Fire Foam Nozzle

Abstract

A fire foam nozzle assembly that produces large flakes for extinguishing fires caused by the burning of vapors of inflammable liquids. The nozzle assembly has a coupling for connecting it with a fire hose and includes an expansion chamber into which water and foam concentrate are introduced by an injector at high velocity and forced through a cone-shaped, wire stream divider. Air inlet openings at the inlet end of the expansion chamber allow entry of primary air by eduction for mixture with the divided, expanding streams of water and foam concentrate. A discharge nozzle receives the flow from the expansion chamber and contains a conical deflector mounted upon radial vanes. The deflector splits and transversely directs the flow against the inner surface of the discharge nozzle. A relatively larger and greater number of air inlet openings at the inlet end of the discharge nozzle surrounds the exterior of the expansion chamber for admitting a large volume of secondary air, by eduction, to be mixed with the water and expanding foam concentrate in the discharge nozzle. The interior surface of the discharge nozzle, beyond the conical deflector, has formations that provide a rough surface designed to retard flow and to induce violent turbulence within the discharge nozzle, causing the water and foam concentrate to be mixed with a great volume of air prior to being discharged from the nozzle. The discharge nozzle delivers a stream of foam at very high velocity, the stream being substantially free from drip and eventually feathering out as the force of the stream becomes spent, the foam then falling gently in the form of large flakes similar to snow flakes. The nozzle assembly is non-metallic except for the hose coupling and the wire divider, and is preferably made from epoxy resin components reinforced with fiberglass, the components being secured together by laminated strips of fiberglass cloth saturated with an epoxy resin and allowed to cure, thereby providing a nozzle structure that is very strong but light in weight.

Description

FIELD OF THE INVENTION

The present invention relates to fire foam nozzles of the type that utilize water under pressure and a foam concentrate to provide foam for use in extinguishing fires and particularly fires resulting from the ignition of vapors of combustible liquids.

DESCRIPTION OF THE PRIOR ART

As is well known, certain types of fires cannot be extinguished by water alone. Hence, a suitable foam, of one kind or another must be used. Many nozzles that are capable of using a protein type foam concentrate cannot be used with a synthetic or detergent type of foam concentrate. This has created the problem of having available special nozzles for spraying different types of foam. For example, an alcohol fire cannot be quickly and effectively extinguished with a synthetic or detergent type of foam, but requires the use ofprotein type foam.

It is also well known that foam extinguishes fire by producing a smothering effect, or by steam formation excluding oxygen from the burning vapors. The thicker or heavier the foam blanket, the more effective it is for confining the fire and preventing reignition or vapors. Many types of fire foam nozzles have been heretofore proposed, but most of these are fabricated from metal parts, resulting in the nozzle being quite heavy and weighing about 60 lbs. Such nozzles are difficult and awkward for one person to handle. While some prior heavy nozzles have been satisfactory for some purposes, they all have the disadvantage of forming a jet stream that will submerge in a body of flammable liquid if played thereon without forming a surface blanket to quickly and effectively extinguish the vapor flames at the top surface of the liquid. This has necessitated impinging the jet against a back plate or deflector so that the foam will rebound and be floated upon the surface of the liquid to form a blanket. This type of operation has the great disadvantage that considerable time is required to completely cover the burning area by deflecting the foam, and in building up a layer of foam thick enough to prevent reignition.

Another objection to prior fire foam nozzles is that their effective range is relatively short, thereby requiring the user of the nozzle to often take a position closer to the fire than is considered safe. Still another objection is that prior fire foam nozzles do not produce a maximum volume of foam in proportion to the amount of water and foam concentrate that is being supplied to the nozzle.

This is due to the fact that they do not create a sufficiently low pressure at the inlet of the nozzle to cause the necessary flow of air and turbulent mixing thereof with the water and foam-producing concentrate. The larger the volume of air that is drawn into the stream, the more violent the turbulence in the nozzle will be and the greater will be the relative volume of foam that is produced.

