Aerosol-forming fire-extinguishing composition with fire retardants

Abstract

The invention relates to fire-extinguishing by aerosol flooding, and more particularly to solid-propellant aerosol-forming compositions. The present aerosol-forming composition contains: 1.0-8.0 wt% fuel-binder, 45.0-65.0 wt% first oxidant in the form of an alkali metal nitrate, 10.0-22.0 wt% gas-forming agent, 0.1-5.0 wt% combustion catalyst, 10.0-25.0 wt% second oxidant in the form of potassium perchlorate, and the balance an additive that generates fire retardants. The result is an increase in fire-extinguishing efficiency with a high rate of combustion of the composition.

Description

[0001] AEROSOL-FORMING FIRE EXTINGUISHING COMPOSITION WITH COMBUSTION INHIBITORS

[0002] Field of technology to which the invention relates

[0003] The claimed invention relates to the field of volumetric aerosol fire extinguishing, in particular to solid fuel aerosol-forming compositions (AFC) and can be used to suppress fire sources in sealed and conditionally sealed and non-sealed volumes.

[0004] State of the art

[0005] The level of technology characterizes the aerosol-forming pyrotechnic composition according to the application RU 2013151115, published on 27.05.2015. This aerosol-forming pyrotechnic composition for volumetric extinguishing of fires in a closed volume includes potassium nitrate, iditol and, as a blowing agent, a heterogeneous mixture of ammonium iodide and thiourea powders in a ratio of 3:1, with the following content of components (wt.%):

[0006] This aerosol-forming pyrotechnic composition is characterized by functional safety and increased efficiency of volumetric extinguishing of fires in closed spaces. The use of a heterogeneous mixture of ammonium iodide with thiourea as a blowing agent, which do not form toxic compounds in the generated extinguishing mixture during combustion, increased the functionality of the aerosol-forming composition.

[0007] The disadvantages revealed in the practice of using the composition according to the prototype are that: - the concentration of combustion inhibitors required to suppress a fire in a closed protected volume is formed slowly due to its flame combustion, as a result of which the release of the functional dispersed phase into the aerosol formation is reduced, worsening the effectiveness of the intended action;

[0008] - as a combustion inhibitor, potassium nitrites and potassium oxides are generated during the chemical reaction, which are fairly weak combustion inhibitors in the range of effectiveness of substances with combustion inhibitory properties;

[0009] - low blowing agent content does not allow creating a sufficient gas phase flow for rapid transfer and mixing of combustion inhibitors in the solid

[0010] 1

[0011] SUBSTITUTE SHEET (RULE 26) phase, which significantly reduces the effectiveness of the composition and does not have high phlegmatizing properties;

[0012] - there are no catalysts in the composition that ensure stable combustion at an optimal rate. For clarity, significant differences in the composition variant in comparison with the composition proposed as an invention are given in Table No. 1.

[0013] Table No. 1

[0014] The level of technology also characterizes the aerosol-forming pyrotechnic composition according to patent RU 2605576, published on 20.12.2016. This aerosol-forming pyrotechnic composition for extinguishing fires in closed spaces, including potassium nitrate, iditol, ammonium iodide and thiourea, and according to the invention, additionally contains urotropine, in the following ratio of components, wt. %:

[0015] 2

[0016] SUBSTITUTE SHEET (RULE 26) The distinctive features of the proposed technical solution ensure increased efficiency of fire extinguishing due to more dynamic achievement of the required concentration of combustion inhibitors in the protected volume to suppress fire sources.

[0017] In the proposed composition, the ratio of the components of the thermal base, close to stoichiometric, practically corresponds to a zero oxygen balance, which ensures complete oxidation of the reagents and gas formation along the developed combustion surface of the charges, increasing the specific yield of the generated gas-aerosol extinguishing mixture.

[0018] The additional introduction of urotropine, with an optimized mass of 2-^-3%, into the structure of the fire-extinguishing pyrotechnic composition, together with thiourea (combustion activator) ensured an increase in the charge combustion rate to 3.8 mm / s, with the accompanying additional gas formation of environmentally friendly CO2 and H2O vapors, which contribute to a more rapid removal of the generated dispersed phase of the functional aerosol to the source of fire.

