Foam fire nozzle

A foam nozzle for fighting fires is disclosed. The nozzle has an over-all conical shape, with a plurality of air holes and a plurality of agitation screens. The nozzle is simply slipped over the end of the traditional non-foam nozzle and held in place with a thumb screw or similar device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention. 
This invention relates generally to the field of fire fighting equipment 
and, specifically, to nozzles for spraying foam. 
2. Description of Related Art. 
From time immemorial, mankind has used water to extinguish fires. In modern 
firefighting units, water still plays a central role in putting out fires. 
With certain types of fires, however, modern firefighters have found it 
advantageous to add foaming agents to the water. The addition of foaming 
agents allows firefighters to apply a thick layer of watery foam to a 
fire, cooling the fire and robbing it of the oxygen which is essential to 
combustion. 
Arguably, the most important component of a foam application system is the 
foam nozzle which is attached to the terminal end of a water hose. The 
foam nozzle performs two critical functions. First, the nozzle mixes the 
water/foaming agent combination with air. Second, the nozzle agitates the 
air, water and foaming agent to produce foam. The prior art foam nozzles, 
while filling a critical need, have been subjected to criticism from 
firefighters on a number of grounds. The prior art nozzles tend to be 
expensive. The prior art nozzles tend to be difficult to use: often, the 
prior art nozzles require that the non-foam nozzle be removed from the 
hose and replaced with the foam nozzle. Most importantly, however, the 
fire fighting community has long felt that the prior art nozzles simply 
did not do a good enough job of producing foam. 
For the foregoing reasons there has been a need for a foam nozzle which was 
inexpensive, could be quickly and simply attached to the existing nonfoam 
nozzle, and did a better job of making foam than the prior art nozzle. 
SUMMARY OF THE INVENTION 
A foam nozzle satisfying the foregoing needs is disclosed. The nozzle has 
an over-all conical shape, with a plurality of air holes and a plurality 
of agitation screens. The nozzle is simply slipped over the end of the 
traditional non-foam nozzle and held in place with a thumb screw or 
similar device. 
It is an object of the invention to provide a foam nozzle which is simple 
to manufacture. 
It is a further object of the invention to provide a foam nozzle which is 
inexpensive. 
It is a further object of the invention to provide a foam nozzle which is 
simple to use. 
It is a further object of the invention to provide a foam nozzle which can 
be used with the traditional non-foam nozzle. 
It is a further object of the invention to provide a foam nozzle which does 
a superior job of producing foam as compared to the prior art. 
Further objects of the invention will appear as the description proceeds.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Looking at FIG. 1, we see a side elevation of the nozzle. The nozzle is 
most inexpensively molded from a hard plastic such as ABS plastic, 
although it is certainly possible to build the nozzle out other materials, 
such as polymer, graphite, fiberglass, or a metal such as aluminum. 
Although the invention has an over-all conical shape, there are actually 
two straight, cylindrical sections connected by an angled, cylindrical 
section. Specifically, the nozzle has a forward section, 10, an angled 
middle section, 20, with a plurality of air holes which are a means for 
allowing air to enter the nozzle and be mixed with water and a foaming 
agent, 40, and a back section, 30, with a thumb screw, 50, which is 
threaded through the back section, 30. In this view we can also see a 
portion of the front of a double screen, 60. This figure also shows, in 
dotted lines, a standard non-foam nozzle in order to demonstrate the 
environment of the present invention. It is anticipated that a firefighter 
will slip the back section, 30, of the nozzle over a standard non-foam 
nozzle, and tighten the thumb-screw, 50, to hold the nozzle in place. The 
thumb screw, 50, is simply one particularly simple and inexpensive way to 
accomplish this holding task. It would certainly be possible to replace 
the thumb screw with other holding hardware without departing from the 
spirit of the present invention. 
Looking at FIG. 2, we see a front elevation of the nozzle showing the front 
section, 10, the front of the double screen, 60, and a retaining ring, 70, 
which holds the screen, 60, inside the front section, 10. 
In FIG. 3 we see a rear elevation of the nozzle, showing the middle 
section, 20, with its plurality of air holes, 40, and the back section, 
30, with its thumb-screw, 50. This figure shows a lip, 80, inside the back 
section, 30, for receiving the standard, non-foam nozzle. 
FIG. 4 is a sectional view of the nozzle showing the front section, 10, the 
middle section, 20, with air holes, 40, the back section, 30, with its 
thumbscrew, 50, and the front of the double screen, 60. The rear of the 
double screen, 61, is also visible. From experimentation, it has been 
found that the best results in foam production can be achieved by having 
the double screens, 60 and 61, rotated approximately ninety degrees with 
respect to each other so that the wires of one screen pass over the holes 
in the other screen, thus increasing the agitation provided by the 
screens. This figure also shows how the retaining ring, 70, fits inside 
the front section, 10, and holds both the front, double screen, 60, and 
61, against a spacer, 71, a rear screen, 90, and a rear retaining ring, 72 
, inside the front section, 10. The retaining rings, 70, 72, and spacer, 
71, can be held in place inexpensively by using an adhesive, although it 
is also possible to hold them in place with removable means such as 
screws. The screens, 60, 61, and 90, are preferably made of a corrosion 
resistant metal, such as stainless steel, with a concave shape being 
desirable. This figure also shows in greater detail the lip, 80, in the 
back section, 30, which receives the standard, non-foam nozzle. Without 
limiting the invention to any particular theory, it is believed that this 
nozzle has two features which allow it to do a better job of producing 
foam than the prior art. First, the use of screens, 60, 61, and 90, gives 
a means for producing superior agitation as compared with the prior art. 
Second, the fact that the front section, 10, is significantly larger than 
the back section, 30, facilitates the expansion of the foam inside the 
nozzle. When used with a standard two-inch diameter nonfoam nozzle, the 
present nozzle would have an overall length of approximately four inches, 
and the front section, 10, would have an inner diameter of approximately 
three and seven-eights of an inch. 
Turning to FIG. 5, we see a perspective view of the nozzle, showing the 
front section, 10, with the retainer ring, 70, and front of the double 
screen, 60, as well as the back section, 30, with its thumb-screw, 50. 
Each of the elements described above, or two or more together, may also 
find a useful application in other types of methods differing from the 
type described above. While certain novel features of this invention have 
been shown and described and are pointed out in the annexed claims, it is 
not intended to be limited to the details above, because various 
omissions, modifications, substitutions and changes in the forms and 
details of the device illustrated and in its operation can be made by 
those skilled in the art without departing in any way from the spirit of 
the present invention. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic or specific aspects of this invention.