Patent Application
20100294518
This invention relates generally to fire suppression systems. More particularly, this invention relates to a fire suppression system providing inert gas flooding fire suppression.
Fire suppression fire systems are often installed in commercial buildings. Typically, those buildings are subdivided into multiple rooms. Commonly, conventional fire suppression systems are designed either as total flooding systems using an inert gas under pressure or localized streaming fire suppression systems using liquid suppressant under pressure. In total flooding systems, an inert gas is rapidly admitted into a room, commonly through a plurality of nozzles mounted in an array in the ceiling of the room, to fill the volume defined within the room. The inert gas may be nitrogen, carbon dioxide, argon, neon, helium or other chemically non-reactive gas, or mixtures of any two or more of these gases. For example, a mixture of 50% argon and 50% nitrogen is commonly used in inert gas fire suppression system. The inert gas not only removes heat from the fire, but also dilutes the oxygen content within the room to a level low enough that combustion can not be sustained. Typically, conventional inert gas systems are sized to reduce the oxygen content in the atmosphere within the environment of the protected area to a level below 12.5 percent within one minute. Consequently, a large number of high-pressure cylinders of inert gas, typically at a pressure between 200 to 300 bars must be provided to store the necessary volume of inert gas. A large centralized storage area must be dedicated for placement of the required inert gas storage cylinders.
Conventional streaming fire suppression systems spray a mist of liquid suppressant over a localized area beneath the spray cone of a distribution nozzle. Commonly, a number of distribution nozzles are arrayed over the space being protected and are supplied with liquid suppressant, for example water or a liquid chemical agent, from a centralized source. Typically, the liquid suppressant is fed under pressure and conveyed through a network of pipes to the various individual distribution nozzles. Generally, the distribution nozzles are designed to emit a mist of liquid suppressant having a droplet size in the range of between 5 and 60 micrometers. The mist may be produced simply by forcing the liquid suppressant through the openings of the nozzle or through atomization means incorporated in the nozzle.
U.S. Patent Application Publication No. US2005/073131A1 discloses a fire and explosion suppression system wherein high pressure water from a central storage tank is suspended in a flow of nitrogen gas or a mixture of nitrogen and argon gases and distributed to an array of a plurality of distribution nozzles and emitted as a mist of water droplets over a localized area. U.S. Patent Application Publication No. 2006/0278410 discloses a fire and explosion system wherein high pressure water from a central storage tank is passed through a network of pipes to a plurality of high velocity low pressure emitters wherein the water is atomized and discharged into a high pressure inert gas stream passing out of the emitter. U.S. Pat. No. 7,153,446, also published as Patent Application Publication No. US2005/0144949A1, discloses a fire and explosion suppression system wherein a liquid chemical agent fire suppressant under pressure from a central storage tank is suspended in a flow of inert gas and is distributed to an array of a plurality of distribution nozzles and emitted as a mist of liquid droplets over a localized area. A number of exemplary liquid chemical agents suitable for use as fire suppressants are also disclosed in U.S. Pat. No. 7,153,446.
A form of fire suppression system using a commercially available liquid chemical fire suppressant is commonly referred to as a clean agent gaseous fire suppression system because the chemical agent leaves no residue upon evaporation. Clean agent fire suppression systems are often installed in rooms or areas of buildings wherein equipment or goods are housed that could be damaged by water, powder or foam. In a system of this type, a chemical fire suppression agent that is stored in a tank or cylinder as a liquid under pressure is pushed by a gaseous propellant, typically nitrogen, argon or carbon dioxide, from a tank or cylinder of propellant arranged in series flow relationship with the tank or cylinder of chemical agent, through a network of pipes to and through a plurality of distribution nozzles arrayed across the ceiling area or walls of the space being protected. The chemical fire suppression agent is a volatile chemical that exists as a liquid when confined under pressure in a closed vessel, but rapidly vaporizes from its liquid state to a vapor state when sprayed via the distribution nozzles into the ambient atmosphere to form a gaseous mixture with the air within the space being protected which does not support combustion and extinguishes fires. The distribution nozzles function to atomize or otherwise break the liquid chemical fire suppressant into small droplets to facilitate evaporation. An example of a clean agent gaseous fire suppression system is disclosed in each of U.S. Pat. No. 6,763,894 and U.S. Patent Application Publication No. US2005/0001065A1.
