Patent Publication Number: US-7216722-B2

Title: Fire extinguishing mixtures, methods and systems

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 10/418,781 filed on Apr. 17, 2003; the entirety of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     There are a multitude of known fire extinguishing agents, and methods and systems for using the same. The mechanism by which these fire extinguishing agents extinguish a fire can vary from agent to agent. For instance, some fire extinguishing agents operate by inerting or diluting mechanisms that act to deprive the fire of necessary chemicals, such as oxygen or fuels. Other fire extinguishing agents operate chemically to extinguish a fire. Such chemical actions may include scavenging free radicals, thereby breaking the reaction chain required for combustion. Still, other fire extinguishing agents operate thermally to cool the fire. 
     Traditionally, certain bromine-containing compounds such as Halon 1301 (CF 3 Br), Halon 1211 (CF 2 BrCl), and Halon 2402 (BrCF 2 CF 2 Br) have been used as fire extinguishing agents for the protection of occupied rooms. Although these Halons are effective fire extinguishing agents, some believe that they are harmful to the earth&#39;s protective ozone layer. As a result, the production and sale of these agents has been prohibited. 
     Relatively recently, fluorocarbons such as hydrofluorocarbons, fluoroethers and fluorinated ketones have also been proposed as effective fire extinguishing agents. Fluorocarbon systems may be relatively inefficient and can be high in cost. In addition, some fluorocarbon fire extinguishing agents may react in the flame to form various amounts of decomposition products, such as HF. In sufficient quantities, HF is corrosive to certain equipment and poses a significant health threat. 
     In addition to fluorocarbon agents, inert gases have been proposed as replacements for the Halon fire extinguishing agents. Gases such as nitrogen or argon, and also blends, such as a 50:50 blend of argon and nitrogen have been proposed. These agents can be very inefficient at fire extinguishing, and as a result, significant amounts of the gas are necessary to provide extinguishment. The large amounts of gases required for extinguishment results in the need for a large number of storage cylinders to store the agent, and ultimately, large storage rooms to house the gas storage cylinders. 
     Hybrids of fluorocarbons and gas blends have also been proposed as fire extinguishing agents. For example, U.S. Pat. No. 6,346,203 to Robin et al. proposes delivering to the fire gas and fluorocarbon fire extinguishing agents. 
     Finally, water mists have also been used for the suppression of compartment fires. Hybrid fire extinguishing systems utilizing a water mist followed by the application of either fluorocarbon or gas agents have been proposed. 
     It would desirable to develop improved fire extinguishing agents and systems. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention provides fire extinguishing mixtures that include a diluent gas and a extinguishing compound such as fluoroethers, bromofluorocarbons, fluoroketones, and/or mixtures thereof. 
     Another aspect of the present invention provides a fire extinguishing mixture comprising water, a diluent gas, and an extinguishing compound that includes fluorocarbons such as hydrofluorocarbons, fluoroethers, bromofluorocarbons, fluoroketones and/or mixtures thereof. 
     In another aspect, a fire extinguishing mixture is provided comprising water and an extinguishing compound that includes fluorocarbons, such as hydrofluorocarbons, fluoroethers, bromofluorocarbons, fluoroketones and/or mixtures thereof. 
     In another aspect, a fire extinguishing mixture is provided that comprises an extinguishing compound that includes fluorocarbons such as hydrofluorocarbons, fluoroethers, bromofluorocarbons, fluoroketones and/or mixtures thereof, and a suppressing additive that includes diluent gases, water and/or mixtures thereof. 
     Fluoroketones useful in accordance with the present invention include CF 3 CF 2 C(O)CF(CF 3 ) 2 , (CF 3 ) 2 CFC(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 2 C(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 3 C(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 5 C(O)CF 3 , CF 3 CF 2 C(O)CF 2 CF 2 CF 3 , CF 3 C(O)CF(CF 3 ) 2 , perfluorocyclohexanone and/or mixtures thereof. 
     Fluoroethers useful in accordance with the present invention include CF 3 CHFCF 2 OCHF 2 , CF 3 CHFCF 2 OCF 3 , (CF 3 ) 2 CHOCHF 2 , CHF 2 CF 2 OCF 2 , CF 3 CFHOCHF 2 , CF 3 CFHOCF 3 , CF 2 ═C(CF 3 )OCF 3 , CF 2 ═C(CF 3 )OCHF 2 , CF 3 CF═CFOCHF 2 , CF 2 ═CFCF 2 OCHF 2 , CF 3 CF═CFOCF 3 , CF 2 ═CFCF 2 OCF 3  CF 3 CH═CFOCHF 2 , CF 3 CH═CFOCF 3 , CF 3 CHBrCF 2 OCF 3 , CF 3 CFBrCF 2 OCHF 2 , CF 3 CHFCF 2 OCH 2 Br, CF 2 BrCF 2 OCH 2 CF 3 , CHF 2 CF 2 OCH 2 Br and/or mixtures thereof. 
     Fluorocarbons useful in accordance with the present invention include trifluoromethane (CF 3 H), pentafluoroethane (CF 3 CF 2 H), 1,1,1,2-tetrafluoroethane (CF 3 CH 2 F), 1,1,2,2-tetrafluoroethane (HCF 2 CF 2 H), 1,1,1,2,3,3,3-heptafluoropropane (CF 3 CHFCF 3 ), 1,1,1,2,2,3,3-heptafluoropropane (CF 3 CF 2 CF 2 H), 1,1,1,3,3,3-hexafluoropropane (CF 3 CH 2 CF 3 ), 1,1,1,2,3,3-hexafluoropropane (CF 3 CHFCF 2 H), 1,1,2,2,3,3-hexafluoropropane (HCF 2 CF 2 CF 2 H), 1,1,1,2,2,3-hexafluoropropane (CF 3 CF 2 CH 2 F), 1,1,1,2,2-pentafluorobutane (CF 3 CH 2 CF 2 CH 3 ), CF 3 CBr═CH 2 , CF 3 CH═CHBr, CF 2 BrCH═CH 2 , CF 2 BrCF 2 CH═CH 2 , CF 3 CBr═CF 2  and/or mixtures thereof. 
