Patent Application
20080149352
1. Field of the Invention
The present invention relates generally to the suppression of fires and, more particularly, to methods and apparatus for suppressing fires including the suppression of fires within human-occupied spaces and clean room-type environments.
2. State of the Art
Fire suppression systems may be employed in various situations and locations in an effort to quickly extinguish the undesirable outbreak of a fire and thereby prevent, or at least minimize, the damage caused by such a fire including damage to a building, various types of equipment, as well as injury or loss of human life. A conventional fire suppression system or apparatus may conventionally include a distribution apparatus, such as one or more nozzles, that deploys a fire-suppressing substance upon actuation of the system. Actuation of the system may be accomplished through means of a fire or smoke detection apparatus that is operatively coupled to the suppression system, through the triggering of a fire alarm, or trough manual deployment. Various types of fire-suppressing substances or compositions may be utilized depending, for example, on where the fire suppression system or apparatus is being employed, how large of an area is to he serviced by the fire suppression system, and what type of fire is expected to be encountered and suppressed by the system.
For example, in some commercial and even residential fire suppression systems, a network of sprinklers is employed throughout the associated building and configured to distribute water or some other fire-suppressing liquid to specified locations within the building upon activation of the system.
However, a system providing a liquid fire suppressant is not suited for all situations. For example, it would not be generally desirable to employ a fire suppression system utilizing water as the suppressant in a location where grease would likely serve as fuel for an ignited fire at the given location. Similarly, it would not be generally desirable to utilize a liquid suppressant in a location that contained electrical equipment including, for example, costly and sensitive electronic or computer equipment. While a liquid suppressant might adequately suppress a fire in such a location, the suppressant would likely impose substantial damage to the equipment housed therein. Further, a liquid suppressant is not ideally suited for use in a clean room environment where the introduction of a liquid material to the clean room would result in contamination of some article of manufacture (e.g., an integrated circuit device).
Other available suppressants include dry chemical suppressants such as, for example, sodium bicarbonate, potassium bicarbonate, ammonium phosphate, and potassium chloride. While such suppressants can be effective in specific implementations, it is often difficult to implement systems that effectively utilize dry chemicals in large areas. Furthermore, use of dry chemicals can pose a health hazard to individuals in the vicinity of their deployment, as well as act as a source of contamination of electronic and computer equipment or even goods being manufactured, for example, in a clean room. Thus, such suppression systems are not conventionally utilized in locations such as clean rooms, computer rooms or spaces designed for human occupation.
Another type of suppressant that has been used includes gas suppressants. For example, gases designated generally as Halons have been effectively used as fire suppressants in the past. Halons include a class of brominated fluorocarbons derived from saturated hydrocarbons wherein the hydrogen atoms are essentially replaced with atoms of the halogen elements bromine, chlorine and/or fluorine. Halons, including the widely used varieties designated as Halon 1211, 1301 and 2402, have been used for the effective suppression of fires in various environments and situations including human-occupied and clean room-type environments. However, in recent years, an effort to phase out Halons has been undertaken due to their ozone depletion characteristics. Indeed, in the year 1994, production ceased of certain Halons, while others are scheduled to be phased out by the year 2010.
Some of the gases that have been used in an attempt to replace the effective Halon gases include, for example, nitrogen and carbon dioxides. Such gases essentially displace the oxygen contained within he air at the location of the fire such that an insufficient amount of oxygen is available for further combustion. However, such gases generally require the distribution of relatively large volumes of the selected gas in order to be effective as a fire suppressant. In order to accommodate such large volumes of gas, expensive and bulky pressure vessels are conventionally required to store the gas in a compressed state in anticipation of its use. Furthermore, such gases sometimes include or produce byproducts that may be harmful to any equipment or individuals located in the area into which the gas suppressant is distributed.
