Method and system for extinguishing fire in an enclosed space

A system for suppressing a fire in an enclosed space, comprising:

• at least one nitrogen supply device selected from the group consisting of compressed nitrogen gas storage tanks and nitrogen gas generators, adapted to supply a first flow of nitrogen gas;
• a nitrogen preparation unit adapted to supply a second flow of nitrogen gas, at a lower maximum flow rate and for a longer maximum duration than said first flow of nitrogen gas supplied by said at least one nitrogen supply device, wherein said nitrogen preparation unit comprises a membrane system that selectively separates nitrogen gas from air, and wherein said membrane system has an air inlet and has a nitrogen outlet;
• at least one nozzle that is arranged in the enclosed space and that is adapted to emit nitrogen gas from said nozzle into the enclosed space;
• a pipe arrangement connecting said at least one nitrogen supply device and said nitrogen outlet of said nitrogen preparation unit to said at least one nozzle;
• and
• an exhaust air outlet channel and a valve interconnected between said exhaust air outlet channel and said air inlet of said membrane system to provide air to said air inlet.

A method of suppressing a fire in an enclosed space, comprising the steps:

• a) detecting a fire in an enclosed space;
• b) after said step a) and in response thereto, supplying a first flow of nitrogen gas at a first flow rate from at least one nitrogen supply device selected from the group consisting of a nitrogen gas storage tank and a nitrogen gas generator, into said enclosed space so as to reduce a prior oxygen concentration to a reduced oxygen concentration in said enclosed space;
• c) after said step b), supplying a second flow of nitrogen gas at a second flow rate from a nitrogen preparation unit including a membrane that is selectively permeable with respect to nitrogen, into said enclosed space so as to maintain said reduced oxygen concentration in said enclosed space, wherein said first flow rate is greater than said second flow rate;
• and
• d) extinguishing said fire because said reduced oxygen concentration is insufficient to sustain said fire.