Liquid fire extinguishing composition

Abstract

Liquid fire extinguishing composition formulated to contain 50% to 99.9% by weight of one or more fire extinguishing halogenated aliphatic hydrocarbons and 0.1% to 20% by weight of one or more polysiloxanes which may or may not include a solvent for the polysiloxane and a pressurizing agent.

Description

This invention relates to liquid fire extinguishing compositions based on halogenated aliphatic hydrocarbons.

Because of their high fire-extinguishing capacity, various halogenated derivatives of C.sub.1-3 aliphatic hydrocarbons have been used to extinguish fires, especially of liquid hydrocarbons or flameless fires, such as those caused by defective electrical installations. However, irrespective of the conditions under which they are used, the distance from which these fire extinguishing agents can be employed for extinguishing a fire is limited.

It has been proposed that the volatility of fire-extinguishing halogenated aliphatic hydrocarbons might be reduced by adding to the composition high boiling point liquid or solid chlorinated hydrocarbons such as hexachloroethane, perchloronaphthalene, hexachlorobenzene and perchlorotriphenylbenzene. However, such chlorinated hydrocarbons usually have only a low solubility in the fire-extinguishing halogenated aliphatic hydrocarbons used as fire-extinguishing agents. In order to increase the solubility of such chlorinated hydrocarbons in the fire-extinguishing compositions, it has been proposed to include a solvent, such as trichloroethylene, in the compositions. However, such solvents have little if any fire-extinguishing action and therefore their inclusion in the compositions causes a dilution of the efficiency of the fire-extinguishing compositions.

It has also been proposed that from 0.5% to 10% by weight alkyl ethers of cellulose might be added to the fire-extinguishing agents. However, since cellulose alkyl ethers are almost insoluble in halogenated hydrocarbons, the cellulose alkyl ethers must be suspended in the halogenated hydrocarbons and, consequently, such ethers do not satisfactorily reduce vaporization of the extinguishing agents.

It is an object of this invention to remedy the above mentioned disadvantages by providing a fire-extinguishing composition that has a much greater capacity for penetrating into the seat of a fire and can therefore be used to combat a fire from a considerably greater distance than known fire extinguishing compositions.

The invention provides a liquid fire-extinguishing composition comprising from 50% to 99.9% by weight of one or more fire-extinguishing halogenated aliphatic hydrocarbons and from 0.1% to 20% by weight of one or more polysiloxanes.

Compositions in accordance with the invention have better penetration and can be projected from greater distances than known fire-extinguishing compositions, especially when they are used to fight various types of fires, referred to as dry fires, greasy fires and/or gas fires. Moreover, their fire-extinguishing properties are as good as or even better than those of known fire-extinguishing compositions.

The fire-extinguishing halogenated aliphatic hydrocarbon is preferably a fluoro-halogenated aliphatic hydrocarbon, especially a C.sub.1-5 chlorofluorinated, bromofluorinated or bromochlorofluorinated aliphatic hydrocarbon, such as a chlorofluorinated, bromofluorinated or bromochlorofluorinated methane, e.g., trichlorofluoromethane, bromochlorodifluoromethane or bromotrifluoromethane, or 1,1,2 -trichloro- 1,2,2 -trifluoroethane, 1,2 -dibromo- 1,1,2,2 -tetrafluoroethane, 1,2 -dibromohexafluoropropane or 3 -bromo- 1,1,1 -trifluoropropane. However, it is also possible to use a non-fluorinated halogenated aliphatic hydrocarbon such as ethyl bromide, chlorobromomethane or bromoform.

Examples of polysiloxanes that may be used in the compositions of the invention are straight-chain polysiloxanes having the formula: ##SPC1##

in which each R is a hydrogen atom or a group of the formula ##SPC2##

in which R.sub.1, R.sub.2 and R.sub.3 is a C.sub.1-3 alkyl, C.sub.6 or C.sub.10 aryl, C.sub.7-9 aralkyl or C.sub.7-10 alkaryl radical optionally substituted by one or more halogen atoms, X is a halogen atom, y is 0 or an integer from 1 to 3, and n is 0 or an integer from 1 to 7,000, and cyclic polysiloxanes of the formula ##SPC3##

in which X and y are as defined above and m is 0 or an integer from 1 to 20.

