Air-dropped fire-extinguishing bomb

Abstract

Provided is an air-dropped fire-extinguishing bomb 1 to be dropped from the air, the air-dropped fire-extinguishing bomb characterized by including a hollow body 2 and a fire-extinguishing agent 3, the hollow body 2 having a wall part containing diatomaceous earth, the fire-extinguishing agent 3 filling the interior of the hollow body 2, and the fire-extinguishing agent 3 being an inorganic fire-extinguishing agent in powder form. Also provided is a method for extinguishing fires, the method characterized by using the air-dropped fire-extinguishing bomb 1 by loading the air-dropped fire-extinguishing bomb 1 onto a transport aircraft and dropping the air-dropped fire-extinguishing bomb 1 toward the scene of a fire from the air over said scene of a fire.

Description

Air-dropped fire extinguishing grenades

[0001] The present invention relates to an air-dropped fire extinguishing grenade. More specifically, the present invention relates to an air-dropped fire extinguishing grenade that can efficiently and accurately spray fire extinguishing agents at the scene of a fire, such as a forest fire, and that is made of environmentally friendly materials.

[0002] A drop-type fire extinguishing bomb has been proposed for use by a flying object such as a helicopter or airplane for dropping from the air onto a fire scene. The drop-type fire extinguishing bomb includes a main container filled with fire extinguishing material, a fastener for sealing the opening in a steady state, a position maintaining means for maintaining the opening in a dropping direction, an altitude detecting means, a timer, and an opening means activated by the output of the altitude detecting means or the timer for opening the fastener (see, for example, Patent Document 1). However, with this drop-type fire extinguishing bomb, when the fire extinguishing material is sprayed from the drop-type fire extinguishing bomb in the air, the fire extinguishing material is fanned and dispersed in the air by fire tornadoes, atmospheric circulation, and other factors, making it difficult to accurately drop the fire extinguishing material onto the fire scene and therefore unable to effectively extinguish the fire. Furthermore, the use of a timer and other components in the drop-type fire extinguishing bomb makes its structure complex, and metal parts such as the timer may fall and cause adverse effects on the natural environment.

[0003] As a fire extinguishing ball used as a fire extinguishing bullet, a fire extinguishing ball filled with a powder fire extinguishing agent and made of a material such as glass or synthetic resin has been proposed (see, for example, Patent Document 2). However, a fire extinguishing ball made of glass has low fire extinguishing efficiency because the fire extinguishing agent filled in the ball is not efficiently scattered due to glass fragments generated when the ball is broken. Furthermore, a fire extinguishing ball made of synthetic resin has low fire extinguishing efficiency because the synthetic resin burns during fire extinguishing.

[0004] As a fire-extinguishing and fire-spread retardant suitable for extinguishing or suppressing the spread of large-scale fires such as forest fires, a fire-extinguishing and fire-spread retardant composition containing a phosphorus salt, a potassium salt, and a dispersion medium, and a container for containing the fire-extinguishing and fire-spread retardant composition have been proposed (see, for example, Patent Document 3). However, because the container of the fire-extinguishing and fire-spread retardant is made of biodegradable plastic, the biodegradable plastic burns during fire extinguishing, resulting in low fire-extinguishing efficiency.

[0005] As a dropped fire extinguisher for extinguishing a fire by dropping it on a fire scene, a dropped fire extinguisher in which a gel-like fire extinguishing agent is filled inside a water-permeable bag has been proposed (see, for example, Patent Document 4). However, the dropped fire extinguisher uses a flammable material, such as paper, kenaf, wood pulp, polyethylene terephthalate (PET), polypropylene, or polyethylene, for the bag, and therefore the bag burns during fire extinguishing, resulting in low fire extinguishing efficiency.

[0006] As a container for suppressing or extinguishing wildfires, a container has been proposed in which a shell containing a solid agent is filled with a slurry, liquid, or gaseous agent (see, for example, Patent Document 5). However, since the shell of the container contains solid carbon dioxide, ice, or the like, a large-scale refrigeration facility is required when transporting the container, making it impractical to drop the container from the air.

[0007] Japanese Patent Laid-Open No. 8-229153 Japanese Utility Model Laid-Open No. 52-78399 International Publication No. 2021 / 181957 International Publication No. 2015 / 129767 Special Publication No. 2003-533302

[0008] In recent years, there has been an urgent need to develop air-dropped fire extinguishing bombs that can be used to efficiently extinguish forest fires and other fires from the air using flying objects such as helicopters, and that do not have a negative impact on the natural environment even when they fall to the ground.

[0009] The present invention has been made in view of the above-mentioned prior art, and has as its object to provide an air-dropped fire extinguishing bomb which has little adverse effect on the global environment when it falls to the ground, and which can be dropped from the sky and has its wall easily destroyed when it collides with a fallen object such as a forest on the ground, so that the extinguishing agent filled inside the fire extinguishing bomb can be efficiently and accurately dispersed on the ground to effectively extinguish a fire.

[0010] Another object of the present invention is to provide a fire extinguishing method using an air-dropped fire extinguishing bomb, which is unlikely to have a negative impact on the global environment even when it falls to the ground, and which can be loaded onto an air transport aircraft and dropped from above the fire site toward the fire site, so that the wall of the fire extinguishing bomb is easily destroyed when it collides with a fallen object such as a forest, and the fire extinguishing agent filled inside can be efficiently and accurately sprayed on the ground to effectively extinguish the fire.