SUMMARY OF THE INVENTION

The present fire foam nozzle overcomes all of the foregoing objections, in that it is made principally from components of fiberglass reinforced epoxy resin, which results in a strong, light-weight nozzle assembly that weighs only 111/2 pounds and can be easily handled; has a longer jet operation range than prior nozzles; is universal in nature, in that it is capable of utilizing conventional foam concentrates either of a protein, synthetic or detergent type; produces violent turbulence within the nozzle assembly to combine a large volume of educted air with the water and foam concentrate; provides a greater volume of foam for a given volume of foam concentrate than prior devices, which have an expansion ratio of about 8 to 1, or about eight parts foam to one part water with protein type foam and a ratio of about 12 to 1 for synthetic and detergent types of foam, contrasted with the present nozzle which will produce a ratio of 12 to 1 with protein type foams and 18 to 1 with synthetic or detergent type foams. This is due to the higher expansion ratio in the present nozzle, whereby a heavier or thicker blanket can be formed with a given amount of foam concentrate, with a correspondingly greater holding power against vapor reignition thus providing the capability of extinguishing and effectively controlling fires in much less time than prior devices.

The present nozzle also eliminates the necessity of using a back plate to deflect the foam and to float it over a burning liquid area, since it provides a stream of foam in the form of flakes, similar to snow flakes, that can be directly sprayed upon the burning area and allowed to gently fall thereon. This makes it possible to direct the spray wherever it is needed and to quickly form a surface blanket of foam of any desired thickness. The flakes quickly cool and extinguish the fire and form a holding blanket. The customary "dunking" encountered with most prior nozzles is not possible due to the flake-like character of the foam.

The fire foam nozzle assembly by which the foregoing results are attained includes a metallic hose coupling for connecting the nozzle with a source of water and a foam-forming concentrate. The water with entrained concentrate is introduced into the nozzle assembly through an injector at high velocity. The injector is secured in the coupling by a body of epoxy resin containing fiberglass filaments. A cone-shaped, wire stream divider consisting of eight pieces of stainless steel wire, is positioned with its base at the outlet of the injector. The injector and wire stream divider are mounted on a hollow member containing a partially spherical expansion chamber. The hollow member has a bottom wall through which the injector extends and to which the divider and the hose coupling are secured by laminations of fiberglass cloth saturated with epoxy resin. The bottom wall has a series of air inlet openings located outwardly of the wire stream divider so that the expansion of the stream of water and concentrate upon introduction into the expansion chamber causes primary air to be educted through the openings into the expansion chamber.

The hollow member is secured to the inlet end of a discharge nozzle by a ring that is laminated to both the hollow member and the inlet end of the nozzle by strips of fiberglass cloth saturated with epoxy resin. The ring has a relatively greater number of air inlet openings for admitting a correspondingly large volume of secondary air by eduction to be mixed with the water and expanding foam concentrate discharging from the expansion chamber into the discharge nozzle. The discharge nozzle gradually tapers from its inlet toward its discharge end to provide a restricted discharge opening for maintaining a back pressure on the discharge stream. The discharge nozzle has a conical stream splitter or deflector mounted therein in axial alignment with, but longitudinally spaced from the wire stream divider. The deflector splits and transversely diverts the flow from the expansion chamber against the inner surface of the discharge nozzle. The inner surface of the discharge nozzle beyond the conical deflector has formations that produce a rough surface designed to retard flow and to induce violent turbulence within the discharge nozzle, causing the water and foam concentrate to be intimately mixed with a great volume of air prior to being discharged from the nozzle. The rough surface can be formed by spraying a uniform layer of epoxy resin on the inner surface of the discharge nozzle and partially embedding irregularly shaped particles of sand in the resin. Alternatively, a layer of epoxy resin and chopped bits of fiberglass can be directly sprayed upon the inner surface of the discharge nozzle. Both methods produce a rough, saw tooth-like surface that retards the flow and induces the desired violent turbulence.

The discharge nozzle delivers a stream of foam at very high velocity, the stream being substantially free from drip for a distance of at least 10 feet from the nozzle and then begins to feather out to a width of about 20 ft. at a distance of about 85 ft. from the nozzle. As the force of the stream is spent, the foam will fall gently onto the burning area in the foam of large flakes, cooling the flames and quickly extinguishing the same as a blanket of the flakes is built up.