[0019] The technical result of this is a reduction in the time for achieving a fire-extinguishing concentration of active combustion inhibitors in the protected volume, interrupting chain oxidation reactions, and, consequently, increasing the efficiency of suppressing fire sources.

[0020] The disadvantages from the practical use of the composition according to the prototype were revealed to be that: - potassium nitrites and potassium oxides are generated as a combustion inhibitor during the chemical reaction, which are fairly weak combustion inhibitors in the range of the effectiveness of substances with combustion inhibitory properties;

[0021] - the use of urotropine increases the hygroscopicity of the composition, which, when used in difficult conditions, increases the risk of reducing the effectiveness of the composition;

[0022] - the relatively low content of blowing agent does not allow for the creation of a sufficient flow of the gas phase for the rapid transfer and mixing of combustion inhibitors in the solid phase, does not allow for the creation of back pressure in non-hermetic volumes to prevent the influx of oxygen, and creates an insignificant phlegmatizing effect when suppressing fires, which significantly reduces the effectiveness of the composition;

[0023] - as a combustion inhibitor, potassium nitrites and potassium oxides are generated during the chemical reaction, which are fairly weak combustion inhibitors in the range of effectiveness of substances with combustion inhibitory properties;

[0024] 3

[0025] SUBSTITUTE SHEET (RULE 26) - there are no catalysts in the composition that ensure stable combustion at an optimal speed.

[0026] For clarity, significant differences in the composition variant in comparison with the proposed composition as an invention are given in Table No. 2. Table No. 2

[0027] The closest analogue to the proposed technical solution (prototype) is the "Aerosol-forming fire extinguishing composition based on saccharides" (patent RU 2740461 dated 18.01.2019), containing sorbitol - 15-40, dicyandiamide - 2-5, iron oxide - 0.1-5, ceresin or copper stearate 0.1-1.0, centralite and / or diphenylamine in an amount not exceeding 0.5 wt. % - 0.1-4.0, potassium nitrate - the rest.

[0028] The disadvantages of the prototype include:

[0029] - low content of blowing agent (dicyandiamide), which does not allow creating a sufficient flow of gas phase for rapid transfer and mixing of combustion inhibitors in the solid phase, has a minimal phlegmatizing effect in suppressing fires, is not capable of creating back pressure in conditionally hermetic and non-hermetic volumes to prevent the influx of additional oxygen, which significantly reduces the effectiveness of the composition;

[0030] 4

[0031] SUBSTITUTE SHEET (RULE 26) - as a combustion inhibitor, potassium nitrites and potassium oxides are generated during the chemical reaction, which are fairly weak combustion inhibitors in the range of effectiveness of substances with combustion inhibitory properties;

[0032] - the use of sorbitol or a mixture of sorbitol with polysaccharides or a mixture of sorbitol with monosaccharides sharply increases the hygroscopicity of the composition, which actually makes the composition unsuitable for use outside moisture-proof volumes or in devices used in a humid environment.

[0033] - the presence of additives in the composition - stabilizers, antioxidants, although it slows down, does not exclude sufficient degradation of the composition, which, as practice has shown, over time significantly affects the fire extinguishing efficiency of the composition.

[0034] For clarity, significant differences in comparison with the proposed composition as an invention are given in Table No. 3.

[0035] Table No. 3

[0036] The technical problem is to overcome the above-mentioned shortcomings of analogs, to increase the efficiency of primary fire extinguishing with an increase in the effectiveness of preventing the spread of fire in a closed or conditionally closed space, in particular, such as an electrical panel, the engine compartment of a car, or the body of an aircraft equipment

[0037] The technical result consists in increasing the fire extinguishing efficiency of the AOS (less than 0.025 g / m3) and increasing the rate of suppression of fire sources in a closed or conditionally closed space, in particular, such as an electrical panel, the engine compartment of a car, or the body of aircraft equipment.