[0011] The present invention relates to: (1) an air-dropped fire extinguishing bomb that is dropped from the air, comprising a hollow body and a fire extinguishing agent, wherein the hollow body has a wall containing diatomaceous earth, the fire extinguishing agent is filled inside the hollow body, and the fire extinguishing agent is a powdered inorganic fire extinguishing agent; (2) the air-dropped fire extinguishing bomb according to (1) above, wherein the wall of the hollow body further contains gypsum, and the mass ratio of diatomaceous earth to gypsum (diatomaceous earth / gypsum) is 30 / 70 to 70 / 30; (3) the air-dropped fire extinguishing bomb according to (1) above, wherein the gypsum is calcium sulfate 0.5 hydrate; and (4) a fire extinguishing method using the air-dropped fire extinguishing bomb, in which the air-dropped fire extinguishing bomb according to (1) above is loaded onto an air transport aircraft and dropped from above the fire site toward the fire site.

[0012] According to the present invention, there is provided an air-dropped fire extinguishing bomb which has little adverse effect on the global environment even when it falls to the ground, and which can be dropped from the sky and has its wall easily destroyed when it collides with a falling object such as a forest on the ground, thereby efficiently and accurately scattering the extinguishing agent filled inside the fire extinguishing bomb on the ground to effectively extinguish a fire.

[0013] Furthermore, according to the present invention, a fire extinguishing method using an air-dropped fire extinguishing bomb is provided in which an air-dropped fire extinguishing bomb that does not have a negative impact on the global environment even when it falls to the ground is loaded onto an air transport aircraft, and the air-dropped fire extinguishing bomb can be dropped toward the fire site from above the fire site, and the wall of the fire extinguishing bomb is easily destroyed when it collides with a fallen object such as a forest, allowing the fire extinguishing agent filled inside to be efficiently and accurately sprayed on the ground, thereby effectively extinguishing the fire.

[0014]

[0023] Figure 1 is a schematic explanatory diagram of a vertical cross section of one embodiment of an air-dropped fire extinguishing bomb of the present invention. Figure 2 is a schematic explanatory diagram of a vertical cross section of another embodiment of an air-dropped fire extinguishing bomb of the present invention. Figure 3 is a schematic explanatory diagram showing a schematic diagram of one embodiment of a method for manufacturing an air-dropped fire extinguishing bomb of the present invention. Figure 4 is a schematic explanatory diagram showing a schematic diagram of another embodiment of a method for manufacturing an air-dropped fire extinguishing bomb of the present invention. Figure 5 is a photograph, substitute for a drawing, of firewood burning vigorously in a drum before a simulated fire extinguishing test was conducted using an air-dropped fire extinguishing bomb of the present invention. Figure 6 is a photograph, substitute for a drawing, of a crane truck used when conducting a simulated fire extinguishing test using an air-dropped fire extinguishing bomb of the present invention. Figure 7 is a photograph, substitute for a drawing, of firewood in a drum after a simulated fire extinguishing test was conducted using an air-dropped fire extinguishing bomb of the present invention.

[0015] The air-dropped fire extinguishing shell of the present invention is a fire extinguishing shell dropped from the air and has a hollow body and a fire extinguishing agent. The fire extinguishing agent is filled inside the hollow body.

[0016] The air-dropped fire extinguishing grenade of the present invention will be described below with reference to the drawings, but the present invention is not limited to the embodiments shown in the drawings.

[0017] Fig. 1 is a schematic explanatory diagram of a vertical cross section of one embodiment of the air-dropped fire extinguishing bomb of the present invention, where the air-dropped fire extinguishing bomb 1 has a spherical cross section. Fig. 2 is a schematic explanatory diagram of a vertical cross section of another embodiment of the air-dropped fire extinguishing bomb of the present invention, where the air-dropped fire extinguishing bomb 1 has a capsule-shaped cross section.

[0018] The hollow body 2 has a wall 2a of the air-dropped fire extinguishing bomb 1. The wall 2a contains diatomaceous earth. Diatomaceous earth is a natural mineral formed by the fossilization of diatoms (phytoplankton), and is non-flammable. When the diatoms die and deposit, the silica shells become diatomaceous earth over a long period of time. Diatomaceous earth was once recognized in Japan as edible soil, and there are records that it was used within the inner walls of Kumamoto Castle in Japan to store food during sieges.

[0019] In this way, since the wall 2a of the air-dropped fire extinguishing bomb 1 contains diatomaceous earth, even if the air-dropped fire extinguishing bomb 1 is dropped from the sky, reaches the ground, and destroys the wall 2a of the hollow body 2, causing the wall 2a of the hollow body 2 to scatter on the ground, the diatomaceous earth used in the wall 2a is unlikely to have an adverse effect on the global environment, and the air-dropped fire extinguishing bomb 1 can be used as an environmentally friendly fire extinguishing bomb.

[0020] The average particle diameter of diatomaceous earth is preferably 10 to 300 μm, and more preferably 50 to 300 μm, from the viewpoint of easily destroying the wall 2 a of the hollow body 2 when the air-dropped fire extinguishing shell 1 hits a fallen object such as a forest where a fire is occurring, and efficiently and accurately dispersing the fire-extinguishing agent filled inside the hollow body 2 on the ground. Here, the average particle diameter of diatomaceous earth means the mode diameter, which is the average of the maximum diameters of diatomaceous earth particles observed under an electron microscope.

