FIELD OF THE INVENTION

The invention generally relates to fire extinguishers and in particular to nozzles for use within fire extinguishers of generally small capacity.

BACKGROUND OF THE INVENTION

A wide variety of traditional pressurized fire extinguishers have been developed over the years. A traditional fire extinguisher typically includes a reservoir (e.g., a cylinder or tank) containing a quantity of extinguishant under pressure. The extinguishant may be, for example, water under air pressure, a dry chemical powder such as ammonium phosphate or potassium bicarbonate under nitrogen pressure, or carbon dioxide under pressure. A trigger mechanism is provided for opening a valve to release the pressurized extinguishant from the reservoir. A nozzle is used to disperse the extinguishant onto the fire to be extinguished. Often, a hose is provided between the trigger mechanism and the nozzle so that the nozzle may be easily pointed toward the base of the fire.

A significant advantage of traditional fire extinguisher designs is that such extinguishers can be configured as handheld devices for use in homes, offices, businesses and the like. However, in many ways, traditional fire extinguishers are not nearly as desirable as foam fire extinguishers used by professional fire fighters. A foam fire extinguisher is a device which combines, typically, water, a foaming agent, and air to produce a foam extinguishant that is highly effective for extinguishing fires. Whereas traditional extinguishants, such as water, often quickly run off of surfaces to be extinguished, foam clings to the surfaces to thereby more effectively extinguish the fire. Water can also cause significant damage to surfaces in the vicinity of the fire, such as adjacent furniture, wallpaper, and the like. Moreover, the mixing of air with the foaming agent generates a very rapidly expanding foam which greatly increases the ejection speed of the extinguishant from the fire extinguisher so as to propel it a greater distance. This allows the person operating the fire extinguisher to stand farther back from the fire itself, thus providing greater safety. Yet another advantage of foam extinguishers is that the extinguishant cools significantly as it expands into foam. A cool extinguishant is more effective at extinguishing certain types of fires, particularly kitchen fires involving fats or oils.

Accordingly, various attempts have been made at providing handheld fire extinguishers. A significant problem, however, is in providing a suitable mechanism for properly mixing air with the extinguishant. Professional foam extinguishing systems typically include expensive and elaborate devices for controlling the admixture of air, foaming agent, and water. A portable fire extinguisher, particularly for consumer use, requires a much simpler device for mixing air with the extinguishant so as to be both easy to use and inexpensive. To this end, at least some nozzles have been provided for use with foam fire extinguishers wherein the nozzle includes a set of air inlets formed around the perimeter of the nozzle. The air inlets permit air to be drawn into the nozzle as extinguishant is ejected from the extinguisher reservoir to thereby mix air and extinguishant directly within the nozzle to generate the foam. One example of such a nozzle is set forth in U.S. Patent Number 5,857,627.

Although nozzles with air inlets have met with some degree of success for use with large portable fire extinguishers, i.e. extinguishers having capacities of six litres or more, problems arise when attempting to implement the air inlet technique in smaller fire extinguishers, such as extinguishers with capacities of only two to four litres. Small fire extinguishers typically utilize a small nozzle and small nozzles typically do not provide sufficient size to allow for adequate mixing of extinguishant with air drawn in through air inlets to effectively produce foam or mist

In U.S. Patent 5,921,471 a nozzle is proposed for use with foam fire extinguishers, which does not require air inlet ports. With the nozzle of U.S. Patent 5,921,471 a pair of channels run parallel to an axis of the nozzle, but are each offset from the axis. A pair of deflecting walls deflect extinguishant from the channels toward a boss mounted at the base of the nozzle. According to this approach, the resulting deflection of the extinguishing fluid causes the fluid to become completely emulsified with ambient air to create a large volume of high-quality spraying foam. U.S. Patent 5,921,471 does not discuss the size of the fire extinguisher or the nozzle.

In any case, it would be desirable to provide an improved nozzle design for use with portable extinguishers of potentially any size, which more effectively mixes air with extinguishant than predecessor designs, and it is to that end that the invention is directed.

SUMMARY OF THE INVENTION

5 In accordance with a first aspect of the invention, a nozzle is provided for use with a fire extinguisher. The nozzle comprises an inlet port to receive a flow of extinguis- hant along an axis of the nozzle, a turbulence-generating channel configured to impart turbulence to the flow of extinguishant to produce a turbulent flow by first deflecting extinguishant away from the axis of the nozzle and then redirecting the o extinguishant again along the axis of the nozzle, and an outlet port configured to mix the turbulent flow of extinguishant with ambient air to produce a foam or mist of the extinguishant.

