Abstract:
A device for supplying fire suppressing agent to the interior of a container for an extended duration may include a plurality of chambers configured to contain and selectively expel the fire suppressing agent, a puncture mechanism configured to puncture a container, and a manifold in flow communication with the plurality of chambers and the puncture mechanism. The device may further include a controller configured to initiate expulsion of the fire suppressing agent from the chambers in a controlled manner, where the device is configured such that the fire suppressing agent may be first expelled from a first one of the plurality of chambers at a first time, and the fire suppressing agent may be expelled from a second one of the plurality of chambers at a second time that is later than the first time.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/952,503, filed Mar. 13, 2014, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to systems and methods for suppressing fires. In particular, the present disclosure relates to systems and methods for suppressing fires associated with containers. 
       BACKGROUND OF THE DISCLOSURE 
       [0003]    Cargo may be transported to its destination using one or more of several different types of vehicles, including, for example, ships, trains, aircraft, and trucks. Such cargo is transported while located in the interior of cargo areas. In some cases, cargo may include hazardous, easily flammable, and/or easily combustible materials that may render transport dangerous to the cargo itself, as well as to the vehicle transporting the cargo and operators of the vehicle. 
         [0004]    In many instances, cargo may be carried in an area separated from an operator controlling the vehicle. As a result, an operator may be unaware of a fire or explosion that has occurred within a cargo container or within the cargo area. Moreover, due to the nature of a cargo vehicle, there may be a limited supply of fire suppressant available. For example, aboard a cargo aircraft, the weight of any fire suppressant may limit the amount of fire suppressant that may be carried for suppressing fires. Therefore, it may be desirable to limit the amount of fire suppressant used to extinguish a fire in order to reduce the weight carried by the aircraft by focusing any release of fire suppressant on the particular area in need of fire suppressant, rather than merely releasing a large enough amount of suppressant to flood the entire cargo area. Furthermore, the fire suppressant itself may be harmful to some types of cargo. Therefore, it may be desirable to limit the release of fire suppressant to the location in need of fire suppression, so as to limit the spoilage of cargo not in need of fire suppressant. 
         [0005]    Because cargo areas experiencing a fire may be located remotely from cargo vehicle operators (i.e., the cargo may be located in an unoccupied and/or difficult to access portion of the vehicle), it may be more difficult to provide fire suppressant to an area experiencing a fire in a timely manner. Therefore, it may be desirable to provide a system for supplying fire suppressant remotely and in a timely manner. 
         [0006]    One example of a cargo vehicle having an operator located relatively remotely from the cargo area is an aircraft. The majority of cargo carried by modern aircraft is transported in cargo containers or on cargo pallets. The containers are generally referred to generically as Unit Load Devices (“ULDs”). For safety considerations, ULDs must often be configured to engage an aircraft cargo locking system in order to restrain the cargo containers under various flight, ground load, and/or emergency conditions. Under federal air regulations, ULDs are considered aircraft appliances, are Federal Aviation Administration (FAA)-certified for a specific type of aircraft, and are typically manufactured to specifications contained in National Aerospace Standard (NAS) 3610. 
         [0007]    In the cargo aircraft example, while some cargo areas may be conventionally equipped with fire extinguishing bottles intended for manual operation, few cargo containers may be accessible to flight crews during a flight, thereby possibly rendering it difficult to manually extinguish a fire located in an aircraft cargo area using fire extinguishing bottles. In addition, fires may occur inside cargo containers, and if those fires are not suppressed or extinguished, they may breach the walls of the container and spread throughout the cargo area. However, it may be difficult, if not impossible, to suppress or extinguish a fire inside a container without discharging fire suppressant into the interior of the container. 
         [0008]    Thus, it may be desirable to provide a system for suppressing a fire associated with a container for which a fire has been detected. In addition, it may be desirable to provide a system for supplying fire suppressant inside the container. Further, it may be desirable to provide a system for supplying a fire suppressant inside the container for an extended period of time or duration of time, for example, so that a cargo aircraft may safely land before a fire spreads throughout the cargo area. 
