Patent GB-405542-A (GB)
Title: Method of and apparatus for making foam for fire-extinguishing
IPC: B01F25/64
Filed: 1933-07-04
Abstract: 405,542. Making foam. ARMATUREN- & MASCHINENFABRIK AKT.-GES. VORM. J. A. HILPERT, 6, Glockenhofstrasse, Nuremberg, Germany. July 4, 1933, Nos. 19006, 19007, and 19008. Convention dates, July 4, 1932, July 18, 1932, and Nov. 17, 1932. [Class 47 (ii).] Air foam for fire-extinguishing is formed and forced to the point of use by means of a liquid ring pump. As shown in Fig. 1, the pump comprises the rotor 2 mounted eccentrically in the casing 1. Air enters the pump at 3 and water under low pressure is admitted to the suction chamber 8 by the pipe 7. Foam stabiliser enters with the air or the water, and foam is discharged at 4. In modifications, water under high pressure is admitted to the delivery chamber of the pump. Fig. 5 shows an apparatus adapted to operate with water from a tank or from a low or high pressure supply. In a casing 11, the rotors 13 and 14 of a centrifugal pump and a liquid ring pump are mounted on a driven shaft 12. The discharge chamber 21 of the centrifugal pump is connected by a passage 31 and non-return valve 32 to the liquid ring pump-chamber, and also to a bore 20 in which a spring-biassed slide valve 22 is arranged. An air intake 25 for the liquid ring pump is connected by a passage 24 to the suction chamber of the centrifugal pump, which has two closable water inlets 26, 27. In use, the inlet 26 is connected to a water tank and the shaft 12 is driven. Water is thus drawn in to the centrifugal pump together with foam stabiliser which enters through a pipe 19 and is atomised by blades 16 on the rotor 13. The mixed water and stabiliser discharged into the chamber 21 passes through the passage 31 to the liquid ring pump and, at the same time, forces out the slide valve 22, closing the passage 24 and opening the intake 25, so that air is drawn into the liquid ring pump. The latter discharges foam through the chamber 34 and outlet 35. If a high pressure water supply is available, this is connected to the inlet 27, which comprises a nozzle 30 which is so designed that the suction effort of the rotor 13 exceeds the pressure at the nozzle. In a modification, Fig. 6, the centrifugal pump rotor 39, having a water inlet 41, discharges to the liquid ring rotor 38 by a passage 42, chamber 49, and nozzle 50. An injector 45 in the passage 42 serves to draw in foam stabiliser through the conduit 46, 48. Air enters the liquid ring pump through the inlet 51, which can be connected to the water inlet 41 through a bore 59 and a passage 56 in a rotary valve 54. The valve 54 also comprises portions of the passages 42 and 51. When a high pressure water supply is connected to the inlet 41, the apparatus operates, with the parts in the position shown. If a low pressure or suction supply only is available, the cock 54 is turned through 180 until the air has been evacuated and water commences to flow, when the cock is returned to the position shown. The nozzles 50 assist in mixing the water and foam stabiliser. By arranging the nozzles midway between the inlet and outlet ports of the pump, and supplying water at a higher pressure than that obtaining in the smallest diameter of the liquid ring, the air in the ring can be compressed.