Abstract:
A liquid mist fire extinguisher, comprising a container for holding a gas and a liquid under pressure. The extinguisher has valve assembly at the upper end of the container, a valve for simultaneously releasing said gas and said liquid separately from the container, and a hose for feeding said gas and said liquid separately through a nozzle. The nozzle assembly includes longitudinal and radial inlets for feeding said gas and said liquid separately through a mixing chamber, and exiting orifices in an end surface of said nozzle assembly for issue of mixed gas and liquid in a fine mist.

Description:
FIELD OF INVENTION 
     This invention relates to a liquid mist fire extinguisher and more particularly a low pressure water atomizing fire extinguisher. 
     BACKGROUND TO THE INVENTION 
     Fires are classified as A, B, C or D as follows: Class A: ordinary combustibles; Class B: flammable liquids; Class C: electrical fires and Class D: flammable metals. Fire extinguishers are certified in Canada and the United States by ULC and UL respectively according to their effectiveness in suppressing the fires of the various classes. A standard extinguisher with an A:B:C rating for example, is effective in suppressing A, B and C class fires. 
     To achieve an A:B:C rating, extinguishers to date have used either dry chemicals or halon. The use of dry chemicals results in a messy and sometimes toxic cleanup. Halon is a clean alternative but has been banned by the Montreal Protocol on Substances that Deplete the Ozone Layer. 
     Water has also been used but prior art water extinguishers have not achieved an A:B:C rating. The standard water extinguisher for example discharges a solid stream of water from a pressurized canister and has a limited Class 2A rating. 
     Another type of known water extinguisher discharges a spray of water droplets and utilizes the same amount of water as the standard extinguisher. This extinguisher typically operates at about 100 psi. While this water extinguisher has been rated A:C, it does not generate the fine atomized mist required for a class B rating. 
     It is a feature of the present invention to provide an extinguisher in which water and air are stored together and released simultaneously and separately to produce a fine liquid mist, capable of class A:B:C rating. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided an apparatus for producing a fine liquid mist, comprising a container for holding a gas and liquid under pressure; valve means for simultaneously releasing said gas and said liquid separately from said container; feed means for feeding said gas and said liquid separately to a nozzle; said nozzle including a mixing chamber and outlet orifices for emission of said liquid mists. 
     In another embodiment of the present invention, there is provided a release valve for simultaneously releasing a gas and a liquid separately from a pressurized container, comprising a first valve controlling a liquid outlet from said container; a second valve controlling a gas outlet from said container; means for feeding said liquid and said gas separately from said valves; means for actuating said valves, simultaneously. 
     In a further embodiment of the present invention, there is provided a liquid mist fire extinguisher, comprising a container for holding a gas and a liquid under pressure; a valve assembly at an upper end of said container; valve means for simultaneously releasing said gas and said liquid separately from said container; a hose for feeding said gas and said liquid separately through a nozzle; said nozzle assembly including means for feeding said gas and said liquid separately through a mixing chamber, and exiting orifices in an end surface of said nozzle assembly for issue of mixed gas and liquid in a fine mist. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section of a fire extinguisher according to the present invention; 
     FIG. 2 is a cross-section of the valve structure at the top of the extinguisher of FIG. 1, to a larger scale, and at right angles to that of FIG. 1; with valve closed; 
     FIG. 3 is a cross section similar to that of FIG. 2, with valve open; 
     FIG. 4 is a cross section of the valve structure, on the axis of the cross section of FIG. 1; 
     FIG. 5 is a longitudinal cross section through the nozzle; 
     FIG. 6 is an end view on the end of the nozzle member, in the direction of arrow A. 
     FIG. 7 is a cross-section of another embodiment of the valve structure of the present invention, on the axis of the cross-section FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The drawings illustrate a fire extinguisher assembly having an A,B and C rating comprising a pressure container  10  of approximately 12 L capacity having at its upper end a valve structure  12 , and flexible hose  14  with a relatively ridged wand portion  16 , and a nozzle assembly  18  at the end of the wand  16 . The valve structure  12  closes the upper end of the container which, in use contains a liquid, for example, water, and its lower portion  20  and a pressurizing gas, for example, air at its upper portion  22 , the gas/liquid in the phase shown at  24 . A tube  26  extends down and from the valve structure  12  towards the bottom of container, finishing a short distance above the bottom. The tube is connected at its upper end to the valve structure  12 . 
     Considering FIGS. 2 and 3 specifically, the valve structure  12  comprises a main body  30 , which is attached, by a fitted threaded connection  32  to a neck portion  34  at the upper part of container  10 . The body  30  has a central longitudinal extending bore, having a varying dimension along its length. At its lower end  36 , the bore is enlarged and receives the upper end of the tube  26 , again conveniently a threaded connection. The bore is then tapered inwardly to form a valve seat  38 . The bore enlarges, at  40 , to form a fluid passage, described later in connection with FIG.  4 . Above the enlargement  40 , the bore decreases in size to form an elongate tubular seating at  42 . Above the valve seat  42 , the bore is enlarged and a plug  44  is inserted to close off the bore, and also to form a chamber which serves as a transfer passage  46 , again described in more detail with respect to FIG.  4 . The plug  44  has a central bore  48  and extending through the bore is an elongate valve member  60 . At its lower end, the valve member has a tapered valve member  62  which cooperates with tapered valve seat  38 , while at an intermediate position, an extended valve portion  64  cooperates with the tubular seating  42 . Valve member  62  and valve seat  38  acts to control flow of liquid from container. The upper end of valve portion  64  acts with the upper end of seating  42  to control flow of gas from the container. 
