During the refilling of a liquid tank, the air in the interior of the liquid tank is displaced by the liquid inserted therein. In order to remove the displaced air from the liquid tank, use is made of special vent valves. Vent valves of this type may be bulky and take up a relatively large amount of construction space.
The document EP 2 008 857 A1 describes, for example, a fuel tank for a motor vehicle, with a vent valve which has a valve housing and a vent opening and is inserted in an upper opening in the tank and protrudes into the interior of the tank and in which a wall opening passes through the wall of the valve housing. A float which is movable between an inoperative position and a closed position is located in the valve housing.