Additionally, as noted above, the requirements of storing gas, conventionally at high pressures and in large volumes, often make such systems expensive and cumbersome in size in that the systems require a significant amount of space available for installation and operation. In order to address some of the concerns listed above, including the ability to provide adequate volumes of suppressant while requiring relatively small storage facilities, various attempts have been made to develop alternative fire suppression systems.
Some of the approaches to provide alternative fire suppression systems include those disclosed by U.S. Pat. No. 6,257,341 to Bennett, U.S. Pat. No. 5,609,210 to Galbraith et al., and U.S. Pat. No. 6,401,487 to Kotliar. The Bennett Patent generally discloses a system that utilizes a combination of compressed inert gas and a solid propellant gas generator. Upon ignition, the solid propellant gas generator generates nitrogen, carbon dioxide, or a mixture thereof. The gas generated from the solid propellant is then mixed and blended with the stored compressed inert gas, which may include argon, carbon dioxide or a mixture thereof, to provide a resulting blended gas mixture for use as a suppressant. The Bennett system claims to provide a system that is smaller in size than prior art systems and, therefore, is more flexible in its installation in various environments. However, due to the fact that the Bennett system utilizes compressed inert gas, appropriate pressure vessels are required that, as discussed above, are conventionally expensive and require a substantial amount of space for their installation, particularly if a large room or area is being serviced by the described system, therefore requiring a large volume of suppressant.
The above-referenced Galbraith patent generally discloses, in one embodiment, a system that includes a gas generator charged with a combustive propellant wherein the propellant, upon ignition, generates a volume of gas. The generated gas is directed to a chamber containing a volume of packed powder such as magnesium carbonate. The gas drives the powder from the chamber for distribution of the powder onto a fire. In another embodiment, Galbraith discloses a system wherein the generated gas is used to vaporize a liquid, thereby generating a second gas, wherein the second gas is used as the fire suppressant. However, the use of powders, as noted above, is not desirable in, for example, areas that are intended for regular human occupancy, areas intended to house sensitive electronic equipment, or other clean room-type environments. The use of vaporizable liquids may introduce additional issues regarding long-term storage of the liquid including the prevention of possible corrosion of the associated storage container.
The above-referenced Kotliar patent generally discloses a system that includes a hypoxic generator configured to lower the oxygen content of the air contained within a room or other generally enclosed space to a level of approximately 12% to 17% oxygen. One of the embodiments disclosed by Kotliar includes a compressor having an inlet configured to receive a volume of ambient air from the room or enclosure. The compressed air is passed through a chiller or cooler and then through one or more molecular sieve beds. The molecular sieve bed may include a material containing zeolites that allows oxygen to pass through while adsorbing other gases. The oxygen that passes through the molecular sieve bed is discharged to a location external from the room or enclosure being protected. The molecular sieve bed is then depressurized such that the gases captured thereby are released back into the room as an oxygen-depleted gas.
While Kotliar discloses that the system may be used as a fire suppressant system, it is not apparent how efficient the system is in rapidly reducing the oxygen level for a given room so as to suppress any fire therein. Moreover, it appears that the Kotliar system is contemplated as being more effective as a fire prevention system wherein the hypoxic generator is continuously running such that the air within a room or other enclosure is continuously maintained at an oxygen-depleted level in order to prevent ignition and combustion of a fuel source in the first place. However, such an operation obviously requires the constant operation of a hypoxic generator and, thus, likely requires additional upkeep and maintenance of the system. Furthermore, while Kotliar asserts that there are no associated health risks to those who spend an extended amount of time in a hypoxic environment (i.e., an oxygen reduced or depleted environment), such a system may not be ideal for those with existing health conditions, including for example, respiratory ailments such as asthma or bronchitis or cardiovascular conditions, or for individuals who are elderly or who generally lead an inactive lifestyle.
