JP5361747B2 - High expansion foam fire extinguishing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a desired expansion ratio even when smoke is sucked. <P>SOLUTION: In the high expansion foam fire extinguishing system, for dynamic surface tension measured at a life time 100 msec by the maximum foam pressure method under the condition of a liquid temperature of 20&deg;C&plusmn;1&deg;C, in order to have a value of the dynamic surface tension of the foam aqueous solution of 18mN/m-24mN/m, a foam fire extinguishing agent at a concentration of 2% or more is mixed in water, and foam is emitted. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a high-expansion foam fire extinguishing equipment used in a pit of an oil tank, a culvert of an oil complex, a cabin, a hold or the like.

  As a fire extinguishing equipment for a building, a sprinkler fire extinguishing equipment is usually arranged, and the fire is extinguished by discharging water. In contrast, oil tanks and cabins are equipped with highly expanded foam fire extinguishing equipment in preparation for oil fires.

  In the high expansion foam fire extinguishing equipment, a foam aqueous solution is discharged from a radiation nozzle, foamed by colliding with a foaming net and entrained with air, and the fire source is completely filled with the foam to extinguish the suffocation. Here, the foaming ratio indicating the volume ratio of the foam aqueous solution and the generated foam is 80 or more and less than 1000 is referred to as high expansion foam fire extinguishing equipment.

In this high expansion foam fire extinguishing equipment, in order to release foam, a synthetic surfactant foam fire extinguishing agent or the like is mixed with water at a ratio of about 3%.
Water itself is a liquid having a large surface tension. However, when the above-mentioned foam fire-extinguishing agent is mixed with this water to make a foam aqueous solution, the surface tension becomes small and foaming tends to occur.

  In order to generate highly expanded bubbles, for example, bubbles with an expansion ratio of 500 or more, it is necessary to take in a large amount of air from the upstream side of the radiation nozzle. When a large amount of air is taken in, a method of sucking outdoor air (Referred to as “outside air”).

  However, in this outside air, since outside air is used, a duct is penetrated in the building, or a bubble generator (foaming machine) is provided by making a hole in the partition wall, which increases costs. There is a problem.

  Therefore, in order to solve the above problem, a high expansion foam fire extinguishing equipment of a system (referred to as “inside air”) that sucks air in a compartment from which bubbles are discharged is used (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 06-165837

  In the inside air high expansion foam fire extinguishing equipment, the foaming ratio is remarkably reduced as compared with the outside air high expansion foam fire extinguishing equipment. The main cause is “smoke” generated in the room due to the occurrence of a fire. The smoke floats in the room as solid fine particles, for example, fine particles having a particle diameter of 1 μm or less. When the fine particles are mixed with the air in the radiation section and sucked into the air suction portion of the foam generator, the fine particles are supplied together with the air to the foaming portion to reduce the foaming ratio.

  In view of the above circumstances, an object of the present invention is to obtain a desired expansion ratio even if smoke is sucked.

This invention uses an aqueous foam solution having a dynamic surface tension value of 25 mN / m or less with respect to a dynamic surface tension measured at a liquid temperature of 20 ° C. ± 1 ° C. by a maximum bubble pressure method with a lifetime of 100 msec. Then, the foam having a foaming ratio of 330 times or more is discharged.

The present invention relates to a dynamic surface tension measured at a lifetime of 100 msec by a maximum bubble pressure method under a liquid temperature of 20 ° C. ± 1 ° C., and the value of the dynamic surface tension of the aqueous foam solution is 18 mN / m to 24 mN / m is mixed with water at a concentration of 2% or more and 7% or less of a foam extinguishing agent containing a fluorosurfactant as a main component to release bubbles having a foaming ratio of 330 times or more. .
In the present invention, the high-expansion foam fire extinguishing equipment causes foaming by colliding the foam aqueous solution radiated from the radiation nozzle against the foaming net and entraining air, and filling the fire source with the foam to extinguish asphyxiation. It is a high expansion foam fire extinguishing facility for inside air to be performed.

  The present invention relates to a dynamic surface tension measured at a liquid temperature of 20 ° C. ± 1 ° C. by a maximum bubble pressure method with a lifetime of 100 msec, and the value of the dynamic surface tension is 25 mN / m or less, for example, 18 mN / m Since the foam aqueous solution of m to 23 mN / m is used, a desired expansion ratio can be obtained even in a smoke environment.

