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Gas Shut-Off Valve Reduces Fire Risk After Major Quake

June 24, 1990|GARY ABRAMS | Abrams is a Los Angeles general contractor and a free-lance writer

"The house was engulfed in flames within 60 seconds and burned to the ground in minutes. Thank God he was not there when it hit."

The words are those of Westwood resident Ron Gabriel describing the Oct. 1, 1987, earthquake in which his father's Whittier house, where he had once lived and where he based his bookkeeping service, was destroyed by a natural gas fire that erupted from a broken pipe.

"Eyewitnesses said that the structure burst into flames so fast that no one could have gotten out in time."

One of the greatest dangers in an earthquake is fire from earthquake-ruptured gas lines. Appliance feed lines may break in a temblor, and the gas spewing into an enclosed space can quickly accumulate to a sufficient concentration to catch fire if it reaches an ignition source such as a still-burning pilot light.

A spokesman for the Southern California Gas Co. said water heaters are particularly susceptible to tipping over in a tremor that sends the water sloshing around inside. A broken water heater gas supply line was the apparent cause of a fire that destroyed a home in LaVerne following the Feb. 28 Upland quake.

The danger of gas fires in an earthquake region has led to the development of quake-activated gas shut-off valves.

A quake shut-off valve is mounted on the main gas supply line leading into a building, usually at the meter. The device senses earth movement generated by quakes averaging 5.4 or greater on the Richter scale and automatically stops the flow of gas through the pipe.

With the flow of gas stopped before it enters the house, any broken pipes within will not be dangerous. The gas remaining in the pipes will not be under pressure and cannot fill the building.

Earthquake gas valves are normally installed by plumbers or plumbing contractors. Prices with installation start at about $400. Some communities require building permits for installation at an additional cost.

The two residential earthquake valves sold in Southern California are made by KOSO International of Santa Fe Springs (213-921-3793) and Quakemaster of Anaheim (714-978-9644).

Both valves are Underwriters' Laboratory listed and approved by the Office of the State Architect.

The KOSO valve utilizes a spring-loaded mechanism triggered by earth motion. The gas supply line enters and leaves the valve at the same level, allowing simple installation. The valve is reset by turning a screw on the valve body. The warranty lasts 10 years.

The Quakemaster valve utilizes gravity by dropping a steel ball into the gas pipe as the shaking starts. Quakemaster provides a lifetime warranty, but installers must be specially trained by Quakemaster or the warranty is void. A special plunger is threaded into the valve body to reset it.

Both valve manufacturers strongly recommend a leak check by a qualified contractor or the gas company before resetting the valve after it is triggered by seismic activity. Obviously, if the valve is reset before the building is inspected, the possibility of broken gas lines poses an extreme danger.

If you are interested in having an earthquake valve installed, satisfy yourself that the contractor has proper qualifications and experience. Ask for references and check them.

Earthquake gas valves are increasingly popular as Californians become more conscious of earthquake safety. Even Sears has recently begun an advertising campaign promoting KOSO valves. However, the valves are not without their detractors.

Many plumbers and gas company personnel claim the valves are frequently tripped by the rumblings of passing trucks or by common smaller quakes.

Representatives of both KOSO and Quakemaster valves say that the only false triggering problems with their products resulted from improper installation. The valves are calibrated not to trip in earthquakes averaging less than 5.4, they say.

"If nuisance tripping were a problem, the many hospitals and factories currently using the valves could not continue to do so because of costly interruptions of ongoing processes," said Bud Steg, president of Environmental Engineering of Arcadia, which distributed KOSO valves.

My personal experience is that false triggering is not a problem. My own valve is placed in a location subject to vibration from passing vehicles and has never tripped, not even during the 5.5-magnitude Upland quake.

A second objection is that if they trip during a major earthquake, it could take several days or more to get the home inspected and the valve reset.

The manufacturer's response is that most people would rather risk the temporary loss of gas service than the loss of their homes or loved ones.

The third objection is often phrased: "What good is it to protect my house with a valve if my next-door neighbors do not? If their houses burn down, chances are mine will, too."

You may lose your home if neighboring houses catch fire. However, the chances are that you and your family will still have time to escape.

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