In view of the shortcomings in the art, it would be advantageous to provide a method, apparatus and system for suppressing fires that provide effective and efficient suppression of a fire within a given location while utilizing a suppressant that is not ozone-depleting yet is fit for use in rooms that are intended for human occupation or that house sensitive components and equipment. It would further be advantageous to provide such a method, apparatus and system that may be adapted for use in numerous locations and in a variety of applications without the need to utilize bulky and expensive storage equipment such as that associated with the storage of compressed gas or other liquid suppressants.
In accordance with one aspect of the invention, a fire suppression apparatus is provided. The apparatus includes a housing defining a first opening therein, a second opening therein and a flow path providing fluid communication between the first opening and the second opening. The apparatus further includes a gas-generating device located and configured to provide a flow of a gas into the flow path such that the flow of the gas draws a volume of ambient air from a location outside the housing, through the first opening and into the flow path.
In accordance with another aspect of the present invention, another fire suppression apparatus is provided. The fire suppression apparatus includes a housing defining a first opening therein, a second opening therein and a flow path providing fluid communication between the first opening and the second opening. A gas-generating device having a solid propellant composition disposed therein is configured such that, upon combustion of the solid propellant, a first gas is produced, which may be introduced into the flow path. An igniting device is configured to ignite the solid propellant composition for production of the gas. A nozzle is coupled with the gas-generating device and is located and configured such that the first gas flows through the nozzle into the flow path and also draws a volume of ambient air from a location external to the housing through the first opening and into the flow path. A filter is disposed between the solid propellant composition and the nozzle. A diffuser is disposed within the flow path located and configured to alter a velocity of the first gas and to also effect mixing of the first gas with the volume of ambient air drawn into the flow path and thereby form a gas mixture. At least one conditioning apparatus is disposed within the flow path for conditioning the first gas, the volume of ambient air, or the resulting mixture thereof.
In accordance with yet another aspect of the present invention, a fire suppression system is provided. The fire suppression system includes at least one fire suppression apparatus including, for example, a fire suppression apparatus as provided in accordance with one of the aspects of the present invention. The fire suppression system further includes a controller configured to generate a signal and transmit the signal to the at least one fire suppression apparatus upon the occurrence of a specified event, wherein the at least one fire suppression apparatus is actuated upon receipt of the signal.
In accordance with a further aspect of the present invention, a method is provided for suppressing fires. The method includes providing a housing with a first opening and a second opening. A flow path is defined between the first opening and the second opening. A fire-suppressing gas is produced and introduced into the flow path. A volume of ambient air is aspirated from a location external of the housing through the first opening and into the flow path. Such aspiration may be accomplished by controlling the introduction of the fire-suppressing gas into the flow path including, for example, the location of introduction within the flow path and the velocity of the gas as it is introduced into the flow path. The volume of ambient air is mixed with the fire-suppressing gas to produce a gas mixture and the gas mixture is discharged through the second opening.
The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
Referring to
A gas-generating device 110 may be disposed at one end of the housing 102 and may contain a propellant 114, such as a solid propellant that is configured to generate a desired gas upon ignition and combustion thereof as described in further detail below. The gas-generating device 110 may be coupled to a nozzle 116 for dispersion of any gas flowing out of the gas-generating device 110. As will be appreciated by those of ordinary skill in the art, through proper configuration of the nozzle 116, the pressure and/or velocity of the gas exiting the gas-generating device 110 via the nozzle 116 may be controlled with considerable accuracy.
The nozzle 116 may be configured to discharge any generated gas into a diffuser 118 or other flow control device positioned within the flow path 108 and to promote an expansion of the discharged gas, thereby reducing the velocity and temperature of the gas. Furthermore, as will be further discussed below, the diffuser 118 may be configured to promote the mixing of gas discharged from the nozzle 116 with a volume of ambient air flowing through the first set of openings 104 into the flow path 108.
