US1876222A - Process and apparatus for combating oil and chemical fires - Google Patents

Description

R. G, GUTHRIE Filed Jan. 29, 1932 PROCESS AND APPARATUS FOR OOMBATING OIL AND CHEMICAL FIRES Sept. 6, 1932.

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Patented Sept. 6, 1932 FICE PATENT ROBERT G. GUTHRIE, F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO SUN OIL COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF NEW JERSEY PROCESS ANI) APPARATUS FOR COMBATING OIL AND CHEMICAL FIRES Application led January 29, 1932. Serial No. 589,557.

The present invention relates to a process and apparatus for combating oil or chemical fires by means of a foam generated by the action of aluminum sulphate and sodium bicarbonate solutions together with a licorice or equivalent compound for providing the necessary surface tension to hold the bubbles of carbon dioxide together. The invention relates more particularly to means for preventing foam which is not of the proper consistency or of too high a specific gravity from entering the tank or receptacle in which the burning oil is contained As the above method is practiced in one form, the aluminum sulphate and sodium bicarbonate powders are contained in a double hopper and fed into a stream of water by means of an injector connected to the double hopper. "When the aluminum sulphate and sodium bicarbonate powders mix with the water, carbon dioxide gas is generated as the aluminum sulphate has an acid reaction in aqueous solutions and the carbon dioxide forms a foam which is held together by a licorice compound contained by sodium bicarbonate powder. This foam is extremely effective for combating oil lires as it spreads over the surface of the burning oil and smothers the flame. Due to the fact that one volume of solution will form eight vol unies of foam, the foam is of a specific gravity very much lighter than the oil, and for this reason iioats on top. In certain cases one or both of the powders above mentioned might stick within the throat of its hopper, and thereby prevent foam of the proper consistency being formed, in which case the foam would contain great quantities of excess water which would sink to the bottom of the receptacle containing the burning oil, and if this condition were permitted to persist, the burning oil would overflow from the tank, thereby scattering the lire over a much larger area.

Another method of generating the foam above described is to maintain supplies of two solutions, one of aluminum sulphate and the other of sodium bicarbonate and licorice compound. These two solutions are then mixed at a point just outside the burning oil tanll and the foam permitted to flow into the tan Both of the foregoing methods are practiced, and both are equally eective, provided foam of the proper consistency is generated. In the latter method one of the pumps might fail, in which case only one solution would enter the oil tank, sink to the bottom, and cause the burning oil to overflow. The sodium bicarbonate solution will also be found to deteriorate partially to normal sodium carbonate while it is in storage, in which case it will not generate foam of the proper consistency when mixed with the proper amount of acid or aluminum sulphate solution. In this case a great deal of water may be carried into the tank containing the burning oil, and sink to the bottom.

The object of the present invention is to provide an apparatus whereby foam of too high a specific gravity is prevented from entering the tank.

Another object of the invention is to provide an apparatus which will eiectively prevent foam of too high a specic gravity from entering the oil tank.

Other objects will be apparent as a description of the accompanying drawing progresses.

Figure 1 is an elevation showing my invention applied to an oil tank which is only partly shown. Figure 2 is a section taken on line A-A of Figure 1. Figure 3 is an enlarged section taken on line B-B of Figure 2. Figure 4: is an enlarged section taken on line G C of Figure l.

My invention is illustrated as applied to an oil tank which is partly shown in Figures l and 2, and which is designated by the numeral l. 2 denotes a mixing chamber and conduit for conveying the generated foam to the interior of the tank l. Pipes 3 and 4 are for the purpose of admitting the foam generating solutions to the mixing chamber. Approximately half-way up the conduit 2 from the inlet pipes, there is attached a valve box 6, which communicates with the conduit 2 by slot 8 cut in the wall thereof. The box 6 is constructed with one side open, and is welded to the outside of the conduit 2, so

that the outer wall of the conduit forms a closure for the open side. The interior of the valve box contains a partition 9, having a valve seat 10 mounted thereon, and a ball check valve 11 cooperating with the valve seat 10. The space in the valve box 6 above the partition 9 communicates with an overflow pipe 14, which leads down into a drum 15. The ball check 11 is prevented from closing up the port communicating with overflow pipe 14 by the bar 13, which is welded to the partition 9, and one wall of the valve box 10, immediately in front of the port communicating with overflow pipe 14. The ball check 11 is hollow and is weighted to a predetermined degree by the shot 12, which is introduced through the threaded opening in the top of the ball. The top of the valve box 6 is removably secured thereto by means of a series of wing nuts and bolts, and a liquid tight joint is maintained between the cover and the box by means of these fastening members, and a gasket between the rim of the box and the cover.

The invention as shown in the drawing is applied for use in a system where two solutions such as mentioned before are used to generate the foam. In use, the separate solutions are introduced into the lower end of the mixing chamber 2 by means of the pipes 3 and 4. On coming into contact with each other, they react to generate a foam which then rises up the conduit 2, and flows from thence into the oil tank 1, spreading over the surface of the burning oil. The foam also enters the lower part of valve box 6 through port 8. Under normal conditions one volume of the mixed solutions will generate eight volumes of foam, but as heretofore explained, the sodium bicarbonate solution may partially decompose to normal sodium carbonate, in which case the amount of foam generated per volume of solution will be a great deal less, or one of the solutions may run out or be accidently shut olf, in which case the other solution alone would enter the tank 1.

