Abstract:
The invention provides systems and methods adaptable to all gaseous agents including Helium to suppress fire in at least one enclosed space. Suppressants are delivered by a dedicated subsystem connected to cargo compartments or to engine nacelles, or by an integrated system connected to cargo compartments and engine nacelles. For example, at least a first reservoir stores fire suppressant composition for knocking down a fire in an enclosed space. Piping delivers the composition from the at least first reservoir to the enclosed space. A pressure sensor senses pressure of the composition in the piping, and a controllable purging device permits air to exit the enclosed space responsive to sensed pressure in the piping of the composition.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to fire suppression systems, and, more specifically to total flood fire suppression systems on board airplanes.  
         BACKGROUND OF THE INVENTION  
         [0002]    Onboard aircraft fire suppression systems for fires occurring in cargo compartments and engines require fire suppressants (or fire suppression agents) that are non-corrosive, volatile, electrically non-conductive, compatible with aircraft materials, have a low freezing temperature, and are non-toxic at fire suppressant concentrations. Fire suppression systems are designed to reduce the intensity of fires to a non-hazardous state.  
           [0003]    Depending on a particular fire and the fire&#39;s environment, fire suppressants, under certain conditions, may extinguish a fire by eliminating or disabling the combustion process. A fire suppression system in an aircraft generally first knocks down a fire, and then maintains the fire suppressed for a time period sufficient for the aircraft to safely land at the nearest airport. This time period can be lengthy for certain aircraft missions, such as over-water flights.  
           [0004]    Presently, halogenated derivatives of methane gas, such as Bromochlorodifluoromethane (CBrClF 2 , commonly known as Halon 1211) and Bromotrifluoromethane (CF 3 Br, commonly known as Halon 1301), have been found to exhibit desired fire-suppressant properties. Further, relatively small volumes of Halon 1211 or Halon 1301 are required to be delivered to a compartment to extinguish a fire in the compartment. Halon 1211 is commonly used as a Streaming agent in portable (hand-held) fire extinguishers and Halon 1301 in total flood fire suppression systems.  
           [0005]    However, halogenated methane derivatives are deleterious to the environment. Halon 1301, for example, has long atmospheric life and slowly migrates to the stratosphere where it catalytically destroys ozone. Under international agreement known as the Montreal Protocol, Halon production ceased in developed countries on Jan. 1, 1994. Existing supplies of Halon are used in commercial aircraft under renewable “critical use exemption” granted by the regulatory agencies of governments that are signatories to the Montreal Protocol.  
           [0006]    As a result, efforts have been made to find replacement fire suppressants as effective as Halon 1301 and Halon 1211 that are environmentally safe and that can be used with a low-weight penalty. Fire suppressants examined include halogenated hydrocarbons (commonly known as halocarbons), water-mist, inert gases and aerosols. Methods evaluated include use of a single suppressant and the use of two different agents, sequentially, to suppress fire in the cargo compartment. However, in general, the overall weight penalty can be high and the system may be complicated compared to present Halon 1301 systems. In addition, some methods may generate high concentrations of corrosive and toxic chemicals.  
           [0007]    Some of the inert gas agent is lost to the outside during constant pressure flooding of an enclosed space in “free efflux” total flooding systems. Generally, volumes of inert gas agents required are relatively larger than the volumes of Halon 1301 to extinguish a fire. As a result, use of agents other than Halon 1301 in currently known aircraft fire suppression systems could introduce into a compartment volumes of the agent that are sufficient to over pressurize the compartment. This could result in damage of the compartment walls and loss of compartment integrity essential for operation of the total flood system.  
           [0008]    Thus, there is an unmet need to knock down and suppress fire occurring in an enclosed space using a lower-weight suppression system that complies with regulatory requirements, is friendly to the environment, and does not pose a threat to compartment integrity.  
         SUMMARY OF THE INVENTION  
         [0009]    The invention includes systems and methods to suppress a fire in at least one enclosed space. The systems and methods of the invention are adaptable to all gaseous agents. In one presently preferred embodiment of the invention, Helium or Helium gas compositions are used as suppressants. Suppressants are delivered by a dedicated subsystem connected to cargo compartments or to engine nacelles. In another embodiment of the invention, the suppressants are delivered by an integrated system connected to cargo compartments and engine nacelles.  
           [0010]    In one non-limiting embodiment, the Helium compositions are stored in a dual-reservoir apparatus having a first bottle and a second bottle. The Helium compositions are delivered from the first and second bottle to the enclosure containing the fire via delivery assemblies attached to the dual-reservoir apparatus. The Helium compositions are rapidly delivered from the first bottle to the enclosure to rapidly reduce the Oxygen concentration of compartment air, using free efflux flooding method, to generally accepted fire-suppressing Oxygen level. The rate of delivery of the knockdown Helium compositions is determined by the pressure-flow characteristics of the delivery system connecting the reservoirs to the enclosure. The rate of delivery is higher from the first bottle than the second bottle in order to rapidly lower ambient Oxygen concentrations to a reduced level that suppresses or knocks down the fire in a cargo compartment. Thereafter, after a designed time delay, the Helium compositions are delivered to the cargo compartment at a significantly lower rate from the second bottle to maintain the reduced Oxygen concentration in the enclosure for extended time to keep the fire suppressed. The second bottle is used in the engine nacelle only if the fire re-ignites or the first bottle discharge fails to adequately suppress the fire. The second bottle discharge, in the case of an engine nacelle fire, is as rapid as the first bottle discharge. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings.  