A hybrid fire suppression system includes a supply of pressurized inert gas, a pipe network connected in inert gas flow communication to the inert gas supply, a first inert gas spray nozzle, a second inert gas spray nozzle, and a water storage cartridge having an interior volume defining a water reservoir storing a limited amount of water. The water reservoir is in water flow communication with the second inert gas spray nozzle. The pipe network has a first terminus associated with a first protected space and a second terminus associated with a second protected space. The first inert gas spray nozzle is connected in flow communication with the first terminus for introducing a flooding flow of inert gas only into the first protected space. The second inert gas spray nozzle is connected in flow communication with the second terminus for introducing a flooding flow of inert gas and the limited amount of water from the water reservoir into the second protected space. The water storage cartridge is disposed in close proximity to the second inert gas spray nozzle. The source of pressurized inert gas may be a source of a pressurized, chemically non-reactive gas selected from the group including nitrogen gas, carbon dioxide gas, helium gas, argon gas, neon gas, and mixtures of two or more thereof.
In an embodiment, the water storage cartridge has an elongated body extending along a longitudinal axis between an aft end and a forward end. The forward end of the water storage cartridge is disposed adjacent the second inert gas spray nozzle. A gas flow conduit establishes flow communication between the supply of pressurized inert gas and the interior volume of the water storage cartridge. A water conduit establishes flow communication between the interior volume of the water storage cartridge and the second inert gas spray nozzle.
In an embodiment, the hybrid fire suppression system further includes a third inert gas spray nozzle in flow communication with a third terminus of the pipe network and a source of pressurized water located remotely from the third inert gas spray nozzle. This water source holds a relatively large amount of water as compared to the limited amount of water stored in the water storage cartridge. A flow of inert gas having water from the remote water source entrained therein is introduced through the third inert gas spray nozzle into a third protected space.
A kit is also provided for retrofitting an inert gas spray nozzle of an inert gas fire suppression system wherein the inert gas spray nozzle is mounted to a terminal section of an inert gas supply pipe connected in flow communication with a source of pressurized inert gas. The kit includes a water storage cartridge having an interior volume defining a water reservoir storing a limited amount of water in close proximity to the inert gas spray nozzle, a gas flow conduit for establishing flow communication between the inert gas supply pipe and the interior volume of the water storage cartridge, and a water flow conduit for establishing flow communication between the interior volume of the water storage cartridge and the inert gas spray nozzle.
For a further understanding of these and other objects of the invention, reference will be made to the following detailed description of the invention which is to be read in connection with the accompanying drawing, where:
Referring now to
The inert gas storage vessels 12, each of which contains inert gas under pressure, typically at a pressure of 200 to 300 bars, are connected in flow communication with the spray nozzle assemblies 20 via a network of pipes 15, 15A and 15B. The pipes 15A and 15B, each of which branches off the main inert gas supply pipe 15 to feed inert gas to a respective one of the spray nozzle assemblies 20, may be referred to as a distribution pipe. As in conventional inert gas fire suppression systems, a pressure regulator 14 is disposed at the outlet of each of the inert gas vessels 12 for regulating the pressure leaving the inert gas vessels 12 to maintain an initial desired gas pressure within the inert gas flow line, typically up to 150 bars. A gas flow regulator 16 is disposed in pipe 15 downstream of the pressure regulator 14 for controlling the flow of inert gas through the pipe 15. Alternatively, the gas pressure regulator 14 and the gas flow regulator 16 may be collocated or even combined into a single valve or flow control device. A sensor 70 may be installed within the protected space 100 for detecting the existence of a fire within the protected space and for generating a fire detected signal. When a fire is detected, a fire detected signal 71 is transmitted from the sensor 70 to the system controller 18 which, in response to receipt of the fire detected signal 71, generates the demand signal 17 and transmits the demand signal 17 to the gas flow regulator 16 which, in response to receipt of the demand signal 17, opens to allow pressurized inert gas from the vessels 12 to flow through the pipes 15, 15A and 15B to the respective spray nozzle assemblies 20.
