JPH062168B2 - Fire-extinguishing agent for fire-retardant hazardous materials and fire-extinguishing method using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fire extinguishing agent for fire-retardant hazardous materials and a fire-extinguishing method using the same.

(Prior art and its problems) Fire extinguishing dangerous substances are roughly classified into the following substances.

Metal powder ・ ・ ・ Mg powder, Al powder, Zn powder, Ti powder, Zr powder, Fe powder, etc.Alkali metal ・ ・ ・ Na, K, Li, etc. Water-prohibited material ・ ・ ・ Calcium carbide, phosphating lime, quick lime, etc. Stable solid ・ ・ ・ Red phosphorus, yellow phosphorus, sulfur, phosphorus sulfide,
Flame-retardant liquid such as magnesium ... Alkyl aluminum, alkyl lithium, silane chloride, diketene, etc. First, metal powders such as Mg, Al and Ti are flammable and often cause a fire and a serious explosion. Since these metal powders react with water at high temperatures to generate hydrogen, and when water is injected, a steam explosion may occur, causing combustion metal powder to be scattered, so that water injection must be absolutely avoided. It is impossible to extinguish with conventional carbon dioxide, halon and powder fire extinguishing agents, and the only way to suppress fire is to sprinkle a small amount of special powder such as dry sand, sodium chloride or sodium carbonate. However, in these methods, a large amount of fire extinguishing agent is consumed, and even if these special powders are sprayed, hot metal slag remains inside, and it is left for a long time, sometimes 30 to 60 minutes, as it is. It had to be kept and there was a risk of reburning under some conditions.

Next, alkali metals such as sodium and potassium are
There is a risk of generating heat by working with water, generating hydrogen, and spontaneously igniting. Therefore, in this case as well, water injection is not possible, and extinguishing is not possible even with known extinguishing agents other than water, carbon dioxide, halon, and powder extinguishing agents. There is also a method of spraying slightly dry sand or a special powder such as sodium chloride or sodium carbonate, but these are slow suffocation and extinguishing due to cooling action, so it takes a long time to completely extinguish and consumes a large amount of extinguishing agent. There were difficulties such as doing.

The solids of water-inhibiting substances such as calcium carbide and quick lime react with water to generate heat or generate flammable gas and burn. These substances are dangerous substances called water-prohibited substances, and they are not applicable because they react with other known extinguishing agents other than water, and there was no particularly effective extinguishing method.
Although suffocation and extinguishing with dry sand could be applied,
In practice, it required a large amount of dry sand and was difficult to extinguish.

The flammable solids of yellow phosphorus, red phosphorus, and sulfur are dangerous substances that are easily ignited at relatively low temperatures. Moreover, some of them are solids with a high burning rate and are toxic, or some generate toxic gas when they burn. Therefore, extinguishing the fire is troublesome.

Alkyl aluminum and silane chloride among the flame-retardant liquids in No. 1 will explosively react when they come into contact with water, so water injection must be absolutely avoided to extinguish these dangerous substances. In addition, it was difficult or impossible to extinguish with carbon dioxide, halon and conventional powder fire extinguishing agents.

(Means for Solving Problems) The present inventor has carried out various studies on extinguishing difficult and difficult to extinguish dangerous substances, and as a result, for the metal fire of the metal powder and the alkali metal, boron oxide powder Was found to be extremely effective in eliminating the shortcomings of conventional fire extinguishing agents for metal fires, and a patent application was filed for this (December 28, 1987, Japanese Patent Application No. 62-335445), but further investigations have been made. As a result of stacking, it was found that boron oxide powder can be applied to extinguish fire-retardant substances other than metals, and that the fire-extinguishing effect of flame-retardant dangerous substances for many types can be further improved. Completed the invention.

