US2183339A - Apparatus for distributing fireextinguishing foam - Google Patents

Description

Dec. 12, 1939. 1.. G. M. TIIMPSON APPARATUS FOR DISTRIBUTING FIRE EXTINGUISHING FOAM Filed Feb. 10, 1938 INVENTOR Lam's 6T Mar/'25 fimpson.

' AoRm-zv Patented Dec. 12, 1939 APPARATUS FOR DISTRH EUT'ING FIBE- EXTINGUISHING FOAM no. a. norm 'Iimpson, Plainfleld, N. 1., as-

Minimax C signor to orporation,

Pyrenc Newark, N. J., a corporation of Delaware Application February 10, 1938. Serial No. 189.109

The invention relates to method and apparatus for distributing a fire-extinguishing foam, and more particularly to a method and apparatus for projecting foam at low pressures and un- 5 der the action of centrifugal force to produce a diverging hollow stream of foam.

In the extinguishing or prevention of fires at the surface of bodies of inflammable liquids, it is customary to cover the surface of the liquid with 10 a blanketing layer of foam. Such foam may be produced chemically, or by bringing about, intimate mixtures of air with a foam-producing liquid. My invention relates to improvements in method and apparatus for distributing both cheml8 ical foam and air foam, but I have found it especiallyefiective in connection with the latter where low pressures e advantageous.

In thepast various means have been employed for efiecting distribution. of fire-extinguishing 20 foam over the surface of inflammable liquids.

In the case of oil tanks, for example, foam distributing units are frequently attached permanently to the side of the tank, with wide bellmouthed nozzles projecting inside the tank and 25 arranged to discharge the foam against the inner sidewalls thereof to fiow down the walls and over the surface of the oil. Sometimes the foam is distributed with the use of hand nozzles of flat fan-shaped form. For extinguishing fires in 80 basements of buildings or dwellings where there is an accumulation of oil such as might be occasioned by an oil tank leak in connection with oil burner equipment, a nozzle known as a cellar nozzle is employed. This type of nomle ordi- 36 narily consists of a rotating head provided with slots through which foam is discharged under considerable pressure.

. It is an object of my invention'to provide nieth-' d and apparatus for distributing fire extinguish- 4p ing-foam which will operate satisfactorily under quite low pressures and which will make possible ya rapid and effective distribution of the foam.

Rapid covering of the surface of the inflammable liquid heretofore has required either the provi- 45 sion of a relatively large number of nomles or a resort to increased pressures or velocities, the production of which requires the use of equipment which is not only expensive but which is subject to operating difficulties. It is therefore 50 a further object of my invention to provide simpler and more effective means for accomplishing rapid covering of the surface of inflammable liquids.

A more specific object is to provide apparall tus of the class described which is readily portable and which can be used either simultaneously or as 'a part of fixed installations.

A further specific object of my invention is to provide method and apparatus of the class described in which rapid and uniform distribution 5 of foam can be effected under low pressures.

Another object is to provide means for distributing air or chemical foam in which the back pressure at the point of discharge of the foam is reduced to a so that variations in pressure of the stream do not seriously affect the uniformity of distribution.

Other objects and advantages will appear as the description proceeds.

In the drawing I have illustrated a preferred embodiment of my improved apparatus in connection with which I shall describe the practice of my invention. Fig. 1 is an elevational view partly broken away in section showing foam distributing apparatus constructed in accordance with my invention mounted atthe side of a tank containing an inflammable liquid.

Figs. 2, 3, and 4 are views of the same nozzle to an enlarged scale, Fig. 2 being a plan view partly in central longitudinal section, Fig. 3 a trans- 26 verse sectional view along the line 3-3 of Fig. 2, and Fig. 4 a sectional view along the line 4-4 of Fig. 2.

-When the invention is applied to extinguishing fires in dip tanks containing inflammable 30 liquids as represented by the tank i in Fig. l, a nozzle 2 of the form to be described my be mounted at the side of the tank in any convenient manner as by means of the adjustable ball and socket connection 3. A pipe 4 is. connected to a source of supply of chemical foam or air foam,

which source is not shown but maycomprise any suitable foam-producing mean's known to the art.