     A further bore  70  extends up through the body  30  and connects to a radial bore  72  extending to the central bore to form a port  76 , between the enlargement  40  and the passage  46 . The outer end of the radial bore  72  is closed by a plug  78  which can be used to provide a connection to a pressure gauge. Considering the valve portion  64 , a reduced diameter portion  66  on the valve member  60  connects with the passageway  46  only, in a closed position, as in FIG. 2, and connects passageway  46  with port  76 , in an open position, as in FIG.  3 . 
     The upper end  80  of the valve member  60  extends beyond the plug  48 . A lever  82 , see FIG. 1, is pivotally mounted on the end of the body  30  and extends over the outer end  80 . A compression spring  81  is mounted on the outer end  80  of the valve member  60  to bias the valve member to a closed position. Pressure by the lever  82  on the outer end  80  of the valve member  60  will open the valves. Various seals are provided for the valve member  60 . An O-ring  84  is provided between the passage  46  and the upper end surface of the body  30 , in the example of the plug  48 , to prevent leakage from the top end. Two further O-rings  86  and  88  are spaced apart in the valve portion  64  to prevent leakage from port  76  to the passage  46  and enlargement  40  in the valve closed position, and to prevent leakage from the port  76  to the enlargement  40  in the valve open position. O-rings  100  and  102  can be provided in a conventional manner to seal threaded connections  32  and the threaded connection between the plug  44  and the upper end of the body  30 . 
     FIG. 4 illustrates the attachment of the flexible hose  14  to the valve body  30 , with connections to the enlargement  40 , and also connection of a flexible tube  110 , inside the hose  14  to the passage  46 . The hose  14  is connected to the body  30  via a threaded connection  112  in a bore  114  connecting to the enlargement  40 . The tube  110  extends up through a bore  116  in the top part of the body  30  to connect to the passage  46 . As seen in FIG. 1, the tube  110  extends through the hose  14  and wand  16  to a nozzle assembly  18 . 
     When the valves are closed, neither the liquid nor gas can flow from the container  10  to the nozzle assembly  18 . Pushing down on the lever  82  opens the valves to a position as seen in FIG.  3 . Liquid escapes up past the lower end of the valve member  60  into the enlargement  40  and up through bore  114  and connection  112  into the hose  14 . Simultaneously, air escapes through bores  70  and  76 , recess  66 , passage  46  and then through the tube  110  to nozzle  18 . 
     One form of nozzle assembly  18  is illustrated in FIG.  5 . This assembly has a nozzle member  120  attached to the end of the wand  16  and an internal member  122  to which the tube  110  is attached. The orifice formed in the internal member  122  is preferably 0.75-1.5 mm in diameter. The member  122  is connected to the nozzle member  120  and a passage  124  provides access, via a port  125 , to a mixing chamber  126  for the liquid in the wand  16 . Port  125  is preferably 2-3.5 mm in diameter. Liquid enters the mixing chamber  126  at right angles to the longitudinal axis of the nozzle  18 . Gas can flow through a central bore  128  of the member  122  into the mixing chamber  126 . The nozzle member  120  is circular in cross section, and has a closed end with a number of orifices  132 . One arrangement is seen in FIG.  6 . The closed ends in face  130  are angled with respect to the longitudinal axis preferably in the range of 60° to 75°. 
     The gas enters the mixing chamber in a longitudinal direction and combines with the jet of liquid that is entering the mixing chamber at port  125 . Thus, this will produce a gas/liquid mixture. The mixture exits the chamber through the orifices  132 , resulting in further expansion and further atomization of the liquid. The orifice pattern combined with the amount of atomization and end face angles produces the described mist pattern. 
     To charge the container  10 , about 6 L of liquid, for example water is placed in the container. The gas, for example air, is fed into the upper part of the container  10  through the wand  16  by removing the nozzle  120  and replacing it with an air valve (not shown). The gas source means is connected to the air valve, the valves are opened and air is fed into the container  10 . After pressurization, the nozzle is replaced. Pressurization in this manner minimizes later tampering. As an alternative, the gas is fed through bore  72  by removing plug  78 . As a further alternative, a pressure gauge can be permanently mounted at the bore  72 , and this can be provided with a T-shaped valved connection having an air valve for connection of a pressurized source of gas. The gas is generally pressurized initially to a maximum pressure of about 175 pounds per square inch. 
     FIG. 7 illustrates an alternate embodiment of the valve structure  12 . The central longitudinal extending bore above enlargement  40  is not enlarged eliminating the need for a plug such as plug  44  in FIG. 4 to close off the bore. The bore  116  extends through the top of the valve body  30 . The top of the bore  116  is closed by a plug  31 . A second bore  33  serves as a transfer passage in place of the chamber  46  (see FIG.  4 ), and is closed by plug  37 . The valve structure  12  is otherwise the same as the previous embodiment including the tube  110  which extends up through bore  116 . 
     A carrying handle can be attached through the valve structure  12  as seen in FIG.  1 . The container is shaped so that such can normally stand upright on a surface.