     In an aspect of the present invention, methods are provided for extinguishing, suppressing and/or preventing fires using the mixtures of the present invention. 
     In an aspect of the present invention, fire extinguishing, preventing and/or suppressing systems that deliver the mixtures of the present invention are disclosed. 
     In an aspect of the present invention, a method for extinguishing a fire in a room comprising introducing water to the room; introducing a diluent gas into the room; and introducing an extinguishing compound. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 . is an illustration of an application of extinguishing mixtures in accordance with an aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     The present invention provides fire extinguishing mixtures which comprise blends of extinguishing agents that extinguish fires through inertion, and/or dilution, as well as, chemical, and/or thermal extinguishment. The present invention also provides methods of extinguishing, preventing and/or suppressing a fire using such fire extinguishing mixtures. The present invention further provides fire extinguishing, preventing and/or suppressing systems for delivering such fire extinguishing mixtures. Exemplary aspects of the present invention are described with reference to  FIG. 1   
     Referring to  FIG. 1 , a space  17  configured with a fire extinguishing system  1  is shown. Fire extinguishing system  1  includes an extinguishing compound storage vessel  3  contiguous with an extinguishing compound dispersing nozzle  7 . As depicted, a combustion  11  occurs within a pan  13  on a pedestal  15 . An extinguishing mixture  9  exists within space  17  and is applied to the combustion to substantially extinguish the flame. 
     While depicted in two dimensions, space  17 , for purposes of this disclosure, should be considered to have a volume determined from its dimensions (e.g., width, height and length). While  FIG. 1  illustrates a system configured for extinguishing fires with in a space that as illustrated appears to be enclosed, the application of the mixtures, systems and methods of the present invention are not so limited. In some aspects, the present invention may be used to extinguish fires in open spaces as well as confined spaces. 
     All combustion suitable for extinguishment, suppression or prevention using the mixtures of the present invention or utilizing the methods and systems according to the present invention, are at least partially surrounded a space. The available volume of this space can be filled with the compositions of the present invention to extinguish, suppress and/or prevent combustion. Typically the available volume is that volume which can be occupied by a liquid or a gas (i.e. that volume within which fluids (gases and liquids) can exchange). Solid constructions are typically are not part of the available volume. 
     Furthermore,  FIG. 1  illustrates a single extinguishing agent storage vessel  3 . It should be understood that extinguishing mixture  9  can be provided to room  17  from multiple extinguishing agent storage vessels  3  and the present invention should not be limited to mixtures that can be provided from a single vessel nor methods or systems that utilize a single vessel. Generally, combustion  11  is extinguished when extinguishing mixture  9  is introduced from vessel  3  through nozzle  9  to space  17 . 
     In one aspect of the present invention extinguishing mixture  9  can comprise, consist essentially of and/or consist of an extinguishing compound and a suppressing additive. In another aspect, extinguishing mixture  9  can comprise, consist essentially of and/or consist of an extinguishing compound and a diluent gas. In a further aspect, extinguishing mixture  9  can comprise, consist essentially of and/or consist of an extinguishing compound and water. In still another aspect, extinguishing mixture  9  can comprise, consist essentially of and/or consist of an extinguishing compound, a diluent gas and water. 
     The suppressing additive employed can include diluent gases, water and/or mixtures thereof. Exemplary diluent gases can include nitrogen, argon, helium, carbon dioxide and/or mixtures thereof. In an exemplary aspect these gases can deprive fires of necessary fuels, such as oxygen. In the same or other aspects these diluent gases resist decomposition when exposed to combustion. In some cases these gases are referred to as inert gases. An exemplary diluent gas can comprise, consist essentially of, and/or consist of nitrogen. In one aspect, the concentration of the diluent gas is from about 5% (v/v) to about 26% (v/v). In another aspect the diluent gas may be employed at a concentration of from about 8% (v/v) to about 32% (v/v). In another aspect the diluent gas may be employed at a concentration of from about 4% (v/v) to about 13% (v/v). 
     It should be understood that the % (v/v) values set forth in this description and in the claims are based on space volume and refer to the design concentration as adopted and described by the National Fire Protection Association in NFPA 2001,  Standard on Clean Agent Fire Extinguishing , 2000 edition, the entirety of which is incorporated by reference herein. The equation used to calculate the concentration of the diluent gas is as follows:
 
