNING, END AND/OR MIDDLE REGARDLESS OF LENGTH.

    HOWEVER, GOOD POINT ON STORED ENERGY, A 2.5" OR 1.75' WITH 250# PRESSURE IN IT, THAT LETS LOSS COULD BE VERY DANGEROUS

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    Forum Member cellblock's Avatar
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    PLEASE STOP yelling.

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    MembersZone Subscriber ullrichk's Avatar
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    Originally posted by JMAC651
    [ The longer the hose, the more stored energy. ]

    MY QUESTION IS THIS, IF YOU CANNOT COMPRESS WATER, AND THE WATER IS SATIC, THE PRESSURE (STORED ENERGY) SHOULD BE THE SAME ANYWHERE IN THE LINE, BEGINNING, END AND/OR MIDDLE REGARDLESS OF LENGTH.

    You are not compressing the water, you are storing energy in the elasticity of the hose, i.e., it's the force of the hose snapping back to its original length, not the water.

    Of course your pump is continuously putting energy into the system. It can manifest itself as either pressure or flow. If you do not have a device to limit flow in case of a burst hose, all that energy which was just creating pressure is now creating flow. It's like an open nozzle at mega-gpm with no one to hold it.
    ullrichk
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    ULLRICHK

    Thanks, thats a better explination then the one i'm getting.

    As I was once told "the longer your in this buisness, the more you realize, the less you know"

    thanks again

  9. #9
    55 Years & Still Rolling hwoods's Avatar
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    Cool Gentlemen,

    Two Things.
    1. Re:LODD hose testing. Some years back, Lt. Dan Raskin of the Chestnut Ridge VFD in Baltimore County, Maryland, died when he was struck by a line that broke loose, but I think that it was a Fire, not a test.
    2. RE: 300 feet at a time. Forget it. We do an entire engine at once.
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