The hollow member, the injector mounted therein, the ring for mounting the hollow member in the inlet end of the discharge nozzle, and the discharge nozzle itself are all preferably made from epoxy resin reinforced with chopped fiberglass, employing dies or mandrels of special shape, while applying the epoxy resin and chopped bits of fiberglass in accordance with well known techniques in the resin spraying and fiberglass arts. The resulting nozzle assembly is very strong, but light in weight. However, it will be understood that the technique of providing a rough surface on the interior of the discharge nozzle is equally applicable to metallic nozzles.

In accordance with the foregoing, the principal object of the invention is to provide a foam-forming nozzle wherein a maximum amount of air can be drawn into the nozzle by the eduction and expanding action of the water anc foam concentrate flowing therethrough, so that the discharging stream is in the form of large flakes that can be sprayed directly upon a body or pool of burning liquid without "dunking" or requiring the use of a deflecting back plate.

Another object is to provide a versatile fire foam nozzle that is capable of effectively and efficiently forming a spray containing either a protein, synthetic, or detergent type of foam forming concentrate.

A further object is to provide a nozzle wherein most of the components can be readily and inexpensively fabricated from epoxy resin components reinforced with fiberglass.

A further object is to provide a heavy duty, lightweight fire foam nozzle that can be easily held and manipulated by one person.

A still further object is to provide a technique for producing a roughened surface on the interior of a fire foam discharge nozzle to retard flow and thus create a highly turbulent condition in the fluid flowing through the nozzle, thereby assuring the intimate mixing of a maximum amount of air with the fluid.

Still another object is to provide a fire foam nozzle that will produce a greater ratio of foam to water than prior fire foam nozzles.

A still further object is to provide a fire foam nozzle that will project a stream of water and foam concentrate introduced into the nozzle at a given pressure, farther than prior nozzles receiving water and foam concentrate at the same pressure.

A still further object is to provide novel means for use in a nozzle for dividing a high velocity stream introduced thereinto into a multiplicity of streams.

A still further object is to provide a foam-forming nozzle wherein the discharging stream will not drip and will travel as a solid stream for a substantial distance before beginning to spread.

Another object is to provide a nozzle for forming foam that will effectively extinguish vapor fires in much less time than is required by prior nozzles.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic plan view of a preferred form of foam producing nozzle shown connected with a fire hose and a source of foam concentrate.

FIG. 2 is an enlarged longitudinal sectional view through the nozzle with a portion of the hose coupling shown in elevation, taken on the staggered line 2--2 of FIG. 1.

FIG. 3 is a further enlarged vertical sectional view, taken on the line 3--3 of FIG. 2, particularly illustrating the fluid stream splitter or deflector and its support means.

FIG. 4 is an enlarged vertical sectional view, taken on the line 4--4 of FIG. 2, particularly illustrating the two sets of openings for admitting primary and secondary air into the nozzle.

FIG. 5 is an enlarged vertical sectional view through the expansion chamber, taken on the line 5--5 of FIG. 2, showing the arrangement of the array of wires of the stream divider for sub-dividing the stream of fluid and foam concentrate as it enters the expansion chamber and before it enters the discharge nozzle.

FIG. 6 is an enlarged fragmentary vertical sectional view, taken on the line 6--6 of FIG. 2 at the converging end of the divider wires.

FIG. 7 is an enlarged fragmentary vertical sectional view, taken on the line 7--7 of FIG. 5, illustrating the manner of applying resin-saturated strips for attaching the flared ends of the divider wires to the end wall of the expansion chamber.

FIG. 8 is an enlarged fragmentary sectional view of a portion of the discharge nozzle illustrating the rough interior surface thereof formed by embedding irregularly shaped sand particles in a layer of resin material.

FIG. 9 is a view similar to FIG. 8, but showing an alternative method of providing a rough interior surface on the nozzle by spraying resin and short lengths of fiberglass thereon.

FIG. 10 is a further enlarged fragmentary sectional view of the inlet end of the nozzle assembly, particularly illustrating the manner of assembling components shown by applying thereto strips of fiberglass fabric saturated with epoxy resin.

FIG. 11 is an enlarged fragmentary vertical sectional view through an adapter fitting and particularly showing the manner of mounting a foam concentrate eductor tube therein.

