Gas flow is controlled only at the appliance where the problem exists.
Automatic Excess Flow Shut-Off Connectors: In the case of a gas rupture or a disconnect from the appliance, TSC EFV detects increase of gas flow and immediately shut-off the supply of gas. 1/2 Inch OD X 3/8 Inch ID, 1/2 Inch MIP x 1/2 Inch FIP 60 Inch SS Gas Connector W/ EFV Thrifco Plumbing 4408993 1/2 Inch OD X 3/8 Inch ID - 1/2 Inch MIP x 1/2 Inch FIP 60 Inch Long Yellow Epoxy Coated Stainless Steel Flexible Gas Connectors with EFV Gastop.