US2260733A - Apparatus for extinguishing oil fires - Google Patents

Description

Oct. 28, 1941. M. B. ANFENGER v A APPARATUS FOR EXTINGUISHING OIL FIRES Filed Aug. 29, 1939 Fig. 4

Fig.3

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, INVENTOR MAXIMILIAN B. ANFENGER ATTQRNEY water, or one or more aqueous solutions.

some types compressed gas or atmospheric air- Patented Oct. 28, 1941 Es PATEN T- OFFICE:

APPARATUS FOR EXTINGUISHING O FIRES v Maximilian B. Ani'enger, San Francisco, Calif., assignor to Standard Oil Company of California, San Francisco, Caliih, a corporation of Delaware Application August 29, 1939, Serial No. 292,449

' sciaims.

This invention relates to improvements in ap-' paratus for introducing a fire extinguishing foam over the rim of an oil tank, in such a manner that the foam will be conveyed to and discharged substantially horizontally over the surface of the oil with a minimum of disturbance to the foam or to the oil surface, and a maximum flow of the foam through and out of the apparatus.

The so-called fire-foam commonly used to extinguish oil fires is a resilient, adhesive mass of small gas bubbles usually formed by the chemical reaction of a gas-forming powdered solid 1in 11 may be used, together with some form of mechanical agitation. The aqueous film covering the bubbles isparticularly designed and intended to be tenacious, sticky, and persistent over a period of hours oreven days, as well as being quite resistant to heat, as from the burning gases overlying a body of oil. The foam is quite capable of adhering to vertical surfaces and, after its formation, can beflowed through conduits only with some difliculty and'for relatively short distances as compared with water, probably because of its low density, usually less than oneflfth that of water, and also because of its adhesive.

spongy, and gelatinous nature, which is believed to cause a stationary layerto form on the walls of the conduit, reducing the effective area of the latter and providing, a high flow coefllcient.

, These properties make it diiflcultrapidly to convey and distribute the foam to the surface of the il in a burning tank, for example.

In the method of generation offlre-fo'am by the introduction of prepared powders into aflowing stream of water, it' is often desirable to use a mixing device in which the velocity of the flowing stream of water is momentarily increased, as by a Venturi nozzle or similar restriction, jet, or the like, so that a zone of low static pressure is created to draw the powdered material into the water stream where it" will react and form the desired fire-foam. The reacting mixture may then-be flowed through a conduit such as standto the apparatus for distributing the foam onto the liquid surface to form a dense blanket thereflowing foam stream, that pressure is unavoidably transmitted back to the foam generator, so that the pressure in the mixing chamber may rise to the point where the powdered reactive mate 4 improved operation, 'rechced rial will no longer feed into the water stream, or at least will not feed in the proper and predetermined proportions to provide an effective foam. Accordingly, it is quite desirable to provide a distributing device that will obstruct the pashave proved unsatisfactory, especially because they unavoidably caused considerable agitation of the foam, and in the case of those which utilized a plurality of small apertures for distributing the foam, caused considerable deterioration of the foam by dividing it into numerous small streams .which would become separated into detached flakes or-masses that were ineffective to produce the coherent blanket' oracoveringof unbroken foam that is required to extinguish oil fires. Also, in practically'all types of downwardly extending conduits with a terminal opening of substantially only the area of the conduit, the foam would tend to pile up or-accumulate'in the lower part ofthe conduit, thus effectively preventing the incoming stream from reaching the open end and flowing therefrom onto the oil surface. This was particularly true in the case of the perforated or porous," flexible tubes andresulted in the lower part of the tube becoming choked with a resilient, adhesive mass of clotted viscous foam that would form a relatively impervious layer next to the tube wall so that the incoming foam was either compressed or collapsed to a thin, ineffective sloppy mass, or was only able toflow from the .tube through the'uppermost perforations or openings where thepressure on-the incoming stream of foam was effective to drive the ma- 1 terial outwardly. Always there was the hazard 45. ard flre hose for only a relatively short distance that the relatively fragile tube material would split at its juncture with its mixing and conveying conduit.

The foam issuing from such a v. height would drop oil as small detached flakes and would either be evaporated by the heat of the flames or would strike the liquid surface in the tank with considerable force, damaging-and disturbing the blanket of foam that it was intended to establish.

