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
  • A62D1/0028—Liquid extinguishing substances
  • A62D1/0035—Aqueous solutions

Definitions

• This invention relates to fire extinguishing solutions for use against fires of all kinds, e.g. dry fires, fires of hydrocarbons and inflammable chemicals, and mixed fires, that is to say, fires of combustible solid substances (wood, paper, rags, etc.) soaked for example with hydrocarbons or chemicals.
• extinguishing solutions disclosed in the present invention have also the advantage of being highly effective against extremely rebellious fires such as those of carbon disulfide, mercaptans and other sulfur compounds which were inextinguishable heretofore with the known solutions.
• potassium salts have interesting extinguishing properties and may be used either in form of powder or in form of aqueous solutions to fight fires.
• a few organic acid salts such as formate, oxalate and acetate figure among the potassium salts already proposed. Both formate and oxalate although effective on some fires, are not used in practice because when decomposed by heat, they result in the formation to toxic products (cyanides in the case of formate and carbon oxide in the case of oxalate).
• Ser. No. 295,213 highly concentrated potassium acetate aqueous solutions will master fires difficult to extinguish such as those of hydrocarbons and inflammable chemicals, but are not effective against fires of sulfur compounds such as carbon disulfide and mercaptans.
• the principal object of this invention is to provide fire extinguishing solutions which are generally effective against all types of fires, but are particularly effective against fires of sulfur-containing materials.
• Another object is to provide a method of extinguishing fires, using the fire extinguishing solution of this invention.
• Substantially more dilute solutions are suitable to extinguish hydrocarbon fires or fires of very' inflammable chemicals difficult to fight but, how- Patented May 24, 1966 ever, not so rebellious as those of sulfur compounds.
• solutions containing 50 g./l. of potassium n-valerate, or 50 to g./l. of potassium n-butyrate, or 100 to 200 g./l. of potassium propionate used to fight gasoline fires times for extinction are very short and practically the same in each case.
• minimum concentration of the salts With respect to the minimum concentration of the salts, obviously it is intended to employ an operable amount, i.e. sufficient to result in at least a finite fire extinguishing activity. For precautionary purposes, however, it is preferable to employ minimum concentrations of about 50 g./l. propionate, 25-30 g./l. butyrates and 25 30 g./l. n-valerate.
• the quantity of alcohol added to the extinguishing solutions disclosed in the present invention should not exceed about 5% by weight of solution, for beyond this amount the extinguishing effect decreases.
• a quantity of from 1 to 2% of alcohol is preferred since it gives excellent results on hydrocarbon fires with solutions containing either 100 to 200 g./l. of potassium propionate, 50 to 100 g./l. potassium butyrates, or about 50 g./l. of potassium n-valerate.
• the above-given figures for potassium salt concentrations are, however, not to be considered as uppermost operable limits; more concentrated solutions are also suitable but obviously it is more economical to work with as dilute solutions as possible.
• aliphatic alcohols having a hydrocarbon radical containing from 1 to 3 carbon atoms that is to say, methanol. ethanol, nand isopropanol are preferably used. These alcohols need not be pure; inexpensive commercial products and mixtures of same are perfectly suitable. In particular, the addition of denatured alcohols which are products of very low cost gives excellent results.
• the quantity of isopropanol added to extinguishing solutions for fighting fires of sulfur compounds should not exceed by weight of solution, for beyond this amount isopropanol being easily inflammable, the solutions themselves may catch fire.
• a quantity from about 5 to 10% of isopropanol is enough to give excellent results even when using less concentrated potassium salt solutions; thus, with the above-mentioned amounts of isopropanol it is economical to use solutions containing either 300 to 400 g./l. potassium propionate, 200 to 300 g./l. of potassium n-butyrate, or 50 to 150 g./l. of potassium n-valerate.
