FI98271C - Use of a swollen macromolecule containing water mixing system as extinguishing water - Google Patents

Abstract

1. The use as an extinguishing agent of a dispersion of an aqueous phase and a phase obtained by hydration of swollen gen particles of a diameter of 0.1 to 3 mm of individual, water-insoluble, polar macromolecules of highly absorptive polymers based on (meth) acrylic acids, which are so cross-linked that they can take up 100 to 200 times their weight of water, the gel particles being present in an amount of 0.1 to 0.6 weight per cent calculated as dry substance and based on the aqueous phase, and the aqueous system having a viscosity below 100 mPa.

Description

s 98271

B

USE OF EXTINGUISHED WATER MIXTURE SYSTEM WITH EXTENDED MACROMOLECYLES AS EXTINGUISHING WATER ± 0

Extinguishing water is mostly used for firefighting in the form it is obtained from the water supply network or, for example, in the case of forest fires, from natural water works. On the other hand, the mode of action of the extinguishing water is based on the fact that when it comes into contact with combustible objects due to its high heat capacity and evaporation temperature, it provides very efficient cooling by sinking below the combustion or ignition temperature of the object. On the other hand, its effect is based on the fact that when it comes into contact with hot objects, it evaporates / The water vapor generated by Da takes up the space needed for combustion, whereupon it causes the flames to go out.

25 A major disadvantage of using water in its conventional form is that much of the water, when not in use, flows into non-combustible parts or is absorbed into the ground. This is a disadvantage, especially in the case of forest fires, when a substantial part of the water, which is often transported with great effort, is completely unused. However, it is firefighting, especially near the surface of the earth, that is an important part of forest firefighting, because in the typical form of forest fires, fire propagates in dry undergrowth (grass, leaves, shrubs) and causes individual fires that then unnoticed. To date, it has not been possible to make optimal use of the water transported, especially because forest fires are often preceded by a long dry season and the soil is correspondingly very water-absorbing.

40 In principle, however, the same problem arises in the case of such fires, such as rafters, in which case the roof is not separated from the lower floors on a fireproof base. In this case, it is usually the case that water flows through floors, bushings, stairs, etc.

2 98271 through the floors below in the building, and thus wasted in terms of extinguishing. At the same time, due to the lack of water in the burning layer, there is a risk of the fire spreading downwards. Downstream water, on the other hand, often causes great damage, so increasing the amount of extinguishing water is also not without problems.

In order to avoid said drawbacks, patent 10 DE-OS 31 14 630 describes the use of gels as a water barrier on the upper surfaces of fire-threatened building components, for example flat roofs, and for the protection of entire ground areas from surface fires. This method is intended to avoid undesired loss of extinguishing water due to runoff and absorption. 15 However, in the present case, it is a real gel with a very high viscosity which covers the objects to be protected as a thick film. Since such gels are not well absorbed by the fire-threatening substance, they have a poor extinguishing effect. Their high viscosity necessitates the need for special equipment to use them.

The fact that the fire-fighting measures with aqueous gels according to DE-OS 31 14 630 have not become more widespread is explained by the fact that the proposed method has a rather modest effect and by the fact that special equipment is required for the fire-fighting measures and results in corrosion. and environmental damage.

The object of the present invention is therefore to provide a fire-fighting means with the aim of reducing water damage in firefighting, reducing environmental damage, enabling the utilization of commonly used equipment and avoiding corrosion damage.

According to the invention, this object must be solved by using an aqueous mixture system in accordance with the claims.

40 Water-insoluble, highly water-swellable polymers are described, for example, in U.S. Patent Nos. 4,017,653 and 4,018,951. These substances are referred to by those skilled in the art as highly active polymers or so-called superabsorbents. This is especially true with acrylic or meta-acrylamide and acrylonitrile, as described in DE-PS 2 706 135.

The dispersion used according to the invention is preferably prepared by adding the potassium or sodium salts of dry, slightly crosslinked copolymers based on sodium acrylate and / or acrylic acid and having a particle size of about 0.02-0.5 mm while stirring with a mixer or recirculation pump. Suitable crosslinking agents are all olefinic at least bifunctional monomers, such as, for example, methylenebisacrylamide, divinylbenzene, trisallyl cyanurate, trisallyl phosphate, etc. The preparation of suitable cross-linked polymers by radical or redox polymerization is known.

To accelerate the expansion, finely divided silicic acid and / or silicate can be added to the non-expandable copolymers. In the case of optionally added active silicic acids, these are products known in particular as fillers or absorbers, in particular silicic acid exergels with a BET surface area of more than 30 m / g, generally more than 100 m / g, or flame hydrolytic active silicone tetrachloride has a BET surface area between 50-450 m / g (aerosol). Instead of active silicic acids, active silicates having a BET surface area of more than 30 m / g blended from water glass * and the corresponding metal salts and possibly mineral acids, in particular calcium, magnesium or 2.3 aluminum, can be used in the form of their xerogels for the invention together with highly active polymers.

The water-soluble dispersion contains gel particles in such concentrations that sufficient free water remains to achieve, on the one hand, an improved extinguishing effect with minimal water damage and, on the other hand, to allow use with very high wetting capacity, such as pure water. According to the invention, a dispersion of 50 to 80% by weight, preferably 60 to 70% by weight, of the total water in the gel particles is used.

