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.
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit of U.S. Provisional Application No. 60/566,327, filed Apr. 29, 2004, the contents of which are incorporated herein by reference.
An additive tank for a vehicle having an internal combustion engine, the tank including a flexible bag which contains the additive and is connected to a device allowing the flexible bag to be pressurized in order to meter the additive.