[0038] 5

[0039] SUBSTITUTE SHEET (RULE 26) Disclosure of the invention

[0040] The specified technical result is ensured in an aerosol-forming fire extinguishing composition (AFC) containing a combustible binder, a gas-forming agent in the following ratios, by 100% of the mass:

[0041] Combustible - binder 1.0+8.0

[0042] Blower 10.0+22.0

[0043] Catalyst 0.1 +5.0

[0044] Oxidizer No. 1, alkali metal nitrate 45.0+65.0

[0045] Oxidizer No. 2, potassium perchlorate 10.0+25.0

[0046] Additive generating highly effective flame retardants rest.

[0047] An additional feature is that the composition contains nitroguanidine or guanidine nitrate or triaminoguanidine nitrate or dicyandiamide or melamine mixed with nitroguanidine or melamine mixed with guanidine nitrate or melamine mixed with triaminoguanidine nitrate or melamine mixed with dicyandiamide as a blowing agent.

[0048] An additional feature is that the composition contains shellac or polyvinyl butyral, or nitrocellulose, or its solution in the form of NC varnish, or paraffin or stearin, or iditol solution as a combustible binder.

[0049] An additional feature is that the composition contains potassium hydroterephthalate as an additive that generates highly effective flame retardants.

[0050] An additional feature is that the composition contains ferrocene or metal oxides as a catalyst.

[0051] Thus, the specified technical result is ensured by two main factors:

[0052] 1. A mixture of substances generating highly effective combustion inhibitors, which, during a chemical reaction, produces highly effective combustion inhibitors in the form of lithium chloride (LiCl) or sodium iodide (Nal) or sodium bromate (NaBr) or potassium chloride (KCl) or mixtures thereof, which allows for a significant increase in the efficiency of fire suppression. It is well known that there is a proven series of combustion inhibitors (Table No. 5).

[0053] Combustion inhibitors are arranged in descending order from the most effective to the least effective. In the case of targeted use in a fire extinguishing composition of initial substances capable of generating 6

[0054] SUBSTITUTE SHEET (RULE 26) the most effective combustion inhibitors may significantly increase the efficiency of extinguishing fires using the condensed phase of combustion of an aerosol-forming composition.

[0055] Table No. 5

[0056] 2. The use of a large amount of blowing agent combined with a high combustion rate of the composition (2.9-M, 8 mm / sec) allows for the rapid creation of a high concentration of uniformly distributed combustion inhibitors in the protected volume and an increased effect from the phlegmatization of the chemical combustion reaction. High-speed saturation of the protected volume with the gas phase and the creation of excess pressure allows for the compensation of the effect of oxygen supply in conditionally hermetic and non-hermetic volumes associated with the convective supply of fresh air into the protected volume, allowing for the creation of counter pressure in conditionally hermetic volumes.A similar approach during comparative fire tests with already used aerosol-forming compositions (AFC) showed a significant, 2-3 times, increase in the efficiency of extinguishing protected hermetic, conditionally hermetic and non-hermetic volumes due to the combination of the properties of highly effective combustion inhibitors and the physical effects of creating back pressure with improved phlegmatization of the combustion reaction.

[0057] The basic composition of the proposed family of AOCs contains a combustible binder - for example, shellac or, for example, polyvinyl butyral or, for example, nitrocellulose or, for example, a solution of nitrocellulose in the form of NC varnish, or, for example, a solution of iditol, a blowing agent, for example, nitroguanidine or, for example, dicyandiamide, or, for example, guanidine nitrate, or, for example, triaminoguanidine nitrate or, for example, their mixtures with melamine, oxidizer No. 1 - alkali metal nitrate, for example, sodium nitrate, oxidizer No. 2, for example, potassium perchlorate, a catalyst, for example, ferrocene, an additive is additionally introduced that generates highly effective combustion inhibitors, for example, potassium hydroterephthalate.

