NOVELTY - The gas generator (100) comprises a housing (102), a reactant that is contained within an interior portion of the housing and is capable of reacting to produce a hydrogen gas, and a gas outlet valve (106). The gas outlet valve comprises a valve body, a valve seat, a moveable valve member, a biasing member, a gas inlet port, a gas outlet port, and a gas flow path through the valve body. The gas flow path comprises the gas inlet port and the gas outlet port. The moveable valve member is biased by the biasing member against the valve seat to block the outlet port.    USE - The gas generator is useful for supplying a gas such as hydrogen to an apparatus (all claimed) such as fuel cell including a proton exchange membrane fuel cell, an alkaline fuel cell, a phosphoric-acid fuel cell, a solid oxide fuel cell and a molten carbonate fuel cell, where the fuel cell is useful as power sources for portable electronic devices and the gas generator is useful as a gas tank.    ADVANTAGE - The user-removable and refillable hydrogen gas generator can be reliably sealed to prevent gas leaks when gas generator is coupled or uncoupled to the fuel cell system and economically manufactured with long service life.    DETAILED DESCRIPTION - The gas generator (100) comprises a housing (102), a reactant that is contained within an interior portion of the housing and is capable of reacting to produce a hydrogen gas, and a gas outlet valve (106). The gas outlet valve comprises a valve body, a valve seat, a moveable valve member, a biasing member, a gas inlet port, a gas outlet port, and a gas flow path through the valve body. The gas flow path comprises the gas inlet port and the gas outlet port. The moveable valve member is biased by the biasing member against the valve seat to block the outlet port when the gas outlet valve is positioned in a closed configuration and a pressure within the gas generator is below a threshold pressure. The moveable valve member is displaced by an actuator insertable into the gas outlet valve from outside the gas generator such that the moveable valve member is separated from the valve seat and the outlet port is open so that the gas is supplied through the gas flow path to the apparatus when the gas outlet valve is present in a gas supplying configuration. When the gas outlet valve is present in a pressure relief configuration, the pressure within the gas generator is at or above the threshold pressure, the moveable valve member is separated from the valve seat and the outlet port is open so that pressure is released through the gas flow path to an external environment. The gas flows through the same gas flow path when the valve is present in the gas supplying configuration and the pressure relief configuration. The biasing member comprises a spring. The gas outlet valve comprises a seal member that forms a seal between the valve seat and the moveable valve member when the gas outlet valve is positioned in the closed configuration. The moveable valve member comprises a piston that is linearly moveable along a longitudinal axis of the valve. The gas generator has no additional pressure relief vent. An INDEPENDENT CLAIM is included for a fuel cell system.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic perspective view of a gas generator.    Gas generator (100)    Housing (102)    Valve assembly (104)    Gas outlet valve (106)    Valves. (108, 110)