         [0012]    [0012]FIG. 1A is a schematic diagram of a Helium gas total flood fire suppression system for airplane cargo compartments;  
         [0013]    [0013]FIG. 1B is a pressure set-point graph depicting the minimum pressure and maximum pressure that activates actuators to control cargo compartment discharge opening apertures;  
         [0014]    [0014]FIG. 2 is a schematic diagram of a Helium gas total flood fire suppression system for airplane engines;  
         [0015]    [0015]FIG. 3A is a schematic diagram of an integrated Helium gas total flood fire suppression system for airplane cargo compartments and engines;  
         [0016]    [0016]FIG. 3B is an alternate embodiment of the Helium reservoir in the integrated Helium gas total flood fire suppression system;  
         [0017]    [0017]FIG. 4 is a partial cutaway, perspective view of airplane compartments incorporating the system of the present invention; and  
         [0018]    [0018]FIG. 5 shows a schematic and pictorial details of an engine nacelle configuration incorporating the system of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    The present invention is a total flood fire suppression system. One present embodiment of the invention uses Helium gas or Helium blended with other inert gases as a fire suppressant. Non-limiting embodiments of the invention will be described below for use in airplane engine compartments, airplane cargo compartments, and airplane cargo and engine compartments.  
         [0020]    One present embodiment of the invention uses Helium because Helium has a better mass efficiency in knocking down and keeping fires suppressed than does Halon 1301. As shown in Table 1 below, less Helium mass is needed to maintain a fire suppressed in a space with a given leakage rate.  
                                           TABLE 1                           Mass of Halon 1301 and Helium Required To Maintain An       Atmosphere That Keeps A Fire Suppressed            Compart-   Mass of Halon 1301 required to   Mass flow of Helium       ment   maintain 3% concentration in the   required to maintain 10.5%       leakage   enclosure   Oxygen concentration       rate   (lb/hour of flight)   (lb/hour of flight)       (cfm)   See Notes 1, 2 &amp; 3   See notes 1 and 2.                     0   0.0   0.0       10   7.73   3.36       20   15.26   6.71       30   22.90   10.07       40   30.53   13.43       50   38.16   16.79       60   45.79   20.14       70   53.42   23.50       80   61.06   26.86       90   68.69   30.21       100    76.32   33.56                                          
 
         [0021]    For example, the weight of Helium required to maintain Oxygen concentration in the hazard approximately 10.50% Oxygen concentration (less than generally accepted concentration for fire suppression of around 12%) is 6.71 lb with a compartmental leakage rate of 20 cfm (typical leakage for a 1000 cubic feet volume cargo compartment). For a compartmental leakage rate of 20 cfm, 15.26 lb/hr of Halon 1301 is needed. Thus, less than half the weight of Halon 1301 is needed using Helium to achieve the same fire suppression capability. It will be appreciated by one experienced in the art of fire suppression in aircraft that Helium provides a significant mass advantage over Halon 1301.  
         [0022]    Other advantages for using Helium is that Helium is readily obtained from natural gas and oil well sources, and is environmentally friendly as it poses no risk to reducing atmospheric ozone. However, as discussed below, halogenated derivatives of methane, such as without limitation Bromotrifluoromethane, or any other gaseous fire suppressant such as inert gases can also be used in various embodiments of the invention.  
         [0023]    A first embodiment of the present invention is applied to fires in storage enclosures or cargo compartments. By way of overview, the first embodiment of the invention is a total flood fire suppression system that uses a two-bottle or two-tank system, where the first bottle or tank is dedicated to rapidly deliver a free efflux flooding of Helium or Helium blended with inert gases (such as Argon, Nitrogen, and Carbon Dioxide) to the storage spaces for suppressing the fire, and the second bottle is dedicated to deliver Helium gas compositions or Helium blended with inert gases (such as Argon, Nitrogen, and Carbon Dioxide) to the storage spaces at a rate sufficient to maintain fire suppressed. The free efflux flooding of Helium gas, or Helium gas blends, rapidly dilutes ambient Oxygen in the storage enclosure or compartment to establish a depleted Oxygen concentration that establishes suppression of the fire by reducing the intensity of the fire, or, depending on environmental conditions, may substantially disable the combustion process and extinguish the fire. Thereafter, Helium or Helium gas blend is delivered from the second bottle or tank to the storage enclosure or compartment at a rate sufficient to maintain the Oxygen concentration in the space at levels that keep the fire suppressed or, depending on environmental conditions, extinguish the fire. A non-limiting application of the first embodiment of the present invention is delivering Helium to at least one airplane compartment such as a cargo compartment.  
