GB2121684A

GB2121684A - Fire-extinguishing concentrates

Info

Publication number: GB2121684A
Application number: GB08315816A
Authority: GB
Inventors: Salvador Morata Lopez
Original assignee: LOSTAO FRANCISCO JAVIER
Current assignee: LOSTAO FRANCISCO JAVIER
Priority date: 1982-06-09
Filing date: 1983-06-09
Publication date: 1984-01-04
Also published as: FR2528317A1; DD209740A5; JPS5985675A; IL68934A0; GB8315816D0; PT76859A; IT1194263B; EP0096426A1; PT76859B; IT8321531A0; ES512991A0; ES8307513A1; AU1566183A; BR8303069A

Description

SPECIFICATION A fire-extinguishing concentrate and a method of producing it The invention relates to a fire-extinguishing concentrate and a method of producing it. A large number of different fire-extinguishing agents are used. For a long time, considerable use was made of carbon dioxide, which extinguishes a fire by displacing the atmospheric oxygen. Carbon dioxide has been found disadvantageous, since in out-of-door fires it is frequently diluted by moving air and thus made less efficient, whereas there is a risk of suffocation if CO2 is used for extinguishing fires in closed rooms. In recent years, therefore, concentrates of mainly synthetic foam-forming agents have been the main substances used for extinguishing fires. Conventional foam-producing concentrates contain the actual foaming agent and a stabilizing additive. The following foaming agents have already been proposed: hydrolyzed proteins, alkyl, aryl, alkyl aryl sulphonates, sulphuric acid esters of higher straight-chain or branched alcohols, sulphates of fatty-acid alkanolamides, fattyacid monoglycerides or methyl taurine in the form of their ammonium or amine salts. The stabilizing additives, which improve the water-retaining capacity of the foam, can be higher alcohols and amides containing 8 to 25 carbon atoms or addition products of alkylene oxide and the aforementioned higher fatty alcohols containining few alkylene oxide molecules. For example, DE-AS 29 33432 discloses a fire-extinguishing agent in which the active components are a hydroxy carboxylic acid, an aliphatic carboxylic acid, a salt of an organic or inorganic acid with a metal and an anionic or amphoteric foaming agent or a hydrolytic decomposition product of a protein. Previously-used foaming extinguishing agents have numerous disadvantages. In many cases, for example, a pulverulent extinguishing agent is first used and greatly reduces foam formation. Other fire-extinguishing concentrates have a reduced foam-forming capacity if diluted with seawater. Many fire-extinguishing agents corrode the storage container or decompose after prolonged storage. Finally, some components of conventional fire-extinguishing agents or decomposition products thereof cause considerable environmental pollution. The object of the invention is to overcome the aforementioned disadvantages and provide an improved fire-extinguishing concentrate which has a high foaming capacity and is biodegradable. According to the invention, the problem is solved by providing a fire-extinguishing concentrate which contains 10 to 40 wt.% alkyl aryl sulphonate, 10 to 40 wt.% fatty-acid alkanolamide, 15 to 50 wt.% alkyl ether sulphate, 0.5 to 6 wt.% polycarboxylic acid ester sulphonate, 3 to 15 wt.% polyethylene glycol, 0.1 to 4 wt.% ammonium fluoroalkyl iodide and 20 to 60 wt.% deionized water, and 0.1 to 3 wt.% formalin if required. The individual constituents will now be described: 1. Alkyl aryl sulphonate The alkyl aryl sulphonates used according to the invention and having the general formula R-Ar-S03Me' comprise alkyl radicals R containing 3 to 16 carbon atoms. Ar denotes a benzene or naphthalene system and the cation Me' is an alkali-metal or triethanol-ammonium cation. Preferance is given to compounds comprising alkyl radicals containing 10 to 14 carbon atoms. According to the invention it is particularly preferred to use dodecyl benzene sulphonate in the form of the sodium or triethanolamine salt in the fire-extinguishing concentrate. 2. Fatty-acid alkanolamide This class of compound, used in the concentrate according to the invention, consists of nonionizable, N-alkylated fatty-acid amides produced by reacting alkanolamines with fatty acids and bearing esterifiable hydroxyl groups in the N-alkyl part. According to the invention, use is made of fatty-acid mono- or di-alkanolamides having the general formula