[0058] The components included in the composition are taken in the following proportions per 100% of the mass:

[0059] 7

[0060] SUBSTITUTE SHEET (RULE 26)

[0061] An increased amount of the blowing agent nitroguanidine or dicyandiamide or guanidine nitrate or triaminoguanidine nitrate or their mixture with melamine allows, in combination with a catalyst and an additive generating highly effective combustion inhibitors, to provide high-speed generation of the gas phase for the fastest possible filling of the protected volume with a condensed phase in the form of a combustion inhibitor and creating a back pressure that stops the flow of additional oxygen during combustion in conditionally hermetic or non-hermetic volumes, and also enhances the phlegmatization of the combustion process, which has a beneficial effect on the efficiency of fire suppression. When the blowing agent content is less than 10 wt. %, the phlegmatization effect is sharply reduced, and the efficiency of fire suppression is reduced to the limit values. The speed and temperature of combustion of the thermal base are also reduced, creating a lack of calorific value and gas generation for generating the extinguishing mixture.

[0062] When the blowing agent content is more than 22 wt. %, gas generation begins to significantly prevail over the generation of the condensed phase in the form of combustion inhibitors, since the additive that generates highly effective combustion inhibitors is also an effective gas generator, supplementing the gas generation of the main blowing agent, which affects the complex reduction of the fire extinguishing properties of the AOS, and incomplete oxidation of carbon also occurs due to the negative oxygen balance with significant formation of carbon monoxide, which has characteristic negative effects on the human body.

[0063] Ferrocene included in the composition is used as a catalyst.

[0064] Chemical compounds of metals or their mixtures can also act as catalysts. If the catalyst content is less than 0.1 wt. %, its efficiency in the AOS becomes insignificant and does not affect the formation of stable combustion of the composition. If the catalyst content is more than 5.0 wt. %, no increase in the combustion efficiency of the composition is observed and further increase in the mass fraction of the catalyst does not make sense.

[0065] Nitrocellulose or its solution in the form of NC varnish or shellac or polyvinyl butyral or paraffin or stearin or solution is used as a combustible binder.

[0066] 8

[0067] SUBSTITUTE SHEET (RULE 26) iditol. When the content of the combustible binder is less than 1.0 wt. %, its quantity becomes insufficient to obtain acceptable technological characteristics obtained for the hardness and impact resistance of the functional charges of the AOS, which affects the possibility of manufacturing pressed charges as such. When the content of the combustible binder is more than 8.0 wt. %, no significant improvement in the hardness and impact resistance of the pressed functional charges is observed, but at the same time the content by weight of the gas-forming composition or mixture of substances generating highly effective combustion inhibitors decreases, which generally reduces the effectiveness of the proposed composition.

[0068] Alkali metal nitrate is used as oxidizer No. 1. The alkali metal nitrate content is less than 45.0 wt. %, even with the addition of oxidizer No. 2 in the form of potassium perchlorate, does not allow creating the necessary oxygen balance of the reaction and obtaining stable combustion of the mixture. The alkali metal nitrate content is more than 65.0 wt. % when adding oxidizer No. 2 in the form of potassium perchlorate, creates a positive oxygen balance, leading to flame combustion of the composition and excess oxygen generation by the AOS in the protected volume, which negatively affects the efficiency of suppressing AOS fires.

[0069] Potassium perchlorate is used as oxidizer No. 2. Potassium perchlorate content of less than 10 wt. % does not allow to intensify combustion of the additive generating highly effective combustion inhibitors in the form of potassium hydroterephthalate. Perchlorate content of more than 25 wt. % does not significantly affect the increase in the combustion rate of the additive generating highly effective combustion inhibitors in the form of potassium hydroterephthalate and is technologically unjustified.

[0070] It is especially worth noting the effectiveness of using the proposed compositions in extinguishing systems for electrical cabinets, electrical sockets and wall boxes, distribution boxes, server racks, underhood spaces of motor vehicles and special equipment, extinguishing technological compartments and control panels of automobile, special and aviation equipment.

[0071] The composition's peculiarity suggests its use in devices operating in relatively small, conditionally hermetic or non-hermetic volumes in severe climatic conditions, with the effect of high-speed extinguishing of the protected volume when creating a displacing pressure, which significantly accelerates the process of suppressing fires.