That is, the present invention is based on a boron oxide powder having a B ₂ O ₃ content of 90% by weight or more and a water content of 2% by weight or less and a particle diameter of 5 to 1000 μm, which is eutectic with a combustion object. The first component that lowers the melting point and exerts suffocation and cooling action, the second component that forms a strong suffocation-blocking layer on the object and the liquid object is removed by absorption, and exerts the suffocation effect. The present invention relates to a fire-extinguishing agent for fire-retardant materials, which comprises any one of the third components or any combination thereof as a sub-component, and further relates to a fire-extinguishing method using the same.

The present invention will be described in more detail below.

The main component of the fire extinguishing agent in the present invention is a B ₂ O ₃ content of 90% by weight or more and a water content of 2% by weight or less, preferably 0.1% or less.
It is necessary that the content of boron oxide be 5% by weight or less. The boron oxide commercially available today is a first-grade reagent, containing 85% by weight of B ₂ O ₃ and 10% of water (containing boric acid).
Although it is about% by weight, boron oxide having such a grade is not suitable as the fire extinguisher of the present invention. The reagent grade, which is obtained by further refining the boron oxide of the grade 1 reagent, has a B ₂ O ₃ content of 97.
Weight% and water content are about 2% by weight. With such a grade, the fire extinguishing agent of the present invention can be managed, but it is not sufficient. When this special grade reagent is further heated at 160 ° C for about 2 hours, the water content becomes 0.
It becomes less than 5%, and the fire extinguishing performance is significantly improved.

The particle size of the boron oxide powder used in the present invention is 5 μm to 10 μm.
It is 00 μm. A fine powder having a particle size of 5 to 200 μm is suitable for filling in a digestive organ, and a fine powder having a particle size of 200 to 1000 μm is suitable for spraying with a scoop, a bucket or the like. Fine powder having a particle size of less than 5 μm is not suitable as a fire extinguisher of the fire-extinguishing dangerous substance of the present invention because it easily scatters to the surroundings during spraying.
If the particle size is larger than 1000 μm, it takes time to melt and a large amount of powder is consumed for extinguishing a fire, which is not preferable.

Next, the subcomponents added to the above main components and the actions they have will be described.

(1) The first component, which has a relatively low melting point, is eutectic with boron oxide to exert a choking action and a cooling action.

: Sodium chloride, potassium chloride, sodium carbonate, magnesium carbonate, sodium tetraborate (anhydrous).

(2) A second component that is eutectic with boron oxide to form a strong air-blocking layer to completely extinguish fire.

: Quartz sand, silica powder, quartz powder, calcium fluoride (3) Liquid combustion The third component which has a liquid absorbing and removing action and a suffocating and cooling action of molten boron oxide for high temperature objects.

: Silica-based porous material / silica / alumina-based, porous material,
Kaolin, calcium carbonate, and pearlite all have a relatively low melting point in the range of 700 to 900 ° C., are easily melted by touching a high-temperature object during combustion, and have a eutectic point when mixed with boron oxide. It has a function of lowering the melting point and covering the combustion surface well. In addition, since these components have a relatively large heat of fusion, they absorb the heat of fusion from the surroundings during melting and exert a cooling effect to extinguish fire.

Applicable flame-retardant hazardous materials: Metal powder, alkali metal, flammable solid, silica silica sand, silica powder, and quartz powder of the _second component are mainly composed of SiO ₂ and heat-resistant glass However, the addition of these powders to boron oxide, which is an important raw material for the melting point of silica (1
It has a function of melting at a temperature lower than 680 ° C. to form a glassy strong air barrier layer on the combustion surface to ensure extinction.

Calcium fluoride also has high heat resistance and is known as a flux during metal smelting. It can be mixed with boron oxide to lower the melting temperature.

Applicable flame-retardant hazardous materials: Metal powder, magnesium solid, especially when a tank or other complicated structure with a vertical wall ignites from the bottom, the extinguishant melts at low temperature and adheres to the vertical wall. Due to its high viscosity, it forms a strong air barrier layer that covers the wall and has an effective fire extinguishing ability. Therefore, it is extremely effective in extinguishing a three-dimensional fire in an aircraft that uses a large amount of magnesium or magnesium alloy.