         [0024]    [0024]FIG. 1A shows a total fire suppression system  10  for a space such as an airplane cargo compartment. The fire suppression system  10  preferably utilizes a fire suppressant containing a Helium composition that is stored in a plurality of storage bottles or reservoirs. The plurality of storage bottles includes a first bottle  12  and a second bottle  22 . Given by way of non-limiting example, in one embodiment the first bottle  12  and the second bottle  22  each contain approximately 4.7 cubic feet pressurized Helium or Helium compositions to approximately 4500 psig in a spherical bottle the maximum outer diameter (OD) at zero pressure equal to approximately 26.125 inch. The first bottle  12  and the second bottle  22  each weigh approximately 77.5 lb when filled with Helium and deliver approximately 1453 ft 3  of Helium at standard temperature and pressure (STP) conditions. This gas volume will reduce Oxygen concentration to approximately 10.5% in a space of about 2000 ft 3  volume. This gas volume, from the second bottle, also maintains the oxygen concentration at approximately 10.5% in a 2000 ft 3  volume compartment for approximately 75 minutes if the compartment leakage rate is 40 cubic feet per minute. It will be appreciated that 10.5% oxygen concentration is substantially lower than the oxygen concentration generally accepted as necessary for fire suppression.  
         [0025]    The first bottle  12  and the second bottle  22  suitably include ancillary equipment such as pressure gauges, pressure transmitters, refilling ports, refilling ductwork or gas delivery apparatus, lifting handles, and installation hardware (not shown). The first bottle  12  and the second bottle  22  are connected to a plurality of airplane compartments, such as a first compartment  40  and a second compartment  42 . The first and second compartments  40  and  42  are suitably cargo compartments of an airplane. The Helium composition stored in the first bottle  12  is used to knock down a fire in either the first compartment  40  or the second compartment  42 . Thereafter the Helium composition stored in the second bottle  22  is used to maintain suppression of a knocked-down fire in either of the first or second compartments  40  and  42 .  
         [0026]    First piping  36  pneumatically connects the first and second bottles  12  and  22  to the first compartment  40  via a first section  33 , a second section  35 , and a first discharge pipe  52  located inside the first compartment  40 . The first discharge tube  52  may be positioned at any location in the first compartment  40 . The first section  33  includes a first squib  14  attached to the first bottle  12  and a first venturi  18  downstream from the first squib  14 . The second section  35  includes a second squib  24  attached to the second bottle  22 , a second venturi  28  downstream from the second squib  24 , and a first valve  32  downstream from the second venturi  28 . The first valve  32  is a pressure-regulating valve that limits the pressure in the second section  35 , downstream of the first valve  32 , to a designed pressure that controls the continuous flow of Helium compositions from the second bottle  22  to the first compartment  40 . The first and second squibs  14  and  24  release Helium from the first and second bottles  12  and  22 . The first venturi  18  reduces the flow of Helium to a first flow rate and Helium pressure in the first section  33 . The second venturi  28  reduces the flow of Helium to a second flow rate that is substantially less than the first flow rate and Helium pressure in the second section  35 . The first flow rate may be on the order of thousands of cubic feet per minute to rapidly reduce the oxygen concentration in the compartment and quickly knock down the fire. The second flow rate may be on the order of tens of cubic feet per minute (approximately half the estimated total compartment leakage) to maintain the depleted oxygen concentration in the cargo compartment and the fire suppressed. The first venturi  18  and the second venturi  28  include any orifice, restrictor, or similarly-functioning flow restriction device.  
         [0027]    Second piping  38  pneumatically connects the first and second bottles  12  and  22  to the second compartment  42  via a third section  37 , a fourth section  39 , and a second discharge tube  54  located inside the second compartment  42 . The second discharge tube  54  may be positioned at any location in the second compartment  42 . The third section  37  includes a third squib  16  attached to the first bottle  12  and a third venturi  20  downstream from the third squib  16 . The fourth section  39  includes a fourth squib  26  attached to the second bottle  22 , a fourth venturi  30  downstream from the fourth squib  26 , and a second valve  34  downstream from the fourth venturi  30 . The third and fourth squibs  16  and  26  release Helium from the first and second bottles  12  and  22 . The third venturi  20  reduces the flow of Helium to a first flow rate and Helium pressure in the third section  37 . The fourth venturi  30  reduces the flow of Helium and Helium pressure in the fourth section  39 . The second valve  34  is a pressure-regulating valve that limits the pressure in the third section  37 , downstream of the second valve  34 , to a designed pressure that controls the continuous flow of Helium compositions from the second bottle  22  to the first compartment  42 .  
         [0028]    An arming switch  60  is electrically connected to a discharge switch  62  that is, in turn, electrically connected to the first squib  14 . The arming switch  60 , when depressed, provides electrical power to the discharge switch  62 . An indicator  58  is electrically connected to the arming switch  60  and illuminates when the arming switch  60  is depressed, thus indicating to an operator that the first squib  14  has been successfully armed. The discharge switch  62 , when depressed, provides electrical power to the first squib  14 . This causes the first squib  14  to discharge, thus permitting the Helium to flow from the first bottle  12 .  
