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Seismic Gas Valves

Earthquake Gas Valves

An earthquake valve or seismic valve is an automatic way to shut off the low pressure regulated gas supply to a structure during a major earthquake and/or if a pipe is broken. These are applicable both to utility supplied natural gas and to gaseous liquified petroleum gas (LPG). These small devices are installed on the property gas meter (usually between the utility company’s metered installation and the structure piping) and are designed to instantly stop the natural gas supply in order to protect the structure if a gas leak or line break occurs during an earthquake.

As of 2002, California law and building codes state that constituents must install an earthquake valve at their home or business on all applicable gas meters on any building that they own. This is to ensure the wider safety of a population living in an area with a history of earthquakes, as well as to decrease the amount of potential damage and costs to the government itself as well as its citizens.

Many gas companies in seismic zones will require homeowners and home builders to install these valves from day one, in order to maintain the integrity of their own gas lines and services to consumers in the event of an earthquake. They recommend you shut off your gas immediately after an earthquake if you smell gas but earthquakes don’t wait for you to be at home, and you may find yourself in the office during an earthquake. Because you’ll be, by definition, unable to turn off any gas service to your home, having earthquake gas valves installed will give you the peace of mind that your home has not caught on fire, exploded, or put any of your loved ones or neighbors in immediate danger.

A gas shut off valve ensures that your home will be protected even if you can’t directly access the gas meter after an earthquake has occurred. It’s important to remember that the damage from an earthquake can be unpredictable, and it simply may be impossible to reach the gas meter to shut it off manually. This could result in increased gas flow and fires or explosions while you and your loved ones are in the home. It could also endanger neighbors who will be in the direct path of a gas fire or explosion.

Insurance companies which cover earthquake damage have begun mandating that their customers install earthquake valves on every meter under their control in an effort to reduce the risk of damage after a major seismic event. Natural gas valves will often have to be installed as a condition of being granted the insurance policy — and if an insured building is found to be without them, it is often deemed to be within breach of the policy and ineligible for reimbursement based on earthquake damage.

Types of valve

Two types of valve are commonly employed, one is sensitive to motion and the other to excessive gas flow. The most secure installations would use one of each type connected in series.

Motion sensing caged ball
A metal ball is retained away from an orifice by sitting upon a ring. Any shaking of the mechanism will cause the ball to roll of its ledge and fall down to block the orifice. it is reset using either an external magnetic device or an internal lift mechanism. If too sensitive it may be triggered by passing vehicles on a rough road. In the case of a severe seismic event, the gas piping should be completely inspected for breaks before resetting and then “sniffed” using a gas detector device after resetting. Since all pilot lights will go out, some appliances must be properly restarted once the device is reset. The safest means is to have the gas supplier inspect the piping and relight the appliances, even though this could take quite a while in an event affecting a wide area. Such inspections and relights are typically performed without charge by the provider.

Excessive flow sensor
A valve is closed when the flow exceeds a certain limit appropriate to the application. This will only operate when a pipe is broken, and so may not operate if a small (yet potentially dangerous) leak is present. If activated, any faults in the piping must be first repaired.

Peace of mind is invaluable, and a properly installed earthquake shutoff valve can help remove the burden of anxiety in times of emergency.


Call Zaragoza Plumbing Today, we will be happy to assist you with any questions!

Seismic Gas Valve
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