In order to facilitate the dissolution of the polysiloxane(s) in the composition, in the case where the polysiloxane is insoluble or only slightly soluble in the fire-extinguishing halogenated aliphatic hydrocarbon(s), from 0 to 49.9% by weight of one or more solvents for the polysiloxanes and/or a pressurizing agent can be included in the composition.

The solvent and pressurizing agent may or may not have fire-extinguishing properties. Examples of solvents that may be used are C.sub.1-3 halogenated aliphatic hydrocarbons other than C.sub.1-3 fire-extinguishing halogenated aliphatic hydrocarbons, e.g. methylene chloride, chlorodifluoromethane, dichlorofluoromethane, dichlorodifluoromethane, carbon tetrachloride, dichloroethane, trichloroethylene and perchloroethylene; C.sub.2-12 aliphatic hydrocarbons such as iso-octane; C.sub.6-10 aromatic hydrocarbons, such as benzene, toluene and solvent naphtha; terpene hydrocarbons, such as oil or terpentine; complex mixtures of hydrocarbons, such as oil gas, kerosene and Stoddard solvent; C.sub.6-10 cycloaliphatic hydrocarbons such as cyclohexane and cyclodecane; C.sub.3-7 carbonyl compounds, such as acetone and methylethylketone; C.sub.2-5 aliphatic acid esters, such as amyl acetate; C.sub.2-6 ethers, such as methyl ether and ethyl ether; C.sub.2-18 hydroxyl compounds, such as ethanol, isopropanol, butanol, and heptadecanol; and cyclic ethers, such as dioxane.

When the composition includes an inflammable solvent or pressurizing agent, the amount of such solvent or pressurizing agent in the composition should not exceed a low percent, for example 4%, by weight of the composition.

A preferred composition in accordance with the invention comprises from 80% to 99.5% by weight of the fire-extinguishing halogenated aliphatic hydrocarbon(s), from 0.5% to 5% by weight of the polysiloxane(s) and from 0 to 19.5% by weight of the said solvent or pressurizing agent.

Liquid fire-extinguishing compositions embodying the features of this invention can be used in mobile, portable or easily carried devices, and in fixed fire-fighting devices, particularly automatic installations for fighting burning liquids or combustible gases. They can be projected under pressure by means of a gas (e.g., nitrogen, carbon dioxide, dichlorofluoromethane) which is compressed, liquefied or dissolved under pressure in per se known manner or by any mechanical system for producing a pressure (e.g., a pump or compressor).

The following examples are given to illustrate the invention:

EXAMPLE 1

4 cubic meters of petrol F (distillation cut between 110.degree. and 160.degree.C, having a specific gravity of 0.742 at 15.degree.C) was burned for one minute, the petrol being contained in a pit having a surface area of 20 square meters. A liquid mixture comprising 95% by weight of the bromochlorodifluoromethane, as extinguishing agent, and 5% by weight of a polysiloxane having the following formula: ##SPC4##

in which n corresponds to a substance with a viscosity of 50 Csk at 25.degree.C, was then projected onto the seat of the fire through a diffuser having a diameter of 26 mm, under a pressure of 10 bars.

The flames were extinguished after 10 seconds when the liquid mixture was projected from a distance of 30 meters from the seat of the fire and the initial ambient temperature was 30.degree.C.

By way of comparison, the procedure described above was carried out with the exception that the liquid mixture did not contain any polysiloxane. The flames were extinguished after 10 seconds when the liquid mixture was projected from a distance of 20 meters from the seat of the fire.

EXAMPLE 2

The procedure described in Example 1 was carried out with the exception that the liquid mixture comprised 98% by weight of bromochlorodifluoromethane and 2% by weight of a polysiloxane having the formula: ##SPC5##

in which n has a value of about 6000.

The fire was extinguished in 8 seconds when the liquid mixture was projected from a distance of 35 meters from the seat of the fire.

EXAMPLE 3

The procedure described in Example 1 was carried out with the exception that the liquid mixture comprised 88% by weight of bromochlorodifluoromethane, 10% by weight of trichlorofluoromethane and 2% by weight of polysiloxane as used in Example 2.

