Gas Shutoff Valve

A gas shutoff valve is any valve that stops the flow of natural gas or propane to a specific appliance or to an entire building. Gas shutoff valves are installed at every gas appliance (water heater, furnace, range, dryer) and at the meter — the whole-building shutoff that utilities or homeowners close during emergencies. Unlike water shutoff valves that range widely in design, nearly all modern gas shutoffs use a quarter-turn ball valve: handle parallel to the pipe = open; handle perpendicular = closed.

Types of gas shutoff valves

• Meter shutoff (curb cock): at the gas meter, operated by the utility during emergencies. Homeowners can close it in emergencies but must call the utility to restore service — the utility will perform a pressure test and relight pilots before leaving.
• Building main shutoff: typically just after the meter, inside or outside the foundation. This is the valve homeowners should know to close for whole-house gas emergencies.
• Appliance shutoff (manual gas valve): individual quarter-turn ball valve at each appliance, on the gas supply line within 6 feet of the appliance connection. Required by code at every gas appliance.
• Flexible appliance connector: the corrugated stainless steel flex connector between the appliance shutoff and the appliance. Not a valve, but connected to the valve and a common point of failure — most jurisdictions require replacement every time an appliance is moved or serviced.

What to do in a gas emergency

If you smell gas strongly, don't operate any switches or look for valves — leave immediately, don't re-enter, and call 911 or your gas utility from outside. If you smell a very faint or localized gas odor (near a specific appliance after it was serviced), you can close the appliance shutoff valve and call a plumber. Never use flames or create sparks while investigating a possible gas leak.

Earthquake shut-off valves

In earthquake-prone areas, seismic gas shutoff valves (ASCE-listed) automatically close the main gas supply when they detect a seismic event — required or incentivized in California and other states.