| 摘要 |
A foam-generating assembly for use in generating a nitrogen-containing foam useful in preventing or extinguishing fires includes a foam generator, a first tank containing a foamable aqueous liquid and a second tank containing nitrogen gas, the foam generator including a header which is hollowed out to provide a swirl chamber defined by an outer cylindrical wall, an inner cylindrical wall and a floor, a spray nozzle in the center of the floor for spraying foamable aqueous liquid supplied from the first tank, and an orifice in the inner cylindrical wall to supply a tangential flow of nitrogen gas from the second tank into the swirl chamber and around the spray nozzle and the liquid spray emitted therefrom and provide a vortex flow of a mixture of foamable aqueous liquid and nitrogen gas. First and second foaming screens are provided through which the vortex flow passes to provide first a coarse nitrogen-containing foam and then a fine nitrogen-containing foam. The first foaming screen can be a inverted frustoconical element formed of three layers of metal mesh. The second foaming screen can be formed of two layers of metal mesh placed over a discharge outlet of the swirl chamber.
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