GB807146A - Improvements in apparatus for generating foam for use in fire fighting - Google Patents

Abstract

807,146. Fire-fighting foam generators. WHITSUN & CO. Ltd., J., and JOSEPH, A. May 17, 1957, No. 15718/57. Class 47. In a foam generating apparatus, nozzle means 22, within a casing 2, has a central convergent nozzle 24 and auxiliary jet apertures 26 radially spaced therefrom which divide a supply of liquid and foam compound under pressure from a pipe section 16 into a central jet and a plurality of auxiliary jets, the central jet being permitted to pass through a central passage 34 in an impeller 32 which is rotated under influence of the auxiliary jets, the vanes 36 of the impeller acting to draw in air between the casing 2 and nozzle means 22 in the direction of the supply of liquid and foam compound, the liquid, foam compound and air being intimately mixed by means provided on the side of the impeller 32 opposite the nozzle 22. The jet apertures 26 in the nozzle 22 are inclined with respect to the normal to the nozzle 22. A circular series of apertures 38 in the impeller 32, radially spaced from the passage 34 by an amount equal to the radial spacing of the apertures 26 and nozzle 24, are inclined in an opposite sense to the auxiliary jet apertures 26, whereby interaction of the auxiliary jets with the aver- -tures 38 causes rotation of the impeller. A peripheral passage 58 defined between members 56, 48, carried by a spider 46, direct the discharges from the apertures 38 inwardly into contact with the central jet discharging through a bore 50 in the member 48, thereby causing the intimate mixing of the liquid, foam compound and air. A cylindrical grating 62 having inwardly extending projections 64, maintains the mixture in its intimately mixed state. The impeller 32 is rotatable upon bearing surfaces provided by collars 30, 44 carried by the nozzle 22 and member 48 respectively.