Fire extinguishers – Portable vessels
Reexamination Certificate
1997-01-24
2001-07-31
Ellis, Christopher P. (Department: 3651)
Fire extinguishers
Portable vessels
C169S043000, C169S009000, C169S013000, C169S014000, C169S030000, C169S071000, C169S085000, C239S152000, C366S336000
Reexamination Certificate
active
06267183
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fire fighting apparatus and, in particular, to apparatus for generating and delivering a fire suppressant foam for use in fire fighting.
PROBLEM
It is a problem in the field of fire fighting to provide a sufficient volume of fire fighting material to suppress a fire. The traditional fire fighting material used for this purpose is water, which has the undesirable side effect of causing a significant amount of water damage to the real property in and around the area in which the fire is engaged. In fact, in many situations the water damage to the real property is significantly in excess of the fire damage to the real property. An alternative fire fighting material in use is fire suppressant foam. However, the difficulty with fire suppressant foam is that the typical materials used for this purpose require complicated mixing and pumping apparatus and still produce a significant amount of water damage due to the relatively high water content of the foam.
In a typical application, the availability of a significant water supply renders water as a fire fighting material the desired choice, since the fire suppressant foam itself requires a significant amount of water. In addition, fire suppressant foam requires complicated generation and delivery apparatus, thereby rendering it impractical for use except in certain selected applications, such as airport fire fighting applications where the use of water is ineffective in controlling the magnitude and extent of a fuel fire. There presently does not exist any apparatus that is effective in fire fighting applications that is simple in architecture and yet causes minimum ancillary damage to real property as a result of the fire suppression activity.
Rural homeowners face additional problems in protecting their property from the danger of wildfires. There is an increasing trend for people to build their homes in locations that are within what is called the wildland/urban interface. This is a term that describes the geographical areas where formerly urban structures, mainly residences, are built in close proximity to flammable fuels naturally found in wildland areas, including forests, prairies, hillsides and valleys. To the resident, the forest represents a beautiful environment but to a fire the forest represents a tremendous source of fuel. Areas that are popular wildland/urban interfaces are the California coastal and mountain areas and the mountainous areas in Colorado (among others).
Residences built in these areas tend to be placed in locations that contain significant quantities of combustible vegetation and the structures themselves have combustible exterior walls and many have untreated wood roofs. Many of these houses are also built on sloping hillsides to obtain scenic views; however, slopes create natural wind flows that increase the spread of a wildfire. These homes are also located a great distance away from fire protection equipment and typically have a limited water supply, such as a residential well with a minimal water flow in the range of one to three gallons per minute. Therefore, residences located in the wildland/urban interface do not have access to an adequate supply of the traditional fire suppressant material—water. Thus, traditional fire fighting technology has severe limitations in terms of its effectiveness and availability in many applications.
SOLUTION
The above described problems are solved and a technical advance achieved in the field by the fire suppressant foam generation and application apparatus of the present invention. This apparatus makes use of a commercially available low moisture content fire suppressant foam mixture in conjunction with novel foam generation and application apparatus to minimize the water damage to real property caused by the fire suppression activity. This apparatus is simple in structure and operation and makes use of a pressurized gas to create the water/foam mixture, propel it through the delivery apparatus and, in one embodiment, power an auxiliary pump to increase the delivery pressure of the fire suppressant materials. This apparatus is lightweight in construction, simple in architecture and can be implemented in a unit that is sufficiently compact to be installed on a lightweight utility vehicle, such as a four-wheel drive pick-up truck or implemented in the form of a backpack unit. This apparatus also does not require a large capacity source of water to create the fire suppressant materials that are applied to the fire since the foam generation apparatus provides a significant expansion to the foam/water concentrate.
In one embodiment, a source of pressurized gas, such as nitrogen, is used to supply the propellant. The nitrogen is applied via a pressure regulator to a supply line that joins with an outlet line from the water/foam mixture supply tank. The pressurized nitrogen supplies a foaming action as the water/foam mixture is driven down the pipe and also forces the resultant foam through the delivery apparatus, such as a conventional fire hose. Interposed in the delivery apparatus between the fixture and the outlet end of the hose is a mixing apparatus, termed “stata tube”, which functions to significantly increase the foam expansion prior to delivery of the foam through the delivery apparatus. The stata tube comprises an exterior housing inside of which is mounted a set of motionless mixing blades that function to mix and expand the foam. The stata tube not only produces a high expansion of the foam but it also produces a more consistent bubble structure which enhances both the longevity and adhesion of the foam when applied to a structure.
An alternative embodiment makes use of a pressurized gas operated pump that can be driven by an auxiliary supply of pressurized gas, such as an air compressor, to supply the water/foam mixture to thereby conserve the pressurized nitrogen for use in the creation of the fire suppressant foam.
The water/foam mixture uses commercially available foaming agents that are expanded by the application of the pressurized gas and the use of the stata tube to create the fire suppressant foam without the need for pressurized water as a propellant. This has multiple benefits, including the reduction in the moisture content of the fire suppressant foam and avoiding the need for complex water pumping apparatus to create the stream of pressurized water. The elimination of water as a delivery agent thereby renders this apparatus independent of a large supply of water that is typically needed for fire fighting purposes. In addition, since water is an incompressible medium, its storage and delivery cannot be improved by pressurization, whereas the use of an inert gas such as nitrogen provides great opportunity for storage efficiency since the gas can be pressurized to extremely high levels, thereby efficiently storing a vast quantity of propellant in a small physical space. Similarly, the use of a pressurized gas powered pumping system to increase the pressure of the delivered water/foam mixture does not unduly complicate the apparatus since pumps of low weight and size are available for this purpose. The resultant apparatus is therefore extremely lightweight, compact in dimensions and inexpensive to implement. Control of the flow of the pressurized gas and water/foam mixture is accomplished by way of simple check valves and pressure regulators, thereby eliminating the complex apparatus presently in use. Use of a water/foam mixture as a fire fighting material is beneficial, since a small quantity of the mixture expands to produce a tremendous volume of fire fighting material. Therefore, a significant volume of fire fighting materials can be created using a small quantity of water/foam mixture and a compact source of pressurized gas. This novel apparatus can therefore be implemented inexpensively in a compact implementation unknown in the prior art.
REFERENCES:
patent: 3255824 (1966-06-01), Rodgers
patent: 3337195 (1967-08-01), Farison
patent: 3342271 (1967-09-01), Anthony, Jr.
patent: 3592269 (1971-07
Duft, Graziano & Forest, P.C.
Ellis Christopher P.
Intelagard, Inc.
Shapiro Jeffery A.
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