GB529225A - Method and apparatus for producing fire foam - Google Patents

Abstract

529,225. Fire-extinguishing. MACANDREWS & FORBES CO. May, 25, 1939, No. 15549. Convention date, April 14. [Class 47 (ii)] Apparatus for producing fire extinguishing foam of the mechanical or air type comprises a rotary compressor having inlet 10, Fig. 1, and outlet 11, an air supply conduit with inlet 22 connected to the compressor inlet 10 and dry foam producing compound as a predetermined uniform rate from a rotary container 5 by a knife 30 to air inlet 22. Water at a predetermined constant rate is supplied from a tank 3 by a cock 34 and pipe 33 to a vessel 20. The compressor agitates and mixes the regulated supply of water, air and foam and discharges it from the outlet 11 at substantial pressure. The compressor comprises a rotary pump of the water ring type with a rotor 7 having blades 8 revolving within an elliptical casing 9. Additional inlet ports 12, 13 open to the rotor chamber from the casing while outlet ports 14, 15 exhaust from the rotor chamber 10 the casing 9 and outlet 11. The foam producing compound is fed from a hopper 23 past a disc 24 secured on a vertical shaft 25. Gear teeth are driven by spur gearing 27 driven from a motor 28. Water is kept at a constant level by a float 37 and valve 36. Additional water is supplied to the compressor by a pipe 43 controlled by a valve 45. In a modification, Fig. 3, the water reservoir is eliminated and water is supplied to a vortex mixer 38 through a pipe 39a under control of a valve 40. A branch pipe 39b controlled by a valve 46 is connected to a pump 6a so that relative amounts of water admitted to the vortex 38 and directly to the pump 6 may be controlled. Dry feeding from a table 24a is the same as before. Materials for producing foam comprise saponin, liquorice extract, tan bark extract, together with an alkaline earth oxide such as calcium, barium or strontium. The compressor may be driven at 3700 r.p.m. and the discharge pressure may be from ten to forty pounds per square inch depending on the length of foam piping.