In the formula, R' denotes the radical of a saturated or unsaturated fatty acid containing 6 to 24 carbon atoms. R denotes a hydrogen atom or alkanol radical and n has a value from 2 to 5. Preferably the substances are derivatives of natural fatty acids, e.g. caproic acid, capric acid, lauric acid, palmitic acid, stearic acid, coconut-oil acid or oleic acid. The diethanolamides of coconut-oil acid, N,N-(2-hydroxyethyl)coconut-oil acid amide, is particularly preferred. 3. Alkyl ether sulphate The alkyl ether sulphates used according to the invention are compounds having the general formula

in which R., denotes an aliphatic radical containing 10 to 20 carbon atoms, R2 is a divalent aliphatic radical containing 2 to 5 carbon atoms, n is an integer from 1 to 10 and X denotes a cation, e.g. ammonium, sodium, potassium, magnesium, calcium, or a monoethanolamine, diethanolamine or triethanolamine radical. According to the invention, preference is given to compounds containing C10-C14-alkyl radicals, in which n is an integer from 2 to 5 and X denotes a sodium cation. According to the invention it is particularly preferred to use sodium lauryl diethyl ether sulphate having the formula

4. Sulphonic acid esters of polycarboxylic acids These compounds used according to the invention comprise mono- and di-esters and higher esters of sulphocarboxylic acids. The carboxylic acid esters are preferably derived from dicarboxylic acids. The ester groups are preferably formed from alcohols having a chain length of 4 to 14 carbon atoms. Particularly preference is given to mono- and di-esters of sulphosuccinic acid having the general formula

which are generally used in the form of their sodium salts. In the formula R = C4-14, R = C4-14 or Na or K and R = Na or K. According to the invention, particular use is made of sodium di-(2-ethyl-hexyl) sulphosuccinate having the formula:

5. Polyethylene glycol The polyethylene glycols used according to the invention are compounds having the general formula HO(CH2CH2O)nH in which n = 80-180. Average molecular weights in the range from 3600 to 7800, more particularly 5000-7000, are preferred. The preferred polyethylene glycol has approximately the following formula: HO(CH2CH2O)135H. 6. Ammonium fluoroalkyl iodide These highly-fluorinated alkyls can have a branched or straight carbon chain. The fluorocarbon component has 3 to 30 carbon atoms, preferably 5 to 12 carbon atoms. According to the invention it is particularly preferred to use the iodide of ammonium polyfluorocarboxylic acid amide having the formula

7. De-ionized water This constituent is water which has been deionized by any of the numerous known methods. 8. Formalin If required, a small amount of formalin is added to the fire-extinguishing concentrate according to the invention. The formalin acts as a preservative, more particularly during prolonged storage, when the fire-extinguishing agent according to the invention is either concentrated or in the form ready for use. Commercial formalin in approx. 40% solution is added. The percentage weights of individual components are as follows (the preferred range is given in brackets):

A particularly preferred fire-extinguishing concentrate according to the invention comprises: 20 wt.% dodecyl benzene sulphonate in the form of the triethanolamine salt, 10 wt.% N,N-(2-hydroxethyl)coconut oil acid amide, 22 wt.% sodium lauryl diethyl ether sulphate

1 wt.% sodium di-(2-ethylhexyl)sulphosuccinate, 7.5 wt.% polyethylene glycol having an average molecular weight of 5 000 to 7 000, 0.1 wt.% iodide of ammonium polyfluorocarboxylic acid amide having the formula

