Pacita's Quick Bytes of Real Estate: Gas Shut Off Valve is an ordinance in Alameda CA

In addition to installation of smoke detectors, strapping of water heaters, testing/repairing/replacing sewer lateral, one of the government requirements to close escrow in Alameda is installation of a gas cut off valve.

Automatic gas cut off valve ensures that the gas is shut off in case of a major earthquake. They are recommended, and in some cities in California, are now mandated when a home is sold. In Alameda, the cost of installation varies, but typically, the one-time cost will run around $525.

Although I haven't seen any links on the City of Alameda's website for a detailed explanation about gas cut off valve, I found a good site and FAQ on the Southern California Gas Company's website that addresses natural gas earthquake shut off valves.

A natural gas earthquake shut-off valve automatically shuts off your gas service when an earthquake of a sufficient magnitude occurs at your home's location.

After the quake has stopped and you have determined that it is safe to do so, follow the manufacturer's instructions for restoring your gas service. You will need to make sure no gas leaks exist and re-light your pilot lights. You must ensure that your appliances are safe before operating them.

In many situations, you should call your local natural gas service provider to re-light the pilot lights.

ALAMEDA LOCAL ORDINANCE

In Alameda, there are specific  provisions itemized in the Local Ordinance disclosure

Effective January 1, 2008, the City of Alameda requires that "buildings that have natural gas service shall have installed an earthquake actuated gas shutoff valve...if either of the following situations exist:

1. The property is being sold or
2. The homeowner has issued a permit for gas piping.

In the case where the property is being sold, the code requires that the valves must be installed prior to close of escrow. "

Now, when people ask me to explain gas cut off valve, I have this as a reference.