By first directing the flow of extinguishant away from the axis of the nozzle before s redirecting the extinguishant along the axis of the nozzle, it is believed that a greater amount of turbulence is achieved within the flow of extinguishant than in predecessor designs, so as to achieve a greater amount of mixing of extinguishant and ambient air within the outlet port of the nozzle to thereby provide a more effective extinguishing foam or mist. The nozzle design is particularly effective for use with o small fire extinguishers (e.g., having capacities of one to five and in particular two to four litres), where other nozzle designs may be ineffective. However, the nozzle design may also be advantageously employed for use with larger fire extinguishers as well. The nozzle is suitable for extinguishers that produce an extinguishing foam as well as for extinguishers that produce an extinguishing mist. 5

In one example, the turbulence-generating channel includes a perimeter containment structure sealing the extinguishant from ambient air as the extinguishant passes through the turbulence-generating channel, and a multidirection flow deflector mounted inside the perimeter containment structure. The multidirection flow deflec- o tor may include a first deflection surface facing the inlet port (and preferably positioned substantially perpendicular to the axis of the nozzle to deflect extinguishant away from the axis of the nozzle), at least two opposing collection channels, each oriented substantially perpendicular to the axis of the nozzle, to collect opposing portions of extinguishant and to redirect the portions back toward the axis, and a 5 second deflection surface facing the outlet port and positioned substantially perpendicular to the axis of the nozzle to deflect extinguishant along the axis of the nozzle into the outlet port.

A portion of the outside surface of the multisection flow deflector and a portion of the inside surface of the containment structure may form a first flow-reversal chamber, positioned generally upstream from inlet apertures of the collection channels, configured to impart additional turbulence to the flow of extinguishant. The second deflection surface is preferably formed within a second flow-reversal chamber, positioned generally downstream from outlet apertures of the collection channels, configured to impart additional turbulence to the flow of extinguishant The outlet port may be substantially conical to permit turbulent flow of extinguishant received from the turbulence-generating channel to mix with air within at least a portion of an interior of the outlet port so as to produce the foam or mist.

In the example, the provision of the first and second flow-reversal chambers serves to impart even greater turbulence to the flow of extinguishant, so as to further en- nance the mixing of air and extinguishant.

In accordance with another aspect invention, a fire extinguisher is provided. The fire extinguisher comprises a reservoir such as a tank to store extinguishant under pressure, a trigger mechanism to control ejection of the extinguishant from the reservoir, a nozzle to direct the extinguishant, the nozzle having an axis and an inlet port to receive a flow of extinguishant from the reservoir along the axis, a turbulence- generating channel configured to impart turbulence to the flow of extinguishant to produce a turbulent flow by first deflecting extinguishant away from the axis of the nozzle and then redirecting the extinguishant again along the axis of the nozzle, and an outlet port configured to mix the turbulent flow of extinguishant with ambient air to produce a foam or mist extinguishant.

In accordance with yet another aspect invention, a method is provided for mixing extinguishant from a fire extinguisher with air to produce a foam or mist extinguis- hant wherein the fire extinguisher includes a nozzle. The method comprises the steps of receiving extinguishant from the fire extinguisher via an inlet port of the nozzle, deflecting the extinguishant away from an axis of the nozzle and then redirecting the extinguishant again along the axis of the nozzle to produce a turbulent flow of extinguishant, and routing the turbulent flow of extinguishant to the outlet port to mix the turbulent flow of extinguishant with ambient air to produce the foam or mist extinguishant.

BFaEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described with reference to an exemplary em- bodiment illustrated in the accompanying figures, in which:

Figure 1 provides a side view of a foam fire extinguisher of the invention;

Figure 2 provides a perspective view of a nozzle for use with the fire extin- guisher of Figure 1;

Figure 3 provides a side cross-sectional view of the nozzle of Figure 2; and

Figure 4 provides a perspective view of a flow deflector of the nozzle of Figure 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, for the purposes of explanation and not limitation, spe- cific details are set forth to provide a thorough understanding of the invention. It will be apparent to one skilled in the art that the invention may be practiced in other embodiments that depart from these specific details. In particular, while an embodiment is described involving a foam fire extinguisher of small capacity, principles of the invention may be advantageously employed within other fire extinguishers, such as extinguishers producing an extinguishant mist (e.g., a water mist).