Downstream from the first set of openings 104 within the Sow path 108 is an oxygen-getting device 120 configured to remove oxygen from any air flowing through the first set of openings 104 and through the associated flow path 108. The oxygen-getting device 120 may be formed of an oxygen reactive material such as, for example, steel, copper, zirconium, iron, nickel or titanium. The material may be configured as, for example, wool, cloth, mesh or shot so that the material may be packed or otherwise distributed within the flow path 108 while also enabling gas to travel therethrough. As shown in
Other processing or conditioning devices may be placed in the flow path 108 and located downstream of the first oxygen-getting device 120. For example, a second oxygen-getting device 123 may be used to further reduce the level of oxygen from any air flowing through the flow path 108 depending on, for example, the efficiency of the first oxygen-getting device 120 and the desired oxygen content of any gas leaving the flow path 108 through the second set of openings 106. Additionally, an NOx scavenging device 124 may be utilized to remove nitric oxide from gases flowing through the flow path 108, which may be present, for example, depending on the composition of the solid propellant 114 and the gas produced thereby. Alternatively, or additionally, a NH3 scavenging device may be used to remove ammonia from gases flowing through the flow path 108.
A heat transfer device 126 may also be located within the flow path 108 and configured to lower the temperature of any gas flowing therethrough prior to the gas exiting the second set of openings 106. The heat transfer device 126 may exhibit a relatively simple configuration including, for example, thermally conductive fins, tubes or shot, configured to allow gas to flow therethrough (or thereover) and transfer heat away from the gas. In another embodiment, the heat transfer device 126 may exhibit a more complex configuration including, for example, a phase change material or a mechanical heat exchanger employing a circulating fluid medium to transfer heat away from any gas flowing through the flow path 108.
Referring now briefly to
Depending on the specific composition being utilized, the igniting composition 134 may be configured to produce a hot gas upon ignition thereof wherein the hot gas provides sufficient heat for the subsequent ignition and combustion of the propellant 114. In another embodiment, the igniting composition 134 may be configured to produce a molten material, such as a metal slag, that is sufficiently hot to ignite and initiate combustion of the propellant 114.
Exemplary igniting compositions 134 may include those disclosed in U.S. Pat. No. 6,086,693, the disclosure of which patent is incorporated by reference herein. It is noted, however, that various igniting compositions may be utilized in the present invention depending, for example, on the composition of the propellant 114, the type of ignition device 132 being employed and the resulting gases that are desired to be produced (or eliminated) during operation of the gas-generating device 110.
Upon ignition of the propellant 114 a gas is generated that, in one embodiment, may include an inert gas suitable for introduction into a human-occupied space or for an environment that houses sensitive electronic equipment. For example, in one embodiment, the propellant 114 may include a composition that is configured to produce nitrogen gas, such as N2, upon combustion thereof. In another embodiment, the propellant 114 may include a composition that is configured to produce H2O (water vapor), CO2 (carbon dioxide) gases or various mixtures of such exemplary gases upon the combustion thereof. Various propellant compositions are contemplated as being used with the present invention. However, depending on various factors such as the intended normal use of the environment being protected by the fire suppression apparatus 100, it may be desirable to utilize a composition that produces a gas (or gas mixture) that is free of ozone-depleting gases (e.g., halogenated fluorocarbons) and/or global warming gases (e.g., carbon dioxide) while still being effective at lowering the oxygen content of air contained within a generally enclosed space.
In one embodiment, an exemplary propellant composition may include a HACN composition, such as disclosed in U.S. Pat. Nos. 5,439,537 and 6,039,820, both to Hinshaw et al., the disclosure of each of which patents is incorporated by reference herein. Of course other compositions may be utilized. In one embodiment, a propellant composition may be configured to produce an inert gas including nitrogen and water vapor.
In one example, it may be desirable to produce approximately 1.5 kilograms (kg) to approximately 300 kg of nitrogen gas from the propellant 114 contained within the gas-generating device 110. In producing such a mass of nitrogen, it may be desirable to produce less than 1% of carbon dioxide by volume with negligible amounts of carbon monoxide. Furthermore, it may be desirable to produce a gas that is substantially residue free so as to not leave a film or coating of residue on any equipment, furniture, etc., that may be located within the environment being protected by the apparatus.
