JPS6216654B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to fire extinguishing foam, and more specifically to improvements in surfactant-based fire extinguishing foam consisting of water and a surfactant. Generally, protein-based fire extinguishing foam is used for large-scale oil fires caused by gasoline, heavy oil, etc., but this foam fire extinguishing agent does not have very good stock solution storage stability or foaming properties. Therefore, in order to improve the drawbacks of this protein-based fire extinguishing foam, a synthetic surfactant-based (hereinafter simply referred to as surfactant-based) foam fire extinguishing agent was developed. However, although this surfactant-based fire extinguishing foam has good stock stability and foaming properties, it has poor heat resistance because it is composed of water and a surfactant, and therefore has insufficient fire extinguishing ability and is not widely used. It has not yet been used. In view of the above-mentioned circumstances, the present invention was completed as a result of various studies to improve the heat resistance of surfactant-based fire extinguishing foam.
It is characterized by being made by mixing the following ultrafine particulate silica, surfactant and water, and further has a particle size of 50m.
It is characterized by being made by mixing silica in the form of ultrafine particles of micron size or less, a halogenated hydrocarbon, a surfactant, and water. The fire extinguishing foam according to the present invention will be described in detail below with reference to Examples. First, the first fire extinguishing foam according to the present invention is made by mixing ultrafine silica particles with a particle size of 50 mμ or less and a surfactant with water. It is desirable to use silica that can be easily formed and has a small particle size, and it is usually appropriate to use anhydrous silicic acid powder or hydrated silicic acid powder. The blending amount is preferably 0.1 wt% or more, but even if it is 10 wt% or more, the fire extinguishing ability will not increase significantly, so 0.1 to 10 wt% is usually appropriate, and preferably 0.5 to 5 wt%. Moreover, the surfactant used in conventional surfactant-based fire extinguishing foams may be used, and any of anionic, amphoteric, and nonionic surfactants may be used. The blending amount may be the same as that for conventional fire extinguishing foam, i.e. 1 to
10 wt%, preferably 2 to 6 wt%. Furthermore, when mixing each component, since ultrafine silica is dissolvable in water, it is necessary to mix it with an appropriate amount of water in advance to prepare an aqueous dispersion, and add a surfactant to this aqueous silica dispersion. It is best to mix it as a solution. The above foam fire extinguishing agent has superior fire extinguishing ability compared to conventional foam fire extinguishing agents, requires a shorter extinguishing time, and has a longer re-ignition time. Although the reason for this is not clear, it is presumed that since silica is in the form of ultrafine particles, the silica is dispersed and retained in the foam membrane during foaming, thereby reinforcing the foam. Next, when a halogenated hydrocarbon is added to the first fire extinguishing foam, the fire extinguishing ability is further increased. That is, the second fire extinguishing foam according to the present invention is a mixture of extremely particulate silica, a halogenated hydrocarbon, a surfactant, and water, and the time required for fire extinguishing is significantly shortened. The same silica and surfactant as in the first fire extinguishing foam are used, and various halogenated hydrocarbons can be used, but usually C ₂ B _r2 F ₄ ,
It is preferable to use CB _r F ₃ , CB _r ClF ₂ , etc. The blending amount is 0.5 to 10 wt% silica, preferably 1 to 5 wt%.
%, surfactant is 1-10wt%, preferably 3-8wt%
%, and the halogenated hydrocarbon is 0.5 to several + wt%, preferably 0.5 to 10 wt%. Furthermore, when mixing each component, it is best to prepare an aqueous dispersion of silica in advance as described above, and when using it, it is discharged from a foaming nozzle, but in this case, the pre-mixed silica is sent to the nozzle. Alternatively, they may be mixed during transportation by creating turbulent flow in piping, or may be mixed within a nozzle. Further, although air is usually used for foaming, if a gaseous halogenated hydrocarbon is used, the halogenated hydrocarbon may be used for foaming. Next, the present invention will be explained in more detail with reference to Examples. In addition, each measurement value was measured as follows unless otherwise noted. (i) Foaming ratio Measure the foaming ratio when the fire extinguishing foam is discharged from the foaming nozzle at a flow rate of 3/min and a discharge pressure of 5Kg/cm ² . (ii) Time required for fire extinguishing Pour water to a depth of 12 cm and gasoline to a depth of 3 cm into an oil pit measuring 77.5 cm x 77.5 cm x 30 cm, ignite it, and after 1 minute, pour fire extinguishing foam at a flow rate of 3/3 cm.
