A nozzle for introducing a gas into an area to be protected by an inert gas hazard-suppression system comprising: a nozzle housing having a gas inlet and a gas outlet; at least a first innermost partition and a second outer partition located within said housing, said first partition defining an inner gas-receiving chamber into which a gas flowing through said gas inlet is received, said first and second partitions (42, 44) cooperating to define a first annular region therebetween, said first annular region being fluidly connected with said inner gas-receiving chamber by a first passage located at the distal end of said first partition, said partitions (42, 44) being configured such that the gas flows in said first annular region in an opposite direction to the gas flowing in said inner gas-receiving chamber, said second partition partially defining a second annular region outboard of said second partition, said second annular region being fluidly connected with said first annular region by a second passage located opposite from said first passage, said second annular region being configured such that the gas flows in said second annular region toward said gas outlet in an opposite direction to the gas flowing in said first annular region, wherein said nozzle further comprises a nozzle stem having a pipe-receiving fitting at one end thereof and an axial bore formed therein operable to conduct the gas through said gas inlet, wherein said nozzle further comprises an inlet end plate having a central orifice, wherein the nozzle stem being inserted through said central orifice so as to direct the gas into the interior of said nozzle, wherein said nozzle stem comprises one or more ports for permitting flow of the gas from said bore into said inner gas-receiving chamber, wherein said first and second partitions (42, 44) are attached to an internal end plate, and wherein said nozzle stem includes a fastener-receiving bore formed in the end opposite from the fitting, said bore being configured to receive a bolt by means of which said internal end plate is secured to said nozzle stem. a nozzle housing having a gas inlet and a gas outlet; at least a first innermost partition and a second outer partition located within said housing, said first partition defining an inner gas-receiving chamber into which a gas flowing through said gas inlet is received, said first and second partitions (42, 44) cooperating to define a first annular region therebetween, said first annular region being fluidly connected with said inner gas-receiving chamber by a first passage located at the distal end of said first partition, said partitions (42, 44) being configured such that the gas flows in said first annular region in an opposite direction to the gas flowing in said inner gas-receiving chamber, said second partition partially defining a second annular region outboard of said second partition, said second annular region being fluidly connected with said first annular region by a second passage located opposite from said first passage, said second annular region being configured such that the gas flows in said second annular region toward said gas outlet in an opposite direction to the gas flowing in said first annular region, wherein said nozzle further comprises a nozzle stem having a pipe-receiving fitting at one end thereof and an axial bore formed therein operable to conduct the gas through said gas inlet, wherein said nozzle further comprises an inlet end plate having a central orifice, wherein the nozzle stem being inserted through said central orifice so as to direct the gas into the interior of said nozzle, wherein said nozzle stem comprises one or more ports for permitting flow of the gas from said bore into said inner gas-receiving chamber, wherein said first and second partitions (42, 44) are attached to an internal end plate, and wherein said nozzle stem includes a fastener-receiving bore formed in the end opposite from the fitting, said bore being configured to receive a bolt by means of which said internal end plate is secured to said nozzle stem.