Each of the spray nozzle assemblies 20 includes a spray nozzle 30A or 30B mounted to the terminus of the terminal section of a respective one of the distribution pipes 15A and 15B that branch off of the inert gas supply pipe 15. The spray nozzle assemblies 20 are disposed above the ceiling 102 of the protected space 100 in the open space 105 that exists above the ceiling 102 and beneath the floor 104 of the next story thereabove or the roof of the structure, commonly referred to as the ceiling void. As in conventional practice, the terminal section of each of the branch pipes 15A and 15B extends generally vertically downward such that the spray nozzles 30A or 30B are disposed subadjacent the room-side, i.e. lower side, surface of the ceiling 102 extending over the protected space 100.
Each of the spray nozzle assemblies 20 of the hybrid inert gas flooding fire suppression system 10 of the invention further includes a reservoir of water 50 disposed in the ceiling void 105 in operative association with its respective one of the spray nozzles 30A and 30B. The reservoir of water 50 is stored at atmospheric pressure within the interior volume 55 of an elongated cartridge 52 having an aft end 54 and a forward end 56. As depicted in the exemplary embodiments shown in
In the exemplary embodiment depicted in
In the exemplary embodiment depicted in
A water conduit 51 establishes water flow communication between the interior volume 55 of the water storage cartridge 52 through an outlet 53 at the lower portion of the forward end 56 of the cartridge 52 and the respective spray nozzle 30A, 30B associated with the cartridge 52. In the exemplary embodiment depicted in
A gas conduit 57 establishes inert gas flow communication between the inert gas distribution line 15A, 15B associated with the water storage cartridge 52 and the interior volume 55 of the cartridge 52 through an inlet 59 at the upper portion of the aft end 54 of the cartridge 52. A back flow prevention means 28, such as a check valve or burst diaphragm, may be disposed in the gas conduit 57 to prevent back flow of water theretrough into gas conduit 57 when the inert gas distribution lines 15A, 15b are not pressurized, that is when inert gas is not flowing therethrough. As depicted in the exemplary embodiment illustrated in
As noted previously, when a fire is detected within the protected space 100, the controller 18 sends a demand signal 17 to the flow control valve 16 causing the flow control valve 16 to open, thereby allowing pressurized inert gas to flow from the inert gas storage vessels 12 at a controlled rate through the main supply pipe 15 to and through the distribution pipes 15A and 15B and into the protected space 100 through the spray nozzles 30A and 30B. Additionally, a portion of the inert gas passing through the distribution pipes 15A and 15B passes through the respective gas conduit 57 associated with each spray nozzle assembly 20 to pressure the interior volume 55 of the water storage cartridge 52 thereby forcing water to flow from the water reservoir 50 through water conduit 51 to be introduced into the inert gas as previously described. As the inert gas is introduced into the interior volume 55 of the water storage cartridge at a gas pressure substantially higher than the gas pressure at the location at which the water is introduced into the inert gas flow, the water within the reservoir 50 will rapidly flow therefrom.