39.3 wt.% deionized water and 0.1 wt.% formalin. The invention also relates to a method of producing the previously-described fire-extinguishing concentrate. In the method, 20 to 60 wt.% (of the whole batch) of deionized water is placed in a container. 10 to 40 wt.% alkyl aryl sulphonate, 10 to 40 wt.% fatty-acid alkanolamide, 15 to 20 wt.% alkyl ether sulphate, 0.5 to 6 wt.% polycarboxylic acid ester sulphonate, 3 to 15 wt.% polyethylene glycol and 0.1 to 4 wt.% ammonium fluoroalkyl iodide are added with continuous agitation, the temperature being kept at 15 to 50[deg]C. If required, 0.1 to 3 wt.% formalin is added to the mixture. Agitation is continued until the components have fully dissolved. Preferably the resulting solution is irradiated with polarized light. The fire-extinguishing concentrate according to the invention is usually mixed with 90 to 99.5 wt.% water. Fresh water or sea-water can be used, without significantly reducing the foaming capacity. The composition according to the invention may be classified as a fluorine-containing fireextinguishing agent in the so-called AFFF (aqueous film forming foam) group of agents. Even at relatively low concentrations, the concentrate produces a surprising amount of foam. The fire-extinguishing agent according to the invention is particularly suitable for use against wood fires, e.g. in houses or furniture-shops or saw-mills, or against forest fires. The fire-extinguishing agent according to the invention has a mainly isolating and cooling effect. Comparative tests with known AFFF agents showed that the fire-extinguishing concentrate according to the invention has the following advantages: (a) The amount of foam produced is greater than from known agents in similar concentration. (b) The quenched substances are greatly cooled. (c) Even when highly diluted, the fire-extinguishing concentrate according to the invention has good extinguishing properties. (d) The agent according to the invention does not contaminate the environment since all its constituents are biodegradable. This is particularly important in large fires, e.g. forest fires, since large quantities of the fire-extinguishing agent are used in such cases. (e) The fire-extinguishing agent according to the invention, in suitable concentrations, produces continuous permanent foam, so that combustible gases cannot escape.(f) The composition according to the invention is extremely stable in storage. Practically no decomposition occurs after five years. The fire-extinguishing agent according to the invention can be supplied in portable or mobile devices to the site of the fire, depending on its position and particularly on the nature of the fire. Alternatively it can be supplied through permanently-installed fire-fighting systems which if required can come into action automatically, e.g. via fuses or optical or thermal sensors. The invention will be illustrated by the following examples:

Example 1: 39.3 wt.% (relative to the total batch) of deionized water was placed in a flask equipped with an agitator and a feed hopper. During the entire production process, the flask was kept by a water-bath at a temperature of 26 to 30[deg]C. Next, 20 wt.% dodecyl benzene sulphonate in the form of the triethanolamine salt, followed by 22 wt.% of sodium lauryl diethyl ether sulphate

agitation. The mixture was additionally agitated, followed by addition of 0.1 wt.% of the iodide

ethylhexyl)sulphosuccinate and 10 wt.% N,N-(2-hydroxyethyl)coconut-oil acid amide. Finally, 7.5 wt.% polyethylene glycol and 0.1 wt.% formalin were added. Agitation was continued at a constant temperature of about 28[deg]C until the components had completely dissolved, after which the solution was irradiated with polarized light. The product was diluted with tap water in the ratio of about 5 wt.% of product to about 95% water. The resulting fire-extinguishing agent was yellow and soluble in water in any ratio. The specific gravity at 20[deg]C was found to be 1.06 and the viscosity was 1200 cP. The solution was anionic, froze at about 0[deg]C and had a pH of 8.2.

Example 2 Manufacture was carried out under the same conditions as described in Example 1. The individual components were added to the mixture in the following proportions (in wt.%):

After complete mixing and after the components have completely dissolved, the solution was irradiated with polarized light.

Claims

1. A fire-extinguishing concentrate characterised in that it contains 10 to 40 wt.% alkyl aryl sulphonate 10 to 40 wt.% fatty-acid alanolamide, 15 to 50 wt.% alkyl ether sulphate, 0.5 to 6 wt.% polycarboxylic acid ester sulphonate, 3 to 15 wt.% polyethylene glycol, 0.1 to 4 wt.% ammonium fluoroalkyl iodide and 20 to 60 wt.% deionized water.

2. A fire-extinguishing concentrate according to claim 1, characterised in that it also contains 0.1 to 3 wt.% formalin.

3. A fire-extinguishing concentrate according to at least one of claims 1 and 2, characterised in that the alkyl aryl sulphonate used comprises an alkyl radical containing 3 to 16 carbon atoms, the aryl radical is a benzene or naphthalene system and the cation is an alkali-metal or triethanol ammonium cation.

4. A fire-extinguishing concentrate according to at least one of claims 1 to 3, characterised in that the fatty-acid alkanolamide used comprises a fatty-acid radical containing 6 to 24 carbon atoms.

5. A fire-extinguishing concentrate according to at least one of claims 1 to 4, characterised in that the alkyl ether sulphate used having the general formula [R1-(OR2)n-SO4]- X+ comprises an aliphatic radical R, containing 10 to 20 carbon atoms and a divalent aliphatic radical R2 containing 2 to 5 carbon atoms, n is an integer from 1 to 10 and X denotes an ammonium, sodium, potassium, magnesium or calcium cation or a monoethanolamine, diethanolamine or triethanolamine radical.

