Device for aerating and ventilating a fuel tank

The valve unit (1) has a tank shutoff valve (2) and tank pressure control valves such as vacuum valve (3) and pressure relief valve (4). The vacuum valve is opened automatically when negative pressure exists in fuel tank. The pressure relief valve is opened automatically when positive pressure exists in the fuel tank. The pressure control valves are operated independent of each other according to negative pressure and positive pressure in the fuel tank. The pressure control valves are arranged within the fuel tank. The tank shutoff valve is provided outside fuel tank.