[0072] 9

[0073] SUBSTITUTE SHEET (RULE 26) The proposed compositions, having an increased volume of gas phase, can be used as a displacing agent in powder and liquid fire extinguishing systems, enhancing the effect of fire suppression.

[0074] The combustion of the pyrotechnic composition occurs dynamically in the volume of the charge, with intensification of gas formation of the working fluid for the transportation of generated combustion inhibitors, including condensed particles of the working aerosol, to the source of the fire, which is actively suppressed.

[0075] Below is a technological example of the implementation of the method for manufacturing an AOS, which has a purely illustrative purpose and does not limit the scope of claims of the set of essential features of the formula.

[0076] The quantitative ratio of the components of the proposed aerosol-forming pyrotechnic composition, within the optimized ranges, was calculated using a mathematical model of experimental planning and confirmed by the results of an experimental check of the operation of prototype charges for their intended purpose, which showed the achievement of improved characteristics for fire extinguishing efficiency in conditionally sealed volumes.

[0077] The description below provides information regarding the implementation of the aerosol fire extinguishing composition and confirmation of the achievement of the specified technical result.

[0078] Implementation of the invention

[0079] In accordance with the variant of manufacturing the AOC, the following information is provided on the preferred variant of implementing the AOC, which is not intended to limit the scope of the requested protection, determined by the features of the independent claim.

[0080] AOS is prepared on industrial equipment according to the following technological scheme of sequential operations of mixing components in the confidence range of their content, ensuring the specified consumer characteristics.

[0081] To prepare the AOS according to the invention, the following is used:

[0082] 10

[0083] SUBSTITUTE SHEET (RULE 26) First, oxidizer No. 1, for example, sodium nitrate, is selected with a particle size of 45±15 µm and dried to a moisture content of no more than 0.08 wt. %, to eliminate its phlegmatizing effect during oxidation of the fuel, in order to stabilize the combustion of the AOC.

[0084] A gas-forming agent, for example, nitroguanidine, is selected with a particle size of 100±15 µm with a moisture content of no more than 0.8 wt.%. Selective selection of finely dispersed powdered nitroguanidine is necessary for its uniform distribution in the composition when mixing the components.

[0085] The ratio of the components of the composition for mixing is selected according to the declared ranges of their content.

[0086] Oxidizer No. 2, for example, potassium perchlorate, an additive that generates highly effective combustion inhibitors are added to a sample of oxidizer No. 1, for example, sodium nitrate, and a combustible binder, for example, an iditol solution, is also added and mixed for 60-20 minutes at a temperature of 40-60 °C, ensuring their uniform distribution, with maximum contact of the active components of the thermal base in the form of autonomous clusters.

[0087] After this, powders of a blowing agent, such as nitroguanidine, and a catalyst, such as ferrocene, are added to the mixer and mixed for 20-30 minutes, forming conglomerates with a coating of fuel and oxidizer, which adhere to the surfaces of thermal base clusters in direct contact along the developed surface of chemical interaction during combustion, which are characterized by good flammability and stable combustion.

[0088] The prepared mixture is then granulated by rubbing in a mixer through a mesh with R2 mm cells. Then the granulated material is laid out on perforated trays in a layer of 2 ^ 3 cm for wilting, combined with drying at a temperature of 35 ^ 45 ° C. In this case, the content of volatile substances and moisture in the composition is controlled to no more than 0.6 wt.%. The drying process of the granulated material lasts 2-3 hours. From the prepared material, charges are formed by volumetric dosing using the extrusion method, blind or through molding.

[0089] During the experiments, accompanied by fire tests, an assessment was made of the comprehensive effectiveness of suppressing fires on a typical TP-4 source, according to GOST R 50898-96 with some changes. The TP-4 source was placed in an electrical panel with an internal volume of 130 liters, in which rectangular holes with an area of ​​I were cut on the side and top walls.

[0090] SUBSTITUTE SHEET (RULE 26) 1500 mm2 each. The composition under test was placed in the protected volume. After the TP-4 fire was set on fire, the cabinet door was closed and the composition was initiated by an electric igniter.

[0091] Variations in the AOC components by 100% mass were summarized in the table.

