Fast-acting shutoff valve

A fast-acting shutoff valve is the remotely operated, fail-closed master valve at a fuel or cargo tank outlet that isolates the supply within a few seconds on emergency demand. On gas-fueled ships the IGF and IGC Codes require such a valve in the gas supply line, closing automatically on leak detection, fire, loss of ventilation, or manual trip so the fuel source is cut off at the tank. The valve is spring-return or hydraulic with the trip routed through the emergency-stop and gas-detection logic, separate from the normal process control, to give an independent safety isolation.