It is a figure which shows 1st Example of this invention, and is a graph which shows the relationship between dynamic surface tension and lifetime. FIG. 1 is a diagram showing a first embodiment of the present invention, in which samples, dynamic surface tension, foaming ratio, and the like are summarized in a table.

  The present inventor has found that it is only necessary to remove the smoke particles in order to solve the above problem, but it is thought that the reduction in the expansion ratio can be prevented without removing the smoke particles. It was.

  The inventors have inferred from the previous studies that the phenomenon that the expansion ratio is reduced by the smoke is caused by the reaction between the surfactant molecules and the smoke particles on the surface of the foam film. That is, when smoke was sucked during foaming, it was assumed that the surfactant molecule density on the surface of the foam film was lowered due to the reaction with the smoke particles, and a phenomenon that the foaming ratio was significantly reduced occurred.

  Conventionally, in a high expansion foam (Hi-Ex) fire extinguishing facility, a synthetic surfactant foam fire extinguishing agent is diluted to an aqueous solution of about 3% and used. The static (at equilibrium) surface tension of these foam aqueous solutions is about 22 mN / m. However, in a dynamic state called “foaming” in which bubbles are radiated from a nozzle in the form of droplets and foam is formed on the foamed net, the surface shape and surface area of the foam aqueous solution change rapidly in a short time.

Therefore, as the surface age, which is the time for forming bubbles, becomes shorter, the adsorption of the surfactant molecules on the surface of the foam film cannot catch up, and the surface tension in a dynamic state increases. For example, when measured by the maximum bubble pressure method, the dynamic surface tension of the aqueous foam solution described above becomes 30 mN / m or more when the bubble lifetime is 100 msec.
Here, “surface age” is the time required for the formation of an interface between an aqueous solution such as bubbles and air, and corresponds to “lifetime” in the maximum bubble pressure method.

  The value of this dynamic surface tension means that the larger the value, the lower the surfactant density on the surface of the foam film. On the other hand, when smoke is sucked during foaming, the surfactant molecule density on the surface of the foam film is further lowered by reaction with the smoke particles, and the foaming ratio is significantly lowered.

  Therefore, in order to improve the durability against smoke and make it difficult for the foaming ratio to decrease, it was considered effective to increase the surface active agent density at the time of foam film formation. As described later, the surface active agent density at the time of foam film formation is reflected in the value of the dynamic surface tension. The lower the dynamic surface tension, the higher the surface active agent density.

  Based on such considerations, the inventors have found from various experiments that the desired foaming ratio can be obtained even by sucking smoke by adjusting the dynamic surface tension of the aqueous foam solution within a predetermined range. Therefore, it demonstrates in detail below.

First, the “method for measuring dynamic surface tension by the maximum bubble pressure method” will be described.
As a method for measuring the dynamic surface tension, there are various methods such as a maximum bubble pressure method (also referred to as “bubble pressure method”) and a drop volume method. As a result of examining the adaptation time range and reproducibility, it was found that the "maximum bubble pressure method" was optimal for the dynamic surface tension measurement of foam aqueous solution, so this measurement method was adopted. .

Therefore, the maximum bubble pressure method will be described.
Bubbles are pushed out from the tip of a thin tube called a probe inserted into the aqueous foam solution using compressed air. In other words, this method is like making a bubbly bubble by inserting a straw into the water in the cup. A pressure sensor is provided at the base of the probe, and a change in internal pressure in the probe is detected by the pressure sensor as bubbles are generated.

The pressure in the probe increases with the generation of bubbles. When the initial internal pressure is P0 and the internal pressure at the time when the pressure reaches the maximum is Pmax, the surface tension γ of the aqueous foam solution is It is expressed by the following formula. Here, r represents the radius of the probe hole.
γ = (Pmax−P0) r / 2
Thus, the method of calculating the surface tension from the pressure change accompanying the bubble generation is the “maximum bubble pressure method”. From this equation, the smaller the dynamic surface tension is, the more bubbles can be produced with a smaller pressure.