FIG. 12 is a side elevational view partly in cross-section, of a modified fire foam nozzle for use with a smaller size coupling and fire hose and wherein the components have been proportionately reduced in size, with the exception of the wire stream divider.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, the fire foam nozzle assembly is generally identified by the numeral 2 and is shown connected with a fire hose 4 serving as a source of water under pressure. An aspirating adapter 6 is connected between the nozzle assembly 2 and the hose 4. A sleeve 8 is welded at one end to the adapter 6, its other end having threads 10 to which one end of a flexible tube 12 is connected by a fitting 14. The other end of the tube 12 is connected to a tank 16 containing a liquid foam concentrate. Such concentrate may be of any known type, protein, synthetic or detergent.

The nozzle assembly 2 comprises a metallic hose coupling section 18 that is internally threaded to receive an externally threaded extension 20 on the adapter 6. The hose coupling 18 has an internal shoulder 22 formed therein, see FIG. 10, and a series of serrations 24 between the shoulder 22 and the end of the coupling. A frusto-conical injector nozzle 26 has its base seated upon the shoulder 22 with its axis aligned with that of the coupling section 18. An eductor tube 28, FIG. 11, for aspirating foam concentrate, has a right angle bend 30 formed therein with one leg 32 welded in an opening formed in the side wall of the adapter 6 and communicating with the interior of the sleeve 8. The other leg 36 of the eductor tube 28, FIG. 10, extends axially through the injector 26 and has an end 38 cut on an angle of about 45.degree. . The injector 26 is made by spraying epoxy resin and filaments of chopped fiberglass upon a waxed mandrel until the desired wall thickness is built up. The technique of spraying employed is well known in the art. In this connection, while reference will be made hereinafter to epoxy resin, it will be understood that a polyester resin or any other suitable and equivalent material can be used.

The nozzle 26 is permanently assembled with the hose coupling 18 by placing the two members on a suitable form in an upright position and filling the space in the coupling 18 between the nozzle 26 and the serrations 24 with epoxy resin containing a reinforcing material such as filaments of fiberglass. A hollow, globe-like member 42 has a side wall 44 shaped to provide a partially spherical expansion chamber 46. The inner surfaces of the side wall 44 are struck on a radius R of 6" from a diametrical line, as shown in FIG. 10. One end of the member 42 has a cylindrical portion 48 that is closed by an end wall 50. The member 42 is formed in one piece by spraying an epoxy resin and chopped fiberglass over a multi-piece mold of the desired shape, previously coated with wax to prevent the resin from sticking to the mold. The mold is rotated and spraying is continued until the desired wall thickness is obtained. The mold is then allowed to stand until the resin cures. Thereafter, the spray-formed member 42 is placed in a lathe and turned to provide a smooth exterior and uniform thickness for the side wall 44 and the bottom wall 50. Next, a tapered axial opening 52 is bored in the bottom wall 50, and a series of circumferentially spaced openings 54 is drilled in the bottom wall 50 a predetermined distance from its center. There are 12 openings 54, each five-eighths inch in diameter.

The opening 50 is tapered and of such size that it snugly receives the outer end portion of the injector nozzle 26. In this manner, a space is formed between the bottom wall 50 of the member 42 and the epoxy material 40 filling the hose coupling 18. Strips 56 of fiberglass of a suitable width, and saturated with epoxy resin are wrapped around the exposed portion of the nozzle 26 until the wrapping material is substantially flush with the outer periphery of the coupling 18. The impregnated fiberglass strips 56 permanently bond the nozzle 26, hose coupling 18 and the member 42 together. After curing, the outermost wrapping of the strips 56 can be ground smooth, if desired, or plain epoxy resin may be sprayed thereon to provide a smooth finish.

The inner end of the injector nozzle 26 projects about one-half inch beyond the bottom wall 50 and strips of fiberglass 58 saturated with epoxy resin are wound there around until a body 60, about 21/4 inches in diameter is formed. The diameter of the body 60 corresponds to the outer diameter of the flared end of a wire stream divider 62, which is about 5 inches long. The stream divider 62 consists of a circular array of stainless steel wires 64, one-eighth inch in diameter, angularly spaced 45.degree. apart, and diverging inwardly for the major portion of their length on an included angle of about 10.degree. . The outer ends of the wires 64 are welded or brazed together, as indicated at 66. The inner ends of the wires 64 are curved outwardly on a radius R2 of fifteen-sixteenths inch, FIG. 10, to provide end portions 68 that flare outwardly and terminate at right angles to the axis of the divider 62. The diametrical dimension across the ends 68 of the wires 64 is equal to that of the body 60 built up by the laminations 58, and against which the ends 68 are positioned.

