an external load circuit to the cathode side creating the current of electricity of the fuel cell stack on the cathode side the oxygen in the oxidant stream reacts with the protons permeating through the membrane and the electrons from the external circuit to form water molecules this reduction half cell reaction is represented by 4h 4e u2212 o 2 2h 2 o anode exhaust from the anode side flows through a backpressure control valve not shown to a combustor cathode exhaust from the cathode side flows through a second backpressure control valve not shown to the combustor a control module not shown regulates the conditions of the hydrogen stream oxygen stream and exhaust streams by operating various control valves not shown backpressure control valves not shown and compressors not shown in response to signals from pressure sensors not shown and electrical power sensors not shown connected to the fuel cell stacks 40 42 during operation of the fuel cell system the valve mechanism 10 is in fluid communication with the hydrogen source the first fuel cell stack 40 and the second fuel cell stack 42 a stream of hydrogen is caused to flow from the hydrogen source and through the inlet 22 into the valve mechanism 10 as the hydrogen flows into the valve mechanism 10 the actuator 12 is caused to rotate the rotor 18 by a controller not shown the rotor 18 is caused to rotate relative to the stator 16 to one of four positions based on input from the controller it is understood that the number of positions in which the rotor 18 may be positioned depends upon the size and shape of the rotor the number of fuel cell stacks to be supplied with hydrogen and other similar.