[0021] Diatomaceous earth is readily available commercially. Examples of commercially available diatomaceous earth include those manufactured by Showa Chemical Industry Co., Ltd. under the trade names Radiolite #200, Radiolite #300, Radiolite #500, Radiolite #600, Radiolite #700, Radiolite #800, Radiolite #900, Radiolite #2000, and Radiolite #3000; and those manufactured by Chuo Kasei Co., Ltd. under the trade name Oplite W3050, but the present invention is not limited to these examples.

[0022] The inventors have fabricated fire extinguishing bullets with walls made of materials such as glass, kaolin, paper clay, clay, and mortar, and conducted air drop tests using these fire extinguishing bullets. As a result, it was confirmed that the fire extinguishing efficiency of these bullets was low because the walls of the hollow bodies of the fire extinguishing bullets were difficult to destroy efficiently, or even if the walls of the hollow bodies were destroyed, the fire extinguishing agent filled inside them was difficult to scatter efficiently.

[0023] In contrast, when an airborne drop test was conducted using an air-dropped fire extinguishing bomb 1 in which diatomaceous earth was used for the wall 2a of the hollow body 2, it was found that, unlike the above-mentioned fire extinguishing bomb, the wall 2a was easily destroyed when it collided with the dropped object, and the fire extinguishing agent filled inside the fire extinguishing bomb was efficiently and accurately dispersed on the ground, thereby improving fire extinguishing efficiency.

[0024] Since the air-dropped fire extinguishing bomb 1 uses diatomaceous earth for the wall 2a of the hollow body 2, the wall 2a of the hollow body 2 is easily destroyed when it collides with a dropped object, allowing the extinguishing agent filled inside the fire extinguishing bomb to be efficiently and accurately dispersed on the ground, thereby achieving the excellent effect of increasing fire extinguishing efficiency.

[0025] In the present invention, the wall 2a containing diatomaceous earth may be composed only of diatomaceous earth, or may contain raw materials other than diatomaceous earth as long as the object of the present invention is not impaired. Therefore, the wall 2a of the hollow body 2 may be composed only of diatomaceous earth, or may contain raw materials other than diatomaceous earth as long as the object of the present invention is not impaired. From the viewpoint of improving fire extinguishing efficiency, the raw materials other than diatomaceous earth are preferably inorganic materials other than diatomaceous earth.

[0026] Examples of inorganic materials other than diatomaceous earth include gypsum, alumina, silica, titania, zirconia, magnesia, yttria, zinc oxide, iron oxide, silicon nitride, titanium nitride, boron nitride, silicon carbide, light calcium carbonate, heavy calcium carbonate, aluminum sulfate, magnesium hydroxide, aluminum hydroxide, potassium titanate, talc, kaolin (kaolin clay), kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, muscovite, phlocopite, biotite, sodium taeniolite, lithium taeniolite, hydrotalc, glass flake, amesite, bentonite, zeolite, calcium silicate, magnesium silicate, and silica sand, but the present invention is not limited to these examples.

[0027] Among inorganic materials other than diatomaceous earth, gypsum is preferred from the viewpoints of imparting appropriate mechanical strength to the wall 2a of the hollow body 2 and efficiently manufacturing the air-dropped fire extinguishing grenade 1. Therefore, in the present invention, it is preferred that diatomaceous earth and gypsum are used in combination in the wall 2a of the hollow body 2 from the viewpoints of imparting appropriate mechanical strength to the wall 2a of the hollow body 2 and efficiently manufacturing the air-dropped fire extinguishing grenade 1.

[0028] Gypsum is a mineral whose main component is calcium sulfate (CaSO4). Gypsum mainly comes in the forms of CaSO4·0.5H2O (calcium sulfate 0.5hydrate), CaSO4·2H2O (calcium sulfate dihydrate), and CaSO4 (calcium sulfate anhydrous). These gypsums may be used alone or in combination. Among these gypsums, calcium sulfate 0.5hydrate is preferred because it reacts with water to harden quickly, thereby reducing the need for water removal procedures when manufacturing the air-dropped fire extinguishing grenade 1. Calcium sulfate 0.5hydrate is readily available as bassaniite.

[0029] Diatomaceous earth and gypsum can be used as a slurry. The slurry can be prepared by mixing diatomaceous earth, gypsum, and water. As the diatomaceous earth content in the slurry increases, the brittleness of the wall 2 a of the hollow body 2 increases, but the time required to dry the wall 2 a of the hollow body 2 when manufacturing the air-dropped fire extinguishing grenade 1 increases. On the other hand, as the gypsum content in the slurry increases, the brittleness of the wall 2 a of the hollow body 2 decreases, but the time required to dry the wall 2 a of the hollow body 2 when manufacturing the air-dropped fire extinguishing grenade 1 can be shortened.

[0030] The mass ratio of diatomaceous earth to gypsum (diatomaceous earth / gypsum) is preferably 30 / 70 or more, more preferably 40 / 60 or more, and even more preferably 45 / 55 or more, from the viewpoint of improving the brittleness of the wall 2a of the hollow body 2 and enabling the wall 2a of the air-dropped fire extinguishing shell 1 to be easily destroyed when the air-dropped fire extinguishing shell 1 collides with a dropped object, and is preferably 70 / 30 or less, more preferably 60 / 40 or less, and even more preferably 55 / 45 or less, from the viewpoint of quickly and efficiently producing the hollow body 2 using the slurry.