• tetrapotassium pyrophosphate When fighting mixed fires such as wood, paper, rags, etc., soaked with inflammable liquids, tetrapotassium pyrophosphate may be added to the solutions disclosed in the present invention, for this salt will give to the combustible solid substances sprayed with extinguishing liquid such fireproof qualities that the risk of re-fiashing is greatly reduced or even avoided. About 100 to 200 g./l. of tetrapotassium phyrophosphate is generally enough to give satisfactory results.
• extinguishing solutions disclosed in the present invention can be sprayed onto the fire by means of any usual type of apparatus without any risk of the spraying nozzles becoming choked, for within the limits of concentration given above, the quantity of each salt contained therein is sufficiently far from saturation point so that the salts do not tend to precipitate during the spraying operation.
• a small quantity of wetting agent may be added to the solutions disclosed in the present invention as is usually done for water and various known salt solutions. Whereas such an addition does not alter the specific effectiveness of said solutions, it can nevertheless improve the extinguishing effect by making the liquid easier to disperse thus facilitating the spraying operation.
• the use of a wetting agent depends mostly on the type of spraying apparatus selected. It is quite obvious that the wetting agent used must be compatible with the salt dissolved.
• a wetting agent of the oxyethylenic alkylphenol type, or a phosphate ester of non-ionic compounds, or quaternary ammonium salts may be used, preferably in quantity not exceeding 2% by weight of solution, specific examples of such wetting agents being compounds of formula R R C H O(CH CH O),,H where n is 6 to 15, R is H or CH and R an alkyl moiety having 8 or 9 carbon atoms, a phosphate ester of a polyoxyethylenic alkyl-(or arylalkyl) phenol, or an alkyl dimethyl benzyl ammonium chloride, the alkyl moiety having 12 to 18 carbon atoms.
• the extinguishing solutions disclosed in the present invention have another outstanding advantage: their freezing point is very low.
• the freezing point of a solution containing 500 g./l. of potassium propionate is below 60 C. and that of n-butyrate solutions containing from 200 to 400 g./l. ranges between 8 and 40 C. It is therefore possible to choose the most suitable composition according to climatic conditions in the place where the solutions will be stored.
• Example 1 Systematic laboratory tests were performed on carbon disulfide fires with an apparatus giving a representative and homothetic picture of field tests, said field tests being carried out in a round pan measuring 1 m. diameter and 0.20 m. high, arranged so that the bottom is horizontal. Testing conditions in laboratory are, however, even more stringent as compared to those of field tests. This is the case because in the laboratory equipment, the angle under which the fire is attacked by the solution spray is such that it creates an important turbulence in the burning substance thereby preventing the formation of a protective salt layer on the fire. Furthermore, the solution being sprayed by means of air, the combustion is activated. In this manner, while laboratory tests serve to determine the optimal concentrations of solutions, the actual limits of utilization are larger than those revealed in the laboratory.
• Aqueous solutions containing from 50 to 700 g./l. of potassium n-butyrate were tested in laboratory under the following conditions: carbon disulfide was ignited and left to burn for 30 seconds, then the solution was projected onto the fire and time for extinction measured. The substance was re-ignited and after 15 seconds of combustion the solution was again projected onto the fire and time for extinction measured. The same operation was carried out ten times following.
• the table hereunder shows the S-test average time required for extinction when using solutions containing respectively 300, 400 and 500 g./l. of n-butyrate.
• the first column of the table gives the extinguishing time for tht first ignition (Ign) and the following columns numbered from 1 to 10 give the extinguishing times for the following reignitions, the time being expressed in seconds.
• Example 2 10 liters of carbon disulfide were poured into a round pan measuring 0.80 m. diameter and 0.20 m. high placed so that the bottom is horizontal, the substance was ignited and left to burn for 1 minute; then a solution containing 500 g./l. of potassium propionate and 2% by weight of a wetting agent of quaternary ammonium salt type was sprayed onto the fire.
