Abstract: A ventilation device has a housing which can be connected with a fluid system to be ventilated. A float is movable in the housing, and controls a valve through an operating device for a ventilation process. The valve opens and closes a ventilation passage. The operating device has an operating magnet with exciter coil, which can be controlled electrically through a switch operable by the float. The operating magnet, with its switching part, operates to open the valve. The ventilating device can function without disturbance in operation, can be manufactured at low cost, can be used even with very high pressures, and, if necessary, can be monitored from a remote point.