Gas Shut-Off May Prevent Quake Fires

Once again Californians are reminded of the seismic threat we live with each day as the strongest earthquake in 40 years strikes our region.

Public officials have been repeating their oft-mentioned earthquake survival advice regarding how to stay safe during a quake and what kinds of emergency supplies to keep on hand.

Because fires after an earthquake usually cause more damage than the shaking itself does, one of the regularly heard suggestions is to tie a wrench to your gas meter so it is always on hand for quick shut-off of the gas supply if a pipe ruptures during a temblor.

This is not bad advice, but it does no good if a quake strikes while we are away from home, or if a gas pipe ruptures and starts a fire or causes an explosion before there is a chance to get out to the meter and shut off the supply.

Gas under pressure escaping from a broken pipe in an enclosed area can create an explosion hazard within seconds under certain conditions.

For these reasons, seismic or “quake-activated” gas shut-off valves were developed. These devices are mounted into the main gas supply line for a house or building and automatically stop the flow of gas before it enters the house when substantial earth movement is sensed.

There currently are 13 manufacturers producing valves that have been tested and approved by the Office of the State Architect of California.

Each approved valve must be carefully calibrated to shut off only during a quake strong enough to cause pipe damage. (average 5.5 on the Richter scale). As such, when the valves are properly installed, nuisance tripping (a very common concern) is not a problem. My own valve is placed in a location subject to vibration from passing vehicles and has never caused a nuisance trip.

The valves are in wide use in homes, hospitals, schools, factories and even in fire houses. In Japan, another quake-prone part of the world, the valves are required by law in all buildings.

A few questions are commonly asked about the valves, such as “How long will it take to get the gas back on if the valve trips?” “Is the valve easy to reset?” and “Why have one if my neighbors do not . . . won’t my house burn anyway?”

If the valve trips due to an earthquake, your house should be inspected by a Gas Co. representative or a licensed plumber to assure that there is no pipe damage before the valve is reset. True, it could take several days after a large quake to get help, but most homeowners who have them agree that the large reduction in the risk of fire the valves afford makes the possibility of inconvenience after a quake inconsequential.

All the valves available can be easily reset by the homeowner should they trigger accidentally (which is a highly unlikely event when properly installed). Some designs require only a screwdriver for resetting and some need a special tool that comes with the new valve.

Regarding the last question of “Why have one if neighbors do not,” representatives of several valve manufacturers respond: “While it may be true that you could still lose your house to fire after a large earthquake, at least you have dramatically increased the odds of getting yourself and your family out of the house safely, as the gas explosion will not occur in your home.”

The typical cost of a quake valve, with installation, is $350 to $600, depending on the size of the gas pipe on which it is installed.

However, it is a one-time investment that requires no maintenance and is designed to last 25 to 50 years. Compared to the cost of earthquake insurance for one year, the valve is relatively cheap protection. Also, the valve usually can be reinstalled in another home if you move.

Earthquake gas valves are normally installed by licensed plumbing contractors, not the Gas Co. Check with your plumber about experience and recommendations regarding make of valve he or she prefers. Make sure that the valve selected is one of the more popular makes and carries State Architect approval.

Some communities require building permits before the valve can be installed, so check with your local building and safety department before proceeding.