GB806048A - Improvements relating to apparatus for the production of foam - Google Patents

Abstract

806.048. Mixing fluids in flow. PYRENE CO., Ltd. May 9, 1955 [May 20, 19541, No. 14906/54. Class 86 [Also in Group XXI] A fire-fighting crash tender providing high pressure air-foam jets from a projector 13 and from hoses connected at 14, 15, has a water tank 1, a foam solution tank 2 and a foam generator 8 of the injector type to which air is supplied under pressure from a blower 7 driven by the engine 4 of the vehicle, the blower shaft being coupled at 6 to a pump 9 which draws water from the tank 1 and delivers it to the generator through a pipe 17. The foam solution is drawn from the tank 2 by water passing 'to an inductor 10 through a pipe 23 branching from the pipe 17 and is delivered into the main suction of the pump 9. Foam from the generator passes through a pipe 11 to the projector 13 and hose connectors 14, 15. At maximum output, the blower and pump give the required relative amounts of air and liquid; at lower outputs, when excess air would otherwise be supplied, provision is made in the generator to bleed off the surplus air and so maintain the correct airliquid ratio. The generator comprises a casing 16 to which is connected the water-foam solution pipe 17, the liquid passing through an orifice 18 to mix with the air from the blower entering through a pipe 75. The liquid flow through the orifice 18 is controlled by a needle valve 21, the valve rod 38 of which can be moved axially by an arm 72 on a shaft 44 actuated from the cab of the tender. The air pipe 75 has a branch connected to the end of a casing 32 secured to the casing 16 and having an outlet 34 to atmosphere. The air flow in the branch pipe is controlled by a mushroom valve 36 carried on a rearward extension of the rod 38, the valve 36 being fully closed when valve 21 is fully open so that at full output all the air is delivered to the foam generator. If the demand for foam decreases, the valve 21 is partly closed, whereupon valve 36 opens to allow the surplus air to discharge through port 34, the engine speed being reduced as necessary to maintain a constant pressure in the pipe 17. The optimum proportion of foam solution in the water entering the generator is automatically maintained by mechanically linking the valve rod 38 to the movable throat member 26 of the inductor 10 which is of the form described in Specification 772,604.