         [0009]    Such a fire suppression system or plurality of systems may be located either in one area of a cargo area, such as a “high risk” area containing particularly hazardous materials, or throughout the cargo area. 
         [0010]    Problems associated with detecting and/or suppressing fires are not limited to the cargo transportation industry. Similar problems may arise, for example, wherever cargo and/or other articles are stored in a location that is remote from a person supervising the cargo or other articles, such as in a storage facility. Thus, in a broad variety of situations, it may be desirable to remotely detect and/or remotely suppress a fire. 
         [0011]    In many applications, it may be impractical or inefficient to store a fire suppression system directly in a container such as a ULD. For instance, containers may be subjected to harsh environments, including extreme cold and heat, shock, vibration, and general abuse. As a result, providing a fire suppression system in each individual container may be impractical due, for example, to accelerated degradation or failure of such systems over time. Moreover, a given company in the cargo freight industry may use thousands of containers, and the cost of equipping each container with a fire suppression system may be prohibitive. Installing, maintaining, and removing the fire suppression system of each container could also be impractical and uneconomical. As a result, there are many possible drawbacks to providing fire suppressing systems in a large number of containers. 
         [0012]    In addition, existing technologies and techniques may only provide a limited fire suppressing window. For example, some methods may be a one-time solution, such as devices that supply a fire suppressing agent into a container during a single application. When a fire suppressing agent leaks out of or disperses from a ULD after introduction into the ULD, the fire may grow again and breach the ULD, potentially spreading to surrounding cargo. This may severely limit the time available for a flight crew to safely land a cargo aircraft, for example. Some tests have shown that a single application of fire suppressing agent into a container may be effective for twenty minutes or less. This may be inadequate, for example, for a cargo aircraft during a transoceanic flight, where it may take several hours to fly to the closest airport suitable for landing. Therefore, it may be desirable to provide a consistent or repeated supply of fire suppressing agent to a container over an extended duration. 
       SUMMARY 
       [0013]    In the following description, certain aspects and embodiments of a device for supplying fire suppressing agent to the interior of a container for an extended duration will become evident. It should be understood that the aspects and embodiments, in their broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should be understood that these aspects and embodiments are merely exemplary. 
         [0014]    One aspect of the disclosure relates to a device for supplying fire suppressing agent to the interior of a container for an extended duration. The device may include a plurality of chambers configured to contain and selectively expel fire suppressing agent, a puncture mechanism configured to puncture a container, and a manifold in flow communication with the plurality of chambers and the puncture mechanism. The device may further include a controller configured to initiate expulsion of the fire suppressing agent from the chambers in a controlled manner. The device may be configured such that the fire suppressing agent may be first expelled from a first one of the plurality of chambers at a first time, and the fire suppressing agent may be expelled from a second one of the plurality of chambers at a second time that is later than the first time. 
         [0015]    As used herein, the term “fire” is not necessarily limited to a fire having visible flames. Rather, the term “fire” is used in a broad sense and may be used to describe situations in which an object and/or surface is exhibiting a higher temperature than desired or considered to be unsafe to a person having skill in the art, such as, for example, a situation in which an object and/or surface is smoldering, smoking, and/or is hot to the touch. 
         [0016]    According to another aspect, a system for supplying fire suppressing agent to the interior of a container for an extended duration may include a plurality of chambers configured to contain and selectively expel fire suppressing agent, a puncture mechanism configured to puncture a container, and a manifold in flow communication with the plurality of chambers and the puncture mechanism. The system may further include a sensor configured to provide signals indicative of a temperature associated with a container to a controller configured to initiate expulsion of fire suppressing agent from the chambers in a controlled manner. The system may be configured such that the fire suppressing agent may be first expelled from a first one of the plurality of chambers at a first time, and the fire suppressing agent may be expelled from a second one of the plurality of chambers at a second time that is later than the first time. The puncture mechanism may be configured to extend and puncture a container after expulsion of the fire suppressing agent. 