         [0029]    An indicator  64  is electrically connected to the first squib  14 . When the first squib  14  is energized, electrical power is supplied to the indicator  64 . This indicates to an operator that the first bottle  12  has discharged. The indicator  64  is also electrically connected to a pressure transducer (not shown) in the first bottle  12 . The indicator  64  extinguishes when pressure in the first bottle  12  falls below a selected pressure threshold, thereby indicating the first bottle  12  has emptied.  
         [0030]    According to the invention, the first compartment  40  and the second compartment  42  incorporate first and second discharge openings  48  and  50 , respectively. The discharge openings  48  and  50  are suitably any acceptable device that can be open and shut, shown without limitation in aperture or plurality of apertures in a range of apertures, guide vanes, a flapper valve, a butterfly valve, or the like. The discharge openings  48  and  50  selectively open and shut, as discussed in detail below, to permit discharge of ambient air (mixed with some helium agent) from the first and second compartments  40  and  42 , respectively. This permits the Helium to replace the ambient air, thus lowering the Oxygen concentration to a level that is unable to support combustion. Advantageously, this feature also prevents over pressurizing the first and second compartments  40  and  42  when large volumes of Helium are rapidly introduced into the first and second compartments  40  and  42 .  
         [0031]    A first actuator  44  is pneumatically connected to the second section  35  and a second actuator  46  is pneumatically connected to the third section  37 . The first and second actuators  44  and  46  are arranged to control opening and shutting of the first and second discharge openings  48  and  50 , respectively, in response to pressure in the second and third sections  35  and  37 , respectively. The first and second actuators  44  and  46  suitably include any acceptable actuator that translates pressure to a control signal or control motion. For example, in one embodiment the actuators  44  and  46  each include a piston (not shown) and a spring (not shown) that open and shut the first and second discharge opening  48  and  50  responsive to pressure sensed in the second and third sections  35  and  37 , respectively. Alternatively, the actuators  44  and  46  suitably include a pressure-sensing transducer that generates an electrical control signal that controls a motor that opens and shuts the discharge openings  48  and  50 .  
         [0032]    A timer  56  is electrically connected to the first squib  14  and the third squib  24 . When the first squib  14  is energized, the timer  56  is activated and the timer  56  begins counting for a predetermined time period that varies according to aircraft. The timer  56  is electrically connected to the second squib  24 . After the timer  56  has counted for the predetermined time period the timer  56  automatically activates the discharge switch  62 . This causes electrical power to be supplied from the discharge switch  62  to the second squib  24 , causing the second squib  24  to discharge and thereby permitting the Helium to flow from the second bottle  22 .  
         [0033]    An arming indicator  57 , an arming switch  59 , the discharge indicator  64 , and the third and fourth squibs  16  and  26  are provided along with the second actuator  46  and second discharge opening  50  to extinguish a fire in the second compartment  42 . The indicator  57 , arming switch  60 , discharge switch  62 , indicator  64 , third and fourth squibs  16  and  26 , timer  56 , second actuator  46  and second discharge opening  50  are interconnected as described above for similar components and operate in the same manner as described above for extinguishing a fire in the first compartment  40 . Accordingly, further detailed description of the construction and operation is not necessary for an understanding of the invention.  
         [0034]    Oxygen depletion to suppress compartment fire is accomplished by Helium free efflux flooding method to knock down compartment fire and by a Helium metered flow method to keep the fire suppressed after being first knocked-down. The free efflux flooding with Helium method uses Helium from the first bottle  12  and the Helium metered flow method uses Helium from the second bottle  22 .  
         [0035]    Each of the first and second compartments  40  and  42  suitably has a fire detection system (not shown). In the event of a fire occurring in either the first compartment  40  or the second compartment  42 , the present invention delivers Helium from the first bottle  12  in a rapid manner using the Helium free efflux flooding method and delivers Helium from the second bottle  22  in a continuous manner using the Helium metered flow method to the first compartment  40  or the second compartment  42 .  
         [0036]    The system  10  employs the Helium free efflux flooding method as follows. The following discussion explains suppression of fire in the first compartment  40  as a non-limiting example. It will be appreciated that fire in the second compartment  42  is suppressed in the same manner and need not be explained for an understanding of the invention. Fire warning signals are sent by the fire detection system (not shown) inside the first compartment  40 . On fire warning the user initiates the fire suppression process by arming the squibs  14  and  24  for the compartment  40  by depressing the arming switch  60 . Upon seeing the indicator  58  lit, that confirms that the first squib  14  is successfully armed, the user depresses the discharge switch  62 . Pressing the discharge switch  62  causes the first squib  14  to fire and allow the Helium compositions to flow out rapidly from the first bottle  12 . Also, pressing the discharge switch  62  causes the timer  56  to start. After a first time delay, the discharge switch  62  automatically fires the second squib  24 , thereby readying the system  10  for subsequent engagement of the Helium metered flow method. The Helium composition flows from the first bottle  12  and the second bottle  22  to the first compartment  40  via the first piping  36  and the first discharge tube  53 .  