[0031] Examples of the external shape of the hollow body 2 include a sphere, a capsule, an oval sphere, a rectangular parallelepiped, a cube, a cylinder, etc., but the present invention is not limited to these examples. Among these external shapes of the hollow body 2, a sphere, a capsule, or an oval sphere is preferred, with a sphere being more preferred, from the viewpoint of reducing air resistance when the air-dropped fire extinguishing bomb 1 is dropped in the air and accurately dropping the air-dropped fire extinguishing bomb 1 at the target fire site.

[0032] The size of the hollow body 2 is not particularly limited and may be any size. Examples of sizes of the hollow body 2 include a sphere having a diameter of 5 to 50 cm, preferably 5 to 30 cm, and more preferably 5 to 20 cm; a cylinder, capsule, or oval sphere having a diameter of 2 to 20 cm and a height of 3 to 50 cm; and a cube or rectangular parallelepiped having a side length of 3 to 30 cm, preferably 3 to 20 cm, but the present invention is not limited to these examples.

[0033] In the present invention, the air-dropped fire extinguishing bomb 1 can be dropped from the sky as it is toward the target fire site to extinguish the fire. Alternatively, a plurality of small air-dropped fire extinguishing bombs 1 can be prepared as the air-dropped fire extinguishing bombs 1, and the plurality of air-dropped fire extinguishing bombs 1 can be placed in a container, which can be dropped from the sky toward the target fire site, the air-dropped fire extinguishing bombs 1 can be released from the container as they fall and can disperse in the air, and the air-dropped fire extinguishing bombs 1 can be destroyed when they reach the ground, thereby extinguishing the fire; or the container can be dropped from the sky above the target fire site, and the container and the air-dropped fire extinguishing bombs 1 inside the container can be destroyed when they reach the fire site, thereby extinguishing the fire.

[0034] When a slurry containing diatomaceous earth and water is used as the raw material for the wall portion 2a of the hollow body 2, the amount of water per 100 parts by mass of diatomaceous earth is not particularly limited, but from the viewpoint of efficiently producing a hollow body 2 having appropriate mechanical strength, it is preferably 10 to 100 parts by mass, more preferably 20 to 80 parts by mass, and even more preferably 30 to 60 parts by mass.

[0035] Furthermore, when a slurry containing diatomaceous earth, gypsum, and water is used as the raw material for the wall portion 2a of the hollow body 2, the amount of water per 100 parts by mass of the total amount of diatomaceous earth and gypsum is not particularly limited, but from the viewpoint of efficiently and quickly producing a hollow body 2 having appropriate mechanical strength, it is preferably 100 to 200 parts by mass, more preferably 110 to 180 parts by mass, and even more preferably 120 to 170 parts by mass.

[0036] The slurry can be easily prepared by mixing diatomaceous earth, water, and optionally gypsum to a uniform composition. The atmosphere during mixing of diatomaceous earth, water, and optionally gypsum is usually air, and the temperature is usually room temperature, but the present invention is not limited by the atmosphere or temperature.

[0037] The slurry may further contain an appropriate amount of binder in order to increase the mechanical strength of the wall 2a of the hollow body 2. Examples of binders include ethylene-vinyl acetate resin emulsion and polyvinyl alcohol, but the present invention is not limited to these examples.

[0038] The thickness of the wall 2a of the hollow body 2 cannot be determined in general terms because the degree of destruction of the wall 2a of the hollow body 2 when it collides with a falling object such as a forest and the state of dispersion of the fire-extinguishing agent 3 filled inside the hollow body 2 will vary depending on the size and shape of the hollow body 2 and the amount of fire-extinguishing agent 3 filled inside the hollow body 2. The thickness of the wall 2a of the hollow body 2 is preferably 3 to 30 mm, more preferably 5 to 25 mm, and even more preferably 10 to 20 mm, from the viewpoints of imparting appropriate mechanical strength to the air-dropped fire extinguishing bomb 1, easily destroying the wall 2a of the hollow body 2 when it falls to the ground, and increasing the fire-extinguishing efficiency of the fire-extinguishing agent 3 filled inside the hollow body 2.

[0039] The extinguishing agent 3 may be a liquid or foam extinguishing agent or a powder extinguishing agent. Among these extinguishing agents 3, the water contained in the liquid or foam extinguishing agent may evaporate due to the heat of the fire before it reaches the fire site, which may reduce the extinguishing efficiency. Therefore, in the present invention, a powder extinguishing agent 3 is used as the extinguishing agent 3 filled inside the hollow body 2 from the viewpoint of reducing the weight of the air-dropped fire extinguishing grenade 1 and improving the extinguishing efficiency.

[0040] The average particle size of the powder fire extinguishing agent 3 is not particularly limited, and is preferably the same as the average particle size of powder fire extinguishing agents generally used in powder fire extinguishers. The average particle size of the powder fire extinguishing agent is usually about 1 to 200 μm, and preferably 3 to 180 μm. The average particle size of the powder fire extinguishing agent can be measured using a laser diffraction particle size distribution analyzer.

