A device for an inert gas installation (5) on a floating vessel, comprising one or several tanks (1) arranged in a manner allowing filling of an explosive liquid (11) via suitable means (13, 14) associated therewith, and/or a gas (12), wherein an air inlet system (3) is connected to the tank (1), wherein the inert gas installation (5) is provided with a shutoff valve (51) arranged to automatically allow closing of an inert gas supply conduit (52), wherein the tank (1) is provided with a sensor (53) arranged to respond to a defined, ambient moisture and pressure level, the sensor (53) also being connected to a valve control system (7), thereby providing control signals to the valve control system (7). The invention also concerns a method of using the device.