         [0037]    Before the first squib  14  is activated to fire by the discharge switch  62  and the second squib  24  is activated to fire by the timer  56 , the first discharge opening  48  is closed. In concert with the pressure in the second section  35 , the first actuator  44  selects apertures among a first range of variable apertures included in the first discharge opening  48  and thus allows the overboard flow of compartment ambient air (mixed with some Helium). Helium rapidly discharges into the first compartment  40  through the first discharge tube  52  and simultaneously ambient air (mixed with some Helium) discharges overboard from the compartment  40  through the first discharge opening  48 . This causes free efflux flooding of the compartment  40  by the Helium compositions while rapidly reducing the Oxygen concentration in the compartment  40  to the design suppression concentration (typically below 12% is generally accepted as adequate for fire suppression).  
         [0038]    A pressure set-point graph shown in FIG. 1B illustrates how the first actuator  44  selects apertures among the first range of variable apertures in the first discharge opening  48 . The pressure set-point graph illustrates the first range of apertures as a discharge open percentage (Discharge Open %). The first pressure set point has a minimum pressure  81  and the second pressure set point is maximum pressure  85 . The discharge open percentage varies from fully closed (Discharge Open %=0%) when the first pressure set point  81  is set to the minimum pressure, to fully open (Discharge Open %=100%) when the second set point  85  is set to the maximum pressure. Pressure increases in the second section  35  as Helium is delivered from the first bottle  12 . When the pressure increases in the second section  35  above the minimum pressure  81  but lower than maximum pressure  85 , an intermediate aperture in the first discharge opening  48  is opened by the first actuator  44 .  
         [0039]    Thus, the first discharge opening is normally closed and starts to open when the pressure in the first actuator  44 , transmitted by the second section  35 , increases above the minimum pressure  81 . The first discharge opening  48  is fully open when the first actuator  44  pressure is equal or greater than the maximum pressure  85 .  
         [0040]    The system  10  employs the metered flow method for delivering a continuous supply of Helium for maintaining suppressed a knocked-down fire as follows. The timer automatically causes the discharge switch  62  to fire the squib  24  on the bottle  22  after elapse of the predetermined time period. Alternatively, the user presses the discharge switch  62 , after a predetermined time in the event the user chooses to operate the system manually causing the second squib  24  to fire. The firing of the second squib  24  causes Helium to flow from the second bottle  22  through the second venturi  28  and through the first pressure regulating valve  32  that is normally open. The pressure regulating valve  32  automatically controls the Helium pressure in the second section  35  to the designed value by throttling the upstream pressure. The pressure transducer (not shown) in the second bottle  22  detects the sudden change of pressure in the second bottle  22  and illuminates the discharge indicator  64 . The illuminated discharge indicator  64  confirms the continuous flow of Helium compositions are being delivered from the second bottle  22  to the first compartment  40 , such that the Oxygen concentration remains reduced inside the first compartment  40 , thereby keeping the fire suppressed.  
         [0041]    It will be appreciated by those experienced in the art that the invention utilizes “free efflux” flooding to quickly knockdown the fire. During free efflux flooding ambient air in the compartment is allowed to be displaced by the incoming Helium suppressant. The ambient air (mixed with some helium) is exhausted overboard through the variable discharge openings  48  and  50  in the compartments  40  and  42 , respectively. The replacement of outflowing compartment air with inflowing Helium suppressant maintains the compartment at low and approximately constant pressure and prevents damage to the compartment structure.  
         [0042]    It will be appreciated that other fire suppressant agents besides Helium may be used in the system  10 . For example, halogenated derivatives of methane, such as without limitation Bromotrifluoromethane, or any other gaseous fire suppressant such as inert gases can also be used as desired in the system  10 .  
         [0043]    A second embodiment of the invention suppresses fires primarily involving combustible fluids and similarly uses the total flood fire suppression system having the two-bottle system, but differs in how the second bottle is used. By way of overview and like the first embodiment of the invention, ambient Oxygen in the space is rapidly depleted to levels unable to sustain combustion using rapid Helium flow or flood delivered by the first bottle. However, should the initially suppressed fire flare up again, or the fire not be sufficiently suppressed using the first bottle, then a secondary Helium flow or flood is delivered to the space using the second bottle. The second embodiment of the invention does not use the actuators and discharge openings to facilitate overboard discharge of ambient compartment air and is useful in suppression of fire in compartments that are normally ventilated.  
         [0044]    An application of the second embodiment of the invention delivers Helium to at least one engine nacelle from the first bottle. Should the engine nacelle fire be extinguished but then flare up (re-ignition by hot surfaces), or if the engine nacelle fire be not sufficiently extinguished with Helium from the first bottle, then the secondary Helium flow or flood is delivered to the engine nacelle from the second bottle.  
         [0045]    [0045]FIG. 2 shows a Helium total fire suppression system  100  for a plurality of airplane engine nacelles. The engine nacelles may be wing mounted, fuselage mounted, or wing and fuselage mounted. Each engine nacelle has a fire detection system (not shown). According to the present invention, the system  100  utilizes a fire suppressant containing a Helium composition, and is stored in a plurality of storage bottles or reservoirs such as a first bottle  102  and a second bottle  104 . The first bottle  102  and the second bottle  104  are comparably constructed as the first and the second bottles  12  and  22  of system  10  (FIG. 1A). The first bottle  102  and the second bottle  104  each have ancillary equipment such as pressure gauges, pressure transmitters, refilling ports, refilling ductwork or gas delivery apparatus, lifting handles, and installation hardware (not shown).  
