US3252902A - Fire extinguishing composition - Google Patents

Description

United States Patent 3,252,902 FIRE EXTINGUISHIN G COMPOSITION Norbert Mevel, Antony, France, assignor to Societe dEtudes Chimiques pour lIndustrie et lAgriculture,

S.E.C.P.I.A., Paris, France No Drawing. Filed July 15, 1963, Ser. No. 295,229 Claims priority, application France, Aug. 3, 1962,

905,978, Patent 1,337,470; Feb. 15, 1963, 924,940,

Patent 83,080; Apr. 4, 1963, 930,451, Patent 83,524

11 Claims. (Cl. 2522) 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.

The 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.

It is well known that many 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). Also, under certain predetermined conditions as disclosed in my concurrently filed U.S.'application, 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, therefore, 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.

Upon further study of the specification and claims, other objects and advantages of the present invention will become apparent.

It has now been found that an excellent extinguishing effect is obtained on fires of all kinds as well as on rebellious fires of organic sulfur compounds by using aqueous solutions containing a potassium salt of propionic, nbutyric, isobutyric or n-valeric acids or a mixture of these salts. These fire extinguishing solutions disclosed in the present invention can be employed in any usual type of apparatus for projecting or spraying water under gas pressure.

The effectiveness of these organic acid potassium salt solutions depends on both the nature of anion selected and the concentration of solution used. It has been surprisingly observed that a practically equivalent extinguishing power is obtained with solutions having a lower concentration when the molecular weight of anion is higher. For instance, when dealing under the same conditions with fires of carbon disulfide and using solutions containing either about 500 g./l. of potassium propionate, 300 to 400 g./l. of potassium n-butyrate, or 100 to 200 g./l. of potassium n-valerate, theresults obtained are excellent and practically equivalent. 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. For example, with 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.

However, it has been observed that for the three abovementioned salts (propionate, n-butyrate and n-valerate) although the extinguishing effect increases with the molecular weight of the anion, the nature of the anion itself seems also to have an influence: indeed, the effect of potassium isobutyrate is not quite so good as that of nbutyrate. The difference is more perceptible when the fire is more difficult to extinguish and when more dilute solutions are used. Thus, laboratory tests have shown that a gasoline fire of given area is extinguished in 3 seconds with a solution of 50 g./l. of n-butyrate while 6 seconds are necessary with a solution of same isobutyrate concentration; with a solution containing 100 g./l. of either salt the same fire is extinguished in less than one second.

It has further been found that beyond a certain concentration of each of the salts mentioned above, the ex tinguishing effect tends to diminish; hence, it is advisable to use solutions containing less than 600 g./l. of propionate or butyrates and less than 400 g./l. of n-valerate. When using a mixture of salts the total concentration of the various salts is to be considered.

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.

It has also been unexpectedly found that by adding to these extinguishing solutions a small quantity of a lower aliphatic alcohol, particularly a lower alkanol, the extinguishing effect is considerably increased for the same potassium salt concentration.

It has been observed that such an addition of alcohol reduces substantially the quantity ofextinguishing solution required to put out a hydrocarbon fire of given area. Field tests were performed on fires of essence F (mineral spirit having a boiling range from 100 to C. under normal pressure) of 0.50 m. area with a spraying apparatus of determined capacity which projects the solution under specific conditions of pressure and flow rate. When the extinguisher is filled with potassium propionate, butyrates or n-valerate solutions without any addition of alcohol, the apparatus can be used for one extinction only: after the first extinguishing operation it is empty or contains a too small quantity of solution to perform a second operation. But if, for example, 2% of methanol are added to these solutions 2 to 4 extinguishing operations can be effected with the same charge.

To fight hydrocarbon fires 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. In practice, 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.

According to the present invention, 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.

When fighting fires of carbon disulfide and other sulfur compounds, it has been observed that addition of isopropanol, in particular, to the solutions has an especially favorable effect. The times for extinction are notably shorter for the same potassium salt concentration and the risk of re-flashing is reduced or even suppressed. Moreover, such an addition of isopropanol gives an equivalent extinguishing etfect with solutions of lower potassium salt concentration.

Thus, for example, laboratory tests performed under the same conditions have shown that the time for the extinction of a carbon disulfide fire can be reduced from 11 to seconds (S-test average) by adding by weight of isopropanol to a solution containing 500 g./l. of potassium n-butyrate. On the other hand, with a solution containing 50 g./l. of potassium n-butyrate to which 10% by weight of isopropanol had been added, it took 21 seconds to extinguish a carbon disulfide fire, whereas with a solution 4 times more concentrated (200 g./l. of nbutyrate) but containing no isopropanol, extinction is uncertain (2 extinctions out of 5 tests).

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. As a general rule, 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.

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.

