EP0804946A1 - Gas-producing composition for extinguishing fires and process for producing this composition - Google Patents

Abstract

The pyrotechnic, aerosol-forming composition (I) for extinguishing fires in closed rooms, contains: (A) 67-72 wt.% potassium nitrate with an average particle diameter (PD) of not more than 25 mu m; (B) 8-12 wt.% phenol-formaldehyde (PF) resin with a PD of not more than 100 mu m; and (C) dicyandiamide as the remainder with a PD of not more than 15 mu m. Also claimed is the production of (I).

Description

The invention relates to fire extinguishing technology, in particular the prevention and extinguishing of fires in closed rooms.

To extinguish a fire in a closed room, it is known to create an atmosphere in this room which prevents combustion. Inert diluents are used as fire extinguishing agents (carbon dioxide, nitrogen, argon, water vapor), volatile inhibitors, in particular halogen-containing agents, fire extinguishing powders (AN Baratov, EM Ivanov, "Extinguishing Fires in the Chemical and Petroleum Processing Industry", Moscow, Chemistry, 1979 ).

The known methods of extinguishing fire in rooms with inert diluents cannot be used to extinguish alkali and alkaline earth metals, some metal hydrides and compounds that contain oxygen in their molecules.

When developing systems for extinguishing in rooms, there are limited possibilities due to the size of the buildings to be protected (with very large sizes of the buildings, it is very difficult to provide a sufficient amount of gas in a certain time). In addition, one must consider a possible danger to people present from suffocation (signaling systems are therefore necessary which indicate the use of the extinguishing process).

Deleting with halogen-containing compounds also has a number of disadvantages. These compositions can have a toxic effect on humans, since the halogen-containing compounds form thermal decomposition products of great corrosion activity when extinguished by fire. In addition, rooms that are particularly at risk of fire are usually protected with very large fire extinguishing systems for room fire extinguishing, in which halogenated hydrocarbons are used. Due to the international measures to protect the ozone layer in accordance with the Montreal Protocol (1987), the use of the fluorocarbons mentioned must be halved by 1995 and completely abandoned by 2000, since these substances have a high ozone-depleting potential.

Systems for extinguishing fire in rooms in which halogen-containing hydrocarbons are used are known (for example GB-PS 2 020 971). A disadvantage of such systems is their harmful effect on the environment. In addition, such systems are of fairly large dimensions and weight, so that their effectiveness in extinguishing fires in vehicles, e.g. in aircraft.

A method for producing a fire extinguishing agent is known, in which a mixture of solid particles and inert gases forms when a charge of a pyrotechnic mass is burned off (WO 92/17244). However, the high temperature of the combustion products leads to an increase in the average room temperature in the room, which leads to harmful effects on living beings. In addition, when burning the pyrotechnic solid fuels, in addition to the primary aerosol products with extinguishing effects, gaseous products (CO, NH ₃ , H ₂ , CH _x and NO _x ) of the incomplete combustion of the organic components also result, which leads to pollution of the environment by these products .

The composition according to the invention solves the task of providing an ecologically harmless composition for extinguishing fire in rooms.

An object of the invention is a pyrotechnic, aerosol-forming composition for extinguishing fires in closed rooms, containing potassium nitrate in an amount of 67-72 mass%, phenol formaldehyde resin in an amount of 8-12 mass%, and dicyandiamide as the remainder, the Particles of potassium nitrate have an average particle diameter of not greater than 25 µm and accordingly have a specific surface area of not less than 1500 cm ² / g, and the average particle diameter of the phenol formaldehyde resin is not greater than 100 µm, and that of dicyandiamide is not greater than 15 µm .

The composition according to the invention preferably additionally contains potassium bicarbonate (KHCO ₃ ), potassium benzoate (C ₇ H ₅ O ₂ K) or potassium hexacyanoferrate K ₃ [(FeCN) ₆ ] with an average particle diameter of the potassium-containing substance of not greater than 15 μm and accordingly a specific particle surface of not less than 500 cm ² / g.