         [0046]    First piping  110  pneumatically connects the first and second bottles  102  and  104  to the first engine nacelle  106  via a first section  111  and a second section  112 . The first section  111  includes a first squib  114  attached to the first bottle  102  and a first venturi  122  downstream from the first squib  114 . The second section  112  includes a second squib  118  attached to the second bottle  104 , and a second venturi  126  downstream from the second squib  118 . The first and second squibs  114  and  118  release Helium from the first and second bottles  102  and  104 . The first venturi  122  reduces the flow of Helium in the first section  111 . The second venturi  126  reduces the flow of Helium in the second section  112 .  
         [0047]    Second piping  113  pneumatically connects the first and second bottles  102  and  104  to a second engine nacelle  108  via a third section  115  and a fourth section  117 . The third section  115  includes a third squib  116  attached to the first bottle  102  and a third venturi  124  downstream from the third squib  116 . The fourth section  117  includes a fourth squib  120  attached to the second bottle  104  and a fourth venturi  128  downstream from the fourth squib  120 . The third and fourth squibs  116  and  120  release Helium from the first and second bottles  102  and  104 . The third venturi  124  reduces the flow of Helium in the third section  115 . The fourth venturi  128  reduces the flow of Helium in the fourth section  117 .  
         [0048]    The first and second squibs  114  and  118  are electrically connected to a first discharge switch  134  that has a first position and a second position. The second and third squibs  116  and  120  are electrically connected to a second discharge switch  136  that has a first position and a second position. The first position of the first discharge switch  134  activates the first squib  114  to release Helium from the first bottle  102 . The second position of the first discharge switch  134  activates the second squib  118  attached to the second bottle  104  to release Helium from the second bottle  104 . The first position of the second discharge switch  136  activates the third squib  116  to release Helium from the first bottle  102 . The second position of the second discharge switch  136  activates the fourth squib  120  attached to the second bottle  104  to release Helium from the second bottle  104 .  
         [0049]    The first engine nacelle  106  suitably has a first fire detection circuit (not shown) and a first engine fire warning annunciator (not shown). The second engine nacelle  108  suitably has a second fire detection circuit (not shown) and a second engine nacelle fire warning annunciator (not shown).  
         [0050]    The need to suppress a fire in the first engine nacelle  106  is determined by activation of the first engine fire warning annunciator. Upon fire annunciation in first engine nacelle  106 , the user closes the thrust reverser lever of the first engine and shuts off fuel to the engine by engagement of a fuel control switch (not shown) to a cutoff position. The first squib  114  is activated by the first discharge switch  134  being placed in the first position by the user for a short duration (such as approximately one second). Helium is then discharged from the first bottle  102  through the first squib  114 , passes through the first venturi  122 , and is reduced in flow rate and pressure inside the first section  111 . From the first section  111 , the Helium is delivered via the first piping  110  to the first engine nacelle  106  as a first knockdown flow or flood. The first knockdown flow or flood of Helium continues until the first bottle  102  empties its contents. The sudden drop in pressure in the first bottle  102  on squib discharge is detected by a pressure transducer (not shown) mounted on the first bottle  102 . The transducer causes a first discharge light  138  to illuminate and stay illuminated until the first bottle  102  is empty. This confirms successful discharge of the first bottle  102 . Should the fire persist as indicated by continued annunciation by the first engine fire warning annunciator for longer than a predetermined time, a second knockdown Helium flow or flood is delivered from the second bottle  104  to the first engine nacelle  106  by the first discharge switch  134  being placed into the second position by the user for a short duration (approximately one second). This activates the second squib  118  attached to the second bottle  104 . Helium is then discharged from the second bottle  104  through the second squib  118 , passes through the second venturi  126 , and is reduced in flow rate and pressure inside the second section  112 . From the second section  112 , the Helium is delivered via the first piping  110  to the first engine nacelle  106  as a second knockdown flow or flood. The second knockdown flow or flood of Helium continues until the second bottle empties its contents. The sudden drop in pressure in the bottle  104  on squib discharge is detected by a pressure transducer (not shown) mounted on the second bottle  104 . The transducer causes a discharge light  140  to illuminate and stay illuminated until the bottle  104  is empty. This confirms successful discharge of the second bottle  104 .  
         [0051]    Knocking down a fire in the second engine nacelle  108  is performed in the same manner as described above. For a fire in the second engine nacelle  108 , the second discharge switch  136  is operated by the user in the manner described above to discharge the third and fourth squibs  116  and  120  in the manner described above. Further description of knocking down a fire in the second engine nacelle  108  is not necessary for an understanding of the invention.  