The wire stream divider 62 is secured to the body 60 by wrapping strips of fiberglass 70 of appropriate width and saturated with epoxy resin, around the body 60 and folding the strips over onto the ends 68 of the wires 64, and onto the exposed side of said body, as is best shown in FIGS. 7 and 10. Several laminations 70 can be employed to provide a good bond between the body 60 and the divider 62.

A discharge nozzle 72 comprises a tapered tubular portion, having an initially smooth inner surface 74, and a ring 76. The side walls of the nozzle 72 converge on an included angle ofabout 10.degree. from an inlet end 78 to a relatively smaller and restricted discharge end 80. The discharge nozzle 72 is made by wrapping fiberglass cloth upon a waxed, tapered mandrel (not shown) and then spraying epoxy resin and chopped fiberglass thereon until a wall of the desired thickness has been built up. The wax prevents the fiberglass cloth from sticking to the mandrel and provides the smooth interior surface 74 in the discharge nozzle 72. The exterior of the mandrel is rough and is given a smooth finish by grinding or turning in a lathe.

A conical stream deflector 82 is mounted within the discharge nozzle 72 on two intersecting plastic vanes 84 arranged at right angles to each other. The vanes 84 are secured in place by short strips of fiberglass cloth 86 saturated with epoxy resin and applied in the regions where the ends of the vanes 84 contact the inner surface 74 of the discharge nozzle 72. The conical deflector 82 is solid and is readily made by filling a conical mold with epoxy resin containing reinforcing fiberglass fibers. The deflector 82 has intersecting grooves cut in its base to receive the vanes 84, and is secured to the vanes, as shown, by strips of fiberglass 88 saturated with epoxy resin. The pointed end of the deflector 82 is axially aligned with the axis of the wire stream divider 62 and is longitudinally spaced a distance of about 3 inches therefrom.

It has been further found that great turbulence can be created in the discharge nozzle 72 by providing a rough surface therein that will retard fluid flow. The desired roughness can be imparted to the inner surface 74 of the discharge nozzle 72 by at least two methods. The preferred method is to uniformly spray the surface 74 over its entire area outwardly of the vanes 84 with an epoxy resin to form a layer 75 and then sprinkling particles 77 of building sand, such as is used in mixing mortar, over the sprayed area and pressing the sand particles into the resin to partially embed the same in the resin. Here again, epoxy resin, polyester resin or any other suitable resin can be used. The sand particles 77 can be pressed into the resin layer 75 by a roller or any suitable means, but it is preferred that the sand particles 77 not be completely embedded in the resin, but that they project inwardly beyond the resin layer 75 to provide randomly projecting formations presenting a rough saw tooth-like surface. Such saw tooth-like surface is best illustrated in FIG. 8.

Another method of providing a rough surface on the interior of the nozzle 72 is to simultaneously spray epoxy resin 79 and filaments of chopped fiberglass 81 of a length of one-quarter inches onto the surface 74. This will result in the resin-coated bits of fiberglass being randomly disposed with some ends projecting inwardly so as to form a very rough saw tooth-like surface, as illustrated in FIG. 9. The chopped bits of fiberglass and resin may be sprayed until a layer of any desired thickness is formed on the surface 74. Upon curing, the resin will be very hard, and at the same time the fiberglass filaments will form a very rough surface that retards fluid flow and is highly conducive to creating great turbulence within the nozzle 72.

Reverting to FIGS. 1 and 10, the ring 76 is formed by placing sheet fiberglass in an annular mold and spraying epoxy resin and chopped fiberglass thereon until a desired thickness of about three-quarters inch is obtained. After curing the ring 76 is turned in a lathe to an outside diameter of 101/2 inches. The ring 76 is bored to provide an opening 90 large enough to receive the spherical portion of the member 42. Additionally, the ring 76 has a series of circumferentially spaced air inlet openings 92 formed therein surrounding the opening 90. There are 27 openings 92, three-quarter inch in diameter.