The 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. As a matter of fact, 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. Thus, for example, 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. Thus, 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.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the specification and claims in any way whatsoever.

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. I

With solutions containing only 200 g./l. of n-butyrate, the fire was extinguished only twice out of 5 tests; average time for extinction for the two successful tests being 49 seconds in the case of first ignition and 2 to 7 seconds for the following re-ignitions.

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.

Concentration of the solution Ign 1 2 3 4 5 6 7 8 9 10 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.

The time required for complete extinction was 10 seconds- For the three following re-ignitions, the fire being left to burn for 30 seconds, it took respectively 10, 3 and 3 seconds to obtain complete extinction.

When 10% of isopropanol were added to the solution disclosed hereabove, the time for extinction was 3 seconds for first ignition, 2 seconds for next re-ignition, but after that the carbon disulfide left in the pan cannot be re-ignited.

' 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.

With addition of 5% of isopropanol to the solution disclosed hereabove, the time for first extinction was 5 seconds and 3 seconds for the next; re-ignition of the 7 carbon disulfide left in the pan was then no more possible.

Example 4 Same operating conditions as for Example 2.

Three series of tests were performed with solutions containing 500 and 300 g./l. of potassium n-butyrate (B), a wetting agent (WA) of the quaternary ammonium type, and (for 2 series of tests) some isopropanol (I). The table hereunder illustrates the average results obtained for each series of tests, s representing seconds.

Ignition Re-ig- Time Time nition for Solution for Numextincextincber tion, 5 tion, 5

500 g./l. B plus 2% WA 30 5 10 to 500 g./l. B plus 2% WA plus 10% I 2 1 5 300 g./l. B plus 1% WA plus 10% I 2 1 2 With solutions containing isopropanol, re-ignition was impossible after the second extinction.

Example 5 Time for extinction (Re-ignition: 8)

Time for extinc- Solution used, g./l. tion (ignition) 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.

From 0.5 to 1 s. From 1.5 to 3 s.

From 0.5 to 1 s. From 2 to 3 s.

Isobutyrate 100 Propionate 100.

Example 6 Two series of tests were performed under the following conditions:

10 liters of-essence F (mineral spirit having a boiling range from to C. under normal pressure) were poured into .a round pan measuring 0.80 m. diameter and 0.20 m. high, ignited and left to burn for one minute. The fire was then attacked using an apparatus containing 9 liters of solution and projecting it onto the fire under the same conditions of pressure and flow rate for each case.

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.

A second series of tests was performed with a solution of same potassium propionate concentration but to which 2% of isopropanol by weight had been added. The average time for extinction was 5 to 6 seconds. 'Out of 10 tests, it was possible to effect 5 times 2 extinctions with one same charge, twice 3 extinctions and 3 times 4 extinctions.

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.

With each charge of the apparatus at least 3 extinguishing operations were effected in each case. The average time for extinction was 3 to 4 seconds.

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 solution containing 300 g./l. of potassium n-butylrate, 100 g./l. of tetrapotassium pyrophosphate, 10% of isopropanol by weight and 1% of 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.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scopethereof, can make Various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.

What is claimed is:

1. A method of extinguishing a hydrocarbon fire, which method 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.

2. 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.

3. The process of claim 1, wherein the aliphatic a1- cohol is selected from the group consisting of methanol, ethanol, nand isopropanol.

4. 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.

5. The solution of claim 4, wherein the aliphatic alcohol is selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, and mixtures thereof.

6. The solution of claim 4, further comprising tetrapotas'sium pyrophosphate.

7. The solution of claim 6, further comprising a wetting agent compatible with the potassium salt.

8. 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.

9. The solution of claim 8, wherein the isopropanol concentration is 510% by weight of the solution.

10. The solution of claim 9, further comprising tetrapotassium pyrophosph ate.

11. The solution of claim 10, further comprising a wetting agent compatible with said potassium salt.

References Cited by the Examiner UNITED STATES PATENTS 9/1946 Craig et al. 260540 XR 3/1959 Jackson et al. 10615 OTHER REFERENCES JULIUS GREENWALD, Primary Examiner.

M. WEINBLATT, Assistant Examiner.

Claims (1)

1. 2. A FIRE EXTINGUISHING AQUEOUS SOLUTION FOR FIGHTING FIRES OF HYDROCARBONS WHICH ON THE BASIS OF A LITER OF SOLUTION COMPRISES A POTASSIUM SALT SELECTED FRO 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 N-VALERATE IN A CONCENTRATION OF ABOUT 50 G./L., AND ABOUT 1-2% BY WEIGHT OF SOLUTION OF AN ALIPHATIC ALCOHOL OF 1-3 CARBON ATOMS, AND SUFFICIENT WATER TO MAKE A LITER OF SOLUTION.