A nozzle apparatus for delivering a fire-retardant foam including a fluid delivery member having an interior passage of a given diameter, an expansion tube connected to the fluid delivery member, an agitator positioned within an interior passageway of the expansion tube and an aspiration port formed in the expansion tube. The interior passage of the fluid delivery member extends to a tapered region having a outlet orifice at a narrow end of the tapered region. The interior passage is connected to a wide end of the tapered region. The aspirator port is positioned between the outlet orifice and the agitator. The expansion tube has an interior passageway extending to an outlet opening opposite the fluid delivery member. The outlet orifice opens to the interior passageway of the expansion tube. The interior passageway has a greater diameter than a diameter of the outlet orifice. The agitator is positioned within the expansion tube so as to turbulently mix the solution with air within the interior passageway. The aspirator port allows air to enter the interior passageway of the expansion tube as the solution passes through the interior passageway of the expansion tube.

A foamer nozzle assembly has dual screens of intersecting strands in spaced sets of strands, the strands of one set being offset relative to the strands of the other set for establishing two turbulence zones as the flow direction of spray particles is deflected when passing through the first screen and as the flow direction of the spray particles is further deflected when passing through the second screen. The screens are located in a cylinder of the assembly which may or may not define a turbulence cylinder depending on the spacing of the screens from the discharge orifice. The screens may be spaced apart a given distance to establish a turbulence zone therebetween.

A device for generating foam by the Venturi effect mixes liquid and gaseous phases. The device has a liquid insertion nozzle on the same axis as a Venturi stage having a converging portion disposed facing the nozzle, a throat of diameter "D", and a gas inlet coaxial with the nozzle and in communication with the converging portion. In operation, the gas is sucked in by the Venturi effect and directed towards a mixing chamber connected to a foam outlet. Mixing between the two phases takes place in a free jet, and the diverging portion of the Venturi has at least three zones of progressive cone angles, with discontinuities between the zones giving rise to a cavitation phenomenon, and opening out into a turbulent chamber.

Apparatus for generating foam for use in fire fighting having two plates housed in a chamber which respectively introduce pressurized air and a water/surfactant solution between the two plates where foam is generated and emitted from an aperture on the side of the chamber. The pressurized water/soap solution enters the chamber through an orifice in one plate. Pressurized air enters the chamber through a number of channels bored through the other plate, such channels appearing in an annular grove which circumscribes the water inlet. The plates are provided with surfaces which are brought together to form a restricted area therebetween. The restricted area balances the pressure between the incoming water and the incoming air by achieving an equilibrium at some particular radius out from the center of the two plates. This equilibrium radius moves in and out from the center as necessary to keep the two pressures balanced. The apparatus also includes a pressure regulating system that automatically cuts off the flow of pressurized water and air when the foam dispensing nozzle is turned off.

Apparatus for generating foam for use in fire fighting having two plates housed in a chamber which respectively introduce pressurized air and water/soap solution into the space between the two plates where foam is generated and emitted from an aperture on the side of the chamber. Pressurized water/soap solution is introduced through an orifice into a small opening through one plate. Pressurized air is introduced into the other plate through a number of channels bored through the plate to an annular grove on the surface of the plate. The plates are provided with flat surfaces which are brought together to form a narrow gap. The narrow gap balances the pressure between the incoming water and the incoming air by achieving an equilibrium at some particular radius out from the center of the two plates. This equilibrium radius moves in and out from the center as necessary to keep the two pressures balanced. The incoming air pressure is set at a desired level, and the incoming water pressure is adjusted to a slightly higher initial pressure. The quality of the foam is then determined by further upward or downward adjustments of the water pressure.