The ring 76 is secured to the member 42 by strips of fiberglass cloth 94 saturated with epoxy resin and placed along the line of juncture between the member 42 and the ring 76 on both sides of the ring. After the resin has cured, the ring 76 is positioned in abutment with the inlet end 78 of the nozzle 72 and permanently secured to the nozzle. This is done by wrapping strips of fiberglass cloth 96 saturated with epoxy resin, around the outer periphery of the nozzle 72 and ring 76 and folding the extended edge of the strips 96 over onto the outer face of the ring 76. Any number of strips 96 of gradually decreasing width can be applied until a lamination of the desired thickness and strength is built up. After the resin has cured, the edges of the strips 96 may be ground to a smooth, curved finish, as indicated at 98 in FIG. 10.

In order to facilitate handling and holding of the nozzle assembly 2, a U-shaped plastic handle 100 having extensions 102 at its opposite ends is positioned upon the discharge nozzle 72 and the ends 102 are secured in place by applying strips of fiberglass cloth 104 saturated with epoxy resin to the nozzle 72 so that they extend across the extension 102.

The dimensions of the various components of the nozzle assembly 2 have been mostly determined by cut and try methods and tested by experimenting. By way of example, and not limitation, in one operable form of the invention for use with a 21/2 inches fire hose, the discharge nozzle 72 has an overall length of about 30 inches, a diameter of about 101/2 inches at its inlet end, and a diameter of about 51/2 inches, or about half that of the inlet, at its outlet end. With such dimensions, the side walls converge outwardly on an included angle of about 10.degree. . The radial wall thickness is at least about seven thirty-seconds inch, except at the discharge end where it is increased to about eleven thirty-seconds inch.

The globe-like member 42 containing the expansion chamber 46 may be constructed with a side wall and end wall thickness of about seven thirty-seconds inch. The outside diameter of the cylindrical portion 48 is about 61/2 inches. The maximum internal transverse dimension of the expansion chamber is about 71/2 inches with the inner surfaces of the chamber being formed on radii R of 6 inches stuck from a diametrical line. The discharge opening of the expansion chamber is restricted and is about 6 inches in diameter. The inner surface of the side walls 44 converge toward the outlet so as to direct the expanding streams in the expansion chamber toward the center of the nozzle 72 and against the sides of the deflector 45 which splits and diverts the flow transversely against the roughened inner surface of the nozzle 72, creating violent turbulence and eduction of a large volume of secondary air into the nozzle. The vanes 84 supporting the deflector 82 are located in a zone a little less than about one-third the length of the discharge nozzle 72 from the inlet end 78 of the nozzle.

The structure described hereinbefore, is suitable for connection to a 21/2 inches diameter fire hose. However, the principles of construction involved are equally applicable to a fire hose of smaller diameter, say 11/2 inches, and in this connection, FIG. 12 illustrates a nozzle assembly that can be used with such smaller hose. In this embodiment, the proportions have been reduced by about one-third, except for the wire divider 62 and the conical deflector 82, which assume positions closer to each other as shown.

The injector 26, for a 21/2 inches nozzle, is about 41/2 inches in length with a 21/2 inches diameter nozzle inlet and a 1 inch diameter orifice at its outlet end. The radial wall thickness is one-eighth of an inch. Such nozzle with a flow rate of 240 GPM at a pressure of 100 psi has a range of 85 ft; and at a pressure of 250 psi and a flow rate of 375 GPM, a range of 125 ft. For a 11/2 inches nozzle, the inlet end of the injector is 11/2 inches in diameter and the discharge orifice is five-eighths inch in diameter. Such nozzle has a range of 45 ft. at a 120 GPM flow rate and pressure of 100 psi; and a range of 65 ft. at a flow of 185 GPM at a pressure of 250 psi. While a pressure of 100 psi has been mentioned, it is to be understood that the present nozzles will work satisfactorily with a pressure as low as 65 psi.