         [0052]    A third embodiment of the invention is an integration of the features of the first and second embodiments of the invention to suppress a fire either in a cargo compartment or in an engine nacelle using the same Helium reservoirs. By way of overview and in the event of a fire in the cargo compartment, the cargo compartment enclosure is provided a rapid flow of Helium from a first bottle, followed after a designed time delay by metered Helium delivered as a continuous flow as determined by a pressure regulating valve. For a flammable fluid fire, such as that may occur in an engine nacelle, the fuel source is first isolated from the fire by shutting off the fuel flow and then the nacelle enclosure is rapidly flooded with Helium from the first bottle to reduce the Oxygen concentration in the nacelle to suppress the fire. Should suppression fail or the fire subsequently flare up, the nacelle enclosure is rapidly flooded with Helium from a second bottle.  
         [0053]    An application of the third embodiment of the invention is an airplane with at least one cargo compartment and at least one engine nacelle. Fire occurring in a cargo compartment is extinguished with the knockdown flow of Helium delivered from the first bottle, followed by continuous flow of Helium delivered by the second bottle. Flammable fluid fire occurring in the engine nacelle is extinguished by first isolating the engine from its fuel source, then rapidly delivering Helium from the first bottle to suppress the engine nacelle fire and, if needed, rapidly delivering Helium from the second bottle to extinguish the engine nacelle fire.  
         [0054]    [0054]FIG. 3A shows an integrated Helium total fire suppression system  300  for airplane engines and compartments. The system  300  includes a compartment subsystem and an engine subsystem that include features of the cargo compartment system  10  (FIG. 1A) and the engine suppression system  100  (FIG. 2), using Helium or Helium blended with inert gases. The system  300  has fire warning systems (not shown) for the cargo compartments and engine nacelles. The fire warning system includes annunciators such as lights, noise alarms, or vibration-generating devices.  
         [0055]    The compartment subsystem includes a fire suppressant containing Helium compositions that is stored in a first bottle  312  and a second bottle  322 . The first and second bottles  312  and  322  are similarly constructed as the first and second bottles  12  and  22  of system  10  (FIG. 1A). The first and second bottles  312  and  322  have ancillary equipment such as pressure gauges, pressure transmitters, refilling ports, lifting handles, and installation hardware (not shown).  
         [0056]    The first bottle  312  is used to knock down fire in a plurality of cargo compartments, such as a first compartment  340  and a second cargo compartment  342 . The first compartment  340  has a first fire detection system (not shown) and the second compartment  342  has a second fire detection system (not shown).  
         [0057]    The Helium composition from the first bottle  312  is delivered to the first compartment  340  via first piping  336 . The first piping  336  pneumatically connects the first bottle  312  to the first compartment  340  via a first section  335  and a first discharge tube  352  located inside the first compartment  340 . The Helium composition from the second bottle  322  is delivered to the first compartment  340  via a second section  333  and the second discharge tube  352 . A first squib  314 , attached to the first bottle  312 , is attached to the first section  335 . Inside the first section  335  is a first venturi  318  downstream from the first squib  314 . The first venturi  318  reduces the Helium flow inside the first section  335 . A second squib  324 , attached to the second bottle  322 , is attached to the second section  333 . Inside the second section  333  is a second venturi  329  downstream from the second squib  324  and a first valve  332  downstream from the second venturi  329 . The second venturi  329  reduces the Helium flow inside the second section  333 .  
         [0058]    A first actuator  344  and a first discharge opening  348  are located preferably at the bottom of the first compartment  340 . Construction and operation of the first discharge opening  348  and the first actuator  344  are the same as set forth above for the discharge opening and actuators for the system  10  (FIG. 1A). Fire occurring in the first compartment  340  is suppressed using the Helium free efflux flooding flow and Helium metered flow methods described for the system  10  (FIG. 1A).  
         [0059]    The Helium composition from the first bottle  312  is delivered to the second compartment  342  via second piping  338 . The second piping  338  pneumatically connects the first bottle  312  to the second compartment  342  via a third section  337  and a second discharge tube  354  located inside the second compartment  342 . The Helium composition from the second bottle  322  is delivered to the second compartment  342  via a fourth section  339  and the second discharge tube  354 . A third squib  316 , attached to the first bottle  312 , is attached to the third section  337 . Inside the third section  337  is a third venturi  320  downstream from the third squib  316 . The third venturi  320  reduces the Helium flow inside the third section  337 . A fourth squib  326 , attached to the second bottle  322 , is attached to the fourth section  339 . Inside the fourth section  339  is a fourth venturi  330  downstream from the fourth squib  326  and a second valve  334  downstream from the fourth venturi  330 . The fourth venturi  330  and the second valve  334  reduce the Helium flow inside the fourth section  339 .  
         [0060]    A second actuator  346  and a second discharge opening  350  are located preferably at the bottom of the second compartment  342 . Construction and operation of the discharge opening  350  and the second actuator  346  are the same as set forth above for the discharge openings and actuators for the system  10  (FIG. 1A). Fire occurring in the second compartment  342  is extinguished using the Helium pressure flow and Helium metered flow methods described for the system  10  (FIG. 1A).  
