The invention relates to a conveyor system, which serves for conveying bulk goods and has at least one transmitter and at least one receiver which are fluidically connected to one another by a suction line system. At least one suction fan is connected to the suction line. The flow cross-section can be closed by at least one non-return valve element (8), which is arranged in the region between the transmitter and the receiver in the suction line system. The valve device has a housing (1) in which at least one non-return valve element (8) is accommodated, by which an inlet (4) of the housing (1) can be closed. The non-return valve element (8) can be moved out of a closed position into a released position by means of at least one actuating element (24), which is connected to a piston (25) which is subjected on one side during suction conveying of the bulk goods to the negative pressure prevailing in the housing (1) and on the other side to a higher pressure.