This composition contains (in% by mass): Potassium nitrate 67-72 Dicyandiamide 9-16 Phenol formaldehyde resin 8-12 Potassium benzoate, bicarbonate or hexacyanoferrate 4-12

The object is also achieved by the process for the preparation of the composition according to the invention, which comprises providing a solution of the phenol formaldehyde resin, mixing the constituents, sieving, granulating and drying, a mixture of ethyl alcohol being used to prepare the solution of the phenol formaldehyde resin Acetone used in a ratio of 30-50: 70-50, the powdered components mixed with the solution of the phenol formaldehyde resin by adding the solution in at least two equal portions until all components are evenly distributed in its entirety, ie until a uniform and stable mass is obtained, the mixture is granulated simultaneously with its drying at temperatures of 20-70 ° C. until a residual moisture and volatile content of not more than 1% and sufficient flowability the granulated composition is reached when it is used.

The ratio and dispersity of the constituents as well as the process for the preparation of the composition ensure a faster and more complete combustion of the composition and a larger amount of highly disperse particles and inert gases (CO ₂ , N ₂ , and H ₂ O as vapor) in the aerosol, which in turn ensures the extinguishing performance of the composition and enables a tolerable toxic level on humans when extinguishing fire.

The use of highly disperse starting products of the powder-forming components (potassium nitrate, dicyandiamide, potassium benzoate, potassium bicarbonate, potassium hexacyanoferrate) and that of the phenol formaldehyde resin as a lacquer solution in ethyl alcohol / acetone mixture, as well as the process according to the invention for the preparation of the composition, make it possible to obtain a finished mixture with the necessary technological and consumption properties the reduction of the production time and the dangerousness of the production (the need for dangerous operations such as revolution is avoided).

The composition according to the invention can be produced in standard pyrotechnic plants.

Table 1 lists formulations of the composition according to the invention in comparison with a known composition and the most important parameters of these compositions. It can be seen from Table 1 that the composition according to the invention surpasses the known in all the parameters mentioned.

Tabelle 2 Nr. Gehalt der Komponente, Masse-%, (mittlerer Teilchendurchmesser, µm) Toxische Wirkung* Feuerlöschende Konzentration g/m³ Grad des Abgangs in das Aerosol, % KNO₃ Phenolformaldehydharz Gas-Aerosolbildner Tod, % Lähmung, % 1 60 (∼320) 15 (∼360) 25 (∼340) DCDA** 79 100 48 76 2 67 (<25) 10 (<100) 23 (∼340) DCDA 0 4,2 36 88 3 60 (<25) 8 (∼360) 32 (∼340) DCDA 100 100 42 80 4 67 (<25) 18 (<100) 15 (∼340) DCDA 0 58,3 38 84 5 60 (<25) 8 (<100) 32 (∼340) DCDA 100 100 40 84 6 70 (<25) 5 (∼360) 25 (<15) DCDA 0 12,5 36 86 7 70 (<25) 15 (<100) 15 (<15) DCDA 0 4,2 34 90 8 70 (<25) 18 (<100) 12 (<15) DCDA 0 16,7 36 90 9 60 (<25) 15 (<100) 25 (<15) DCDA 79 79,2 42 80 10 58 (<25) 5,5(<100) 36,5(<15) DCDA 79 100 56 78 11 69 (<25) 12 (<100) 17 (<15) DCDA 0 4,2 26 97 12 65,5(<25) 14 (<100) 20,5(<15) DCDA 0 17,4 28 95 13 68 (<25) 13 (<100) 19 (<15) DCDA 0 4,2 26 96 14 70 (<25) 11 (<100) 19 (<15) DCDA 0 0 24 99,3 15 54 (<25) 12 (<100) 34 (<15) DCDA 100 100 120 68 16 70 (<25) 11 (<100) 12%(<15) DCDA+ 7%(<15) KB 0 0 27 97 17 70 (<25) 10 (<100) 10%(<15) DCDA+ 10%(<15) KBC 0 0 22 99 18 69 (<25) 8 (<100) 11%(<15) DCDA 12%(<15) KHCF 0 0 23 98 19 75 (<25) 10 (<100) 15% (<15) DCDA 12,5 100 40 90 20 76 (<25) 15 (<100) 9% (<15) DCDA 14,7 100 44 85 21 72 (<25) 10 (<100) 18 (<15) DCDA 0 0 26 97 *) Die Ergebnisse resultieren aus Untersuchungen an weißen Mäusen, die über 15 Minuten einer Konzentration von 60 g/m³ ausgesetzt waren und danach 2 Wochen kontrolliert wurden. **) DCDA - Dicyandiamid
KB - Kaliumbenzoat
KBC - Kaliumbicarbonat
KHCF - Kaliumhexacyanoferrat Table 2 shows formulations of the composition according to the invention (Nos. 11, 14, 16, 17, 18 and 21) in comparison to compositions in which the amount and / or the dispersity of the constituents lie outside the range according to the invention. From Table 2 it can be seen that the composition of the invention has a reduced toxic effect. A lower concentration of extinguishing agent is also required to extinguish the fire. Furthermore, the composition according to the invention ensures a larger amount of highly disperse particles and inert gases in the aerosol.

