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Seismic gas shut off valve

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  • Seismic gas shut off valve

    i have a newly built, 5 year old apartment building that has seismic gas shut off valves. these valves are attached to the downstream side of the gas meter and are triggered by a quake of 5-5.5 or more.

    but in the last month, they have had 2 fail on their own. they tripped and don't reset. gas company tried and i came and replaced the first one a month ago and the other one last week.

    here is a sample of the valve on display at the supply house.

    they are made by little firefighter and are required to have a 25 year warranty for california.

    there are 2 basic designs. the horizontal and the vertical.

    the ones that failed are the horizontal.

    i'll explain their operation and for those of you that have never seen one.

    it's an aluminum valve body that is a glorified check valve with a magnetic catch that's on a spring loaded pendulum.

    when it shakes the magnet moves a little and the magnetic field is lost between the magnet and the little screw on the flapper valve.

    tried to take some close ups, but not sure if you can see them clearly.


    upper section is the magnet with the pendulum. the green disc is the check and the screw is the spot the magnet sticks to.

    valve is shown in the tripped/ closed position.

    valve shown in the open position.

    mock up of the horizontal and the vertical valve shown with the required stabilizer bracket.
    Attached Files
    Last edited by PLUMBER RICK; 06-18-2009, 01:37 AM.
    phoebe it is

  • #2
    Re: Seismic gas shut off valve

    now that you've seen the horizontal valve, here's the vertical valve.

    a very simple design.

    basically a ball bearing/ pin ball that's sitting on a small shelf. the ball is centered on a little drilled hole to keep it from rolling. when it gets shacked from a quake, it rolls off its resting point and onto the gas port over an o-ring seal. the gas flow is from the top down and it holds the ball in place.

    resetting is done via a screw that lifts the ball back onto its perch.


    shown in its open position through the site port glass.

    shown in the tripped position
    Attached Files
    Last edited by PLUMBER RICK; 06-18-2009, 01:46 AM.
    phoebe it is


    • #3
      Re: Seismic gas shut off valve

      thanks Rick hope the phone doesn't ring. Istopped using those 3 years ago acci now
      I can build anything You want , if you draw a picture of it , on the back of a big enough check .