Method and apparatus for extinguishing a fire in an enclosed space

A system for fighting a fire in an enclosed space has at least one container for holding a fire extinguishing agent under pressure. A pipe system connects a container outlet to a discharge in the enclosed space. A controllable flow control valve in the pipe system is responsive to a flow control signal generated by a control unit in response to sensed characteristics (pressure and/or temperature) of the agent. A trigger action initially opens the container to the pipe system. The valve is initially held open until concentration (A) of fire extinguishing agent in the enclosed space is sufficient to suffocate a started fire. Thereafter, the valve is opened intermittently to maintain a lower concentration of fire extinguishing agent in the space sufficient to prevent rekindling. More than one container may be used but only one is equipped with a valve controllable by a control unit.