Porous powder with high heat resistance and fine powder with high heat resistance, such as the third component, absorbs burning liquid substances when sprayed on a fire of a fire-retardant liquid dangerous substance or a flammable solid with a low melting point. , The effect of removing combustibles is exhibited. When the temperature becomes higher, boron oxide, which is the main component, is melted to exert suffocation and cooling action.

Also, since the fire of water-prohibited dangerous substances such as calcium carbide that heats and ignites in contact with water is caused by moisture,
When these porous powder and heat-resistant fine powder are sprinkled, water is absorbed and, as a result, the effect of weakening the fire is also exerted.

Applicable flame-retardant hazardous substances Water-prohibited substances ・ ・ ・ Calcium carbide, quick lime, etc. Combustible solids ・ ・ ・ Red phosphorus, sulfur, phosphorus sulfide, etc. (Because it has a low melting point, it burns in a molten state) Flame-retardant liquid ・..Alkylaluminum, silane chloride, diketene, etc. The requirements that these subcomponent powders must have are as follows.

Silica-based porous body containing SiO _{2 in an amount} of 80% by weight or more, and having a pore diameter of 0.1 to 100 μm,
A silica-based porous body having a bulk specific gravity of 0.2 to 0.5 and a particle diameter of 5 μm to 1000 μm.

Silica / alumina-based porous material Containing 90% by weight or more of the sum of both components of SiO ₂ and Al ₂ O ₃ ,
Pore diameter 0.1-1000 μm, bulk specific gravity 0.3-0.7, particle size 5
A silica-alumina-based porous material having a size of μm to 1000 μm. This includes perlite made from pearlite.

Include quartz sand SiO ₂ 90 wt% or more, a true specific gravity of 2.5 to 2.7 diameter 1μ
Natural silica sand of m to 500 μm and its processed products.

Silica powder SiO ₂ containing 93% by weight or more, true specific gravity 2.5 to 2.65 particle size 1
Silica powder of μm-500 μm.

Quartz powder SiO ₂ containing 95% by weight or more, true specific gravity 2.6 to 2.65 particle size 1
It is obtained by artificially crushing quartz (crystal) with quartz powder of μm to 500 μm.

Kaolin High fire resistance, true specific gravity 2.55-2.65, average particle size 0.3μm-
5 μm is suitable.

It is desirable that the sodium chloride content is 98% by weight or more and the Mg salt content is reduced as much as possible to prevent hygroscopicity. It is preferable that the product is processed to prevent moisture from solidifying to prevent solidification. Not suitable for use in the invention. Particle size is 5μm ~
A range of 500 μm is suitable. Melting point 801
° C.

A potassium chloride having a KCl content of 98% by weight or more and a Mg salt content as low as possible is preferable in terms of moisture absorption and solidification prevention. It is also possible to add a small amount of a solidification inhibitor. A particle size of 5 μm to 500 μm is suitable. Melting point is 776 ° C.

Anhydrous sodium carbonate, Na ₂ CO ₃ content 99% by weight or more, particle size 5 μm to 50
The one with 0 μm is used.

Calcium carbonate CaCO ₃ whose content is 98% by weight or more and whose particle diameter is in the range of 1 μm to 200 μm is used.

Magnesium carbonate MgCO ₃ whose content is 97% by weight or more and whose particle diameter is in the range of 1 μm to 200 μm is used.

Calcium fluoride, the main component of fluorspar, CaF ₂ min 98% by weight or more, particle size 1
It is extremely stable at μm to 500 μm and melting point of 1360 ° C.

Sodium tetraborate (anhydrous) Anhydrous Na ₂ B ₄ O ₇ min 99% or more, particle size 5 μm to 1000 μm
m, true specific gravity 2.36, melting point 741 ° C.