  The time from when bubbles are generated (P0) until the internal pressure reaches the maximum (Pmax) is referred to as “lifetime”. By changing the lifetime, the surface tension in various time ranges can be measured.

  “BP-D5” (trade name, manufactured by Kyowa Interface Science Co., Ltd.) and SITAt60 (trade name, manufactured by Eiko Seiki Co., Ltd.) were used as dynamic surface tension meters for the maximum bubble pressure method.

“Relationship between dynamic surface tension and life lime of foam aqueous solution measured by maximum bubble pressure method will be described with reference to FIG.
This graph shows the dynamic surface tension measured by changing the bubble lifetime from 10 msec to 10000 msec (10 seconds) using the following samples (No. 1 to No. 4) at a liquid temperature of 20 ° C. ± 1 ° C. γ (mN / m) is plotted. In general, when the temperature rises, the molecular motion of the liquid becomes active, so that its surface tension decreases. Therefore, it is necessary to control the liquid temperature of the sample when measuring the dynamic surface tension. In the present invention, the liquid temperature was measured at 20 ° C. ± 1 ° C.

No. 1 Foam aqueous solution A3: Foam extinguishing agent A mainly composed of a fluorosurfactant. This foam fire extinguishing agent A is used in a mixing ratio with water, that is, a concentration of 3%. For the following drugs, “concentration” indicates the mixing ratio with water.
No. 2 Foam aqueous solution A6: Foam extinguishing agent A mainly composed of a fluorosurfactant is used at a concentration of 6%.
No. 3 Foam aqueous solution C3: A synthetic surfactant foam fire extinguishing agent C mainly composed of a hydrocarbon-based surfactant used in high expansion foam fire extinguishing equipment is used at a standard concentration of 3%.
No. 4 Foam aqueous solution E3: Water film foam extinguishing agent E mainly composed of a fluorosurfactant used in low expansion foam fire extinguishing equipment is used at a standard concentration of 3%.

  The measurement results are as shown in FIG. 1 (graph). In this graph, the vertical axis represents dynamic surface tension γ (mN / m), and the horizontal axis represents lifetime (msec).

  As can be seen from the graph, the dynamic surface tension γ (mN / m) of each sample increases as the lifetime decreases, and decreases as the lifetime increases. Here, the surface tension when the lifetime is extended to infinity corresponds to a so-called “static (at equilibrium) surface tension”. The static surface tension of each sample measured at a liquid temperature of 20 ° C. ± 1 ° C. was about 16 mN / m for the aqueous foam solutions A3, A6, and E3, and 22 mN / m for the aqueous foam solution C3.

In the graph of FIG. 1, when the aqueous foam solution A3 and the aqueous foam solution A6 are compared, when the lifetime is 1000 msec or more, they overlap and no difference is observed. On the other hand, as the lifetime becomes shorter at 1000 msec or less, the difference between the two becomes clearer. At 100 msec, the aqueous foam solution A3 was about 22 mN / m and A6 was about 20 mN / m. That is, even with the same foam drug, the higher the concentration, the smaller the dynamic surface tension. Such a difference is considered to be caused by the content of the surfactant.
In addition, the fluorosurfactants A and E have a smaller dynamic surface tension than the hydrocarbon surfactant C even at the same foam chemical concentration. For example, the dynamic surface tension of the foam drug C3 at a lifetime of 100 msec is 33 mN / m, the dynamic surface tension of the foam drug E3 is 27 mN / m, and the dynamic surface tension of the foam drug A3 is 22 mN / m. Such a difference is considered to be caused by the type of surfactant contained in the foam drug.

  Some of the commercially available dynamic surface tension meters cannot measure the surface tension with a lifetime of 30 msec or less. It is effective to use a value measured at about 100 msec.

Next, the “relationship between dynamic surface tension and expansion ratio in smoke” will be described.
In order to know the above relationship, measurement of dynamic surface tension γ (mN / m) at a lifetime of 100 msec using samples (No. 1 to No. 14) in FIG. The foaming ratio was measured.