Table 2 No. Component content,% by mass, (average particle diameter, µm) Toxic effects * Fire extinguishing concentration g / m ³ Degree of discharge into the aerosol,% KNO ₃ Phenol formaldehyde resin Gas aerosol formers Death, % Paralysis,% 1 60 (∼320) 15 (∼360) 25 (∼340) DCDA ** 79 100 48 76 2nd 67 (<25) 10 (<100) 23 (∼340) DCDA 0 4.2 36 88 3rd 60 (<25) 8 (∼360) 32 (∼340) DCDA 100 100 42 80 4th 67 (<25) 18 (<100) 15 (∼340) DCDA 0 58.3 38 84 5 60 (<25) 8 (<100) 32 (∼340) DCDA 100 100 40 84 6 70 (<25) 5 (∼360) 25 (<15) DCDA 0 12.5 36 86 7 70 (<25) 15 (<100) 15 (<15) DCDA 0 4.2 34 90 8th 70 (<25) 18 (<100) 12 (<15) DCDA 0 16.7 36 90 9 60 (<25) 15 (<100) 25 (<15) DCDA 79 79.2 42 80 10th 58 (<25) 5.5 (<100) 36.5 (<15) DCDA 79 100 56 78 11 69 (<25) 12 (<100) 17 (<15) DCDA 0 4.2 26 97 12th 65.5 (<25) 14 (<100) 20.5 (<15) DCDA 0 17.4 28 95 13 68 (<25) 13 (<100) 19 (<15) DCDA 0 4.2 26 96 14 70 (<25) 11 (<100) 19 (<15) DCDA 0 0 24th 99.3 15 54 (<25) 12 (<100) 34 (<15) DCDA 100 100 120 68 16 70 (<25) 11 (<100) 12% (<15) DCDA + 7% (<15) KB 0 0 27 97 17th 70 (<25) 10 (<100) 10% (<15) DCDA + 10% (<15) KBC 0 0 22 99 18th 69 (<25) 8 (<100) 11% (<15) DCDA 12% (<15) KHCF 0 0 23 98 19th 75 (<25) 10 (<100) 15% (<15) DCDA 12.5 100 40 90 20th 76 (<25) 15 (<100) 9% (<15) DCDA 14.7 100 44 85 21 72 (<25) 10 (<100) 18 (<15) DCDA 0 0 26 97 *) The results are the result of studies on white mice that were exposed to a concentration of 60 g / m ³ for 15 minutes and were then checked for 2 weeks. **) DCDA - dicyandiamide
KB - potassium benzoate
KBC - potassium bicarbonate
KHCF - potassium hexacyanoferrate