It is a condition necessary for achieving the object of the present invention that the content of water in the powder which is inert and has heat resistance is 5% by weight or less, preferably 2% by weight or less.

It is difficult to add moisture resistance (hydrophobicity) to powder fire extinguishing agents and improve the fluidity of the surface of the powder, or to add organic substances such as magnesium stearate. It must be avoided because it significantly interferes with.

(Function) Generally, as a function and effect necessary for extinguishing a fire, (1) removal effect (removes combustibles from the combustion source system) (2) asphyxiation effect (blocks oxygen supply source) (3) cooling effect ( It is known that the combustion heat is absorbed and cooled to lower the temperature below the ignition temperature to suppress the combustion.) (4) The suppression effect (to suppress and prevent the chain reaction of combustion). These effects often act synergistically rather than alone.

When the high-purity boron oxide powder with low water content, which is the main component of the fire extinguishing agent of the present invention, is sprayed on the solid combustion part of the fire-retardant hazardous material to which the fire extinguishing agent of the present invention is applied, the burning high temperature Softening starts near the surface of the solid dangerous substance (softening temperature of B ₂ O ₃ of about 320 ° C.), particles and particles start to adhere to each other to form an ice burn, and then melt (melting point of B ₂ O ₃ is 450 (Remarkably low as a heat-resistant substance at ℃), the powder coalesces with each other and finally becomes glassy and transparent. Moreover, since boron oxide has a unique property that it retains a high viscosity even at a temperature of 1100 ° C or higher, it does not flow out, and since it has a starch syrup-like shape and its adhesive strength is extremely strong, it completely covers the surface of the burning part. The air is blocked by covering it, and the suffocation effect is maximized and the fire is completely extinguished.
Furthermore, since the boiling point of boron oxide is as extremely high as 2250 ° C., it does not vaporize during the extinguishing of these fire-retardant dangerous substances, and therefore exhibits extremely excellent fire extinguishing ability.

Except when reducing metal oxides in a high temperature, vacuum or inert atmosphere, fires of these fire-retardant hazardous materials occur in an oxidizing atmosphere (usually in air). However, there is no danger that boron oxide will be reduced and rather generate high heat.

The heat of fusion of boron oxide is 75.7 cal / g, and the heat of fusion of ice (7
9.7cal / g) is so large as to be comparable, so when the fire extinguisher sprayed on the solid combustion part melts, it absorbs heat of fusion from the surroundings, a large cooling effect appears, and it acts to weaken the fire.

(Example 1) A shallow stainless steel having a diameter of 30 cm, and 20 g of red phosphorus and sulfur, which are typical combustible solid dangerous substances, are placed on each of them, ignited by a gas torch, and pre-combusted for 20 seconds. The results of spraying the extinguishing agent of the present invention at this time are shown in Table 1.

Low-melting flammable substances such as red phosphorus and sulfur have the property that they melt once before being burned and become liquid before burning, and if a small amount of silica-based porous material is added to high-purity boron oxide with little water content. The fire extinguishing performance is improved and the fire extinguishing time is shortened by 10 to 20%. Silica instead of silica-based porous material
The same effect can be obtained by adding the alumina-based porous body.

(Example 2) In a stainless steel container having a diameter of 10 cm and a depth of 6 cm, 20 g of calcium carbide was added and 10 ml of water was added to generate acetylene gas for ignition, and after 20 seconds of preliminary combustion, the extinguishing agent of the present invention was sprayed. It is shown in Table 2.

As described above, the fire extinguishing performance is improved by adding a small amount of the silica-based porous body to the powder of high-purity boron oxide having a low water content. In this way, when the porous powder is used together, the moisture that causes the fire of calcium carbide is absorbed, and as a result, the fire is weakened and the fire extinguishing time is shortened.