The ball check 11 is so weighted that it will be floated by water or foam which is of so high a` specific gravity that water may separate therefrom and sink to the bottom of the tank 1. As before stated, the normal expansion from solution to foam is one to eight. However, where one of the solutions has deteriorated or is partially shut off, the full expansion will not be realized, and a great deal of surplus water will be carried with the foam. I have determined that an expansion from solution to foam of one to four is the lowest possible expansion desirable. In View of this the ball 11 is weighted so that it will float upon foam which is only fifty per cent of its possible volume, or corresponding to the ratio of one to four.

It is therefore apparent that foam which is too heavy will float the ball 11, pass through the part defined by the valve seat 10, and flow down the conduit 14 into the barrel 15. rI`he barrel 15, is at all times maintained partially filled with water to prevent leakage of any vapor from the tanks as the tank is usually under about two pounds vapor pressure. As soon as the trouble causing foam of too high a specific gravity to be fed to the chamber 2 is remedied and the foam attains its proper specific gravity, the ball 11 will again seat itself and prevent the lighter foam from passing through the overflow device.

While I have described the procedure used where two solutions are employed to generate the foam, the facts stated also hold where the first described method is used. In this first method, wherein the powders are mixed with water flowing through a tube, only one inlet to the lower part of conduit 2 is necessary. Either or both of pipes 3 or 4 could be used in this instance. y

If the device has been used to extinguish a fire, a certain amount of water and foam will be found to have accumulated in the lower end of the conduit, or mixing chamber 2. This water is drawn off by removing the threaded plug 5.

It is quite possible that other apparatus may be used for the purpose above set forth without departing from the spirit and scope of my invention, and I do not wish to be limited to the specific apparatus and process shown and described herein.

I claim:

1. Apparatus for feeding a fire smothering foam to an oil tank comprising a foam chamber, an outlet from the foam chamber to an oil tank, an auxiliary outlet from the foam chamber to a point outside the oil tank and means associated with said auxiliary outlet whereby foam of too high a specific gravity is passed out through the auxiliary outlet.

2. Apparatus for feeding a fire smothering foam to an oil tank comprising a foam chamber, an outlet from the foam chamber to an oil tank, an auxiliary outlet from the foam chamber to a point outside the oil tank and means associated with said auxiliary outlet whereby foam of too high a specific gravity is automatically passed out through the auxiliary outlet.

3. Apparatus for feeding a lire smothering foam to an oil tank comprising a foam chamber, a main outlet from the upper end of the foam chamber to an oil tank, an auxiliary outlet from the foam chamber below said main outlet to a point outside the oil tank, and means associated with said auxiliary outlet whereby foam of too high a specific gravity is passed out through the auxiliary outlet.

4. Apparatus for feeding a fire smothering foam to an oil tank comprising a foam cham ber, a main outlet from the upper end of the foam chamber to an oil tank, an auxiliary out .IFT

let from the foam chamber to a point outside L3?.

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the oil tank, valve means connecting the foam chamber and the auxiliary outlet constructed and arranged whereby foam of too high a specific gravity is automatically passed from 5 the foam chamber to said auxiliary outlet.

5. Apparatus for feeding a fire smother-ing foam to an oil tank comprising a foam chamber, a main outlet from the upper end of the foam chamber to an oil tank, a valve box having upper and lower compartments, a

iuid connection between the lower compartment and the foam chamber, an auxiliary foam outlet connected to the upper valve box compartment, and valve means between the compartments constructed and arranged whereby foam of too high a specific gravity is passed out through the auxiliary outlet.

6. Apparatus for feeding a re smothering foam to an oil tank comprising a foam chamber, a main outlet from the upper end of the foam chamber to an oil tank, a valve box having upper and lower compartments, a fluid connection between the lower compartment and the foam chamber, an auxiliary foam outlet connected to the upper valve box compartment, and a float valve between the compartments constructed and arranged whereby foam of too high a specific gravity is automatically passed out through the auxil- 00 iary outlet.

7 The process of combating oil and chemical fires comprising feeding foam generating materials to a generating chamber, withdrawing foam from the chamber to the locus where it is desired for use, and preventing foam of too high a specific gravity from reaching the point of withdrawal from the chamber.

8. The process of combating oil and chemical fires comprising feeding foam generating materials to the lower end of a generating chamber, withdrawing foam from the upper end of the chamber to the locus where it is desired for use, and preventing foam of too high a specific gravity from reaching the point of withdrawal from the chamber.

9. The process of combating oil and chemical lires which comprises feeding foam-generating materials to a foam generating locus,

passing foam from said locus to the body of material which is afire, and maintaining below a predetermined maximum the specific gravity of the foam passing to said material by by-passing foam exceeding such maximum specific gravity from the locus of generation until the specific gravity of the foam is reduced below said maximum.

10. The process of combating oil and chemical fires which comprises feeding foam-gen- 00 erating materials to a foam generating locus, allowing the foam within said locus to escape from the upper part of the body of foam to the body of material which is afire, providing a path of escape for the foam from a point substantially below the upper end of

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