[0041] Examples of powder fire extinguishing agents include inorganic powder fire extinguishing agents such as ammonium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium carbonate, potassium bicarbonate, potassium tetraborate, and ammonium sulfate; and organic powder fire extinguishing agents such as potassium acetate, potassium citrate, potassium lactate, potassium oxalate, potassium maleate, potassium tartrate, and silica. Among these powder fire extinguishing agents, inorganic powder fire extinguishing agents are used because they are environmentally friendly. Preferred inorganic powder fire extinguishing agents include phosphates such as ammonium phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate; carbonates such as sodium bicarbonate and potassium bicarbonate; and sulfates such as ammonium sulfate, with phosphates being more preferred. Inorganic powder fire extinguishing agents are readily available commercially, for example, from Yamato Protec Co., Ltd.

[0042] The amount of fire extinguishing agent 3 filled inside the hollow body 2 cannot be determined in general terms, as it differs depending on the internal volume of the hollow body 2. From the viewpoint of effective use of the air-dropped fire extinguishing grenade 1, it is preferable that the hollow body 2 be filled with the fire extinguishing agent 3.

[0043] The hollow body 2 can be produced by using a mold having a male mold and a female mold, filling the mold with a slurry, and molding the mold. More specifically, the hollow body 2 can be produced, for example, based on the steps shown in Figures 3 and 4.

[0044] 3 and 4 are schematic explanatory diagrams each showing one embodiment of a manufacturing method for the air-dropped fire extinguishing grenade 1. Figures 3 and 4 are respectively schematic illustrations for the purpose of making it easy to understand the structures of the mold and hollow body 2, and the actual mold and hollow body 2 may have structures different from those shown. Furthermore, the shape of the mold shown in Figures 3 and 4 is arbitrary, and the present invention is not limited by the shape of the mold.

[0045] Fig. 3 is a schematic explanatory diagram showing one embodiment of a manufacturing method for the air-dropped fire extinguishing grenade 1. In the embodiment shown in Fig. 3, a hollow body 2 having a spherical outer shape and a hollow interior is manufactured.

[0046] The air-dropped fire extinguishing grenade 1 can be manufactured, for example, using a female mold 11 and a male mold 14 as molding dies, as shown in FIG. 3 . Examples of materials for the female mold 11 and the male mold 14 include rubbers such as silicone rubber, acrylonitrile rubber, styrene-butadiene rubber, and natural rubber; resins such as ABS resin, polyester, polypropylene, AS resin, and polystyrene; metals such as iron, copper, brass, and stainless steel; and elastomers such as olefin-based elastomers, styrene-based elastomers, urethane-based elastomers, ester-based elastomers, amide-based elastomers, and vinyl chloride-based elastomers, but the present invention is not limited to these examples. Among these materials, rubber and elastomers are preferred, rubber is more preferred, and silicone rubber is even more preferred, because the molded air-dropped fire extinguishing grenade 1 can be easily removed from the molding dies by flexing the female mold 11 and the male mold 14.

[0047] 3(a), the female die 11 has a semispherical curved surface on the inner surface. The bottom surface of the female die 11 has a through-hole 11a for filling the extinguishing agent 3 into the produced hollow body 2. The diameter of the through-hole 11a is not particularly limited, but is preferably about 20 to 30 mm from the viewpoint of making it easy to inject the extinguishing agent 3 through the through-hole 11a.

[0048] A stopper 13a is detachably disposed in the through-hole 11a to prevent the slurry 12 from leaking out from the bottom surface of the female die 11 when the slurry 12 is poured into the female die 11. The length (not shown) of the stopper 13a protruding from the inside of the female die 11 is preferably equal to or longer than the length from the bottom surface of the female die 11 to the inner surface of the hollow body 2, from the viewpoint of forming a through-hole 11b in the hollow body 2 simultaneously with molding.

[0049] First, a predetermined amount of slurry 12 is poured into the female die 11 fitted with the stopper 13a. The predetermined amount of slurry 12 is the amount of slurry 12 that is neither too much nor too little for forming a compact.

[0050] Next, as shown in FIG. 3( b ), the male die 14 is attached to the female die 11 , and the slurry 12 is filled between the female die 11 and the male die 14 .

[0051] The slurry 12 filled between the female die 11 and the male die 14 hardens over time, but in order to accelerate the hardening of the slurry 12, it is preferable to remove the male die 14 from the female die 11 when the slurry 12 has hardened to a certain extent. In addition, in order to accelerate the hardening of the slurry 12, the slurry 12 may be heated by irradiating it with microwaves or the like.

[0052] After the slurry 12 has hardened, the formed compact A15 is removed from the female die 11. The obtained compact A15 has a hollow hemispherical shape and has a through-hole 11b in the center of the bottom.

[0053] 3(c), in the same manner as described above, a stopper 13b is detachably disposed in the through-hole 11a of the female die 11 to prevent the slurry 12 from leaking out from the bottom surface of the female die 11 when the slurry 12 is poured into the female die 11. Since it is not necessary to form a through-hole 11b in the hollow body 2, the length of the stopper 13b protruding from the inside of the female die 11 (not shown) is preferably the same as the thickness of the female die 11, in other words, the same as the length from the bottom surface of the female die 11 to the outer surface of the hollow body 2.

[0054] A predetermined amount of slurry 12 is poured into the female mold 11 fitted with the stopper 13b. The predetermined amount of slurry 12 is the amount of slurry 12 that is neither too much nor too little for forming a compact, as described above.