Foam is generated from a foaming nozzle at a discharge pressure of 5 kg/cm ² , and the time required to extinguish the fire is measured. (iii) Re-ignition time: Pour water into a 27cm x 33cm x 14cm oil pit to a depth of 4.
cm, n-heptane to a depth of 3 cm, and a diameter of 54 mm and a height of 54 mm to the center of the oil pit.
A stainless steel pipe of 100mm and 3.5mm thickness is stood upright, and the n-beptane outside the stainless steel pipe is ignited, and after 1 minute, fire extinguishing foam is applied at a flow rate of 3/min.
Foam is discharged from the foaming nozzle at a discharge pressure of 5 kg/cm ² to extinguish the fire. Next, 3 minutes after extinguishing the fire, the foam extinguishing agent inside the stainless steel pipe is removed and ignited, and the time from the time of ignition until the n-heptane outside the pipe is re-ignited is measured. <Example 1> Using anhydrous silicic acid powder or hydrated silicic acid powder as ultrafine particulate silica, anionic surfactants were added and mixed to an aqueous dispersion of these to prepare fire extinguishing foams of various compositions, and the foaming was performed. Measure the magnification, extinguishing time and re-ignition time. The anhydrous silicic acid powder is manufactured by Nippon Aerosil Co., Ltd. under the trade name Aerosil-200 (particle size 12 mμ, specific surface area 200 m ² /g), and the hydrated silicic acid powder is manufactured by Nippon Silica Kogyo Co., Ltd. under the trade name Nipsiru LP (particle size 16 mμ, Specific surface area: 230 m ² /g), and the surfactant used was Alscope LE-213 (trade name, manufactured by Toho Chemical Co., Ltd.). Comparative examples include those that do not contain ultrafine particulate silica, or precipitated silica with a large particle size (particle size 57).
µ, specific surface area 510 m ² /g) or those using crushed silica (particle size 12 µ, specific surface area 2300 cm ² /g) were also measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the fire extinguishing foam according to the present invention has extremely superior fire extinguishing ability compared to those that do not contain silica or those that contain coarse particulate silica. If you use
It can be seen that the fire extinguishing ability increases significantly up to 2wt% and 5wt% when using hydrated silicic acid powder, and gradually increases when the amount is increased beyond that. In this example, Aerosil-200 or Nipsil-LP was used as the ultrafine particulate silica, and Arscope was used as the surfactant.
I used LE-213, but

[Table] Almost the same results were obtained when other ultrafine particulate silica with a particle size of 50 mμ or less and other surfactants were used. <Example 2> Using the anhydrous silicic acid powder (Aerosil-200), hydrated silicic acid powder (Nipsil-LP) and surfactant (Arscope LE-213) used in Example 1,
Furthermore, a halogenated hydrocarbon was blended to prepare a fire extinguishing foam, and the time required for extinguishing the foam was measured (see Table 2). In addition, when using C ₂ B _{r 2} F ₄ , the mixed dispersion of each component is foamed and discharged from a foaming nozzle, and when using CB _r F ₃ and CB _r ClF ₂ , silica and surfactant are mixed. The dispersion liquid, CB _r F ₃ and CB _r ClF ₂ are separately discharged from a foaming nozzle into a foaming chamber, and CB _r F ₃
In the case of CB _r ClF ₂ , air was introduced to cause foaming. From the results in Table 2, it can be seen that when ultrafine particulate silica and halogenated hydrocarbon are blended, the time required for extinguishing is significantly shortened.

