US2388014A - Fire extinguishing composition - Google Patents

Description

Patented Get. 330, 1%45 FIRE EX'llNGUlISc: 9* G cormosrrron Robert E. Sargent and Matthew W. M. Dewitt, Elmhurst, Long Island, N. 2!.

No Drawing. Application April 4%, 1942, Serial No. 437,694

3 Claims.

The instant invention relates to a composition of matter and more particularly to a composition for extinguishing fires not readily extinguished by ordinary methods, such as water under pressure. More particularly, the invention is concerned with a composition of matter for use in extinguishing fires of a type which are not extinguished by ordinary methods, but in which the rate of combustion is, in fact, accelerated by such methods.

One of the primary objects of the invention, therefore, is the making of a composition of matter which will function to emciently extinguish a stubborn fire produced by incendiary bombs and the ignition of readily ignitable materials, such as magnesium in all its forms, among which may be mentioned solid magnesium, magnesium chips, turnings and ribbons, magnesium alloys, also metallic paint powders generally, aluminum chips and powders, sodium and phosphorus fires and the like.

It is readily agreed by experts in the fire fighting field that the most efiicient manner of extinguishing fires of the character referred to above is based on sufiocationand it is, therefore, one of the primary purposes of this invention to make a composition of matter which will accomplish this result quickly and efficiently.

Still another aim of the invention is a composition of matter including ingredients which are readily available and of low cost.

In fires of the character described above, it is frequently recommended'that dry sand be used to sufiocate the same and to confine the ignited material to a limited area. While this is good as far as it goes, there is a definite limitation to its use which may be in part explained as follows. Ordinary sand is composed of a large number of individual sharp grains of silica and it is diificult, therefore, to form an impervious oxygenexcluding layer over the aforementioned ignited materials. Accordingly, it will be understood that oxygen from the air in some quantities will find access to the burning materials and, therefore, aid or accelerate the combustion thereof, thus prolonging the burning time. It is consequently a further purpose of the composition of the instant invention to function well without handicap of the characteristic connected with the use of sand as a suffocating agent.

Set out below are the ingredients which I have found to be best suited for the purposes hereinbei'ore mentioned, the proportions being given inapproximate parts by weight:

Ounces Sodium chloride 704 Finely divided pitch 20 Graphite 16 The principal ingredient of the composition, as

will be noted, is sodium chloride. This ingredient performs a plurality of functions in the use of the composition. First, it serves as an excellent conductor of heat and operates to remove the heat from the burning mass. Secondly, the

great heat liberated by burning materials of the type set out above will decompose the sodium chloride with the liberation of chlorine gas, the latter operating as a suffocating blanket over the fire excluding oxygen therefrom. As is well known, chlorine gas itself is not a supporter of combustion. The pitch acts as a binder, serving to unite the crystals of sodium chloride. Thus, when the product, containing the pitch as a binder, i s applied to a burning mass, the heat melts the pitch and causes the intergranular spaces in the sodium chloride to become thoroughly filled or plugged up by said melted pitch, so that in the use of the composition an impervious mass of material will cover the burning materials. In this manner the drawback in the use of ordinary dry sand, as explained hereabove, will be obviated.

The graphite acts as a lubricant in the use of the composition and is particularly valuable when the composition is employed in the vicinity of machinery, particularly machinery upon which metallic magnesium or the like is being processed with the formation of magnesium chips, ribbons or powders.

Finally, the graphite will coat the surface of each grain of sodium chloride serving to inhibit the normal absorption of moisture from the air by the salt. The value of this property is enhanced when ordinary commercial salt is employed. As will be understood, the commercial product is apt to contain relatively large quantities of hygroscopic materials, among which may be mentioned magnesium and calcium chlorides. In order to keep down the cost of the composition,

it might be desirable in many instances to use such commercial salt in preference to the chemically pure varietya Thus, it will be appreciated that the graphite, in addition to its function as a lubricant, will inhibit the rate of absorption of moisture from the air by the salt. Then, again, the graphite, by lubricating each grain of salt, highly decreases intergranular friction resulting in a free-fiowing'and highly mobile mass.

While sodium chloride is preferable in the composition, it will be understood that other alkali metallic salts may be employed, such as potassium and lithium chlorides. the alkali earth metallic chlorides might be found useful. Also, in certain rare instances, substitutes might be found for the pitch among which may be mentioned rosin or other similar materials having a high melting point.

Under certain conditions it might be found advantageous or desirable to omit the graphite and it is within the scope of-this invention to do this.

The advantages of the composition forming the subject matter of this invention, it is believed, will now be readily apparent. .While the composition and the proportions of its various in- In some instances, even,

gradients have been set out in detail, it will be understood that slight variations within the teachings of the instant disclosure may be made and it is contemplated to cover all such and to be limited in this respect only as may be necessary by the scope of the claims hereto appended.

What we claim and desire by Letters Patent is: l. A mixture suitable for use in extinguishing stubborn fires comprising a member from the group consisting of alkali metal chloride and alkaline earth metal chloride, and pitch and graphite, the chloride predominating.

2. A mixture suitable for use in extinguishing stubborn fires composed of sodium chloride, pitch and graphite, the sodium chloride predominating.

3. A mixture suitable for use in extinguishing stubborn fires composed of the ingredients set out below in the approximate proportions by weight indicated:

Ounces Sodium chloride 'l 704 Pitch 20 Graphite- 16 ROBERT E. SARGEN'I. MATTHEW W. M. DEVITT.