The gas-generating device 110 may further include a filter 136 such as, for example, a screen mesh or an amount of steel shot disposed within the housing 130. The filter 136 may be used to prevent slag or molten material produced during combustion of the propellant 114 from leaving the housing 130. The prevention of slag or other solids from leaving the gas-generating device 110 may be desirable to prevent the blocking or clogging of the nozzle 116, to prevent damage to other components located within the flow path 108 (
Referring to both
The ignition and subsequent combustion of the propellant 114 results in the generation of a gas that flows through the nozzle 116 of the gas-generating device 110 as indicated by directional arrow 140. The nozzle 116 is configured to substantially control the flow of the generated gas including the velocity of the gas exiting the nozzle 116 as it enters into the flow path 108. In one embodiment, the nozzle 116 is configured such that gas exits the nozzle 116 at sonic or supersonic velocities. The high-velocity gas flow exiting the nozzle 116, combined with the geometric area ratios and the location of the nozzle 116 within the flow path 108 relative to the first set of openings 104, causes ambient air (i.e., air external to the fire suppression apparatus 100) to be drawn in through the first set of openings 104. In other words, the high-velocity production of gas effects an aspiration or eduction of ambient air located outside the fire suppression apparatus 100 through the first set of openings 104 and into the flow path 108 as indicated at 108A.
The ambient air drawn into the flow path 108 passes through the oxygen-getting device 120 that, through a chemical reaction, reduces the level of oxygen within the ambient air flowing therethrough. For example, the oxygen-getting device 120 may be at least partially formed of a material comprising iron that may adsorb approximately 0.4 pounds of oxygen per pound of material (lbs. oxygen/lb. mat'l). The iron material will react with the ambient air flowing through the oxygen-getting device 120 to reduce the oxygen content thereof and produce Fe3O4 within the oxygen-getting device 120. In another exemplary embodiment, the oxygen-getting device 120 may be at least partially formed of a material comprising copper that may adsorb approximately 0.25 lbs. oxygen/lb. mat'l. The reaction of the ambient air with the copper will result in the production of CuO within the oxygen-getting device 120.
In a further exemplary embodiment, the oxygen-getting device 120 may be at least partially formed of a material comprising nickel that may adsorb approximately 0.27 lbs. oxygen/lb. mat'l. The reaction of the ambient air with the nickel will result in the production of NiO within the oxygen-getting device 120. In yet another exemplary embodiment, the oxygen-getting device 120 may be at least partially formed of a material comprising titanium that may adsorb approximately 0.67 lbs. oxygen/lb. mat'l. The reaction of the ambient air with the titanium will result in the production of TiO2 within the oxygen-getting device 120. Another exemplary material that may be used in the oxygen-getting device includes zirconium that may adsorb approximately 0.175 lbs. oxygen/lb. mat'l. It is noted, however, that the above materials are exemplary and that other materials may be used as well as other means and methods of extracting oxygen as will be appreciated by those of ordinary skill in the art.
As noted above, heat associated with the combustion of the propellant 114 may be transferred to the oxygen-getting device 120. For example, it is estimated that temperatures within the gas-generating device 110 may rise to between approximately 2500° F. and approximately 3500° F. in some embodiments. The transfer of heat away from the gas-generating device 110 provides the benefit of reducing potentially dangerous levels of heat and the dispersement of such heat over a larger area for effective cooling of the gas-generating device 110. Additionally, the transfer of heat to the oxygen-getting device 120 will also enhance the process of removing oxygen from any aspirated air passing therethrough by expediting the chemical reaction that takes place between the ambient air and the material disposed within the oxygen-getting device 120.