[0055] The slurry 12 filled between the female die 11 and the male die 14 hardens over time as described above, but in order to accelerate the hardening of the slurry 12, it is preferable to remove the male die 14 from the female die 11 in the same manner as described above when the slurry 12 has hardened to a certain extent. In addition, in order to accelerate the hardening of the slurry 12, the slurry 12 may be heated by irradiating it with microwaves or the like.

[0056] After the slurry 12 has hardened, the formed compact B16 is removed from the female die 11. The obtained compact B16 has a hollow hemispherical shape.

[0057] 3(d), the opening of molded body A15 and the opening of molded body B16 are overlapped with each other via adhesive 17 to bond molded body A15 and molded body B16, or the opening of molded body A15 and the opening of molded body B16 are overlapped with each other via adhesive 17, and then adhesive tape is applied to the boundary between the two to integrate molded body A15 and molded body B16. As the adhesive 17, slurry 12 can be used, as well as mortar, silicone sealant, etc.

[0058] By joining the molded body A15 and the molded body B16 in the manner described above, the hollow body 2 can be obtained.

[0059] Next, as shown in Figure 3 (e), the fire extinguishing agent 3 is filled into the hollow body 2 through the through hole 11b of the hollow body 2 obtained above, and the through hole 11b is sealed with a sealing material 18, thereby obtaining an air-dropped fire extinguishing grenade 1.

[0060] Examples of the sealing material 18 include rubbers such as silicone rubber, acrylonitrile rubber, styrene-butadiene rubber, and natural rubber; resins such as ABS resin, polyester, polypropylene, AS resin, and polystyrene; metals such as iron, copper, brass, and stainless steel; elastomers such as olefin-based elastomers, styrene-based elastomers, urethane-based elastomers, ester-based elastomers, amide-based elastomers, and vinyl chloride-based elastomers; and plugs made of fillers such as mortar and silicone sealant, but the present invention is not limited to these examples.

[0061] The spherical hollow body 2 can be produced using a balloon made of rubber, for example. More specifically, the hollow body 2 can be produced by preparing a balloon having a spherical outer shape, applying the slurry 12 to the surface of the balloon, and drying the balloon. The resulting hollow body 2 is provided with a through-hole 11b for filling the interior with the fire-extinguishing agent 3. When providing the through-hole 11b in the hollow body 2, the balloon may burst. From the viewpoint of obtaining an environmentally friendly air-dropped fire extinguisher 1, it is preferable to remove the burst balloon through the through-hole 11b. If cracks occur in the wall 2a of the hollow body 2 when the balloon is burst, a release agent such as a silicone release agent may be applied to the surface of the balloon in advance to facilitate peeling of the balloon from the wall 2a of the hollow body 2, or an appropriate amount of the binder may be added to the slurry 12 to increase the mechanical strength of the wall 2a of the hollow body 2. After the fire extinguishing agent 3 is filled into the hollow body 2, the through-hole 11b is blocked with a slurry 12 or the like, and the blocked part of the through-hole 11b is solidified by a method such as drying, thereby obtaining a spherical air-dropped fire extinguishing bomb 1.

[0062] Next, another embodiment of the method for manufacturing the air-dropped fire extinguishing bomb 1 will be described with reference to Fig. 4. Fig. 4 is a schematic explanatory view showing another embodiment of the method for manufacturing the air-dropped fire extinguishing bomb 1.

[0063] The air-dropped fire extinguishing grenade 1 shown in Fig. 4 can be manufactured using a female mold 11 and a male mold 14 as molding dies, similar to the embodiment shown in Fig. 3. The materials of the female mold 11 and the male mold 14 are similar to those of the embodiment shown in Fig. 3. Among the materials of the female mold 11 and the male mold 14, rubber and elastomers are preferred, rubber is more preferred, and silicone rubber is even more preferred, because the molded air-dropped fire extinguishing grenade 1 can be easily removed from the molding die by bending the female mold 11 and the male mold 14.

[0064] First, as shown in Fig. 4(a), a predetermined amount of slurry 12 is poured into a female die 11 having a tapered surface 11c on the inner surface thereof for easy removal of the green body. The predetermined amount of slurry 12 is the amount of slurry 12 that is neither too much nor too little for forming a green body.

[0065] Next, as shown in FIG. 4( b ), the male die 14 is inserted into the female die 11 , and the slurry 12 is filled between the female die 11 and the male die 14 .

[0066] Subsequently, the filled slurry 12 is dried to produce a molded body X19. There is no particular limitation on the method for drying the slurry 12. Examples of the drying method include natural drying and heat drying. The molded body X19 obtained as described above is taken out of the female die 11 by removing the male die 14.

[0067] A molded body Y20 having an opening with an inner diameter larger than the outer diameter of the opening of the molded body X19 is produced by a method similar to that of the molded body X19 described above. Either the molded body X19 or the molded body Y20 may be produced first.

[0068] 4(d), the opening of the compact X19 is overlapped with the opening of the compact Y20, and the opening of the compact X19 is inserted into the opening of the compact Y20. When the openings of the compact X19 and the compact Y20 are overlapped, the compact X19 and the compact Y20 can be integrated so that they do not easily separate, but in order to fix the compact X19 and the compact Y20 together, the joint between the compact X19 and the compact Y20 may be bonded with the slurry 12, the binder, or the like.

[0069] By joining the molded body X19 and the molded body Y20 in the above manner, the hollow body 2 can be obtained as shown in FIG. 4(d).