No. 1-7 (Invention) Foam aqueous solution A: Foam extinguishing agent A mainly composed of a fluorosurfactant is used in 2, 3, 7, 9, 10, 12, 14%
No.8-10 (Invention) Foam aqueous solution B: Water film foam extinguishing agent B mainly composed of fluorosurfactant used in conventional low expansion foam extinguishing equipment is 5, 10, 12% use
No.11 (Conventional product) Comparative example C: Uses a synthetic surfactant foam fire extinguishing agent C used in conventional high expansion foam fire extinguishing equipment at a standard concentration of 3% (main component is hydrocarbon surfactant)
No. 12 (Conventional product) Comparative Example D: Uses a synthetic surfactant foam fire extinguishing agent D used in conventional high expansion foam fire extinguishing equipment at a standard concentration of 3% (main component is hydrocarbon surfactant)
No. 13 (Conventional product) Comparative Example E: Water film foam extinguishing agent E used in conventional low expansion foam extinguishing equipment is used at a standard concentration of 3% (main component is fluorosurfactant)
No.14 (Conventional product) Comparative example F: Water film foam extinguishing agent F used in conventional low-expansion foam extinguishing equipment is used at 6% twice the standard concentration (the main component is a fluorosurfactant) )

    The measurement results are as shown in FIG. The foaming ratio in the smoke was measured at a smoke concentration of 15% / m of light extinction rate after burning a rubber tire. The dynamic surface tension γ is measured at a sample liquid temperature of 20 ° C. ± 1 ° C.

As can be seen from FIG. 2, the smaller the dynamic surface tension γ at a lifetime of 100 msec, the higher the foaming ratio in the smoke. In order to put it into practical use as a high expansion foam fire extinguishing equipment, it is sufficient that the expansion ratio is about 300 times or more, so it is understood from the graph that the dynamic surface tension of the aqueous foam solution should be 25 mN / m or less. That is, in the table of FIG. 2, the value of the dynamic surface tension of sample No. 3 is 24, and the foaming ratio in smoke is 330 times. Is 25 mN / m or less.
Further, as can be seen from Sample Nos. 1 to 7 and Samples Nos. 8 to 10 in FIG. 2, it can be seen that the foaming ratio increases as the foam drug concentration increases.
As described above, in order that the dynamic surface tension at 100 msec is 25 mN / m or less, the smaller the equilibrium surface tension, the smaller the dynamic surface tension can be achieved with a relatively small drug concentration. For this purpose, it is desirable to use a foam fire-extinguishing agent whose main component is a fluorosurfactant having a low equilibrium surface tension even at the same agent concentration, and the equilibrium surface tension of the aqueous foam solution is 16 to 18 mN / m. preferable.
However, the “water film foam extinguishing agent” mainly composed of a fluorosurfactant has a lower smoke-free foaming ratio than the “synthetic surfactant foam extinguishing agent” under normal concentration conditions (3 to 4%). So far, it has not been used in high expansion foam fire extinguishing equipment.
The foam fire extinguishing agent A used in sample Nos. 1 to 7 in FIG. 2 is a foam extinguishing agent prepared with a higher concentration of a fluorosurfactant than that produced as a conventional “water-film foam extinguishing agent”. is there. In addition, the foam extinguishing agent B used for sample Nos. 8 to 10 is conventionally used as a water film forming foam extinguishing agent for low expansion foam extinguishing equipment at a standard concentration of 3%, with a mixed concentration of 4% or more. When used, the dynamic surface tension at a lifetime of 100 msec is 25 mN / m or less.

As a comparative example, the conventional foam aqueous solutions C, D, E, and F all have a dynamic surface tension of 27 mN / m or more at a lifetime of 100 msec and a foaming ratio in smoke of 200 times or less. Is not suitable.
On the other hand, each of the foam aqueous solutions A and B of the present invention has a dynamic surface tension of 25 mN / m or less at a lifetime of 100 msec, a foaming ratio in smoke of 300 times or more, and is practical as a high expansion foam fire extinguishing equipment. Suitable for
Further, as described above, as the foam extinguishing agent concentration increases, the dynamic surface tension decreases, and the foaming ratio in the smoke increases. However, when the value of dynamic surface tension measured at a liquid temperature of 20 ° C ± 1 ° C at a lifetime of 100 msec is 18 mN / m or less, the foaming ratio in smoke is saturated, and the foam extinguishing agent concentration is further increased. However, the expansion ratio does not increase.
As the foam extinguishing agent concentration increases, the amount of foam extinguishing agent stored as equipment increases, so the cost of the equipment also increases. The foam extinguishing agent concentration with a dynamic surface tension value of 18 mN / m or less at a lifetime of 100 msec, measured at a liquid temperature of 20 ° C ± 1 ° C, where the foaming ratio in the smoke is saturated is just enough to meet the increase in equipment costs The effect of increasing the expansion ratio cannot be obtained.
From these facts, the practically effective foam aqueous solution used in the high expansion foam fire extinguishing equipment of the present invention has a dynamic surface tension of 18 to 25 mN / m or less at a lifetime of 100 msec measured at a liquid temperature of 20 ° C. ± 1 ° C. Preferably there is.