Figure 1 illustrates an exemplary foam fire extinguisher 100 having a reservoir such as a cylinder or tank 102 containing extinguishant incorporating a foaming agent. Preferably, the tank 102 holds between two and four litres of extinguishant under pressure. A manually operated trigger mechanism 104 releases the extinguishant through a nozzle 106. In use, the fire extinguisher 100 is manually held in the vicinity of a fire to be extinguished with the nozzle 106 pointed toward the base of the fire. The trigger mechanism 104 is activated causing extinguishant to be expelled through the nozzle 106. As will be more fully described below, as the extinguishant passes through the nozzle 106 it mixes with ambient air within an outlet port of the nozzle 106 to convert the extinguishant into foam. The combination of the pressure in the tank 102 as well as the expansion of the extinguishant as it is converted into foam

causes the extinguishant to be expelled at high velocity from the nozzle 106, thus allowing the operator of the extinguisher 100 to stand safely back from the fire.

Figure 2 provides a perspective view of nozzle 106, particularly illustrating an outlet port 108 from which the extinguishant is expelled. An outside perimeter 110 of the nozzle 106 includes no openings or apertures for intake of air. As will be explained, the unique internal design of the nozzle 106 ensures adequate mixing of extinguishant and ambient air without the need for any air intake ports. Although the nozzle 106 can be made of any of a variety of sizes, in one example, it is about 20 to 40 millimetres (mm) in length.

The internal design of nozzle 106 is illustrated in Figure 3. The nozzle 106 includes an inlet port 112 for receiving extinguishant under pressure from the tank 102 of the fire extinguisher via the trigger mechanism 104 (Figure 1). The flow of extinguishant received through the inlet port 112 typically has a substantially laminar flow, i.e. there is little or no turbulence. However, such is not required, and the input flow of extinguishant may instead be non-laminar. Once inside of nozzle 106, the extinguishant flows through a turbulence-generating channel (or conduit) 114, which is configured to impart turbulence to the flow of extinguishant to produce a highly turbulent flow so that, once the extinguishant reaches outlet port 108, it has a high degree of turbulence ensuring adequate mixing of the extinguishant with ambient air within the outlet port 108. As the extinguishant mixes with ambient air inside the outlet port 108, the extinguishant expands rapidly. As already noted, the combination of the pressure of the extinguishant and the expansion thereof as it is converted to foam serves to propel the extinguishant from the outlet port 108 at high velocity.

Now considering the turbulence-generating channel 114 in greater detail, the channel is configured to first deflect the extinguishant away from a central axis 116 of the nozzle 106 and then to redirect the extinguishant again along the axis of the nozzle 106 for ejection via outlet port 108. By first deflecting the extinguishant away from the axis of the nozzle 106, before redirecting it back along the axis, is believed that a greater degree of turbulence can be imparted to the extinguishant than with predecessor nozzles. To achieve this result, channel 114 is formed within a perimeter containment structure 118, which seals extinguishant from ambient air as the extinguishant passes through the channel 114. A multi-direction flow deflector 120 is mounted inside the perimeter containment structure 118.

Containment structure 118 and flow deflector 120 provide several deflection surfaces and flow-reversal chambers, which collectively enhance of the amount of turbulence imparted to the flow of extinguishant. More specifically, a rear or downstream portion of flow deflector 120 provides a deflection surface 122 (also referred to herein as the first deflection surface), which is positioned substantially perpendicular to axis 116 of the nozzle 106 to deflect the extinguishant away from the axis at substantially right angles. (Herein, "downstream" refers to the direction along axis 116 from the outlet port 108 toward the inlet port 112. "Upstream" refers to the direction along the axis 116 from the inlet port 112 toward the outlet port 108.) A pair of opposing collection channels 124 and 126 collect two separate flows of the extinguishant and redirect the separate flows back toward axis 116. Collection channels 124 and 126 are each oriented substantially perpendicular to the axis of the nozzle 106, and are pointed toward one another, such that the two separate flows of extinguishant collide with one another, thereby imparting still further turbulence to the overall flow of extin- guishant.

Although only two collection channels 124 and 126 are illustrated, in other implementations, more or fewer collection channels may be employed. For example, rather than having only a pair of diametrically opposite collection channels, three collection channels may be provided, oriented 120° relative to one another. In any case, following the collision of the diametrically opposing flows emanating from channels 124 and 126, a portion of the extinguishant travels rearward along the axis of the nozzle 106 and strikes against a deflection surface 126 (also referred to herein as the second deflection surface), which faces the outlet port 108 and is positioned substantially perpendicular to the axis of the nozzle 106 to thereby deflect extinguishant back along the axis of the nozzle 106 toward outlet port 108.

