pressure between the side of the diaphragm of the reformer unit facing the anode side and the cathode side of the fuel cell module is held below a predefined value in addition fuel cell systems are provided for holding the differential pressure may contain a pressure relief valve which may be controlled by a sensor a bursting disk or a flow resistance or another controllable valve on the low pressure side upstream from the anode side of fuel cell unit application_number US 77742704 A description 0025 fig1 shows a schematic representation of a fuel cell system for carrying out the method the core of the fuel cell system is composed of a reformer unit 1 and a fuel cell unit 2 which are each indicated by dash two dots lines reformer unit 1 contains a reformer 3 and a diaphragm module 4 reformer 3 is connected to a fuel tank 7 such as a gasoline tank a diesel tank or a methanol tank for example via a line 5 and a controllable valve 6 furthermore reformer 3 is connected to a water tank 10 via a line 8 and a controllable valve 9 finally reformer 3 is connected to a compressor 12 having a suction line 13 via a line 11.