In accordance with the Pipeline and Hazardous Materials Administration (PHMSA), all natural gas operators are required to install an excess flow valve on all single residential service lines that operate at not less than 10 psi (pound per square inch of pressure).
What Excess Flow Valves Do
An excess flow valve is a device that will restrict gas flow in a customer's natural gas service line by automatically closing in the event that the service line is broken, cut completely, torn apart, or otherwise separated - usually caused by some type of excavation or digging. A natural gas service line is the piping from the gas main near the street to the customer meter set and runs underground through the customer's yard.
Excess Flow Valve Limitations
An excess flow valve will not protect against the following: