Extinguishing composition

Abstract

The invention relates to an extinguishing composition comprising: - a dicyandiamide reducing agent present in a content by weight of between 10% and 30%; - an alkali metal nitrate or alkaline-earth metal nitrate oxidizing agent, the oxidizing agent being present in a content by weight of between 55% and 75%; and - a cellulose resin present in a content by weight of between 5% and 20%, the cellulose resin being chosen from derivatives of carbohydrates or derivatives of glucides.

Description

Technical Field

[0001] The invention relates to a fire extinguishing composition, that is to say a composition the combustion of which generates an aerosol comprising particles capable of extinguishing a fire. Prior art

[0002] Fire extinguishing compositions are known for example from document US2014 / 0041882 and contain an oxidant, a reducer and a phenol-formaldehyde resin.

[0003] However, the inventors found that the phenol-formaldehyde resin used in these fire extinguishing compositions imposes significant conditions on the entire production and storage cycle of the fire extinguishing compositions.

[0004] For example, phenol-formaldehyde resin must be kept cold to prevent it from clumping, and the temperature during the preparation processes of fire extinguishing compositions must not exceed 50°C because the resin risks liquefying if this temperature is exceeded. Finally, the resin can cause accelerated aging in contact with other components of the fire extinguishing composition, particularly in the presence of the reducing agent.

[0005] It is desirable to have a fire extinguishing composition free from the disadvantages mentioned above. Statement of the invention

[0006] Thus, the invention relates, according to a first of its aspects, to an extinguishing composition comprising: a dicyandiamide reducing agent present in a mass content of between 10% and 30%; an alkali metal nitrate or alkaline earth metal nitrate oxidizing agent, the oxidizing agent being present in a mass content of between 55% and 75%; and a cellulose resin present in a mass content of between 5% and 20%, the cellulose resin being chosen from polysaccharides.

[0007] An extinguishing composition according to the invention is characterized by its capacity to extinguish a fire, when it is placed in contact with it.

[0008] Throughout the application, the mass content of a compound in the fire extinguishing composition is defined as the ratio of the mass of said compound in the composition to the mass of the entire composition. The mass content is taken before combustion of the fire extinguishing composition.

[0009] Dicyandiamide is a reducing compound derived from guanidine with a high nitrogen content, and the formula C 2 H 4 N 4 .

[0010] For the purposes of the invention, the term "alkali or alkaline earth metal" designates all the elements in the first and second columns of the periodic table. In particular, the oxidizing agent may be chosen from sodium nitrate, potassium nitrate and strontium nitrate, or mixtures thereof.

[0011] The oxidizing agent allows, by reacting with the cellulose resin, the production of particles comprising at least one alkali or alkaline-earth metal. For example, such particles may be particles of alkali metal carbonate and / or alkali metal chloride, for example K 2 CO 3 and / or KCl. Such particles may also be particles of alkaline-earth nitrate, for example Sr(NO 3 ) 2 . In particular, it has been observed that a fire extinguishing composition in accordance with that described above is compatible with a dry preparation process. In particular, the level of particles generated by the combustion of a composition of the invention, as well as its capacity to self-sustain combustion at low pressure, makes the composition suitable for use as a fire extinguishing composition.Furthermore, the use of a cellulose resin instead of a phenol-formaldehyde resin provides an extinguishing composition with improved resistance to aging.

[0012] In one embodiment, the mass content of cellulose resin is between 8% and 15%.

[0013] In one embodiment, the oxidizing agent is potassium nitrate.

[0014] Such a feature is advantageous because potassium nitrate is more commercially available.

[0015] In one embodiment, a composition according to the invention may further comprise an alkaline earth metal hydroxide endothermic agent, the endothermic agent being present in a mass content of less than or equal to 5%. For example, the mass content of endothermic agent is between 1.5% and 3%.

[0016] In one embodiment, the endothermic agent is magnesium hydroxide. It is not outside the scope of the invention if the endothermic agent is a mixture of alkaline earth metal hydroxides such as, for example, a mixture of calcium hydroxide and magnesium hydroxide.

[0017] Such an endothermic agent makes it possible to further improve the extinguishing capabilities of an extinguishing composition of the invention, since its release makes it possible to lower the temperature of the fire and thus to inhibit it more effectively.

[0018] In one embodiment, the mass content of reducing agent is between 20% and 30%.

[0019] The inventors have in fact noted that this mass content of reducing agent makes it possible to further reduce the combustion temperature of the extinguishing composition.

[0020] In one embodiment, the mass content of oxidizing agent is between 60% and 70%.

[0021] The inventors have in fact noted that this mass content of oxidizing agent makes it possible to further reduce the combustion temperature of the extinguishing composition.

[0022] The inventors have in fact found that by using these optimized levels of reducing agent and / or oxidizing agent, a combustion temperature and a particle rate comparable to that of the composition of US 2014 / 0041882 are obtained.

[0023] In a particular embodiment, the mass content of reducing agent is between 20% and 30%, and the mass content of oxidizing agent is between 60% and 70%.

[0024] According to a second of its aspects, the invention relates to a fire extinguisher comprising a body containing a composition as defined above and an igniter capable of initiating the combustion of the composition.

[0025] According to a third of its aspects, the invention relates to a method for extinguishing a fire using the extinguisher described above and comprising the ignition of the composition by an igniter so as to generate an extinguishing aerosol, and the projection of this aerosol onto the fire. Description of the embodiments

[0026] The inventors evaluated the relevant characteristics of various extinguishing compositions using the Ophélie computer code. The formulations of the evaluated extinguishing compositions and the associated measured quantities are provided in Table 1.

[0027] Composition 1 corresponds to a composition outside the invention.

[0028] Compositions 2 and 3 are compositions according to the invention.

[0029] Tc corresponds to the combustion temperature and OB corresponds to the oxygen balance.

[0030] Composition 2 differs from composition 1 only in the nature of the resin, the contents of each of the other components being identical.

[0031] Composition 2 has a higher combustion temperature Tc and a lower particle rate than composition 1 but is still suitable for use as a fire extinguishing composition. It has improved aging resistance compared to composition 1.

[0032] Composition 3 has a cellulosic resin content identical to that of composition 2, but optimized oxidizing agent and reducing agent contents. The latter make it possible to lower the combustion temperature and increase the particle rate compared to composition 2, thus providing an extinguishing composition with properties similar to those of composition 1 outside the invention and which has improved resistance to aging.

[0033] The expression "between ... and ..." must be understood inclusively.

Claims

1. An extinguishing composition comprising: - a dicyandiamide reducing agent in a content of between 10 and 30 wt.%; - an alkali metal nitrate or alkaline-earth metal nitrate oxidizing agent, the content of the oxidizing agent being between 55 and 75 wt. %; and - a cellulose resin in a content of between 5 and 20 wt. %, the cellulose resin being chosen from among polysaccharides.

2. The extinguishing composition according to claim 1, additionally comprising an alkaline-earth metal hydroxide endothermic agent, the content of the endothermic agent being less than or equal to 5 wt. %.

3. The extinguishing composition according to claim 2, wherein the endothermic agent is magnesium hydroxide.

4. The extinguishing composition according to any of claims 1 to 3, wherein the oxidizing agent is potassium nitrate.

5. The extinguishing composition according to any of claims 1 to 4, wherein the content of reducing agent is between 20 and 30 wt.%6. The extinguishing composition according to any of claims 1 to 5, wherein the content of oxidizing agent is between 60 and 70 wt.%.

7. A fire extinguisher comprising a body containing a composition according to any of claims 1 to 6 and ignition means able to initiate combustion of the composition.

8. A fire extinguishing method using the extinguisher according to claim 7, comprising ignition of the extinguishing composition by the ignition means to generate an extinguishing aerosol, and spraying of this extinguishing aerosol onto the fire.

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