A
system for suppressing fire in an enclosed space, e.g. an aircraft cabin or freight compartment, includes
nitrogen tanks and / or generators to rapidly supply a limited quantity of
nitrogen with-a high flow rate, and a membrane
system to supply an essentially unlimited quantity of
nitrogen at a lower supply rate for a long duration. The membrane
system includes a selectively permeable membrane that separates
nitrogen gas from ambient environmental air that is supplied into the membrane system. Once a fire is detected, nitrogen is supplied from the
nitrogen gas tanks and / or generators at a
high rate to rapidly increase the nitrogen concentration and establish a reduced
oxygen concentration (e.g. 12 vol. %) in the enclosed space. Then, nitrogen is supplied from the membrane system at a reduced rate for a long duration to maintain the reduced
oxygen concentration in the enclosed space until the fire is extinguished by
oxygen starvation.