[Table] <Example 3> Polyoxyethylene was added to a dispersion consisting of 2 parts by weight of ultrafine silicic anhydride powder with a particle size of 12 mμ (Aerogil 200 manufactured by Nippon Aerosil Co., Ltd.) used in Example 1 and 95 parts by weight of water. Alkyl phenol ether sulfate sodium salt (anionic surfactant)
Parts by weight were added and mixed to prepare a fire extinguishing foam. The foaming ratio of this fire extinguishing foam is 9 times, and the time required for extinguishing is 50 seconds.
Reignition time was 14 minutes. <Example 4> 3 parts by weight of polyoxyethylene nonylphenol ether (nonionic surfactant) was added to a dispersion of 2 parts by weight of Aerosil-200 used in Example 1 and 95 parts by weight of water, and the mixture was mixed to form foam. A fire extinguishing agent was prepared. The foaming ratio of this fire extinguishing foam was 9 times, the time required for extinguishing was 58 seconds, and the time for re-ignition was 14 minutes. In this example, the time required for extinguishing the fire was measured using n-heptane instead of gasoline. <Example 5> 3 weights of Snowrap-H (trade name, anionic surfactant) manufactured by Nissan Chemical Industries, Ltd. were added to a dispersion consisting of 2 parts by weight of Aerosil-200 used in Example 1 and 95 parts by weight of water. 1 part and mixed to prepare fire extinguishing foam. The foaming ratio of this fire extinguishing foam was 10 times, the time required for extinguishing was 60 seconds, and the time for re-ignition was 11 minutes. <Example 6> To a dispersion consisting of 2 parts by weight of Aerosil-200 used in Example 1 and 92 parts by weight of water, 3 parts by weight of Snowlap H used in Example 5 and dibromotetrafluoroethane (C ₂ B _r2 A fire extinguishing foam was prepared by adding 3 parts by weight of F ₄ ) and emulsifying and dispersing it. The foaming ratio of this fire extinguishing agent is 9 times, the extinguishing time is 28 seconds, and the re-ignition time is 10 times.
It was hot in minutes. <Example 7> San-ai Oil Co., Ltd. was added to a dispersion consisting of 3 parts by weight of ultrafine hydrated silicic acid powder (Nipsil-LP manufactured by Nippon Silica Kogyo Co., Ltd.) with a particle size of 16 mμ used in Example 1 and 94 parts by weight of water. A fire extinguishing foam was prepared by adding and mixing 3 parts by weight of SUPERFOAM (Aeon-based surfactant) manufactured by KK. The foaming ratio of this fire extinguishing foam was 10 times, the time required for extinguishing was 62 seconds, and the time for re-ignition was 10 minutes. <Example 8> Nipsil-LP3 parts by weight used in Example 1 and 91 parts by weight of water
A fire extinguishing foam was prepared by adding 3 parts by weight of the superfoam used in Example 7 and 3 parts by weight of dibromotetrafluoroethane (C ₂ B _r2 F ₄ ) to a dispersion consisting of parts by weight and emulsifying and dispersing them. The foaming ratio of this fire extinguishing foam was 8 times, the time required for extinguishing was 30 seconds, and the time for re-ignition was 11 minutes.

Claims (1)

[Claims] 1. Ultrafine silica particles with a particle size of 50 mμ or less,
A fire extinguishing foam made by mixing a surfactant and water. 2. The fire extinguishing foam according to claim 1, wherein the silica is anhydrous silicic acid powder or hydrated silicic acid powder. 3 Ultrafine silica particles with a particle size of 50 mμ or less,
A fire extinguishing foam made of a mixture of halogenated hydrocarbon, surfactant and water. 4. The fire extinguishing foam according to claim 3, wherein the silica is anhydrous silicic acid powder or hydrated silicic acid powder.