Tests of this invention have demonstrated that deterioration and the use of much smaller quantities of the foam can be effected by utilizing. as a distributor a extends for a sufflcient distance along the tube so that a high oil level in the tank will not submerge it, and preferably is wider at the bottom or outlet end than at the top of the tube so that, in case the foam does pile up or adhere to the tube wall and restrict the effective area of flow it'will have more opportunity to emerge from the opening near the lower portion of the conduit at the surface of the oil where the opening is widest. A150,, there may be employed means for defining the width of theopening that will also serve to render the initially empty, vertically -hanging tube substantially cylindrical without depending on the distending action of the incoming foam, making the flow rate more rapid and the effectiveness of the foam much more pronounced.

It is an object of this invention to provide an improved means for introducing fire-foam into a structure,- such as a tank, to discharge the foam substantially horizontally and gently at the level of the liquid in the tank to extinguish a fire therein.

Another object is to provide an improved means for handling and applying a stream of fire-foam which is of much stiffer consistency than that heretofore used in this art.

Another-object is to provide an improved arrangement of a flexible conduit which may be suspended or, placed vertically in a tank, such as a burning oil.tank, and will discharge firefoam from the lowest point in a vertical opening in said conduit so that the foam will issue quietly onto the liquid surface onto which it is to be applied, and will form an ever-widening smooth blanket on the said liquid.

Another object is to. provide a distributor which is particularly, although not necessarily, adapted to the recently developed fire-foams using organic compounds known as wetting agents or detergents which substantially reduce the surface tension of the water used and also act as stabilizers of the foam, these foams being characterized by a consistency somewhat similar to that of stifliy whipped cream, and an increased tenacity and resistance to disintegration which is reflected in their flowing properties. Tests of such foams with flexible and porous distributors heretofore used show such means to be unsuited to successful operation and led to the present invention.

' These and other objects of the invention will be further apparent-from the following description and from the accompanying drawing which forms a part of this specification and illustrates a preferred embodiment of the apparatus of this invention as well as an alternative form.

In the drawing,

Figure 1 is a vertical sectional view of a tank partiallyfilled with liquid in which a flexible conduit embodying this invention is in place and .discharging foam onto the surface of the liquid.

Figure 2 is a front elevational view of one form of tube in which a single vertical slot or opening is defined by means of tie I members extending thereacross.

Figure 3 is a front elevational view of an alter- .native form of flexible conduit in which the verment of resilient spacers to define the edges of the vertical opening.

Referring to the drawing, reference numeral ill designates a tank in which is an inflammable liquid H on the surface of which it is desired to introduce a foam known as fire-foam which may be of any well-known type and produced in any desired manner. An elongated foam mixing and conducting tube l2, usually portable and of light metal, isadapted to be placed over the rim of tank 10 and may terminate in a bend which extends downwardly inside the tank for a short distance; At the inner end of tube I2 is connected a flexible conduit 13 which may be temporarily secured in a bundle and selectively released to extend downwardly preferably to a point at or below the level of the liquid ii in tank ID. This conduit is usually made of a fire-resistant material such as woven asbestos reinforced with Wire although it could be of rigid material, such as steel or a heat resisting alloy, which would necessitate raising the tubes l2 and [3 to a greater height when introducing them into tank It]. At one side of tube l3 and extending for the desired portion of its length is a longitudinal slot or opening 14 through which the foam I5 may emerge and flow gently over the surface of the liquid ll.

As pointed out heretofore, the foam 15 may be of the consistency of stiflly' whipped cream,

tenacious, and adherent, as well as low in den-' sity, so that it tends to build up a layer on the inside of tube I3 rather than pass longitudinally through it. It has been found that when tube I3 is of the perforated or porous type such as that heretofore used, the foam will pile up or accumulate in the lower part, possibly by a sort of jelling or congealing action, so that the lowest perforations are closed by a thick, adherent layer of foam and hence are not effective to release the foam freely and horizontally. This may be due, in part, to its light weight and consequent lack of effective hydrostatic head. The general result is that the foam only emerges from such a reticulated tube at an increasing higher level until it reaches a zone of sufficiently high such a height has a relatively high velocity so" that it tends to agitate the liquid in the tank and also to mix with it. In addition, it becomes separatedinto fine flakes or small masses which do not readily merge with the spreading blanket of foam which it is desired to establish on .liquid I I.