It will be apparent that the angle of divergence of the wires 64 of the wire divider 62 is less for a 11/2 inches nozzle in view of the reduced size of the discharge orifice of the injector. However, in both the 11/2 inches and the 21/2 inches size nozzle, the design is such that the projected jet discharging through the injector orifice does not strike the arcuate portion of the wires 64 until the jet is about one-half inch beyond the end of the discharge orifice. This dimension is important in effecting the desired division of the incoming stream and for creating turbulence in the expansion chamber, and the eduction of a large quantity of primary air into the expansion chamber 46 through the openings 54.

As has been indicated hereinabove, there are 12 primary air openings 54, five-eighths inch in diameter providing a total area of 3.68 sq. in. There are 27 of the secondary air openings 92, three-quarters inch in diameter providing a total area of 11.93 sq. in. As will be seen from these figures, the ratio of the area of the openings for admitting secondary air into the nozzle 72 is about 31/4 times as great as the total area of the openings 54 for admitting primary air into the expansion chamber 46. By providing for a maximum of admission of air into the nozzle, and for creating great turbulence in both the expansion chamber 46 and nozzle 72, the necessary quantity of air for producing great expansion and the flake-like foam, is mixed with the water and foam concentrate.

As has been indicated, tests have been made to demonstrate the operability and capabilities of the present fire foam nozzle to extinguish fires with the flake-like foam, compared with conventional fire foam nozzles. Thus, one test using a conventional fire foam nozzle to extinguish a very hot pit fire of heptane, 30 gallons of foam concentrate were proportionately added to the water, and it took a period of 5 minutes to put out the fire. A blanket of foam over the liquid surface was formed to a depth of only one-half inch, which was not thick enough to be effective to prevent reignition. The surface of the pit was cleared and the combustible liquid reignited to provide the same type of fire. The nozzle of the present invention was employed to extinguish the fire with the result that the flakes first landing on the burning area were instantly converted into steam vapor in large volume, thus quickly cooling the burning vapor. A foam blanket two inches thick was formed over the liquid surface, requiring only two gallons of foam concentrate, and completely extinguished the fire in an elapsed time of only 20 seconds. The foam blanket of 2 inches was adequate to effectively hold the vapor and prevent reignition from the hot surface of the liquid.

While certain specific dimensions and procedures for making the present nozzle assembly have been disclosed herein by way of example, and not limitation, it will be understood that the principles involved may be incorporated in devices of modified dimensions, made by other techniques, and employing different materials, without departing from the scope of the annexed claims.

Claims

We claim:

1. In a foam-forming nozzle assembly, a hollow, tapered nozzle having an inlet end and a relatively smaller restricted outlet end; and means in said nozzle providing irregular and randomly located rough formations on the inner surface thereof for producing turbulence and retarding flow of a foam-forming fluid therethrough.

2. A nozzle as defined in claim 1, wherein the means providing the rough formations on the interior of the nozzle comprises particles of sand partially embedded at random in a resin material applied to the inner surface of the nozzle.

3. A nozzle as defined in claim 1, wherein the means providing the rough formations on the interior of the nozzle comprises randomly disposed bits of chopped fiberglass and epoxy resin applied to the inner surface of the nozzle.

4. In a nozzle as defined in claim 1, means at the inlet end of the nozzle for introducing foam-forming fluid therein at high velocity; and means in the nozzle, in the path of flow of the foam-forming fluid, for directing said fluid laterally against the flow-retarding formations in the nozzle.

5. In a foam-forming nozzle assembly; a hollow tapered nozzle having an inlet end and a relatively smaller restricted outlet end; means arranged to introduce a foam-forming fluid into said inlet end of said nozzle at high velocity; air inlet means arranged to admit air by eduction into said nozzle, said nozzle having formations on the inner surface thereof for retarding flow therethrough; and means in said nozzle adjacent said inlet end for deflecting said foam-forming fluid laterally against said flow-retarding formations to effect turbulent mixing of educted air with said foam-forming fluid prior to discharge from said nozzle.

6. A foam-forming nozzle for use in extinguishing fires, comprising: a tubular discharge nozzle having an inlet end and side walls converging therefrom toward a discharge end of substantially smaller diameter; a hollow member containing an expansion chamber mounted at the inlet end of said discharge nozzle; said hollow member having openings for admitting primary air by eduction; means for introducing a jet of foam-forming liquid at high velocity into said expansion chamber; means in the path of said jet for dividing said jet into a plurality of streams and effecting turbulent mixing of educted primary air therewith in said expansion chamber; means axially aligned with said expansion chamber for deflecting flow therefrom laterally against the inner surface of said discharge nozzle; and means for admitting secondary air by eduction into said discharge nozzle.