 X= 2.303( Vs/s )log 10 (100/100 −C )
 
where:
         X=volume of diluent gas added (at standard conditions of 1.013bar, 21° C.), per volume of hazard space. (m 3 )   V s =specific volume of diluent gas agent at 21° C. and 1.013 bar.   s=specific volume of diluent gas at 1 atmosphere and temperature, t (m 3 /kg)   t=minimum anticipated temperature of the protected volume (°C.)   C=diluent gas design concentration (%)       

     In another aspect of the present invention, the suppressing additive includes water. Water may be stored and delivered by any standard water storage and delivery system. In one aspect, the water is delivered at a pressure from about 34 kPa to about 690 kPa and, in another aspect it is delivered at a pressure from about 69 kPa to about 827 kPa. In one aspect, the water is delivered at a flow rate of from about 0.03532 L\min\m 3  to about 1.06 L\min\m 3  and, in another aspect, from about 0.1766 L\min\m 3 to about 0.71 L\min\m 3 . 
     Water may exist in the fire extinguishing mixture in the form of droplets, fog, steam, gas and/or mixtures thereof. In the case of droplets, the majority of water particles can be about 100 μm or less in diameter, and/or from about 20 μm to about 30 μm. 
     In the case of fog, the majority of water particles can be from about 1 μm to about 10 μm in diameter. The fog may be produced and delivered using any technique and/or system known in the art such as dual injections nozzle system. Fog might also be produced using a higher pressure nozzle system. 
     In the case of steam, the water may have particle sizes of less than 1 μm and may be produced and delivered using any known technique or system for vaporizing water. 
     The extinguishing compound can include fluorocarbons such as fluoroketones, fluoroethers and/or mixtures thereof. 
     Fluoroketones useful as extinguishing compounds in accordance with the present invention can include CF 3 CF 2 C(O)CF(CF 3 ) 2 , (CF 3 ) 2 CFC(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 2 C(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 3 C(O)CF(CF 3 ) 2 , CF 3 (CF 2 ) 5 C(O)CF 3 , CF 3 CF 2 C(O)CF 2 CF 2 CF 3 , CF 3 C(O)CF(CF 3 ) 2 , perfluorocyclohexanone and/or mixtures thereof. The extinguishing mixture can comprise from about 0.2% (v/v) to about 10% (v/v) fluoroketone, in some applications, from about 0.1% (v/v) to about 6% (v/v) fluoroketone and, in particular applications from about 0.5% (v/v) to about 4% (v/v) fluoroketone. The fluoroketone can comprise, consist essentially of and/or consist of CF 3 CF 2 C(O)CF(CF 3 ) 2 . In another aspect, the extinguishing mixture comprises from about 1.7% (v/v) to about 3.8% (v/v) CF 3 CF 2 C(O)CF(CF 3 ) 2 . 
     The equation used to calculate the concentrations of extinguishing compounds has likewise been adopted by the National Fire Protection Association and is as follows:
 
 W=V/s ( C/ 100 −C )
 
Where:
         W=weight of extinguishing compound (kg)   V=volume of test space (m 3 )   s=specific volume of extinguishing compound at test temperature (m 3 /kg)   C=concentration (% (v/v))       