         [0017]    According to a further aspect, a method for supplying fire suppressing agent to the interior of a container for an extended duration may include detecting sensor signals indicative of a temperature associated with a container, determining via a controller that the fire suppressing agent should be supplied to the interior of the container based at least in part on the sensor signals, and initiating via the controller expulsion of fire suppressing agent from a chamber containing fire suppressing agent. The method may further include puncturing a surface of the container with a puncture mechanism to provide flow communication between the chamber and the interior of the container to permit supply of fire suppressing agent into the interior of the container at a first time. The method may further include initiating, via the controller, expulsion of fire suppressing agent from a second chamber containing fire suppressing agent at a second time after the first time. The method may further include supplying fire suppressing agent from the second chamber into the interior of the container. 
         [0018]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
         [0019]    The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several exemplary embodiments and together with the description, may serve to explain the principles of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a schematic, cut-away, perspective view of an exemplary vehicle; 
           [0021]      FIG. 2  is a schematic, cut-away, front view of an exemplary embodiment of a system for supplying fire suppressing agent to the interior of a container in an exemplary cargo area; 
           [0022]      FIG. 3  is a schematic, partial cut-away, top view of an exemplary embodiment of a system for supplying fire suppressing agent to the interior of a container; 
           [0023]      FIG. 4  is a schematic, cut-away, top view of an exemplary embodiment of a chamber containing a fire suppressing agent; 
           [0024]      FIG. 5  is a schematic, partial cut-away, side view of an exemplary embodiment of a system for supplying fire suppressing agent to the interior of a container during operation in an initial, non-deployed configuration; 
           [0025]      FIG. 6  is a schematic, partial cut-away, side view of an exemplary embodiment of a system for supplying fire suppressing agent to the interior of a container during operation in a partially-deployed configuration; 
           [0026]      FIG. 7  is a schematic, partial cut-away, side view of an exemplary embodiment of a system for supplying fire suppressing agent to the interior of a container during operation in a fully-deployed configuration; 
           [0027]      FIG. 8  is a schematic, partial cut-away, side view of an exemplary embodiment of a puncture mechanism during operation with an exemplary pressure plug removed; 
           [0028]      FIG. 9  is a schematic, partial cut-away, side view of an exemplary embodiment of a pressure plug assembly in a non-extended configuration; 
           [0029]      FIG. 10  is a schematic, partial cut-away, side view of an exemplary embodiment of a pressure plug assembly in a fully-extended configuration; 
           [0030]      FIG. 11  is a schematic, top view of an exemplary embodiment of a puncture mechanism; 
           [0031]      FIG. 12  is a schematic, partial cut-away, side view of an exemplary embodiment of a puncture mechanism during operation with an exemplary pressure plug; 
           [0032]      FIG. 13  is a schematic, top view of an exemplary embodiment of a removable puncture tip; and 
           [0033]      FIG. 14  is a schematic, partial cut-away, side view of an exemplary embodiment of a removable puncture tip. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0034]    Reference will now be made in detail to exemplary embodiments, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0035]      FIG. 1  shows an exemplary vehicle  10  for transporting containers. The vehicle  10  may include a body  12  defining an interior  14  of the vehicle, a deck  16  within the body  14 , the deck  16  being configured to support a plurality of containers  18 , and a ceiling  20  spaced above the deck  16 . 