The fire was extinguished in 8 seconds when the liquid mixture was projected from a distance of 38 meters from the seat of the fire.

EXAMPLE 4

The procedure described in Example 1 was carried out with the exception that the liquid mixture comprised 98% by weight of bromochlorodifluoromethane and 2% by weight of a mixture of polydimethylcyclopolysiloxanes having the formula: ##SPC6##

in which n is from 0 to 17.

The fire was extinguished in 12 seconds when the liquid mixture was projected from a distance of 30 meters from the seat of the fire.

EXAMPLE 5

The procedure described in Example 1 was carried out with the exception that the liquid mixture comprised 80% by weight of bromochlorodifluoromethane, 18% by weight of trichlorofluoromethane and 2% by weight of polysiloxane as used in Example 2.

The fire was extinguished in 12 seconds when the liquid mixture was projected from a distance of 40 meters from the seat of the fire.

It will be understood that changes may be made in the details of formulation and operation without departing from the spirit of the invention, especially as defined in the following claims.

Claims

We claim:

1. A liquid fire extinguishing composition consisting essentially of from 50% to 99.5% by weight of at least one fire extinguishing halogenated aliphatic hydrocarbon selected from the group consisting of fluorohalogenated C1-C5 aliphatic hydrocarbon, ethyl bromide, chlorobromomethane and bromoform, from 0.5% to 20% by weight of at least one polysiloxane, 0 to 49.9% by weight of a polysiloxane solvent, and 0 to 49.9% by weight of a pressurizing agent, and in which the amount of polysiloxane solvent and/or pressurizing agent does not exceed 4% by weight of the fire extinguishing composition when the polysiloxane solvent and pressurizing agent are inflammable.

2. A composition as claimed in claim 1 in which the polysiloxane is straight chained and is represented by the formula: ##SPC7##

in which each R is a hydrogen atom or a group having the formula ##SPC8##

in which R.sub.1, R.sub.2 and R.sub.3 is selected from the group consisting of a C.sub.1-3 alkyl, C.sub.6 or C.sub.10 aryl, C.sub.7-9 aralkyl and C.sub.7-10 alkaryl radical unsubstituted or substituted by one or more halogen atoms, X is a halogen atom, y is O or an integer from 1 to 3, and n is 0 or an integer from 1 to 7000.

3. A composition as claimed in claim 1 in which the polysiloxane is cyclic and is represented by the formula: ##SPC9##

in which X is a halogen atom, y is 0 or an integer of from 1 to 3 and m is 0 or an integer of from 1 to 20.

4. A composition as claimed in claim 1 in which the solvent is selected from the group consisting of a C.sub.1-3 halogenated aliphatic hydrocarbon (other than a C.sub.1-3 fire-extinguishing halogenated aliphatic hydrocarbon), a C.sub.2-12 aliphatic hydrocarbon, a C.sub.6-10 aromatic hydrocarbon, a complex mixture of hydrocarbons, a C.sub.6-10 cycloaliphatic hydrocarbon, a C.sub.3-7 carbonyl compound, a C.sub.2-5 aliphatic acid ester, a C.sub.2-6 ether, a C.sub.2-18 hydroxyl compound, and a cyclic ether.

5. A composition as claimed in claim 1 in which the fire-extinguishing halogenated aliphatic hydrocarbon is a C.sub.1-5 chlorofluorinated, bromofluorinated or bromochlorofluorinated aliphatic hydrocarbon.

6. A composition as claimed in claim 5, in which the fire-extinguishing halogenated aliphatic hydrocarbon is a chlorofluorinated, bromofluorinated or bromochlorofluorinated methane.

7. A composition as claimed in claim 1 in which the fire-extinguishing halogenated aliphatic hydrocarbon is selected from the group consisting of trichlorofluoromethane, 1,1,2-trichloro-1,2,2-trifluoroethane, bromotrifluoromethane, bromochlorodifluoromethane, 1,2-dibromo-1,1,2,2-tetrafluoroethane, 1,2-dibromohexafluoropropane or 3-bromo-1,1,1-trifluoropropane.

8. A method of extinguishing a fire with or without a flame comprising projecting from a container onto the fire a liquid composition of claim 1.