US2716458A - Non-static snow discharge horn - Google Patents

Description

11g- 30, 1955 G. B. lsAAcs 2,716,458

NON-STATIC SNOW DISCHARGE HORN Filed Feb. 9, 1955 '3 Mmmm I Z MMIV/MM rroR/VEY.

United States Patent O NON-STATIC SNOW DISCHARGE HORN George B. Isaacs, Los Angeles, Calif.

Application February 9, 1953, Serial No. 335,815

3 Claims. (.Cl. 169-11) This invention relates generally to tire extinguishing equipment and in particular to horn and nozzle combination for directing and controlling Athe spread of a fluid stream.

.Heretofore directing horn and nozzle combinations have been used in nre extinguishers, particularly the inert gas type re extinguisher such as those employing carbon dioxide or other inert gas. ln many instances, the horn for directing the gas, or, in the case of carbon dioxide lire extinguishers, directing the carbon dioxide usually discharged from 4the nozzle in the form of snow,'has been made of either metal or iiber. The horn is either at tached to the nozzle permanently or is secured to it by a fastening device. Metal or liber horns have not proven too satisfactory since the metal horns can be permanently deformed and rendered ineffective while ber yhorns can be broken. In either case, the entire horn combination must be replaced.

One of the commonest applications ofthe inert gas type of fire extinguisher, such as those employing carbon dioxide as the iire flghting'medium, has been in extinguish ing res occurring in or around electrical installations where water or the soda-acid type of tire extinguisher cannot be employed. The use of metal horns in such apparatus is not desirable since there is always the possibility that the horn may come in contact with a 'live portion of the electrical installation thereby subjecting the operator to the danger of shock, burn or even electrocution. Fiber horns can be used to avoid this danger but as stated above, the majority of materials used in making horns of this type are not very resilient and can be easily broken or cracked.

The object of my invention is to provide a unitary directing horn and :nozzle combination that is light in weight, resilient, isa non-conductor of electricity, and

can be easily `attached to the fitting at the end of the delivery hose from the pressurized gas tank.

A related object of my invention is to provide a unitary directing horn and nozzle combination that is capable of effectively increasing the distance to which a stream of gas can be thrown over that normally attained by existing devices.

A further object of my invention is to provide a unitary directing horn and nozzle combination that ywill not accumulate a static charge. In the carbon dioxide type of fire extinguisher the gas is usually discharged from the nozzle inthe form of a snow. Some of the carbon dioxide snow will come in contact with the inner surface ofthe directing horn and in the case of some typesof materials will generate a static charge.

My invention provides a directing horn nozzle .combination in which the nozzle is irremovably and permanently interlocked and gripped in the molded plastic horn and is provided with coupling means that will engage `the fitting at the end'of the delivery hose from apressurized gas bottle. .The horn is made of a resilient plastic that is capable of reassuming its normal shape -after deformation, is not affected :by solvents, isa nonconductorof electricity and will not` accumulate a static charge.

A suitable plastic that meets the above requirements -is polyethylene. This material is substantially unaifected by corrosive fumesl or solvents, isa nonconductor of electricity, will not accumulate a static charge especially when the surface comes in ,contact with carbon dioxide snow, is cheap and can be molded into ,any desired conliguration, and is extremely resilient. Horns made of this material may b e deformed, flattened, `dropped or bent innumerable times and will always return to .their original molded shape.

A feature of my unitary 'horn and nozzle combination is that :due to its construction it is `possible to effectively project an inert .gas stream or a stream of carbon dioxide snow., va much greater distance than has been heretofore possible. -I accomplish this by introducing ahead lof, through, and downstream of the nozzle orifice a stationary spiral 'member formed by twisting a ribbon-like strip .of rigid material about its longitudinal axis. This element imparts a spiral motion to the gases passing through the orifice 4that tends to offset .the .tendency or the gas to assume Yturbulent flow characteristics that would normally .be present when gases under high pressure are suddenly released through an orifice .of small area into a region of low pressure and 4of greatly increased area. Turbulence effectively decreases the velocity .of the Vdischarged gases and reducesthe distance to which they are projected from Athe pointof exit.

The foregoing and other features of my invention will be more ,clearly understood by referring to the accompanying drawings in which:

Fig. l is a view of a unitary ihorn and nozzle combination ,partly in vcrosssection showing how the nozzle is secured -to v-the horn. Y

Fig. 2 is a fragmentary cross-section view taken on line 2 2 of Fig. L1 and showing a portion `of the horn irnmediately surrounding the nozzle.