  Furthermore, by setting the dynamic surface tension to 23 mN / m or less, the expansion ratio in smoke becomes 400 times or more, which is more preferable. The foam aqueous solution of the present invention used for the high expansion foam fire extinguishing equipment is not particularly limited because the foaming ratio is improved as the dynamic surface tension at a lifetime of 100 msec is smaller, but the dynamic surface tension is 18 mN / m as described above. In the following, since the expansion of the expansion ratio is saturated, it is preferable to set the lower limit to 18 mN / m for practical use. Alternatively, the lower limit value may be a value taken by the equilibrium surface tension.

The foam fire extinguishing agent A prepared as the foam extinguishing agent of the present invention used for the high expansion foam extinguishing equipment is a dynamic surface at a lifetime of 100 msec measured at a liquid temperature of 20 ° C. ± 1 ° C. when the mixed concentration with water is 2%. The tension is 24 mN / m or less. (Fig. 2, Sample No. 1)
Therefore, it is preferable to use a foam aqueous solution in which the foam extinguishing agent of the present invention is mixed at a concentration of 2% or more for the high expansion foam fire extinguishing equipment, and thereby, a foaming ratio of 300 times or more can be obtained even in smoke. .
The upper limit value of the mixed concentration is preferably 10% at which the dynamic surface tension value at a lifetime of 100 msec is 18 mN / m.

The foam aqueous solution of the present invention used in the high expansion foam fire extinguishing equipment preferably uses a foam fire extinguishing agent containing a surfactant that reduces the static surface tension at a concentration higher than the micelle critical concentration, such as a fluorosurfactant. .
The foam extinguishing agent used in the conventional high-expansion foam extinguishing equipment is a “synthetic surfactant foam extinguishing agent” according to the fire certification standard mainly composed of a hydrocarbon surfactant. This static surface tension is about 22 mN / m as in the above example.

On the other hand, the “water film foam extinguishing agent” in the fire fighting certification standard contains a fluorosurfactant as the main component, and the equilibrium surface tension is generally saturated at the lower limit at a mixed concentration of 0.5% or less. The micelle critical concentration is said to be about 16 to 17 mN / m. As can be seen from the foam aqueous solutions C3 and E3 in FIG. 1 (graph), the dynamic surface tension tends to be relatively smaller when the equilibrium surface tension value is smaller. Therefore, the one containing a fluorosurfactant like the “water film-forming foam fire extinguishing agent” is more suitable as a foam extinguishing agent used for an aqueous foam solution used in a smoke situation.
As described above, in order to improve the foaming performance in the presence of smoke, it was found that the dynamic surface tension needs to be reduced. I can say that. In other words, regarding foam chemicals, “the main component of the foam fire extinguishing agent is a water film forming / fluorine-based surfactant” and “the concentration of the surfactant is increased”.

Here, as a result of investigating the dynamic surface tension of the conventional water film forming foam extinguishing agent (foam aqueous solution E, F) containing a fluorosurfactant, the liquid temperature was 20 ° C. ± 1 at the standard use concentration. The dynamic surface tension at a lifetime of 100 msec measured at ℃ is 26 mN / m or more, and it is not suitable for use in a high expansion foam fire extinguishing equipment under smoke conditions. However, it was found that the dynamic surface tension at a lifetime of 100 msec can be reduced to 25 mN / m or less by adjusting the concentration higher than the standard use concentration.