[0070] As shown in Fig. 4(e), the hollow body 2 obtained above is provided with a through-hole 21 for filling the interior with the fire-extinguishing agent 3, and after the fire-extinguishing agent 3 has been filled into the hollow body 2 through the through-hole 21, the through-hole 21 is sealed with a sealant 18, thereby obtaining an air-dropped fire extinguisher 1 as shown in Fig. 4(f). The sealant 18 is preferably the same as the sealant 18 used in the embodiment shown in Fig. 3.

[0071] The air-dropped fire extinguishing bomb 1 obtained in the above manner maintains its shape when dropped from the sky, preventing the powder fire extinguishing agent from scattering or diffusing in the air as in the past. When it collides with a falling object such as a forest, the hollow body 2 is easily destroyed, allowing the fire extinguishing agent 3 filled inside the hollow body 2 to scatter and be dispersed on the ground. This means that the fire extinguishing agent 3 can be efficiently and accurately dispersed directly at the scene of a fire such as a forest fire, and has the excellent effect of not having any adverse effect on the global environment such as forests.

[0072] The mechanism by which the air-dropped fire extinguishing bomb 1 has such excellent effects is not clear, but it is thought that when the air-dropped fire extinguishing bomb 1 is dropped from the air to the ground, the hollow body 2 that constitutes the air-dropped fire extinguishing bomb 1 is destroyed, scattering the extinguishing agent 3 filled inside it. Since diatomaceous earth is used for the hollow body 2, diatomaceous earth particles fly up when the hollow body 2 is destroyed, just like when dust rises when an earthen wall is destroyed. Since diatomaceous earth has a higher specific gravity than water (specific gravity: approximately 2.1 to 2.3), the diatomaceous earth particles with a higher specific gravity fall to the ground, taking the extinguishing agent 3 floating in the air with them. This prevents the extinguishing agent 3 from being dispersed in the air, and therefore it is thought that this is due to the fact that the extinguishing agent 3 can be efficiently and accurately dispersed near the point where the air-dropped fire extinguishing bomb 1 falls.

[0073] Thus, air-dropped fire extinguishing bomb 1 does not simply use diatomaceous earth out of consideration for the environment, but rather cleverly utilizes the unique property of diatomaceous earth, which is to inhibit the diffusion of fire extinguishing agent 3 in the air, and because diatomaceous earth is non-flammable, it has the excellent effect of increasing fire extinguishing efficiency by using the diatomaceous earth together with the fire extinguishing agent 3. Furthermore, because diatomaceous earth is used in hollow body 2 of air-dropped fire extinguishing bomb 1, it has the excellent effect of allowing the fire extinguishing agent 3 to be efficiently and accurately dispersed near the impact point of air-dropped fire extinguishing bomb 1. Furthermore, when diatomaceous earth and gypsum are used in hollow body 2 of air-dropped fire extinguishing bomb 1, not only can the same effects be achieved as when diatomaceous earth is used in hollow body 2 of air-dropped fire extinguishing bomb 1, but the mechanical strength of hollow body 2 can be increased and the productivity of hollow body 2 can be improved.

[0074] A method of extinguishing a fire using the air-dropped fire extinguishing bomb 1 includes loading the bomb onto an air transport aircraft and dropping the air-dropped fire extinguishing bomb 1 toward the fire site from the air above the fire site. According to this method, the air-dropped fire extinguishing bomb 1 is loaded onto an air transport aircraft and dropped toward the fire site from the air above the fire site, whereby the bomb is easily destroyed when it collides with a falling object such as a forest, and the extinguishing agent 3 filled inside can be dispersed at the fire site. Therefore, the extinguishing agent 3 used in the air-dropped fire extinguishing bomb 1 can be used efficiently without waste, and fires such as forest fires can be effectively extinguished at the fire site.

[0075] In the present invention, air transport aircraft refers to air transport means such as helicopters, airplanes, and drones.

[0076] Therefore, in today's world where forest fires are occurring frequently not only in Japan but also in other countries, the air-dropped fire extinguishing bomb 1 can be dropped directly and accurately onto the fire scene from an air transport aircraft, and the fire extinguishing agent 3 contained in the dropped air-dropped fire extinguishing bomb 1 can be used efficiently, thereby enabling firefighting activities to be carried out efficiently, and it is therefore expected that the air-dropped fire extinguishing bomb 1 will be used as an alternative to fire extinguishing materials that are conventionally sprayed from the air by helicopters, etc.

[0077] Next, the air-dropped fire extinguishing grenade 1 will be described in more detail based on an embodiment, but the present invention is not limited to only such an embodiment.

[0078] Example 1 Diatomaceous earth and water were used as raw materials for the wall of a hollow body used in an air-dropped fire extinguishing bomb. 1800 g of diatomaceous earth and 600 g of water were placed in a 10 L (liter) container and mixed to obtain a uniform composition, thereby obtaining a slurry.

[0079] Using the slurry obtained above, a cylindrical hollow body (wall thickness: 10 mm) with a diameter of approximately 5.5 cm and a height of approximately 15 cm was prepared in accordance with the method shown in Figure 4, and the inside of the hollow body was filled with a powdered inorganic fire extinguishing agent containing phosphate as the main component (manufactured by Yamato Protec Co., Ltd., Type 3 powder), thereby producing six air-dropped fire extinguishing bombs.

