January 2016, Vol. 243, No. 1
Features
Industry Becoming More Comfortable with Excess Flow Valves
When I first joined the natural gas industry in 1981, excess flow valves (EFVs) were the most controversial issue in distribution pipeline safety. EFVs are simple devices installed in gas-service lines at the connection to the main that remain open under normal flows but close if a surge in flow exceeds the EFV’s trip point, such as might occur if the service line is severed by excavation equipment. EFVs are inexpensive to install when a service line is first installed or later replaced, but significantly more expensive to retrofit on an existing service or replace if the valve fails or a customer installs gas-burning equipment that requires more gas than the EFV will allow through the serv
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