example 1

Very good results when using the composition according to the invention and the process for its preparation are obtained if the following formulation (in% by mass) is used: Potassium nitrate with a specific particle surface area of 2000 cm ² / g 70 Dicyandiamide with an average particle size of 12 µm 12th Phenol formaldehyde resin as a 50% solution in a mixture of ethyl alcohol and acetone in a ratio of 50:50 (calculated as solid) 11 Potassium benzoate with a specific particle surface area of 600 cm ² / g 7

The pre-ground powder components (potassium nitrate, dicyandiamide, potassium benzoate) are placed in a mixer and mixed for 10 minutes. Then a phenol formaldehyde resin solution is added in three equal portions. The contents of the mixer are mixed for 5 minutes after the addition of the appropriate portion of the formaldehyde resin. Mixing takes place at a temperature of 40 ° C with the lid open. The mixture thus obtained is emptied from the mixer and introduced through a sieve into a granulator with continuous gassing with hot air at a temperature of 40 ° C. The pre-dried granulate is placed in bands in 2-3 cm thick layers and dried for additional removal of moisture and volatile components up to 1%. The total mixing and granulating time is approximately 1 hour.

The mixture thus obtained can be further dried in the compressed state if the moisture and volatile content exceeds 1%.

The pyrotechnic, aerosol-forming composition according to the invention and the method for its production make it possible to load aerosol fire extinguishing generators with it and, with their help, to effectively extinguish a fire of gaseous, liquid and solid combustible substances in stationary rooms, in means of transport in rail and road traffic, to be carried out on ocean-going and river ships, in aircraft, including in blow-through devices, for example in aircraft engines, as well as detecting fires and preventing the spread of a fire at special manufacturers to an explosion in storage rooms and in fire and explosion-prone production facilities.

Claims (4)

Pyrotechnic, aerosol-forming composition for extinguishing fires in closed rooms, containing potassium nitrate in an amount of 67-72% by mass, phenol formaldehyde resin in an amount of 8-12% by mass, and dicyandiamide as the rest, characterized in that the particles of potassium nitrate have an average diameter of not more than 25 µm, that of the phenol formaldehyde resin has an average diameter of not more than 100 µm and that of the dicyandiamide has an average diameter of not more than 15 µm. Pyrotechnic, aerosol-forming composition according to Claim 1, characterized in that it additionally contains potassium bicarbonate, potassium benzoate or potassium hexacyanoferrate in an amount of 4-12% by mass and with an average particle diameter of not greater than 15 µm. Process for the preparation of an aerosol-forming composition for extinguishing fires according to one of Claims 1 or 2, characterized in that a solution of the phenolformaldehyde resin in a mixture of ethyl alcohol with acetone in a ratio of 30-50: 70-50 is prepared, the powdery constituents having the Phenol formaldehyde resin solution mixed with portionwise addition of the solution until a uniform distribution of the constituents in the mass of the composition was obtained and the granulation of the mixture simultaneously with drying at a temperature of 20-70 ° C. to a content of moisture and volatile constituents of no more than 1%. A method of making an aerosol-forming fire extinguishing composition according to any one of the claims 1 or 2, characterized in that a solution of the phenol formaldehyde resin is prepared in a mixture of ethyl alcohol with acetone in the ratio 30-50: 70-50, to this solution in portions and with constant stirring, an aqueous potassium nitrate solution is added in an amount such that Mixture obtained, the volume ratio of aqueous potassium nitrate solution to phenolformaldehyde resin solution is 40-60: 60-40, the powdered constituents are added in portions and with constant stirring into the resulting mixture until a uniform distribution of the constituents in the composition is obtained and the mixture is granulated simultaneously with drying at a temperature of 20-70 ° C to a moisture and volatile content of not more than 1%.