Thus, the combination of first deflection surface 122, opposing collection channels 124 and 126, and second deflection surface 126 serves to initially deflect extinguis- hant away from the axis of the nozzle 106 and then redirect the extinguishant again along the axis of the nozzle 106, as already summarized. This ensures at least several sharp deflections to provide turbulence. Additional surfaces and structures within the nozzle are provided to further enhance the turbulence. For example, a portion 128 of the outside surface of flow deflector 120 and a portion 130 of the inside sur- face of containment structure 118 together form a first flow-reversal chamber 132, which is positioned generally upstream from inlet apertures of collection channels 124 and 126. After the extinguishant is a deflected away from the axis of the nozzle

106 by deflecting surface 122, a portion of the extinguishant travels past the inlet apertures of the collection channels 124 or 126 and passes into flow-reversal chamber 132 where it eventually reverses direction before being drawn into the collection channels. This reversal imparts still further turbulence to the overall flow of extin- guishant.

Note that nozzle 106 is a substantially axially symmetric (with the exception of the collection channels 124 and 126) and so flow-reversal chamber 132 actually has a generally toroidal shape, i.e. it extends around the circumference of flow deflector 120. Flow deflector 120 is separately illustrated in Figure 4, which shows the generally axially symmetric configuration of the flow deflector 120 while also illustrating the inlet aperture of collection channel 124. Although not shown in Figure 4, an inlet aperture of collection channel 126 is diametrically opposite that of channel 124.

Returning to Figure 3, a second flow-reversal chamber 134 is illustrated, which is downstream from the outlet apertures of collection channels 124 and 126. The aforementioned second deflecting surface 126 forms the rearward or downstream wall of flow-reversal chamber 134. After extinguishant emerges from the collection channels 124 and 126, a portion of the extinguishant flows rearwardly into the sec- ond flow-reversal chamber 134, where it strikes the second deflection surface 126, then reverses direction before being ejected through outlet port 108. This imparts still more turbulence to the overall flow of extinguishant.

Hence, once the extinguishant enters outlet port 108, it is highly turbulent. The out- let port 108 is configured to permit the turbulent flow of extinguishant received from the turbulence-generating channel 114 to mix with air within at least a portion of an interior of the outlet port 108 so as to produce foam. That is, ambient air is drawn into the outlet port 108 due to the turbulence of the extinguishant, where the air mixes with extinguishant to produce expanding foam, which is propelled out of the outlet port 108 at high velocity. Preferably, the outlet port 108 has a substantially conical structure with an internal diameter increasing in the downstream direction. In one example, an internal angle of the outlet port 108 is 6° to 20° and preferably about 12°.

In the illustrations, flow deflector 120 is shown as a single integral structure, which is fitted inside containment structure 118, and held in place by a mounting cap 136, with a washer 138 interposed between an outer perimeter of the flow deflector 120

and an upstream end of the containment structure 118. However, the entire nozzle 106 can instead be configured as a single integral structure, or may be subdivided into a greater number of sub-components. As can be appreciated by those skilled in the art, the particular choice may depend upon the capabilities of the equipment used to manufacture the components of the nozzle 106. A variety of materials may be used to fabricate the nozzle 106. Preferably, the nozzle 106 is fabricated using highly durable materials, such as durable plastics or metals, which are sufficiently durable to contain the high-pressure, high velocity, and highly turbulent flows of extinguishant. If a metal is used, a metal should be chosen which does not corrode in the presence of the extinguishant.

Although the invention has been described primarily with reference to the configuration and structure of the nozzle, the invention also provides a method for mixing extinguishant from a fire extinguisher with air to produce a foam or mist extinguis- hant. Briefly, in accordance with the method, extinguishant is received from the fire extinguisher via an inlet port of a nozzle. The extinguishant is then deflected away from the axis of the nozzle and then redirected along the axis of the nozzle to produce a turbulent flow of extinguishant. The turbulent flow of extinguishant is then routed to an outlet port of the nozzle to mix the turbulent flow of extinguishant with ambient air to produce the foam or mist extinguishant

The nozzle described above may advantageously be used in combination with extinguishers that produce a foam extinguishant as well as with extinguishers that produce a mist extinguishant. Accordingly, one and the same extinguisher may be filled with either an extinguishant type that is capable of producing a foam or an extinguishant type that is capable of producing a mist.

Moreover, while the invention has been described with respect to particular embodiments, those skilled in the art will recognize that the invention is not limited to the specific embodiments described and illustrated herein. Therefore, while the invention has been described in relation to exemplary embodiments, it is to be understood that this disclosure is only illustrative. Accordingly, it is intended that the invention be limited only by the scope of the claims appended hereto.