         [0036]      FIG. 2  is a cross-sectional view of the exemplary vehicle  10  of  FIG. 1 . The vehicle  10  may include a system  22  for supplying fire suppressing agent  32  (see  FIG. 3 ) to the interior of a container  18  supported by the deck  16 . The system  22  may be attached, for example, to the ceiling  20  above at least one location configured to receive a container  18 . The system  22  may include a sensor  24  and a controller  26 . The system  22  may further include at least two chambers  30  containing a fire suppressing agent  32 , a puncture mechanism  34  with a conveyance tube  36  and a puncture tip  38  (see  FIG. 5 ), and a manifold  40  connecting the chambers  30  to the puncture mechanism  34  that allows for flow of the fire suppressing agent  32  from a chamber  30  to the puncture mechanism  34  during operation of the system  22 . In the exemplary embodiment shown, each chamber  30  is coupled to the manifold  40 , for example, via a threaded screw connection  42 . 
         [0037]    The fire suppressing agent  32  may include any suitable substance or combination of substances. For example, the fire suppressing agent  32  may include, for example, a pyro-propellant configured to both generate driving pressure and provide a fire extinguishing or fire suppressing gas or aerosol. For example, the fire suppressing agent  32  may include one or more of sodium azide, 5-amino tetrazole, potassium 5-amino tetrazole, guanidine nitrate, potassium chlorate, potassium nitrate, potassium perchlorate, strontium nitrate, copper nitrate (basic), copper oxide (black), ammonium perchlorate, or a LOVA propellant. Other substances having similar characteristics are contemplated for use as the fire suppressing agent  32 . Additionally, the fire suppressing agent  32  may employ byproducts of chemical reactions, such as, for example, producing potassium carbonate through a combustion reaction in the form of a finely-dispersed, micro-pulverized aerosol. 
         [0038]    In the exemplary embodiment shown in  FIG. 3 , the chambers  30  are arranged about the manifold  40  in a circumferential manner. The system  22  may be configured such that only a single chamber  30  discharges a fire suppressing agent  32  into the manifold  40  at a given time. The controller  26  may be configured to control ignition of the fire suppressing agent  32  within each chamber  30  according to an ignition schedule, such that fire suppressing agent  32  may be supplied to a container  18  over an extended duration by releasing the fire suppressing agent  32  from a plurality of the chambers  30  at spaced time intervals. The activation rate of each chamber  30  and/or the discharge rate of fire suppressing agent  32  from each chamber  30  may be controlled by the controller  26 . For example, the controller  26  may include a timer using fixed time intervals, a sensory input-based program, or any other suitable time-regulating mechanism. 
         [0039]    The sensor  24  may be configured to detect undesirably high temperatures, such as from a fire within a container  18 . The sensor  24  may be any suitable fire-detection mechanism, such as a thermal sensor, a smoke detector, or thermally sensitive materials. In some embodiments, the sensor  24  is in communication with the controller  26 , for example, via hard-wiring and/or a wireless communication link. In the event that the sensor  24  detects a fire, such as through an elevated temperature reading or by detecting smoke, the sensor  24  is configured to send a signal detectable by the controller  26 . 
         [0040]    The controller  26  may include one or more processors, microprocessors, central processing units, on-board computers, electronic control modules, and/or any other computing and control devices known to those skilled in the art. The controller  26  may be configured to run one or more software programs or applications stored in a memory location, read from a computer-readable medium, and/or accessed from an external device operatively coupled to the controller  26  by any suitable communications network. 
         [0041]    After receiving the signal from the sensor  24 , the controller  26  may use any suitable means, such as software programming, mechanical components, or chemical reactions, to initiate operation of the system  22 . Initiating operation may be accomplished, for example, via sending an activation signal to an igniter  44  located within a chamber  30  containing the fire suppressing agent  32 , for example, as shown in  FIG. 4 . When exposed to heat from the igniter  44 , the fire suppressing agent  32  may undergo a chemical reaction, rapidly expanding and increasing pressure within the chamber  30 . According to some embodiments, following activation of the igniter  44 , the controller  26  sends a signal to a reporting unit (not shown) notifying a user that the system is operating, such as to a remote flight crew within an aircraft cockpit. It is contemplated that other mechanisms and methods may be used to trigger release of fire suppressing agent  32 . 