[0092] Composition No. 1 had a high burning speed, about 6.2 - 7.3 mm / sec, which is unacceptable in AOS. Such a result was obtained due to the increased content of additives generating highly effective combustion inhibitors. The generation of additional gas was relatively low, which did not allow the correct formation of the fire-extinguishing concentration of combustion inhibitors in the entire volume. The result is that the model hearth TP-4 according to composition No. 1 was extinguished by an AOS weighing 4.2 grams.

[0093] Composition No. 2 had high efficiency, good characteristics of composition pressing, but was still less effective in extinguishing the model source than composition No. 3. The efficiency of the composition was increased by increasing the gas-generating additive, which allowed to create a better dispersion of the combustion inhibitor and fill the protected volume with fire-extinguishing aerosol faster. Also, a large amount of generated gas allowed to create increased pressure in the protected cabinet and squeeze out some of the oxygen inside the protected volume. The model source of TP-4 in the protected volume was extinguished by AOS weighing 3.1 grams. Result - the model source according to composition No. 2 was extinguished.

[0094] Composition No. 4 was worse in extinguishing efficiency than composition No. 3, and had a lower burning rate and generation of extinguishing aerosol, which led to a longer extinguishing of the model source. A decrease in the burning rate of the composition led to a slower rate of filling the protected volume with a combustion inhibitor and ineffective creation of excess pressure in the protected volume to displace oxygen. In fact, the time to achieve the extinguishing concentration of the combustion inhibitor increased. As a result, the model source TP-4 was extinguished with composition No. 4 with an AOS consumption of 4.2 grams.

[0095] 12

[0096] SUBSTITUTE SHEET (RULE 26) Composition No. 5 had a low burning rate, the generation of the condensed phase was low. The combustion is unstable. The model source is not extinguished. A significant increase in the gas-generating additive reduced the amount of the combustion inhibitor released into the protected volume compared to mixtures Option No. 3, Option No. 4. Also, compared to Option No. 4, the combustion rate of the composition dropped, which was 1.0-1.4 mm / sec, which did not allow the necessary fire-extinguishing concentration of combustion inhibitors to be created in a conditionally hermetic volume. Result: the model source according to composition No. 5 is not extinguished.

[0097] As experiments have shown, the best characteristics for extinguishing the model TP-4 fire source are composition No. 3. It is characterized by a high stable burning rate of about 3.7-4.5 mm / sec, a high level of gas phase generation and a sufficient content of the condensed phase consisting of highly effective combustion inhibitors. Extinguishing the TP-4 fire source in a protected volume of 130 liters was performed by an AOS weighing 2.82 grams. The result is that the model TP-4 fire source was extinguished effectively using composition No. 3.

[0098] 13

[0099] SUBSTITUTE SHEET (RULE 26)

Claims

Invention formula 1. An aerosol-forming fire extinguishing composition (AFC) containing a combustible binder and a blowing agent in the following ratios, per 100% of the mass: combustible binder 1.0-^8.0 oxidizer No. 1, alkali metal nitrate 45.0-^65.0 blowing agent 10.0-^22.0 catalyst 0.5-5.0 oxidizer No. 2, potassium perchlorate 10.0-^25.0 additive generating highly effective combustion inhibitors, the rest.

2. The composition according to claim 1, characterized in that it contains nitroguanidine or guanidine nitrate, or triaminoguanidine nitrate or dicyandiamide, or melamine mixed with nitroguanidine, or melamine mixed with guanidine nitrate, or melamine mixed with triaminoguanidine nitrate, or melamine mixed with dicyandiamide as a blowing agent.

3. The composition according to paragraph 1, characterized in that it contains shellac or polyvinyl butyral or nitrocellulose or its solution in the form of NC varnish, or paraffin or stearin or iditol solution as a combustible binder.

4. The composition according to paragraph 1, characterized in that it contains potassium hydroterephthalate as an additive that generates highly effective combustion inhibitors.

5. The composition according to paragraph 1, characterized in that it contains ferrocene or metal oxides as a catalyst. 14 SUBSTITUTE SHEET (RULE 26)

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