A rapid flow rate of water is desired in order to empty the water from the reservoir 50 within a relatively short period of time, typically one minute or less. To provide a relatively constant flow rate over the short period of time in which the reservoir 50 is to be emptied, a water flow orifice assembly 60 may be disposed in the water conduit 51 downstream of the outlet 53 from the water storage cartridge 52. The orifice is sized appropriately to provide a desired pressure drop sufficient to affect a relatively constant mass flow ratio of water mass flow rate through the water conduit 51 to inert gas mass flow rate. Due to the high pressure of the inert gas emitted into the interior volume within the water storage cartridge 52, without the orifice present to provide this pressure drop, the water flow through the water conduit 51 will decay over the time period required to empty the reservoir 50 from a relatively high flow rate initially to a relatively low rate near the end of the time period.
In conventional inert gas flooding fire suppression systems, the inert gas not only raises the heat capacity of the atmosphere in the protected space into which the inert gas is introduced, but also reduces the volumetric concentration of oxygen in the atmosphere within the protected space to a level less than 14%, which is generally accepted as a volumetric oxygen concentration that gives personnel within the protected space an adequate opportunity to evacuate the premises. In combination, the increase in heat capacity and reduction in oxygen concentration establishes a fire extinguishing atmosphere within the protected space. Thus, in buildings or other installations equipped with conventional inert gas systems that operate to totally flood the protected space with a fire extinguishing atmosphere, personnel within the protected space at the time of activation of the fire suppression system can safely remain within the protected space for only a short period of time and therefore must rapidly evacuate the protected space.
Applicants have found that the admission of a limited amount of water into the inert gas flooding flow results in a hybrid inert gas fire suppression system that not only floods the protected space with an effective fire extinguishing atmosphere, but also provides a safer atmosphere for humans and animals within the protected space. Referring now to
However, the volumetric oxygen concentrations in the fire extinguishing atmosphere produced via the hybrid inert gas fire suppression system of the invention, represented by bars C, range from about 13% to about 14.5%. Further, for each defined volume, the volumetric oxygen concentration of the fire extinguishing atmosphere produced via the hybrid inert gas fire suppression system of the invention was about 2% higher than the volumetric oxygen concentration characteristic of a conventional pure nitrogen gas fire suppression system (bars B), and about 4% higher than the volumetric oxygen concentration characteristic of a conventional argon/nitrogen gas fire suppression system (bars A). With a higher volumetric oxygen concentration in the resultant fire extinguishing atmosphere, the hybrid inert gas fire suppression system of the invention is safer for humans and animals present in the protected space at the time of activation of the fire suppression system. The higher volumetric oxygen concentration within the resultant fire extinguishing atmosphere improves the conditions and lengthens the time conducive for emergency evacuation, thereby providing personnel within the protected space a better opportunity to safely evacuate the premises.
The added water augments the fire suppression capability of the inert gas by increasing the heat capacity of the resultant fire extinguishing atmosphere as compared to pure inert gas systems. This increase in heat capacity compensates for the lesser reduction in the volumetric oxygen concentration. Thus, the hybrid inert gas fire suppression system of the invention is capable of providing an effective flooding fire extinguishing atmosphere while providing a safer atmosphere for personnel occupying the protected space at the time of activation of the fire suppression system. Additionally, the amount of inert gas required in operation of the hybrid inert gas fire suppression system of the invention is reduced relative to the amount required in a similarly sized conventional inert gas system because the heat capacity of the fire extinguishing atmosphere has been augmented by the water introduced into the inert gas flow. As a result, the amount of inert gas that must be stored for use in connection with an installed inert gas system can be reduced.
The amount of water introduced into the inert gas should be limited. If an excessive amount of water is introduced into the inert gas, the inert gas flooding effect would be lost and the system would operate similar to conventional water streaming fire suppression systems. The amount of water introduced into the flow of inert gas should also be limited to ensure that all of the water is rapidly evaporated upon introduction into the protected space. For example, with the hybrid inert gas fire suppression system of the invention installed in a building for fire suppression within a room having a volume of about 100 cubic meters, to suppress a fire therein, between 4 and 15 liters of water would be introduced into a mass flow of about 30 kilograms of inert gas introduced into the room through a single spray nozzle.