Referring briefly to
Referring briefly to
Referring now briefly to
Considering the graphs 200, 214 and 220 together as shown in
For example, after a material has been selected for use in the oxygen-getting device 120 based on information such as shown in
Referring more particularly to
The gas mixture then exits the second set of openings 106, as indicated at 108D, at a reduced velocity. In some embodiments, it may be desirable to reduce the velocity of the gas mixture such that it exits the second set of openings 106 at a subsonic velocity. Additional components may be utilized within the flow path 108 to control the velocity of the gas mixture. For example, as shown in
As the gas mixture exits the second set of openings 106, the gas mixture contains a volume of inert gas, such as nitrogen, configured to displace the oxygen contained with the air of a substantially enclosed environment. The gas mixture also includes an amount of oxygen-depleted air, which was initially drawn from the substantially enclosed environment, such that the overall level of oxygen available to support combustion is substantially reduced and, desirably, prevents further combustion of any fire that may be occurring within the environment serviced by the fire suppression apparatus 100.
Referring now to
One or more of the fire suppression apparatuses 100 may be strategically located within the environment 150 to draw in air from the environment 150 and distribute a gas mixture, such as described hereinabove, back to he environment 150. The number of the fire suppression apparatuses 100 utilized and their specific location within the environment 150 may depend, for example, on the size of the environment 150 (e.g., the volume of air contained thereby), the intended use of the environment 150 (e.g., human-occupied, clean room, etc.), and/or the type of fire expected to be encountered with in the environment 150.
The fire suppression system 152 may include one or more sensors 154 such as, for example, smoke sensors, heat sensors, or sensors that are configured to detect the presence of a particular type of gas. The system 152 may also include one or more actuators 156 that may be manually triggered by an occupant of the environment 150 upon the occurrence of a fire. The sensors 154 and actuators 156 may be operably coupled with a control unit 158 that may include, for example, a dedicated control unit or a computer programmed to receive input from or otherwise monitor the status of the sensors 154 and actuators 156 and, upon the occurrence of a predetermined event, actuate the gas-generating device 110 (
Thus, for example, upon the detection of smoke by a sensor 154, or upon the manual triggering of one of the actuators 156, an appropriate signal may be relayed to the control unit 158. The control unit 158 may then generate an appropriate signal that is relayed to the fire suppression apparatuses 100, thereby igniting the ignition device 132 (
Referring now to
Various processing devices may be placed in the flow path 108′ including, for example, oxygen-getting devices. NOX scavengers, filters ad/or heat transfer devices such as described above. Additionally, various flow control devices, such as diffusers, baffles or redirected flow paths, may be incorporated into the fire suppression apparatus 100′ to control the flow of the gas mixture that ultimately exits the second opening 106′.
The structure 170 into which the fire suppression apparatus 100′ is integrated may include a room of a building or the cabin of a land, sea or air vehicle such as, for example, an automobile, a train car, a plane or some other vehicle. For example, the structure 170 may include an automobile and the wall or panel 172 may include a portion of the dashboard or a side panel associated with a door. Thus, the fire suppression apparatus 100′ may be located in various strategic locations in numerous types of environments.
Referring briefly to
Thus, in operation, a user may be able to deploy the actuator 180, dispose of the fire suppression apparatus 100″ in an identified environment (e.g., in a room of a building, the cabin of an automobile or other vehicle etc.) and, if necessary, remove themselves from the fire suppression apparatus 100″ to a remote location prior to the ignition and operation thereof.
While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
This application is a continuation of application Ser. No. 10/727,093 filed Dec. 2, 2003, which will issue as U.S. Pat. No. 7,337,856 on Mar. 4, 2008, which application is also related to copending U.S. patent application Ser. No. 10/727,088 entitled MAN-RATED FIRE SUPPRESSION SYSTEM, also filed on Dec. 2, 2003, pending, and assigned to the Assignee of the present application, the disclosures of which are each incorporated by reference herein in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10727093 | Dec 2003 | US |
| Child | 12042200 | US |