(Example 3) 20 g of Mg powder was placed on a stainless steel shallow dish having a diameter of 30 cm, ignited by a gas torch, and when the entire surface of the Mg powder was ignited, the burning part was stirred and the Mg powder was accompanied by a white glowing flame.
It burned violently while producing a strong heat. Table 3 shows the results of spraying a fire extinguishing agent obtained by igniting a low-moisture high-purity boron oxide powder with a powder having a relatively low melting point (first component) as an auxiliary component of the present invention at this time.

In this way, high purity boron oxide powder with a small amount of powder of an inert inorganic material having a relatively low melting point was added to the high purity boron oxide powder alone when sprayed on the burning part of a metal fire. Not only in the high temperature part, but in a semi-molten state, it spreads to the relatively low temperature part of the combustion surface, and completes the extinction.

(Example 4) 20 g of Mg powder was placed on a stainless steel shallow dish with a diameter of 30 cm, ignited with a gas torch, and when the entire surface of the Mg powder was ignited, the combustion powder was stirred and the Mg powder accompanied a white glowing flame.
It burned violently while producing a strong heat.

At this time, as a subsidiary component of the present invention, an inert fire-resistant powder (second component) having a relatively high melting point (second component) was added to a low-moisture, high-purity boron oxide powder, and the result of spraying the extinguishing agent is shown in Table 4. Shown in.

Thus, silica (melting point 1680 ° C.) powder having a melting point much higher than that of boron oxide and calcium fluoride (melting point 13
The fire extinguishing agent with a small amount of powder added becomes a semi-molten or molten state when it comes into contact with the high temperature part of a metal fire, and forms a stronger shell that covers the combustion surface than when boron oxide is used alone. , The air is completely shut off, and the fire is easily extinguished.

(Example 5) Into a stainless steel container having a diameter of 10 cm and a depth of 6 cm, 20 ml of a representative material of an incombustible liquid dangerous substance, alkylaluminum and 50 ml of trichlorosilane, were respectively taken, ignited and pre-combusted for 30 seconds, and then, Table 5 shows the results of spraying the fire extinguishing agent obtained by adding the silica-based porous body (third component), which is an accessory component of the invention, to low-moisture, high-purity boron oxide powder.

As described above, even with regard to the difficult-to-fire extinguishing liquid dangerous substance, it is possible to extinguish the fire by spraying an extinguishing agent obtained by mixing the high-purity boron oxide powder and the silica-based porous body powder.

In extinguishing a liquid dangerous substance with a large combustion heat such as alkylaluminum, first, an inert solid powder such as a silica-based porous material is sprayed to absorb the liquid, and the dispersed silica-based porous material is After the surface is heated to a high temperature, a low-moisture, high-purity boron oxide powder is sprinkled to form an air barrier layer of molten boron oxide on the surface layer, whereby the fire can be easily extinguished completely.

(Example 6) A magnesium plate having a thickness of 5 mm, a width of 10 cm, and a height of 30 cm is laid almost vertically on the side surface of a refractory brick, and the magnesium plate is ignited by a gas torch so that about half of the area of the magnesium plate burns violently. Table 6 shows the results of spraying the fire extinguishing agent after that.

In this way, in a metal fire on a nearly vertical surface, the powder of the conventional method for metal fire extinguishing agent fell almost without adhering to the combustion surface, and extinguishing was impossible, whereas The fire extinguisher powder according to the present invention adhered to a substantially vertical combustion surface, and was quickly melted by the heat of the high temperature portion to form an air blocking layer, and the fire could be extinguished in a short time.

This is the apparent resistivity of low-moisture, high-purity boron oxide, which is the main component of the fire extinguishing agent according to the method of the present invention (specific resistance of 2.6 at 25 ° C.
X10 ¹⁶ Ωcm) and particle size are suitable, so that they are easily charged by spraying in air or spraying from a closed container into air, and adhere to the burning metal surface. It can be explained that a small amount of heating causes melting and vitrification. Moreover, since high-purity boron oxide maintains a high viscosity even at a high temperature of 1100 ° C. or higher, it adheres to the surface of a high-temperature burning metal (substantially an oxide) and peels off during or after extinguishing fire or after extinguishing fire. Nothing like falling was observed.