         [0042]      FIG. 5  shows an exemplary system  22  immediately following activation. Following activation of the igniter  44 , which may provide, for example, an igniter flame  45  in the chamber, the fire suppressing agent  32  heats and expands within the chamber  30 . One or more pressure control plugs  46  located in a passage  48  between the chamber  30  and the manifold  40  may be displaced, dislodged, or otherwise removed by pressure from the expanding fire suppressing agent  32 . (To illustrate the presence and flow of the expanding fire suppressing agent  32 , a darker shade is used in  FIGS. 5-7  for the activated fire suppressing agent  32  than for unactivated fire suppressing agent  33  in an unactivated chamber  30 ). The pressure control plug  46  may be formed from any suitable material as long as it prevents external pressure and heat from affecting an inactive chamber  30  (i.e., while the system is not activated). As shown in  FIG. 6 , once a pressure control plug  46  is dislodged, the chamber  30  may be placed in flow communication with the manifold  40 , and the fire suppressing agent  32  may flow out of the chamber  30  and into the manifold  40 . The fire suppressing agent  32  may continue to expand while pressurizing the interior space of the manifold  40 . 
         [0043]      FIG. 6  shows the fire suppressing agent  32  as it expands within the manifold  40 , further exerting force upon a pressure disk  50  located at the interface between the manifold  40  and the puncture mechanism  34 . (Arrows are used in  FIGS. 6-8  to schematically indicate the flow of the fire suppressing agent  32 .) The force exerted upon the pressure disk  50  may cause the puncture tip  38 , initially located in a retracted position within a conveyance tube  36  of the puncture mechanism  34 , to extend along the conveyance tube  36 . The puncture tip  38  may include an angled piercing edge  39 , a puncture tip opening  41 , and a puncture tip side port  71 . The puncture tip  38  may extend to a certain point, such as until the puncture tip  38  reaches one or more guide stops (not shown) on the conveyance tube  36 . When the puncture tip  38  strikes the container  18 , pressure may continue to build up on the pressure disk  50  as a result of the expanding fire suppressing agent  32 , which may increase the force upon the puncture tip  38  through the pressure disk  50 , thereby causing the puncture tip  38  to penetrate an exterior wall of a container  18 . 
         [0044]    In some embodiments, the conveyance tube  36  further includes a locking mechanism (not shown) that locks the puncture tip  38  at its furthest-traveled position, thereby preventing the puncture tip  38  from contacting an object and bouncing back into the conveyance tube  36 . The locking mechanism maximizes the likelihood of successful container  18  penetration, minimizing the possible waste of fire suppressing agent  32  during operation of the system  22 . 
         [0045]    As shown in  FIGS. 7 and 8 , as the puncture tip  38  translates along the extent of the conveyance tube  36 , but before the puncture tip  38  reaches its maximum extension, a pressure plug  52  located on the pressure disk  50  may be displaced by a pressure plug cable  54  fastened to the interior of the manifold  40 . Displacement of the pressure plug  52  exposes an orifice  56  within the pressure disk  50  that allows the fire suppressing agent  32  to flow from the manifold  40  to the conveyance tube  36  through the orifice  56 . The puncture tip  38  penetrates the skin of a container  18  before the pressure plug  52  is displaced from the pressure disk  50 , thereby allowing the fire suppressing agent  32  to flow through the conveyance tube  36  and into the interior of the container  18  through the puncture tip opening  41  and/or the puncture tip side port  71 . (The flow of fire suppressing agent  32  through the conveyance tube  36  is shown with schematic arrows in  FIG. 8 ). 