  As described above, the foam fire extinguishing agent B used in the high expansion foam fire extinguishing equipment of the present invention is conventionally used at a standard concentration of 3% as a water film foam extinguishing agent for low expansion foam fire extinguishing equipment, and has a lifetime. The dynamic surface tension at 100 msec is 25 mN / m or less at a mixed concentration of 4% or more. In the present invention, by using this foam extinguishing agent B at a concentration of 5% or more, it is possible to obtain an expansion ratio of 400 times or more in the smoke.

However, any water film-forming foam fire-extinguishing agent can be used in the highly expanded foam fire-extinguishing equipment of the present invention as long as the concentration is higher than the standard use concentration. For example, as in the case of the conventional product F in Fig. 2 above, even if it is 6%, which is twice the standard concentration, the dynamic surface tension at a lifetime of 100 msec is about 28 mN / m, and the foaming ratio in the smoke Some are less than 200 times.
If this foam fire extinguishing agent F is used, it is necessary to make the concentration 10% or more in order to reduce the dynamic surface tension at a lifetime of 100 msec to 25 mN / m or less. As the cost increases, it is inappropriate.
Moreover, although the foaming ratio can be increased by increasing the concentration of the foam drug, the foaming ratio is saturated even if the concentration is increased. For this reason, raising the concentration more than necessary increases the amount of fluorine-based surfactant to be added, which increases the drug cost. Therefore, it is possible to increase the expansion ratio by reducing the dynamic surface tension. However, considering the saturation of the expansion ratio, the lower limit value of the dynamic surface tension γ is approximately 18 mN / m. Become.

By the way, in the conventional high-expansion foam fire extinguishing equipment, since it was not possible to foam up to a magnification effective for fire extinguishing in smoke, only the foaming magnification in a smokeless state was a problem. As shown in the table of FIG. 2, there is no clear correlation between the expansion ratio in the smokeless state and the equilibrium surface tension or dynamic surface tension.
In the field of detergents and the like, the correlation between the dynamic surface tension of a detergent (main component is a hydrocarbon surfactant) and foaming properties (good foaming) has been studied in the past. As a result, it has been found that the smaller the dynamic surface tension, the better the foaming, but this relationship was in clean (no smoke) air.
The main component of "synthetic surfactant foam fire extinguishing agent" that has been used in conventional high expansion foam fire extinguishing equipment is "hydrocarbon surfactant" similar to these detergents, but the foaming ratio in smoke is Even when the concentration was changed (the dynamic surface tension was changed), it was not possible to obtain foam having a foaming ratio effective for fire extinguishing. In addition, “water-based film foam extinguishing agent” mainly composed of fluorosurfactant with low equilibrium surface tension and dynamic surface tension at the same chemical concentration is “synthetic surfactant foam extinguishing agent” under normal concentration conditions. It has not been used in high expansion foam fire extinguishing equipment because of the problem that the expansion ratio in the smokeless state becomes smaller.
Because of the above circumstances, in the field of high expansion foam fire extinguishing equipment, the relationship between foaming performance and dynamic surface tension that can obtain an effective foaming ratio in smoke has not been studied so far.

A3 Foam aqueous solution A6 Foam aqueous solution C3 Foam aqueous solution E3 Foam aqueous solution

Claims (3)

For dynamic surface tension measured with a maximum bubble pressure method at a liquid temperature of 20 ° C. ± 1 ° C. with a lifetime of 100 msec, the foaming ratio was determined using an aqueous foam solution having a dynamic surface tension value of 25 mN / m or less. Releases a foam of 330 times or more . Regarding the dynamic surface tension measured at a lifetime of 100 msec by the maximum bubble pressure method at a liquid temperature of 20 ° C. ± 1 ° C., the value of the dynamic surface tension of the aqueous foam solution is 18 mN / m to 24 mN / m. The foam extinguishing agent mainly composed of a fluorosurfactant is mixed with water at a concentration of 2% to 7% to release bubbles having a foaming ratio of 330 times or more. High expansion foam fire extinguishing equipment. The high expansion foam fire extinguishing equipment is:
It is a high expansion foam fire extinguishing equipment for inside air that extinguishes suffocation by causing foam solution by colliding the foam aqueous solution radiated from the radiation nozzle against the foaming net and entraining the air and filling the fire source with this foam. The high expansion foam fire extinguishing equipment according to claim 1 or 2.

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