Fig. 3 shows the nozzle fandhorn of Fig. 2 with'the connecting delivery tube and lspiral lmember in position.

Fig. 4 `is a fragmentary cross-sectional view of an a'lternate horn design.

Referring to the drawings, `there `is shown in Fig. l

a :plastic 'directing'member or horn 10 preferably in the shapeof an )elongated funnel, having a gradual taper and provided with .a discharge opening :11 at the larger end. lt :has fbeen found 'that the yincrease in diameter of the horn, withrespect'to `the length thereof between the small entry end andthe larger discharge end may be varied between the ratios of I1:10 and 1:20.

The smaller or inlet fend of the plastic horn surrounds and securely holds a nozzle-coupling member 12 that is permanently .molded within and to the smaller end of the vdirecting horn-thereby providing a unitary hornnozz`le-,coupling assembly that can be Ieasily attached to a deliveryconduitfrom aihigh pressure gas container. The .nozzle-.coupling lmember 12 is preferably molded so that it is ushwith the inlet end of the horn to facilitate assembly.

Heretofore .when it has been attempted to secure a metal member in a plastic such as polyethylene, by molding`the plastic around the metal member, it has been difiicult 'to grip the metal rigidly `and permanently in the plastic and avoid -turning or axial movement of the metal part :within the plastic when it is subjected to tor sional or axial stresses such as encountered, for example, when the metal member is icoupled to, or disconnected from the fitting at'theend-of the conduit or subjected to rough handling. 'Since this equipment yis to handle gases under rpressure, a loose nozzle-coupling member within the plastic horn is particularly undesirable. -In attempting to :overcome this diculty, the surface of the.

metal around which the plastic has been molded has been given various polygonal congurations such as a hexagonal or octagonal contour. Where metal member was cylindrical, the surface has been deeply knurled in an attempt to allow the plastic to grip the metal surface more securely. None of these expedients have proven satisfactory and often times the plastic horn and the nozzle have become completely separated.

My invention eliminates the above difficulty by the provision of nozzle-coupling member 12 which comprises a substantially cylindrical body portion 13 provided on its outer surface with transverse and longitudinal grooves. The embodiment shown in the drawings, by way of example, shows circumferential grooves 14 andlS of substantial depth located near each end 16 and 17. That portion of the cylindrical surface 13 between circumferential grooves 14 and 15 is also provided with a plurality of axial grooves 1S also of substantial depth. These grooves 18 may be replaced by splines if desired. When the member 12 is molded into the plastic horn, the plastic that enters the grooves 14, 1S and 18 is integral with the material forming the inlet end of the horn and when the molding process is completed, the plastic shrinks and grips the metal member securely interlocking the metal member and the horn. The configuration into which the plastic is molded prevents any relative rotational or axial movement between the plastic horn and the nozzle-coupling member.

Outer end 17 of cylindrical body member 13 is provided with an axial bore 19 that extends into body member 13 a substantial distance. This bore is provided with a suitable coupling means to engage the tting at the end of a gas supply conduit. The coupling means preferably employed is internal threading 20 that extends substantially the entire length of the bore 19.

A partition 23 provided with an axial orifice 24 is located at the opposite or inner end 16 of cylindrical body member 13. A pressure chamber 21 is positioned between threaded bore 19 and partition 23 and is in communication with orifice 24. Pressure chamber 21 is preferably smaller in diameter than threaded bore 19 thereby forming a shoulder 22.

The gas or solid carbon dioxide snow escaping through oriiice 24 enters the directing horn 10 and is conducted to the discharge opening 11. Since the area into which the gas is discharged from the orifice is much larger than the area of the orifice, there is a tendency for the gases to assume turbulent flow characteristics as soon as they leave the orice. To minimize this tendency, l place ahead of, into, and downstream of the orifice a stationary member 25. This member comprises a narrow strip of rigid material, such as metal, in the form of a narrow ribbon twisted about its longitudinal axis to form a spiral. The ribbon is preferably wide enough to pass snugly through orifice 24. This spiral member is securely held in place so that it will not be moved or dislodged by the gases flowing past it. Spiral member 25 imparts a swirling motion to the gas and helps it to reach the discharge opening 11 with greater velocity.

