Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62D—CHEMICAL MEANS FOR EXTINGUISHING FIRES OR FOR COMBATING OR PROTECTING AGAINST HARMFUL CHEMICAL AGENTS; CHEMICAL MATERIALS FOR USE IN BREATHING APPARATUS
  • A62D1/00—Fire-extinguishing compositions; Use of chemical substances in extinguishing fires
  • A62D1/0071—Foams
  • A62D1/0085—Foams containing perfluoroalkyl-terminated surfactant

Definitions

• the present invention relates to new concentrated aqueous compositions generating foam. It also relates to a process for obtaining said foams. It also relates to the application of these foams, in particular to extinguishing fires.
• compositions according to the invention will be designated by the term "concentrated foam concentrate”. These are compositions capable of generating, after dilution in water, a foam by stirring with a gas.
• foaming mixture will denote the composition obtained by diluting the concentrated foam concentrate in water.
• Aqueous foams are considered to be the most advantageous materials for fighting fires of this nature. These foams must combine various properties such as in particular a high expansion rate, a high foam stability over time, a high water retention.
• the concentrated emulsifiers which are used to prepare such foams generally comprise water, a foaming surfactant, a foam stabilizer and an additive acting as an antifreeze and a third-solvent facilitating the dissolution of various constituents of the mixture in the aqueous phase.
• AFFF Aqueous Film - Forming Foam
• the concentrated emulsifiers according to the present invention contain from 20% to 80% by weight of water [A] and from 80% to 20% by weight of the organic mixture [B].
• the compounds which are particularly suitable are the following:
• the compounds which are particularly suitable are the following: r ranging from 10 to 20 r ranging from 2 to 8
• non-fluorinated surfactant (8) is not critical as soon as it is a foaming agent of an anionic nature. These compounds are known and have been widely described in the art.
• surfactant (S) one can refer for example to the Encyclopedia of Chemical Technology, Kirk-Othmer, volume 19, pages 512 to 531.
• alkali sulfonates such as alkylsulfonates, arylsulfonates or alkylarylsulfonates, in particular sodium alkylbenzenesulfonates such as sodium dodecylbenzenesulfonates, tridecylbenzenesulfonates sodium, sodium nonylbenzenesulfonates, sodium hexadecylbenzene sulfonates, sodium decylbenzenesulfonates; alkali metal salts of dialkyl sulfosuccinates derived from long chain alcohols such as the sodium salts of di (2-ethylhexyl), didecyl, dilauryl, dioctyl, ditridecyl sulfosuccinates; dialkyl sulfates, mixed alkyl and alkanolamine sul
• the mixed alkyl sulphates containing at least 8 carbon atoms in the alkyl and alkali metal residue can be used preferentially.
• the film-coating polymers (b) which are used in the compositions according to the present invention can be very various when they are soluble in an aqueous medium.
• the film-coating polymers which are preferably used are generally synthetic gums belonging to the class of heteropoiysaccharides of microbial origin.
• heteropolysaccharides of microbial origin means linear exocellular products of high molecular weight, preferably greater than one million, obtained by fermentation of a carbohydrate under the action of bacteria of the genus XANTHOMONAS, or ARTHROBACTER or mushrooms belonging to the genus SCLEROTIUM.
• Representative species of bacteria or fungi which can be used in the manufacture of these heteropolysaccharides include, for example: XANTHOMONAS BEGONIAE, XANTHOMONAS CAMPESTRIS, XANTHOMONAS CAROTAEN, XANTHOMONAS HEDERAE, XANTHOMONAS INCANAE, XANTHOMONAS , XANTHOMONAS PHASEOLI, XANTHOMONAS PISI, XANTHOMONAS VASCULORUM, XANTHOMONAS VESICATORIA, XANTHOMONAS VITIANS, XANTHOMONAS PELARGONII; ARTHROBACTER STABILIS, ARTHROBACTER VISCOSUS; SCLEROTIUM GLUCANICUM, SCLEROTIUM ROLFSII.
• stabilizing agent for foams (c) it is possible to use very diverse compounds well known to those skilled in the art. However, use is preferably made of aliphatic fatty alcohols comprising from 8 to 25 carbon atoms in the aliphatic residue such as lauric, myristic and cetyl alcohols.
• additive (d) playing the role of antifreeze and third-solvent for the various ingredients of the concentrated foaming composition use may be made of glycols or polyols or their alkanol ethers such as ethylene glycol, diethylene glycol, diglyme, butoxyethanol. Mixtures of such additives can be used.
• the concentrated emulsifiers according to the invention are obtained by adding the various ingredients together or separately to water which may contain the third solvent if necessary; depending on the case, it is also possible to dissolve or disperse one or two ingredients in water and the other (s) in the third solvent and then mix the solutions and / or dispersions thus obtained.
• the foaming mixture thus obtained is then stirred using a gas (air, nitrogen, argon) by the usual means well known to those skilled in the art in order to generate the foam.
• a gas air, nitrogen, argon
• any type of device can be used which ensures efficient dispersion of a gas in a liquid and vigorous stirring of the latter. It can be a system for injecting a gas into a liquid by means of a nozzle and a venturi tube or a turbine stirring system for example.
• the concentrated foam concentrates according to the present invention are particularly intended for fires of polar solvents miscible with water and of hydrocarbons. Mixed with fresh water, or with sea water and used in foam equipment, said concentrated foam concentrates form a foam whose behavior ensures complete extinction of fires.
• the concentrated foam concentrates according to the invention may still be suitable in other applications.
• they can be used for the fight against dust in enclosures or in the open air: for example they can be used to rid of enclosures contaminated accidentally or not by toxic or radioactive dust by completely filling said enclosures with foam ; they can also be used to prevent the spread of dust from the most diverse supports or vectors.
