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sprinkler \"leak\"

I have a friend whose house I plumbed and did the heat in.He had another contractor install a residential sprinkler system in this house that has a 300+gal. or so storage tank. To this a pump is attached and when a head would pop a sensor/clapper would start the whole thing to start up and put of the fire,in theory.
Since they have moved in they will be awaken in the night by the pump starting up. the system(pump side) aparently has a small leak in a check valve that lets the water pressure out enough to start the system up(repressurize) for a few seconds, and all the alarms...nice at 2am. If the system pump & check valve were flushed would this help the problem? Any other ideas,short of dismantling the whole thing.I don't work on these systems so am reluctant to touch it... tia kpc


  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    There's usually...

    an inspection port if it's a swing check. If not, total dismantling is required. It's probably a piece of teflon tape. That's what I find 96 percent of the time.

  • Douglas Hicks
    Douglas Hicks Member Posts: 69
    Sprinkler leak

    There are several things that may be at fault.

    1. I have not seen a swingcheck valve in an inspector's test port. I expect with a resevoir and fire pump, the test port cycles the water back into the resevoir. Open the test valve and see if this cures the problem. I have seen swing check valves on the discharge side of a pump. For fire use we use swing check valves w/a rubber facing on the swing part of the valve. Plumbers use a metal to metal swing. Do not ask me why the difference. I have seen a bit of dirt or gravel hold the valve open just a bit. If this is the case, you may be able to cure the problem by removing the swing and cleaning the gasket. I don't think this is the problem. Of course, when you open the valve, the liqued will drain out.

    2. There also may be air trapped in the piping, hence the on/off action of the pump. The air may be trapped in farthest away , longest section of pipe. This may be easy to fix, just open the inspectors test port to relieve the trapped air. However, you need to know if the system is charged with water or an antifreeze solution. If water, open the test port and allow the water/air to run. If the system is charged w/an antifreeze solution, you need to use more care. The antifreeze cost can be $40.00 to $50.00 a gallon. You cannot use automotive antifreeze! Automotive antifreeze is flammable, and toxic. The air can also be trapped in a pipe w/o a drain, meaning sprinkler heads may need to be removed to get rid of the air. Have a bucket ready

    3. The alarm switch also may be too sensitive. I am assuming a water flow switch w/ a paddle is being used. Those water flow switches usually have a delay feature, that can be adjusted.

    4. There could be a minor leak in the piping. You did not tell us what pipe is being used, as this is residential, I expect plastic. I have seen holes in plastic from rubbing fart fan hoses. A bad joint may cause problems also. The plastic pipe is orange Blazemaster. The OD is different than other plastic pipe and a special adhesive is used. If matal pipe is used, a small pinhole in the casting may be the problem.

    Now that I have given you some ideas, I would call the sprinkler contractor and talk to him.

    Douglas Hicks
    General Fire Equipment Co of Eastern Oregon, Inc

    The words that appear to be mis-spelled are instead in code. Don't you wish you had kept yhouy secret decoder ring?
  • David Efflandt
    David Efflandt Member Posts: 152
    Make sure check has composition disc

    I do not know if there are U.L. Listed checks for home size fire systems, but make sure that the check valve has some sort of rubber or composition seal on the clapper instead of metal to metal seating. Otherwise the least little sand or grit could cause it to leak.

    But something also needs to be adjusted for the flow switch that trips the alarm (time delay). Because that should not trip just bringing a static system up to pressure (unless there is air trapped somewhere in the piping).
  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
    the system piping...

    is done in a combination of Blasemaster and copper tubing. kpc
  • hot_rod
    hot_rod Member Posts: 21,804
    Are there

    heads located outside or piping located in areas prone to freezing? If so it could, or should have an antifreeze. The antifreeze seletion is crucial, you cannot use glycols like a copper or iron pipe system. The CPVC requires a glycerin based antifreeze. Be sure to capture any you drain out, it is very expensive.

    The biggest problem with the plastic was tiny hair line cracks. Generally caused by rough handling, of the pipe, along the way. Often just throwing it on the ground would cause these splits, especially in cold weather. Sometimes these splits only show up under high pressure, like the required hydrostatic test for inspection.

    All things considered, unless you are licensed and insured for fire protection work, check you liability policy!,think I would turn this over to a fire sprink specialist :)

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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