6. A fire-extinguishing concentrate according to at least one of claims 1 to 5, characterised in that the sulphonic acid ester used is a polycarboxylic acid having the general formula

in which R' is an aliphatic radical containing 4 to 14 carbon atoms, R is a radical containing 4 to 14 carbon atoms or denotes Na or K and R denotes Na or K.

7. A fire-extinguishing concentrate according to at least one of claims 1 to 6, characterised in that the polyethylene glycol used has an average molecular weight in the range from 3 600 to 7800.

8. A fire-extinguishing concentrate according to at least one of claims 1 to 7, characterised in that the ammonium fluoroalkyl iodide used comprises an alkyl iodide radical having a branched or straight chain containing 3 to 30 carbon atoms.

9. A fire-extinguishing concentrate according to claim 1, characterised in that it contains 20 wt.% dodecyl benzene sulphonate in the form of the triethanolamine salt,

10 wt.% N,N-(2-hydroxyethyl)coconut-oil acid amide, 22 wt.% sodium lauryl diethyl ether sulphate,

1 wt.% sodium di-(2-ethylhexyl)sulphosuccinate,

7.5 wt.% polyethylene glycol having an average molecular weight of 5 000 to 7 000, 0.1 wt.% iodide of ammonium polyfluorocarboxylic acid amide having the formula C9F19CONH(CH2)3N(CH3)3J

39.3 wt.% deionized water and 0.1 wt.% formalin. 10. A method of producing a fire-extinguishing concentrate according to claim 1, characterised in that de-ionized water making up 20 to 60 wt.% of the total batch is placed in a flask equipped with an agitator and feed hopper at a temperature of 15 to 50[deg]C and the following are added in succession, with agitation and while maintaining the last-mentioned temperature: 10 to 40 wt.% alkyl aryl sulphonate, 15 to 50 wt.% alkyl ether sulphate, 0.5 to 4 wt.% ammonium fluoroalkyl iodide, 0.5 to 6 wt.% polycarboxylic acid ester sulphonate, 10 to 40 wt.% fatty-acid alkanolamide, 3 to 15 wt.% polyethylene glycol and, if required, 0.5 to 3 wt.% formalin in the sequence as given, and the resulting mixture is agitated until the components have completely dissolved.

11. A method of producing a fire-extinguishing concentrate according to claim 10, characterised in that the added alkyl aryl sulphonate has an alkyl radical containing 3 to 16 carbon atoms, the aryl radical is a benzene or naphthalene system and the cation is an alkali-metal or triethanolammonium cation.

12. A method of producing a fire-extinguishing concentrate according to at least one of claims 10 to 11, characterised in that the added fatty-acid alkanolamide comprises a fatty-acid radical containing 6 to 24 carbon atoms.

13. A method of producing a fire-extinguishing concentrate according to at least one of claims 10 to 12, characterised in that the added alkyl ether sulphate having the general formula [R1-(OR2)n-SO4] - X+ comprises an aliphatic radical R, containing 10 to 20 carbon atoms and a divalent aliphatic radical R2 containing 2 to 5 carbon atoms, n is an integer from 1 to 10 and X is an ammonium, sodium, potassium, magnesium or calcium cation or a monoethanolamine, diethanolamine or triethanolamine radical.

14. A method of producing a fire-extinguishing concentrate according to at least one of claims 10 to 13, characterised in that the added sulphuric acid ester is a polycarboxylic acid having the general formula

in which R' is an aliphatic radical containing 4 to 14 carbon atoms, R is a radical containing 4 to 14 carbon atoms or Na or K and R denotes Na or K.

15. A method of producing a fire-extinguishing concentrate according to at least one of claims 10 to 14, characterised in that the added polyethylene glycol has an average molecular weight in the range from 3 600 to 7 800

16. A method of producing a fire-extinguishing concentrate according to at least one of claims 10 to 15, characterised in that the added ammonium fluoroalkyl iodide comprises an alkyl iodide radical having a branched or straight chain containing 3 to 30 carbon atoms.

17. A method according to any of claims 10 to 16, characterised in that the solution obtained is irradiated with polarized light.