• This is how we can eliminate the dust generated by an ore conveyor such as a coal conveyor at the bottom of the mine; they can also be used to fix the dust existing on blocks of the most diverse materials: for example coal, hard coal.
• the concentrated foam concentrates according to the invention can also be used as a means of preventing fires. Indeed, the aqueous foams obtained, very stable, can be used as protection in a room exposed to fire and not accessible, for example a rear mine size, in particular coal. This foam, poured into the rear size plays the role of an airtight barrier and prevents contact between the ore and the air. A fineness bonding produced, which leads to a very significant reduction in oxidation and therefore in the heating of the ore.
• foams also constitute a preferred means of extinguishing fire in a rear mine size, given that the aqueous foam is the only water vehicle that can be easily introduced into a rear mine size without damage to the mining equipment. cut.
• a low expansion foam of between 8 and 10 is prepared and used for the extinction of a tank containing isopropanol on fire.
• the conditions for carrying out the test (characteristic of the tank, volume of liquid to be extinguished, methods of making and spraying the foam, re-ignition test) comply with AFNOR S 60-201 standard, paragraph 5.4. The extinction time and the total re-ignition time are noted.
• test A An identical test was carried out using the foam concentrate sold by the company 3M under the name Light Water ATC-type FC 600 (test A).
• Example 1 A test identical to Example 1 was carried out with an emulsifier having the same composition as that indicated in this example except as regards the foaming surfactant material (a): use is now made of a combination of a surfactant -active fluoro carbon (a) nonionic of the formula: C6F13-0- (CH2-CH2-0) rH (r ranging from 10 to 20) with a surface - non fluorinated anionic active (mixed sodium lauryl sulfate).
• a surfactant -active fluoro carbon a nonionic of the formula: C6F13-0- (CH2-CH2-0) rH (r ranging from 10 to 20) with a surface - non fluorinated anionic active (mixed sodium lauryl sulfate).
• Example 1 the extinction tests are carried out as indicated in Example 1 by modifying, in the foam concentrate, only the composition of the foaming surfactant material (a).
• Example 1 we will show in this example that the foaming mixture described in Example 1 can also be used to extinguish a hydrocarbon fire with performances equivalent or superior to those of a commercial AFFF foam concentrate.
• the test consists in extinguishing a gasoline fire F by operating according to the indications provided in standard AFNOR S 60-201, paragraph 5.2.
• Example 2 we will show using two tests that the concentrated foam concentrate described in Example 1 does not belong to the AFFF category.
• This first test consists in measuring the surface tension of the liquid resulting from the decantation of a foam similar to that obtained in accordance with Example 1.
• This test consists in demonstrating the film-forming power of a foaming mixture by measuring the evaporation of cyclohexane contained in a container on the surface of which is deposited a small amount of said foaming mixture.
• the method used is that which is described in the review: FIRE TECHNOLOGY, volume 13, February 1977 (pages 13 to 20) under the title: A technique for the Evaluation of AFFF Sealing Characteristics.
• the principle of this test consists in sending a stream of nitrogen onto the surface of the assembly: cyclohexane + thin film supernatant of foaming mixture and recovering, using an appropriate collector, the nitrogen sweep stream possibly charged by the evaporation cyclohexane.
• An infrared spectrophotometer makes it possible to measure the proportion of cyclohexane entrained. For a foaming mixture lacking a film-forming power, the proportion of entrained cyclohexane is maximum and it is then said that the seal is zero.
• the intensity of the absorption band at 2920 cm -1 is used to measure the concentration of cyclohexane in the sweeping gas.
• the infrared detector is equipped so as to directly provide a curve giving the variation of the infrared absorption of the recovered sweep gas as a function of time, which curve is then easily converted into a curve of sealing percentages.
• Example 1 The fact that the concentrated foam concentrate described in Example 1 does not belong to the category of AFFF, coupled with the fact that it is capable of generating foams that are as effective and even more effective (in particular as regards time total re-ignition) than the foams from AFFF foam concentrates to extinguish fires with hydrophobic liquids (cf. example 10), constitutes another criterion of non-obviousness of the present invention.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Fire-Extinguishing Compositions (AREA)
• Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
• Paints Or Removers (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Cosmetics (AREA)
• Fertilizers (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Physical Water Treatments (AREA)

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Cited By (8)

Citations (4)

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• 1980
  • 1980-02-14 FR FR8003640A patent/FR2475926B1/fr not_active Expired
• 1981
  • 1981-02-12 AT AT81420015T patent/ATE5126T1/de not_active IP Right Cessation
  • 1981-02-12 DE DE8181420015T patent/DE3161254D1/de not_active Expired
  • 1981-02-12 EP EP81420015A patent/EP0034553B1/de not_active Expired
  • 1981-02-12 GR GR64118A patent/GR73518B/el unknown
  • 1981-02-12 IL IL62126A patent/IL62126A/xx unknown
  • 1981-02-13 PT PT72505A patent/PT72505B/pt unknown
  • 1981-02-13 ES ES499434A patent/ES499434A0/es active Granted
  • 1981-02-13 JP JP1918181A patent/JPS56132968A/ja active Pending

Patent Citations (4)

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