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The gel particles consist of high-activity copolymers, the structure of which is designed to rapidly absorb 100 to 200 times its own weight of water, but is still insoluble in water. If excess water is added to the gel particles swollen in this way, the excess water remains a pure aqueous phase which acts as a carrier for the gel particles and retains its viscosity, while the gel particles can be considered as individual discrete macromolecules.

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According to the invention, a dispersion is used in which the expansion particles based on polyacrylic acids (in the form of sodium or potassium salts) optimally meet the requirements of the invention and do not cause any load on the environment.

When such a product is always added to an amount of about 0.6% by weight in water, only a very slight increase in viscosity is observed. The liquid remains fully pumpable, and when switching from pure water to water with expansion particles in the event of extinguishing, the spray crew did not notice any difference in handling. At higher concentrations, the viscosity increases exponentially, and the free water characteristic of the use of the dispersion according to the invention decreases rapidly. Up to a viscosity of up to 100 mPa, one can speak of "extinguishing water", which can be treated like pure water.

The addition of a wetting agent is possible and may be useful in special cases / such as extinguishing cotton bales.

The effect of the extinguishing water prepared by adding expansion particles in an amount of 0.4% to the water is excellent, as found in the experiments: in a standard room fire it was found that the required amount of extinguishing water was reduced by 30-35% and the amount of water flowing out of the fire area was reduced by 85%. By adding 0.5 - 0.6% of the swelling particles, the vision cosity already increases considerably, but the extinguishing operation can still be performed in the usual way.

The discrete gel particles of the dispersion used according to the invention have nothing in common with the known thickeners which have been proposed to increase the adhesion of water and which cause a high viscosity increase with its associated disadvantages.

By adjusting the pH of the ve-20 internal mixture system of the dispersion used according to the invention to 6-8, corrosion phenomena can be avoided in the extinguishing devices used and in the articles irrigated for fire safety.

The use of an aqueous dispersion system for dispersion according to the invention as extinguishing water does not require any special pumps or pipes due to the low viscosity. Existing equipment can also be used to prevent or fight forest fires from the air. In addition, it is possible to use type W fire extinguishers and sprinkler devices-30. equipment utilized.

When the dispersion for fire protection * is used according to the invention, the added gel particles do not prevent water from being absorbed into the substance but into the substance, but they do not have a substantial tendency to flow out and adhere to fire-threatened or combustible objects due to their own holding capacity. free of steam so that all extinguishing water is available for cooling and steam generation. In this way, the required amount of extinguishing liquid is substantially reduced compared to current substances. In addition, very effective protection against the spread of fire is provided.

When fighting fires in tanks, cooling the tank wall is very important. The use of the dispersion according to the invention makes it possible to spray the wall of the container 10 from time to time with the same syringe during the extinguishing operation, whereby the adhering gel particles make co-spraying unnecessary and allow a better spray capacity to be used. Due to the gel particles adhering to the extinguished substance, the risk of re-ignition of the fire is reduced.

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The addition of the expansion particles can take place in the tank of a tank fire extinguisher, a "water bomber", or in special mixing tanks, whereby during the spraying and a couple of minutes after the spraying is completed the mixture is gently mixed or the liquid is circulated by moderate pumping. The swollen gel particles do not stick to each other. Although they precipitate little during longer periods of inactivity, they can be recycled by pumping even after weeks without any problems, or they can be mixed with a mixer, which is not normally necessary.

A conventional way of using the invention is to inject the dispersion so that it already contains the gel particles formed. Under certain conditions, the preferred modification is to add the expansion particles in an unexpanded state shortly before the injection tube. Although this does not take advantage of the higher adhesion of the gel particles to protect objects that have not yet adhered to the fire, a very no-35 effective protection against water damage is quickly achieved, as after a short time the expanded expansion particles seal the joints and cracks. Once a sealing layer of gel has formed, if this seems reasonable, proceed with clean water.

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In the case of forest fires, part of the gel, due to its adhesion, remains hanging from the trees, and provides good protection for fire to jump from one tree top to another. A layer of water is created in the floor pieces 5, which can prevent the spread of fire to the rest of the building.

The dispersion can be used to make fire blankets, for example in the form of keeping ready-made diapers for escape assistance from fire-threatening facilities, large buildings such as hotels, etc. Such fire blankets contain expansion particles in an expanded state and are sealed to prevent moisture loss, e.g. .

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Claims (5)

Use of a Water Mixing System as Extinguishing Water, which water mixing system contains an aqueous phase and a phase by hydrating coagulated gel particles of 0.1 - 0.3 mm diameter of separate, water-insoluble polar macromolecules of (meth) acrylic acid derivatives, which are so branched that they can absorb 100 - 200 times water of their weight, the gel particles in the aqueous phase being 0.1 - 0.6% by weight based on the dry weight, and that the water mixing system has a viscosity below 100 mPa.s. Use of an aqueous mixing system according to claim 1 for the purpose of claim 1, wherein the aqueous mixing phase contains sodium, potassium or ammonium ions and the macromolecules are polyionic acrylic acid mixed polymers. Use of an aqueous mixing system according to claim 1 for the end portion of claim 1, wherein the total water therein contains the gel particles 50-80% by weight, preferably 60-70% by weight. Use of an aqueous mixing system according to claim 1 for the end of claim 1, wherein it contains active silicic acids and / or silicates. Use of an aqueous mixing system according to any one of claims 1-4 for the ends of claim 1, "for use in extinguishing or sprinkler systems.