zontal flow of foam l5 onto liquid-l I. If desired the width of slot l4 may be defined by means of spaced tie members I5 50 that th e tube will retain its conduit nature and not completely fiatten out, as might be the case if tie members IS were not provided. One alternative arrangement to define the width of slot l4 alongv the length of tube I3 is shown in Figures 3 and 4 and may comprise resilient semi-circular ele-' of the length or the conduit and preferably but ductor for the first foam to enter from tube l2. 5

Also the lower elements I1 may be made of less stiffness than the upper ones so that they will distortmore readily and permit the lower endof slot M to open widely under the small horizontal component of force exerted by any 1 0 accumulation of the low-density foam; Tie members l6 may likewise be variably resilient in the same mannerand for the same purpose. A

further advantage of flexible or resilient meansto define the edges of slot It, is that as the foam .15

I5 tends to accumulate in tube l3v at the surface of the liquid -l| due to its low density and its coherent nature it will expand slot l4 and thus facilitate fiow outwardly onto the liquid. Desirably the means used to define the width of slot ll should be of such nature that if tube l3 is of a flexible material it may be folded or rolled at the top of delivery tube I! to facilitate its introduction into tank III.

In this example the means for producing the fire-foam are illustrated diagrammatically in Figure 1, and include a mixer 20 into which a powdered material 2| may be poured and through which a high-pressure stream of water from any suitable source 22 is conducted by means of a hose 23. Hose 24 leads from the outlet of mixer 20 to the lower end of tube l2, and, by the use of this/invention, may be much longer than those heretofore used. The decreased pressure drop in the flowing foam stream between mixer 20 and the outlet M from flexible conduit l3, due primarily to the improvement described for the latter, not only delivers the foam to the oil surface I I at a more rapid rate but also results in improved operation and more accurate proportion- 40 ingof liquid to powder in mixer 20, so that the whole system is benefltted thereby. When other types of foam generators or systems of producing foam are used, suchas mechanical agitators or the use of two reactive aqueous solutions, the

opening, and circumferentially acting means deadvantages of the invention will be realized in generally improved operation and rapidity of foam application, it beingdistinctly understood that the application of the invention is not limited to the powder generator of this example.

Although it is obvious that many changes and modifications could be made in the arrangement shown it is considered that the invention resides u in an improved method ofhandling a stifi firefoam and in apparatus therefor, including the provision of a substantially unobstructed vertical slot or opening in a conduit adapted to be placed vertically in a tank to introduce fire-foam there -in, said slot extending throughout at least part not necessarily increasing in width downwardly so that said foam may be selectively confined in its outward flow and discharged :under a low pressure substantially only at a point above the surface of the said liquid, the edges of said opening desirably being defined by resilient means, for the purpose specified.

I claim:

1. A fire-foam distributing device comprisinga tube of fire-resistant material having a single longitudinal opening in the wallthereof for only a portion of its length, said opening increasing in width toward the outlet end of said'tube.

2. A fire-foam distributing device comprising a flexible tube of fire-resistant material having a single longitudinal opening therein extending from the outlet part way to the inlet of said tube, and increasing in width toward the outer end of said tube and circumferentially acting means cooperating with the edges of said opening to define the width thereof.

3. A fire-foam distributing device according to claim 2 in which said edge-defining means for said opening are expansible to permit widening of said opening under internal pressure, in said tube. i

4. A fire-foam distributing device according to I claim 2 in which said edge defining rneans for said opening are effective tohold said tube in a distended position when it is emptyand hanging in a vertical position. I

5. A fire-foam distributing device according to claim 2 in which said edge defining means for said opening are expansible and extend back-z .wardly from said opening around said tube wall 6. Av fire-foam distributing device according to claim 2 in which edge defining means'extend across .said opening and are spaced to leave a substantially unrestricted passage outwardly throughout the length oi?v said opening.

7. A fire-foam distributing device comprising a. flexible tube of substantially impervious fireresistant material, part of the length of said tube being provided with only a single longitudinal fining the width of said opening, the length of said opening being substantially greater than the diameter of said tube, said opening being widest at the outlet end of said tube.

8. A fire-foam distributing device comprising a tube of fire-resistant material having a single longitudinal opening in the wall thereof for only a portion of its length, so constructed and arranged that said opening will increase in width toward the outlet end of said tube during the passage of fire-foam through said .tube.

MAXIMILIAN B. ANFENGER.

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