Since the fire extinguishing agent of the present invention has such excellent properties,
It can also be applied to extinguishing a three-dimensional fire in an aircraft that uses a large amount of magnesium or magnesium alloys today.

(Example 7) 1.0 kg of Mg powder was spread on a stainless steel shallow dish with a diameter of 50 cm, ignited with a gas torch, and when the entire surface of the Mg powder was ignited, the whole mixture was stirred and the Mg powder shined a white glowing flame. It burned violently. At this point, the result of extinguishing the fire using a portable fire extinguisher (type 20) filled with a fire extinguisher in which the main component of boron oxide was added with the secondary component of the second component and the conventional extinguishing agent for commercially available metal fires The results of extinguishing the fire are shown in Table 7.

Further, in an experiment conducted at the same time, it was compared with the case of boron oxide alone, but it took 20 seconds to extinguish the fire, and the effect of natural silica was confirmed.

(Effects of the Invention) As described in detail above, according to the present invention, (1) the fire of a fire-retardant material is easily and promptly suppressed,
You can put out the fire in a short time.

(2) Compared to conventional dry sand, sodium chloride, sodium carbonate, and other special powder fire extinguishing agents, there is almost no sound or smoke generated during powder spraying, and there is no odor or scattering of powder around.
Fire fighting is easy.

(3) Compared with conventional extinguishing agents, the extinguishing effect is more reliable and the required amount of extinguishing agent is smaller.

(4) The fire extinguisher of the present invention is, of course, a horizontal fire.
It also has an excellent effect on vertical fires, so it is also effective on three-dimensional metal fires.

(5) Since the burning surface of the fire-extinguishing dangerous substance is completely covered with a strong layer, post-treatment after extinguishing the fire is easy and does not pollute the surroundings.

(6) The fire extinguishing agent powder of the present invention has various excellent effects such that it can be used by filling it in a digestive organ or can be stored in a container and sprayed with a bucket, a scoop or the like.

Claims (6)

[Claims] 1. A boron oxide powder having a B ₂ O ₃ content of 90% by weight or more and a water content of 2% by weight or less and a particle diameter of 5 to 1000 μm as a main component, and being eutectic with the main component in a combustion object. The first component that lowers the melting point and exerts suffocation and cooling action, the second component that forms a strong suffocation-blocking layer on the object and the liquid object is removed by absorption, and exerts the suffocation effect. A fire-extinguishing agent for fire-extinguishing dangerous substances, comprising any one of the third components or any combination thereof as an auxiliary component. 2. The fire extinguisher according to claim 1, wherein the first component is at least one selected from the group consisting of sodium chloride, potassium chloride, sodium carbonate, magnesium carbonate and sodium tetraborate (anhydrous). 3. The fire extinguisher according to claim 1, wherein the second component is at least one selected from the group consisting of silica sand, silica powder, quartz powder, and calcium fluoride. 4. The third component is a silica-based porous body, a silica / alumina-based porous body, kaolin, calcium carbonate,
The fire extinguisher according to claim 1, which is at least one selected from the group consisting of perlite. 5. A boron oxide powder having a B ₂ O ₃ content of 90% by weight or more and a water content of 2% by weight or less and having a particle diameter of 5 to 1000 μm as a main component, and being eutectic with the main component in a combustion object. The first component that lowers the melting point and exerts suffocation and cooling action, the second component that forms a strong suffocation-blocking layer on the object and the liquid object is removed by absorption, and exerts the suffocation effect. A method of extinguishing a non-extinguishable dangerous substance, characterized by using an extinguishing agent containing any one of the third components or any combination thereof as an accessory component for extinguishing a burning object. 6. The fire extinguishing method according to claim 5, wherein the burning object has a side surface that is steeply inclined with respect to the ground surface or has a bottom surface facing the ground surface.