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Natural Gas Excess Flow Shutoff Valve

Excess flow valves are a calibrated sized "egg" in the piping against a spring. If the flow from a broken main pushes the egg against it's seat, the gas pressure holds it ther, stopping flow. A wee bit of gas gets by, but not much.

Shutting off the service allows the pressures to equalize, and the E.F.V. reseats itself open.

There's lots of them in the ground, and we rarely even heard them mentioned. I think they were pretty reliable.

I wonder what they use, now.



  • Just got a notice that natural gas mains are being replaced in my neighborhood. Unsure about my individual branch--it appears fairly modern (grey plastic over metal).

    Utility offered to install an "excess flow" shutdown device for $80 with "repair or replacement" cost currently estimated at $900 to be automatically billed.

    Are these devices:

    1) Accurate--e.g. no false problems? and USER resettable?

    2) Long lasting? (I know that the "earthquake sensing" devices proved UTTERLY unreliable.)

  • Still called an "EFV" as authorization is sent "Attn: EFV"

    So it's installed underground on the high pressure side ahead of the meter, correct?

    In theory then, should I have a pipe after the meter rupture (like earthquake) it will stop the flow of gas and house won't go kaboom.

    Why do I have this terrible feeling that they're going to screw up my underground irrigation system??? I spent a fortune doing it right--full overspray, 18" minimum deep, gravity drain, etc.
  • Sounds like a futile utility hoax to me....

    Did they offer to add magnets to it while they had it opened up?

    Seriously, if there is a quake large enough to level your house, what makes them think their mains and branches will survive?

    We have "gas sniffer valves" required in certain AHJ's for use with LP gas where a natural drain can not be set up. They are electricaly powered normally closed solenoids. I think I'd go for that before I'd go for the EFV.

    But thats just my opine.

  • Ron Schroeder
    Ron Schroeder Member Posts: 998
    I can say that they work

    not always when you want but then again I had no idea what I was up against the first time around one. I think in an earthquake all bets are off, however if some one was to open a valve in a line that was being worked on then it could be a life saver, or someone acidentally brakes a line, its a good thing.

  • Marty
    Marty Member Posts: 109

    They work.... They will also tend to drop/close when purging gas lines.

  • Here's the first two paragraphs of the letter:

    "In accordance with Federal Pipeline Safety Regulations, please be advised that AmerenUE is required to notify you that an additional safety device that meets Federal Performance Standards is available for installation on new and/or replaced natural gas service lines at your cost.

    This safety device, known as an excess flow valve, is designed to automatically restrict the flow of gas if the service line breaks outside the home. The excess flow valve is not designed to shut-off if a small leak occurs between the street and your home or a gas leak occurs inside your home."

    What was I thinking? Nothing to do with inside--only the branch service line.

    Won't even operate if the 1" interior line ruptures, right?

  • Ron Schroeder
    Ron Schroeder Member Posts: 998
    There you have me stumped

    as I had one shut down trying to recharge a system after working on it, large system so it might have been a lot of flow, I would call and ask as I bet it has to do with how much pressure drop there is compared to the size of the line it services.
  • They'll slug closed if...

    a guy turns the meter cock on too fast.

    I had the propane sniffing detector/valves all over campus for a while. Every time the power farted, the things would close, and any equipment running, or with a pilot, would be OUT till someone came to tend it in person.

    Some were near vent pipes on boiler feed tanks, and the air from the steam system (Smith 28A-13) would set off the gas detector, and put the heat out.

    Overtime detectors, we called them....
  • Plumdog_2
    Plumdog_2 Member Posts: 873
    Excess Flow Device

    can be had inside the end of a certain brand of Flex gas connector that is sold thru Ace hardware. Not gonna effect the main line coming in, but could prove useful in the event that a water heater fell over or such.
  • Greg_40
    Greg_40 Member Posts: 43


    I work for 'the gas company'. Yes, we are required by US-DOT regulations to offer the device. I was surprised to see the low cost for the EFV. We offer them as required, very few if any customers opt for them. We do not really recommend their installation, but will if any customer wishes. As with any device, they will need some maintenance - lubrication, occasional testing, etc. at the customer's expense. They must be installed to be accessible- manhole, valve cover or other access. They are maybe a good idea in theory, but in practice can close for any number of reasons in addition to pipe breakage, as mentioned. While it would not hurt to install one... if it were my home, I'd say "no thank you" and sleep OK without it.

  • Thanks for the honest opinion Greg!
  • Dale
    Dale Member Posts: 1,317

    We are currently sending out a letter like that. However soon, because of lawyers, we will just put one on for "free" starting next year. If I were you, with an outside meter, I would like the kids "just say no". The problem with the efv is if it freezes up or strangly people cut the little 1/2 pe service lines and don't know it because the efv closes, they plant the tree and we dig up the tree when they have no gas. The efv is a very good idea IMHO for inside meters where the service piping comes through the basement wall and there's line pressure in the house. These are almost always steel services that if hooked by the backhoe can fill a bsmt up with gas very quickly. The efv is also IMHO good when you have no space between buildings in a downtown area or when there's curb to building paving. The efv's are mandated now by local utilities because of lawsuits, like the ones resulting in explosions in St. Cloud MN a few years ago, where the first responders made allot of mistakes and some buildings blew and people died. The NTSB in their report said if the gas service had an efv the explosion probably wouldn't have happened. Guess what happened when the lawyers read that.
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