         [0046]    In the exemplary embodiment shown in  FIG. 9 , the pressure plug cable  54  may be initially coiled within a pressure plug cable sleeve  58  located within the manifold  40 . The pressure plug cable sleeve  58  protects the pressure plug cable  54  from damage or deformation during the initial expansion of the fire suppressing agent  32  within the manifold  40 . The pressure plug  52  is displaced by the pressure plug cable  54  when the pressure plug cable  54  reaches its full extension, such as when the puncture tip  38  translates within the conveyance tube  36  away from the manifold  40  to a certain distance from the manifold  40 . An exemplary embodiment of a fully-extended pressure plug cable  54  attached to a pressure plug  52  is shown in  FIG. 10 . The pressure plug cable  54  may be made of any suitable material, such as stainless steel or other materials having similar characteristics. Collectively, the pressure plug  52 , pressure plug cable  54 , and pressure plug cable sleeve  58  form a pressure plug assembly  59 . 
         [0047]    Pressure may mount within the manifold  40  and/or chamber  30  if the puncture tip  38  does not translate far enough within the conveyance tube  36  to displace the pressure plug  52  from the pressure disk  50  via the pressure plug cable  54 . To alleviate such pressure before it causes damage to the manifold  40  and/or chamber  30 , the pressure disk  50  may further include an emergency pressure release valve  60 . 
         [0048]    In the exemplary embodiments shown in  FIGS. 11 and 12 , the emergency pressure release valve  60  on the pressure disk  50  may include a pressure plate  62 , springs  64 , and ports  66 . The ports  66  of the emergency pressure valve  60  may allow the fire suppressing agent  32  to bypass the orifice  56  that would otherwise be exposed by displacement of the pressure plug  52 , and the fire suppressing agent  32 , through the ports  66 , may then exert pressure upon the pressure plate  62 . In the exemplary embodiments shown, the pressure plate  62  is connected to the pressure disk  50  by springs  64 , and includes a pressure plate orifice  68  in the center of the pressure plate  62  configured to allow the fire suppressing agent  32  to flow through the pressure plate  62  without impediment upon removal of the pressure plug  52  by the pressure plug cable  54 . The pressure plate  62  may block the flow of any fire suppressing agent  32  traveling through the ports  66  if the pressure plug  52  remains in place, however, until the pressure from the fire suppressing agent  32  in the ports  66  directed against the pressure plate  62  exerts sufficient force to displace the pressure plate  52 . 
         [0049]    The strength of the springs  64 , which dictates the force required for displacement of the pressure plate  62 , may be determined, for example, by considering the critical system pressure and a factor of safety, and may be selected to permit the pressure plate  62  to separate from the pressure disk  50  prior to any pressure damage occurring to the manifold  40  or chambers  30 . In the exemplary embodiment shown in  FIG. 12 , when the fire suppressing agent  32  within the manifold  40  exerts sufficient pressure against the pressure plate  62  and stretches the springs  64 , thereby displacing the pressure plate  62 , the fire suppressing agent  32  enters the conveyance tube  36  through the pressure plate orifice  68 , even if the puncture tip  38  is not fully extended. (The flow of the fire suppressing agent  32  is schematically shown with arrows). The use of springs  64  is exemplary, and the pressure plate  62  may be displaced by alternative mechanisms, such as valves or electrical pressure transducers (not shown). 
         [0050]    In the exemplary embodiments shown in  FIGS. 13 and 14 , the puncture mechanism  34  may further include a puncture tip disconnect  70  that allows for easy removal of the puncture tip  38  from the conveyance tube  36  after operation of the system  22 . The puncture tip disconnect  70  may allow the puncture tip  38 , for example, to remain in the container  18  following penetration of the container  18  until the puncture tip  38  can be safely removed during inspection. 
         [0051]    The system  22  may further include a heat sink  72  configured to cool the fire suppressing agent  32  after ignition and before the fire suppressing agent  32  enters one or more of the manifold  40 , puncture mechanism  34 , and container  18 . The heat sink  72  may be formed from any suitable material in an arrangement with high surface area and high thermal conductivity, such as, for example, a series of baffles or an array of fins. The heat sink  72  may be provided in one or more of the chamber  30 , manifold  40 , or conveyance tube  36 . 
         [0052]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.