         [0061]    The engine subsystem of the system  300  also includes the first bottle  312  and the second bottle  322 . The system  300  delivers a primary knockdown Helium flood and a secondary knockdown Helium flood to fires located inside a plurality of aircraft engine nacelles such as a first engine nacelle  306  and a second engine nacelle  308 . The first engine nacelle  306  has a third fire detection system (not shown) and the second engine nacelle  308  has a fourth fire detection system (not shown). Third piping  310  pneumatically connects the first bottle  312  to the first engine nacelle  306  via a fifth section  309 . The fifth section  309  connects to the first bottle  312  via a fifth squib  370 . Downstream from the fifth squib  370  is a fifth venturi  378  that lowers Helium flow and Helium pressure in the fifth section  309 .  
         [0062]    The third piping  310  pneumatically connects the second bottle  322  to the first engine nacelle  306  via a sixth section  311 . The sixth section  311  connects to the second bottle  322  via a sixth squib  374 . Downstream from the sixth squib  374  is a sixth venturi  382  that lowers Helium flow in the sixth section  311 .  
         [0063]    Fourth piping  313  pneumatically connects the first bottle  312  to the second engine nacelle  308  via a seventh section  317 . The seventh section  317  connects to the first bottle  312  via a seventh squib  372 . Downstream from the seventh squib  372  is a seventh venturi  380  that lowers Helium flow in the seventh section  317 .  
         [0064]    The fourth piping  313  pneumatically connects the second bottle  322  to the second engine nacelle  308  via an eighth section  315 . The eighth section  315  connects to the second bottle  322  via an eighth squib  376 . Downstream from the eighth squib  376  is an eighth venturi  384  that lowers Helium flow in the eighth section  315 .  
         [0065]    Fire occurring in either the first engine nacelle  306  or the second engine nacelle  308  is extinguished via the same methods described above for the system  100  (FIG. 2) using the same squib activation circuits (not shown) used in the system  100 .  
         [0066]    Although Helium compositions are the preferred fire suppressant utilized in the integrated system shown in FIG. 3A, it will be appreciated by those experienced in the art that other gaseous fire suppressants such as halocarbons, halogenated methane (Halon 1301), inert gases, etc., may also be used.  
         [0067]    The bottles  312  and  322  of the system  300  contain the Helium compositions required to suppress the fire occurring in the cargo compartment or engine nacelle. Those experienced in the art will appreciate that this aspect of the invention results in use of fewer fire suppression agent bottles and lower mass of total fire suppressant carried on board the airplane. Also, this results in greater fire suppression capability for the non-critical fires. The non-critical fire is defined herein as the fire that requires lower quantity of fire suppression agent than that available on board. For typical commercial airplanes, the noncritical fire would be engine nacelle fire.  
         [0068]    It will be appreciated that the number of Helium reservoirs of the present invention is not limited to the dual body reservoir system of the preferred embodiments. More than two reservoirs can be used, with each reservoir having a plurality of piping not limited to a dual piping set. Alternatively, FIG. 3B represents an alternate non-limiting example of the Helium reservoir or bottle used in the system  300 . The Helium reservoir may be used to replace the first bottle  312  or the second bottle  322 . A Helium reservoir  400  has a single manifold  404  attached to a single bottle  402 . The single manifold  404  has a first squib  406 , a second squib  408 , a third squib  410 , and a fourth squib  412 . The piping sections  309 ,  317 ,  336  and  337  of the bottle  312  are connected to the single manifold  404  with the set of four squibs  406 ,  408 ,  410 , and  412 . Similarly, the piping sections  311 ,  315 ,  333  and  339  are connected to the single manifold  404  with the set of four squibs  406 ,  408 ,  410 , and  412 .  
         [0069]    [0069]FIG. 4 is a partial cutaway, perspective view of airplane compartments incorporating the systems of the present invention arranged in an airplane  500 . The first compartment  40  is located in a forward section of a fuselage and the second compartment  42  is located in an aft section of the fuselage of the airplane  500 . The first bottle and the second bottle are located just aft of the first compartment  40 . The pictorial representation of FIG. 4 represents one configuration given by way of non-limiting example. It will be appreciated that many alternative arrangements of the compartment configuration are possible.  
         [0070]    [0070]FIG. 5 shows schematic and pictorial details of an engine nacelle configuration incorporating the system of the present invention arranged in an airplane  600 . The first bottle  102 , the first piping  110 , the first section  111 , the second section  112 , the second bottle  104 , the second piping  113 , the third section  115 , and the fourth section  117  are schematically and pictorially displayed in the airplane  600 . The first discharge switch  134  and the second discharge switch  136  are shown as part of an instrument panel  610  located approximately at a center section of the airplane  600 . The discharge switch  134  controls the delivery of Helium gas from the first bottle  102  and from the second bottle  104  to the first engine nacelle  106 . The discharge switch  136  controls the delivery of Helium gas from the first bottle  102  and the second bottle  104  to the second engine nacelle  108 . The first bottle  102  and the second bottle  104  are shown located approximately at a center section  620  of the airplane  600 . The schematic and pictorial representation of FIG. 5 represents a single configuration example. It will be appreciated that many alternative arrangements of the engine nacelle configuration are possible.  
         [0071]    While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.