In the construction shown in the drawings, member 2S is secureld held by means of a cross-member 2'7. The end of the spiral member is secured to the central portion of cross member 27 by suitable means such as welding, soldering, brazing, riveting, etc. Cross member 27 is made longer than the diameter of pressure chamber 21 but is proportioned to slide into threaded bore 19. The width of cross member 27 should be such as to avoid interference with the flow of gas as much as possible, yet it should be sufficiently strong to securely support the spiral member against the force of the escaping gas. Spiral member 25 extends as shown in Fig. 3 from shoulder 22, through pressure chamber 21, through orifice 24, and into the region downstream from the discharge end of orifice 24.

Fig. 4 shows a modiiication of the horn construction.

In this modification the inner diameter 28 of that portion of the horn immediately adjoining the discharge orifice 24 of nozzle coupling member 12, is substantially the same as the diameter of the end 16 of the nozzle member. This portion of the horn continues at a slight taper for a distance of between 10% and 25% of the length of the horn until it reaches a position 29. From zone 29, the horn may be a cone of greater angularity than the initial portion. Differently stated, the horn may, for l0%-20% of total length, comprise an initial conical portion of given angularity, an outwardly directed step at zone 29 wherein the internal diameter rapidly increases by about 5%-l5% of the diameter at the end of such initial portion, and an outer cone portion of the same or slightly greater angularity than the initial cone portion adjacent the nozzle. In these modiL fied forms, the relatively restricted initial cone portions appear to have a tendency to build up pressure which facilitates the propulsion of snow to a greater distance with greater accuracy.

In operation the unitary horn and nozzle combination is secured to the tting 30 at the end of the delivery conduit 31 which leads the gas under pressure from a container (not shown), by merely threading the coupling member and fitting together, as shown in Fig. 3. When tting 30 is in place it clamps cross member 27 to shoulder 22, thus securely holding the spiral member sta-v tionary in position. Gases under pressure are then released and ilo-w through conduit 31 into pressure chamber 21, through orifice 24 and into the directing horn. In owing past spiral member 25 the gases assume a corresponding spiral flow and since the spiral member extends beyond the end of the orice the gases will continue to be spirally projected into the horn. The gas stream leaves the spiral owing in a laminar path. The stream gradually increases in diameter as it progresses downstream and thus avoids any abrupt changes in area thereby minimizing the tendency to assume a turbulent flow.

The novel type of horn according to my invention permits an increase in the throw of gas released under pressure a considerable distance beyond that possible of attainment with existing horns. For example, in a pressure system in which the gas is under about fifteen pounds pressure the normal horn will project the gas or snow approximately six feet. Under the same conditions my horn and nozzle combination will project the gas or snow a distance of from l0 to 12 feet. This is particularly advantageous in fighting tires since it is possible for the operator to position himself further away from the point of danger thus minimizing the risk of burns or injury.

In summary my invention makes available a horn and nozzle combination that is easy to connect to the conduit from a gas storage bottle, is unaffected by corrosive fumes, solvents, is a non-conductor of electricity, will not accumulate a static charge, and can be cheaply constructed. The combination is furthermore capable of throwing inert gas or carbon dioxide in the form of snow a considerably greater distance than has been heretofore possible from the point of release.

Having described the preferred embodiment of my invention, it is to be understood that the invention is not to be limited to the exact details herein set forth, which may be varied without departing from the spirit of my invention as set forth in the appended claims.

I claim:

1. In a fire-fighting horn for forming, directing and discharging solid carbon dioxide snow, the provision of:

a one-piece discharge horn of homogeneous polyethylene composition having an inlet end and a larger discharge end; a unitary nozzle and coupling member molded into and irremovably associated with the smaller end of said discharge horn, the external surface of said member including circumferential and longitudinal grooves adapted to receive integral portions of the horn; the

outer end portion of the coupling member being provided with an internally threaded bore and the inner end portion of the member being provided with an axial orifice, said horn being provided with a bore rapidly increasing toward the discharge end thereof for a distance of between 75% and 90% of the horn length, whereby liquid carbon dioxide supplied to the horn through said coupling member may be discharged through said orifice in snow-forming condition and the snow discharged through said horn without generation of static.

2. A horn of the character stated in claim 1, wherein said horn is provided with a virtually cylindrical bore for between 10% and 25% of its length adjacent said member.

3. A fire-fighting horn as stated in claim 1, wherein the axial orice is in a transverse partition at the inner end of the member and a pressure chamber is References Cited the iile of this patent UNITED STATES PATENTS 2,158,965 Hcigis -f May 16, 1939 2,569,490 Newman Oct. 2, 1951 2,603,299 Mapas L July 15, 1952 2,645,292

Williams July 14, 1953

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