[0080] In order to conduct a simulated fire extinguishing test using the air-dropped fire extinguishing bombs obtained above, firewood was placed in a drum split in half lengthwise and ignited, and the firewood was allowed to burn vigorously. When the firewood was burning vigorously as shown in Figure 5, six air-dropped fire extinguishing bombs were lifted to a height of 6 m from the ground by a crane as shown in Figure 6 and dropped onto the burning firewood.

[0081] Figure 5 is a photograph (substitute for a drawing) of firewood burning vigorously inside a drum used in a simulated fire extinguishing test using an air-dropped fire extinguishing grenade, and Figure 6 is a photograph (substitute for a drawing) of a crane truck used in a simulated fire extinguishing test using an air-dropped fire extinguishing grenade.

[0082] The situation after six air-dropped fire extinguishing bombs were dropped on the burning firewood is shown in the photograph in Figure 7. Figure 7 is a photograph in place of a drawing of the firewood in a drum after a simulated fire extinguishing test was conducted using air-dropped fire extinguishing bombs.

[0083] As shown in Figure 7, it was confirmed that when an air-dropped fire extinguishing bomb was dropped onto burning firewood, the firewood could be quickly extinguished.

[0084] As described above, the air-dropped fire extinguishing bomb of the present invention was able to efficiently extinguish fires even when dropped from a position of 6 m above the ground. Therefore, when the air-dropped fire extinguishing bomb of the present invention is dropped from the sky by a helicopter or the like, the wall of the hollow body of the air-dropped fire extinguishing bomb is likely to be destroyed by the strong impact force when the air-dropped fire extinguishing bomb reaches the ground, and therefore, fires can be efficiently extinguished at the scene of a fire such as a forest fire.

[0085] Example 2 Diatomaceous earth, gypsum (powder of calcium sulfate 0.5 hydrate), and water were used as raw materials for the wall of a hollow body used in an air-dropped fire extinguishing bomb. 500 g of diatomaceous earth, 500 g of gypsum, and 1,300 g of water were placed in a 10 L (liter) container and mixed to form a uniform composition to obtain a slurry.

[0086] Using the slurry obtained above, a spherical hollow body having a diameter of 20 cm (wall thickness: 20 mm) was produced according to the method shown in Fig. 3. Since the slurry contained gypsum, the slurry could be hardened in about 30 minutes.

[0087] Next, six air-dropped fire extinguishing bombs were prepared by filling the interior of the hollow bodies obtained above with a powdered inorganic fire extinguishing agent (Type 3 powder, manufactured by Yamato Protec Co., Ltd.) whose main component was phosphate.

[0088] Using the air-dropped fire extinguishing bomb obtained above, a simulated fire extinguishing test was carried out in the same manner as in Example 1. As a result, it was confirmed that when the air-dropped fire extinguishing bomb was dropped on burning firewood, the wall of the hollow body was destroyed and the resulting powdery fragments were prevented from scattering over a wide area, thereby quickly putting out the firewood, in contrast to the air-dropped fire extinguishing bomb obtained in Example 1.

[0089] Since the fire was effectively extinguished even when the air-dropped fire extinguishing bomb was dropped from 6 m above the ground, it is thought that if the air-dropped fire extinguishing bomb is dropped from the air by a helicopter or the like, the strong impact force when it reaches the ground will make the walls of the hollow body even more likely to be destroyed, thereby enabling the fire to be effectively extinguished at the fire scene.

[0090] From the above results, it can be seen that the air-dropped fire extinguishing bomb of the present invention can efficiently and accurately spray extinguishing agent at the scene of a fire such as a forest fire, is unlikely to have a negative impact on the global environment even if it falls on a forest, and is not easily affected by weather such as strong winds.When it collides with a falling object such as a forest at the fire scene, the wall of the hollow body is destroyed, allowing the extinguishing agent filled inside the hollow body to be efficiently and accurately sprayed at the fire scene.Therefore, it is expected that this will contribute to the early extinguishing and reduction of the scope of fires such as forest fires around the world, which are thought to become more frequent in recent years due to global warming.

[0091] DESCRIPTION OF SYMBOLS 1 Air-dropped fire extinguishing bomb 2 Hollow body 2a Wall of hollow body 3 Fire extinguishing agent 11 Female mold 11a Through hole 11b Through hole 11c Tapered surface 12 Slurry 13a Stopper 13b Stopper 14 Male mold 15 Molded body A 16 Molded body B 17 Adhesive 18 Sealant 19 Molded body X 20 Molded body Y 21 Through hole

Claims

1. An air-dropped fire extinguishing bomb that is dropped from the air, comprising a hollow body and a fire extinguishing agent, the hollow body having a wall portion containing diatomaceous earth, the fire extinguishing agent filled inside the hollow body, and the fire extinguishing agent being a powdered inorganic fire extinguishing agent.

2. The air-dropped fire extinguishing grenade according to claim 1, wherein the wall of the hollow body further contains gypsum, and the mass ratio of diatomaceous earth to gypsum (diatomaceous earth / gypsum) is 30 / 70 to 70 / 30.

3. An air-dropped fire extinguishing grenade according to claim 1 or 2, wherein the gypsum is calcium sulfate 0.5 hydrate.

4. A fire extinguishing method using an air-dropped fire extinguishing bomb, comprising loading the air-dropped fire extinguishing bomb according to claim 1 or 2 onto an air transport aircraft and dropping the air-dropped fire extinguishing bomb from above the fire site toward the fire site.

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