7. A nozzle as defined in claim 6, including means in the discharge nozzle for retarding flow and producing violent turbulence to mix great quantities of educted air with said foam-forming liquid.

8. A nozzle as defined in claim 6, wherein the converging side walls of the discharge nozzle provide a passage that converges toward the discharge end thereof on an included angle of about 10.degree..

9. A nozzle as defined in claim 6, wherein the hollow member has a transverse end wall at the outlet end of the expansion chamber and wherein the means for introducing the jet of foam-forming liquid is an injector nozzle having its discharge end extending into the expansion chamber beyond said end wall.

10. A nozzle assembly as defined in claim 9, wherein the injector nozzle is frusto-conical in shape with inwardly converging side walls, and is mounted in the end wall of the hollow member containing the expansion chamber.

11. A nozzle as defined in claim 10, wherein the converging walls of the injector nozzle form a passage that tapers toward the discharge end thereof on an included angle of about 22.degree..

12. A nozzle as defined in claim 6, wherein the expansion chamber has confronting, arcuate side walls forming a partially spherical expansion chamber.

13. A nozzle as defined in claim 12, wherein the arcuate side walls of the expansion chamber curve inwardly at the outlet end of the expansion chamber to deflect the expanding streams formed therein toward the axis of the discharge nozzle.

14. A nozzle as defined in claim 9, wherein the means for dividing the foam-forming liquid into a plurality of streams is a divider comprising an array of converging wires joined together at one end, and flaring radially outwardly at their other end, and wherein the flared end of the divider is disposed adjacent the discharge end of the injector nozzle.

15. A nozzle as defined in claim 14, wherein the hollow member is made of reinforced epoxy resin, and wherein the flared ends of the wires are secured to the end wall of the hollow member by strips of fiberglass cloth initially saturated with epoxy resin.

16. A nozzle as defined in claim 14, wherein the outwardly flaring ends of the divider are arcuate and the portion thereof in the projected path of the discharge orifice is spaced a predetermined distance from said orifice.

17. A nozzle as defined in claim 14, wherein the joined ends of the wires of the divider terminate at a point slightly beyond the point of maximum diametrical distance between opposite walls of the expansion chamber.

18. A nozzle as defined in claim 14, wherein the joined ends of the wires of the stream divider are secured together to form a zone-like structure.

19. A nozzle as defined in claim 14, wherein the wires are equi-angularly spaced apart circumferentially in circular array and wherein the included angle between diametrically opposed wires is about 10.degree..

20. A nozzle as defined in claim 9, wherein an eductor tube for supplying foam concentrate is disposed axially within the injector nozzle and has an outlet end that terminates in the region of the discharge end of said injector nozzle.

21. A nozzle as defined in claim 14, wherein the flow deflector comprises a cone-shaped member having its apex confronting but longitudinally spaced from the joined ends of the wires of the stream divider.

22. A nozzle as defined in claim 21, wherein the flow deflector is supported in the discharge nozzle by radial vanes.

23. A nozzle as defined in claim 22, wherein the flow deflector and radial vanes are located in a zone a little less than about one-third the length of the discharge nozzle from the inlet end of the discharge nozzle.

24. A nozzle as defined in claim 9, wherein the air inlet openings for the primary air are formed in the end wall of the hollow member radially outwardly of the stream divider; and wherein a ring mounts the hollow member in the inlet end of the discharge nozzle, and wherein the means for admitting the secondary air comprises air inlet openings formed in said ring.

25. A nozzle as defined in claim 24, wherein the ratio of the total area of the inlet openings for secondary air to the total area of the openings for primary air is about 31/4 to 1.

26. A nozzle as defined in claim 25, wherein the discharge nozzle, hollow member, and ring are formed of reinforced epoxy resin, and wherein the ring is secured to the hollow member and to the inlet end of the discharge nozzle by strips of fiberglass cloth initially saturated with epoxy resin.

27. A nozzle as defined in claim 6, including a handle connected to the discharge nozzle.