In accordance with my invention the foam is projected under pressure created bythe centrifu- 40 gal force of a stream flowing .in a spiral course to produce a hollow stream of foam moving at relatively low velocity and diverging from a circle lying substantially inthe plane of one side of the spiral course. In the construction illustrated the circle referred to is defined by the orifice of the nozzle 2, and the diverging hollow stream of foam flowing from this orifice is indicated in schematiccross-section at 5... I have found that when a stream is. projected in this manner the foam spreads very rapidly over the surface of the liquid in the tank. 1

Referring to Figs. 2, 3, and. 4, I shall now describe the preferred construction of the nozzle 2. This nozzle consists essentially of a member which 6 may conveniently be made as a metal casting and which is provided with an open spiral passage 0. The passage 6 is formed by the spiral bottom wall I and side walls I, I which together constitute a channel for the foam. A tubular conduit ll communicates with the spiral passage t. The conduit III may be formed as an integral part of the nozzle casting or if desired, as a separate member. It is connected with or may form a part of the pipe 4 leading from the source of supply of the foam.

At one side of the spiral passage 6 a circular orifice H is provided. This orifice lies substantially in the plane of one side of the spiral passage I and its center preferably coincides with the asymptotic point of the spiral. The diminishing radii of curvature of the bottom wall I in the direction of flow of the stream brings the bottom of the passage 6 progressively closer to the edge of the orifice H. In other words, the channel, of which the height is determined by the side wall 8, is of diminishing depth in the direction of flow of the stream, 1; e., clockwise as viewed in Fig. 2. There is thus produced an overflow discharge around substantially the entire circumference of the orifice II in a direction substantially normal to the plane of the spiral course 6.

A particular feature of the structure illustrated resides in the maintenance of a stream of uniform width for an appreciable distance in advance'of the point where the stream enters the spiral chamber 6. Thus the tubular conduit I0 is so constructed that the width of the channel in the plane of the spiral passage 6 is substantially uniform as it approaches the point represented by the shaded area I! where the stream-is discharged into the spiral passage. In the construction shown, the width a is equal to the width b, the side walls i3 and ll of the conduit Ill be ing concentric cylindrical surfaces. If the conduit I 0 should be made to converge sharply in width toward the point i2, the stream of foam flowing therein would be caused to converge beyond the point I2. I have found that this is undesirable when projecting streams of foam.

My arrangement, on the other hand, is particularly advantageous for the delivery of air foam under relatively low pressures and velocities. It is also advantageous for handling chemi-- cal foam under conditions of variable pressure because the back pressure is reduced and the effect of variations in back pressure minimized.

Another feature of the construction illustrated resides in the location of orifice ll substantially in the plane of one side of the spiral passage 6.

With this arrangement; the stream flowing through the orifice diverges outwardly without restriction which is of'.further advantage in producing more uniform flow under varying conditions of pressure in the conduit II. The arrangement is also advantageous under conditions of low pressure in the conduit II when a reduction in back pressure assists in producing'a stream of good covering power.

As an example of the practice of my invention, a nozzle of the form described is arranged at one side of the area to be sprayed and connected to a suitable source of supply of air foam which is delivered to the conduit it under a pressure of approximately 4 to 5 pounds per square inch. The foampasses beyond the point I! into the spiral passage I at low velocity and without converging in width to any appreciable degree. The stream of foam thus entering the spiral passage is constrained to flow in a spiral course. The surface of the stream overflows the edge of the orifice ll constantly diminishing in depth so that the orifice acts as a weir over which a stream of foam of substantially uniform depth flows under the pressure produced by the centrifugal force of the foam swirling in the spiral passage. The discharge of foam through the orifice I I is in the form of a hollow stream diverging outwardly in the direction of flow which at the point of discharge is substantially normal to the plane of the orifice.

It will be understood that the invention may be applied otherwise than as specifically illustrated. The nozzle may be used as a wall or overhead fixture, and may be adjusted to either vertical or horizontal positions. It is suitable for use in cellars in connectionwith extinguishing oil burner fires. When mounted at the side of a chemical dip tank such as illustrated in Fig. 1, my foam nozzle is useful in spraying foam over dipped articles hanging above the tank while simultaneously laying a layer of protective foam over the surface of the chemicals in the tank.

Other possible variations in the arrangement of the structure illustrated will occur to those skilled in the art and I have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the scope of the claim.

I claim:

Apparatus for distributing a fire-extinguishing foam comprising a nozzle having walls defining an open spiral passage therein, a closed rectangular conduit communicating with said spiral passage, the width of said conduit in the plane of said spiral passage being substantially uniform in a region terminatng at the entrance to said spiral passage, and a circular opening in a side wall of said spiral passage with its center substantially opposite the asymptotic point of the spiral, the side wall of said spiral passage adjacent said circular opening being constructed and arranged to cause foam discharged through said opening to diverge outwardly from a circle lying substantially in the plane of said wall.

LEWIS G. MORRIS 'I'IMPSON.

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