• Example 3 Example 2 was repeated, potassium propionate being replaced by potassium n-valerate (125 g./l. of solution).
• Time for first extinction was 9 seconds and for the next three: respectively 11, 2 and 3 seconds.
• Example 4 Same operating conditions as for Example 2.
• n-Valerate 50 2 s n-Valerate 100 0.5 s n-Butyrate 100-... From 0.5 to l s.. n-Butyrate 50 3 s grom 0.5 to 1 s From 1 to 5 s. 0.5 s.
• a first series of tests was performed with a solution containing 200 g./l. of potassium propionate.
• the average time for extinction was 30 seconds. It was not possible to effect two extinctions running without refilling the apparatus.
• Example 7 Same operating conditions as for Example 6, but essence F was replaced by motor gasoline having a density not exceeding 0.760, a final point of distillation below 205 C., and an octane number of 92.
• a solution containing 200 g./l. of potassium propionate and 2% of denatured alcohol by weight was used.
• Example 8 Ten liters of carbon disulfide were poured-into a round pan measuring 0.80 m. diameter and 0.20 m. high placed so that the bottom is horizontal, then some old rags and pieces of wood were .piled on top, ignited and leftto burn for 2 minutes until the Whole stake was fiercely ablaze.
• a wetting agent oxethylenic long chain amine
• Time for extinction was 3 seconds. After re-ignition and 30 seconds of combustion, second extinction took 2 seconds. Re-ignition of the carbon disulfide left in the pan was then no more possible.
• a method of extinguishing a hydrocarbon fire comprises. contacting the source of the fire with an aqueous solution of less than about 5% by weight of an aliphatic alcohol of 1-3 carbon atoms a. salt selected from the group consisting of potassium propionate, potassium n-butyrate, potassium isobutyrate, potassium nvalerate, and mixtures thereof, said salt being present in an amount sufiicient to result in at least a finite fire extinguishing activity.
• a method of extinguishing a fire of an organic sulfur compound which method comprises contacting the source of the fire with an aqueous solution of less than about 20% by weight of isopropanol and a salt selected from the group consisting of potassium propionate, potassium n-butyrate, potassium isobutyrate, potassium n-valerate, and mixtures thereof, said salt being present in an amount sufiicient to result in at least a finite fire extinguishing activity.
• aliphatic a1- cohol is selected from the group consisting of methanol, ethanol, nand isopropanol.
• a fire extinguishing aqueous solution for fighting fires of hydrocarbons which on the basis of a liter of solution comprises a potassium salt selected from the group consisting of potassium propionate in a concentration of about 100-200 g./l., potassium butyrate in a concentration of about 50-100 g./l., and potassium nvalerate in a concentration of about 50 g./1., and about 12% by weight of solution of an aliphatic alcohol of 1-3 carbon atoms, and sufficient Water to make a liter of solution.
• a potassium salt selected from the group consisting of potassium propionate in a concentration of about 100-200 g./l., potassium butyrate in a concentration of about 50-100 g./l., and potassium nvalerate in a concentration of about 50 g./1., and about 12% by weight of solution of an aliphatic alcohol of 1-3 carbon atoms, and sufficient Water to make a liter of solution.
• An aqueous solution for extinguishing fires of organic sulfur compounds which on the basis of a liter of solution comprises less than about 20% by weight of isopropanol, and a potassium salt selected from the group consisting of potassium propionate in a concentration of about 300-400 g./l., potassium n-butyrate in a concentration of about 200300 g./l., and potassium n-valerate in a concentration of about -150 g./l. and sufficient Water to make a liter of solution.

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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)

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Citations (2)

• 0
  • BE BE634505D patent/BE634505A/xx unknown
• 1962
  • 1962-08-03 FR FR905978A patent/FR1337470A/fr not_active Expired
• 1963
  • 1963-04-04 US US83524A patent/US3252902A/en not_active Expired - Lifetime
  • 1963-07-11 GB GB27502/63A patent/GB1008880A/en not_active Expired
  • 1963-07-16 CH CH888563A patent/CH430463A/fr unknown
  • 1963-07-20 LU LU44098D patent/LU44098A1/xx unknown

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