It is to be understood that the hybrid inert gas flooding fire suppression system 10 may be installed in a building as the sole fire suppression system, or in combination with a conventional inert gas flooding fire suppression system, or in combination with a conventional centralized streaming fire suppression system, or in combination with a conventional localized streaming fire suppression system, or in combination with other conventional fire suppression systems, or in combination with any combination of two or more conventional fire suppression systems. For example, referring now to
As noted before, when activated the hybrid inert gas fire suppression system of the invention establishes a fire extinguishing atmosphere that has a higher oxygen content then would be establish through a conventional pure inert gas fire suppression systems. In large multi-purpose buildings, there are typically a variety of rooms serving different functions that need to be protected with a fire suppression system, including for example business offices, hotel quest rooms, conference rooms, libraries, computer rooms, electronic equipment rooms, telecommunication centers, food service kitchens, boiler rooms, among other spaces. To optimize fire suppression, more than one type of fire suspension system may be installed based upon the various rooms/spaces to be protected. The hybrid inert gas fire suppression system 10 is advantageously suited for installation in connection with protecting generally occupied rooms such as offices, retail shops, hotel guest rooms, conference rooms and the like. Conventional pure inert gas suppression systems are particularly suited for installation in rooms/spaces where water, chemical foams or fire suppressant residue could damage equipment, books or other or property, such as computer rooms, electronic equipment rooms, telecommunication centers, libraries and the like. Localized streaming fire suppression systems are advantageously suited for use in connection with rooms/spaces where a large amount of water or liquid chemical agent fire suppressant is typically needed for fire suppression and water/liquid damage is of lesser concern, such as kitchens, boiler rooms, and like spaces.
With respect to each room, if a fire is detected within that room, a central controller 18 activates the fire suppression system associated with that room. To suppress a fire in room 100, the controller 18 opens inert gas flow control valve 16 and also opens the shut-off valve 101 to allow pressurized inert gas to pass through pipe 15 and branch pipe 15-1 to and through the spray nozzles 30 to flood the protected space defined by room 100. A portion of the inert gas passing through the branch pipe 15-1 also pressures the cartridge 50 forcing the water stored therein into the inert gas flowing into the protected space defined by room 100. To suppress a fire in room 200, the controller 18 opens inert gas flow control valve 16 and also opens the shut-off valve 201 to allow pressurized inert gas to pass through pipe 15 and branch pipe 15-2 to and through the spray nozzles 230 to flood the protected space defined by room 100.
To suppress a fire in room 300, the controller 18 opens inert gas flow control valve 16 and also opens the shut-off valve 301 to allow pressurized inert gas to pass through pipe 15 and branch pipe 15-3 to and through the spray nozzles 330. Additionally, the controller opens water flow control valve 382 and opens propellant gas flow control valve 314 to permit propellant gas from storage tanks 312 to propel water or other liquid fire suppressant chemical from the local storage tank 380 into the inert gas flowing through pipe 15-3 to be introduced into the protected space defined within room 300 through the spray nozzles 330 as a mist of water or other liquid fire suppressant chemical. To suppress a fire in room 400, the controller 18 opens inert gas flow control valve 401 to permit the inert gas to propel the water or other liquid fire suppressant chemical from the central storage tank 480 through pipe 15-4 to be introduced into the protected space defined within room 400 through the spray nozzles 430 as a mist of water or other liquid fire suppressant chemical.
While the present invention has been particularly shown and described with reference to the preferred mode as illustrated in the drawing, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the invention as defined by the claims.
This application is related to International Patent Application Serial No. PCT/US07/(Attorney Docket No. 1463—001), entitled “INERT GAS FLOODING FIRE SUPPRESSION WITH WATER AUGMENTATION”, filed with the United States Patent and Trademark Office on the same date as this application and subject to assignment to the common assignee of this application.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US07/20590 | 9/24/2007 | WO | 00 | 6/30/2010 |