     In another aspect of the present invention, the extinguishing compound can be selected from the group of fluoroethers consisting of CF 3 CHFCF 2 OCHF 2 , CF 3 CHFCF 2 OCF 3 , (CF 3 ) 2 CHOCHF 2 , CHF 2 CF 2 OCF 2 , CF 3 CFHOCHF 2 , CF 3 CFHOCF 3 , CF 2 ═C(CF 3 )OCF 3 , CF 2 ═C(CF 3 )OCHF 2 , CF 3 CF═CFOCHF 2 , CF 2 ═CFCF 2 OCHF 2 , CF 3 CF═CFOCF 3 , CF 2 ═CFCF 2 OCF, CF 3 CH═CFOCHF 2 , CF 3 CH═CFOCF 3 , CF 3 CHBrCF 2 OCF 3 , CF 3 CFBrCF 2 OCHF 2 , CF 3 CHFCF 2 OCH 2 Br, CF 2 BrCF 2 OCH 2 CF 3 , CHF 2 CF 2 OCH 2 Br and/or mixtures thereof. 
     The extinguishing mixture can comprise from about 0.2% (v/v) to about 5.8% (v/v) fluoroether, in some applications from about 0.1% (v/v) to about 6.0% (v/v) fluoroether and, in particular applications from about 0.1% (v/v) to about 4.8% (v/v) fluoroether. The fluoroether can comprise, consist essentially of and/or consist of CF 3 CHFCF 2 OCHF 2 . In another aspect, the extinguishing mixture can comprise from about 0.1% (v/v) to about 4.8% (v/v) CF 3 CHFCF 2 OCHF 2 . 
     In another aspect of the present invention, the extinguishing mixture can include a bromofluoropropene selected from the group consisting of CF 3 CBr═CH 2 , CF 3 CH═CHBr, CF 2 BrCH═CH 2 , CF 2 BrCF 2 CH═CH 2 , and/or mixtures thereof. The extinguishing mixture can comprise from about 0.2% (v/v) to about 5% (v/v) bromofluoropropene, in some applications from about 0.1% (v/v) to about 5% (v/v) bromofluoropropene and, in particular applications, from about 1 % (v/v) to about 3% (v/v) bromofluoropropene. The bromofluoropropene can comprise, consist essentially of and/or consist of CF 3 CBr═CH 2 . In an application, the extinguishing mixture can comprise from about 0.2% (v/v) to about 4.2% (v/v) CF 3 CBr═CH 2 , and, in some applications from about 0.2% (v/v) to about 3.0% (v/v) CF 3 CBr═CH 2 . 
     In another aspect, the extinguishing mixture can include hydrofluorocarbons selected from the group consisting of trifluoromethane (CF 3 H), pentafluoroethane (CF 3 CF 2 H), 1,1,1,2-tetrafluoroethane (CF 3 CH 2 F), 1,1,2,2-tetrafluoroethane (HCF 2 CF 2 H), 1,1,1,2,3,3,3-heptafluoropropane (CF 3 CHFCF 3 ), 1,1,1,2,2,3,3-heptafluoropropane (CF 3 CF 2 CF 2 H), 1,1,1,3,3,3-hexafluoropropane (CF 3 CH 2 CF 3 ), 1,1,1,2,3,3-hexafluoropropane (CF 3 CHFCF 2 H), 1,1,2,2,3,3-hexafluoropropane (HCF 2 CF 2 CF 2 H), 1,1,1,2,2,3-hexafluoropropane (CF 3 CF 2 CH 2 F) and/or mixtures thereof. In one aspect, the extinguishing mixture can comprise from about 1% (v/v) to about 10% (v/v) hydrofluorocarbon and, in some applications, from about 3% (v/v) to about 6% (v/v) hydrofluorocarbon. The hydrofluorocarbon can comprise, consist essentially of and/or consist of heptafluoropropane. In one aspect, the extinguishing mixture can comprise from about 4% (v/v) to about 9% (v/v) heptafluoropropane. 
     Referring again to  FIG. 1 , systems according to the present invention provide for the storage and discharge of the extinguishing mixtures described above. In an exemplary aspect, the extinguishing compound may be stored in vessel  3  connected via appropriate piping and valves to discharge nozzle  7  located proximate space  17 . Vessel  3  may be connected to the same nozzle  7  used to discharge the gas and/or water stored in the same or alternative vessel. Vessel  3  may be a conventional fire extinguishing agent storage cylinder fitted with a dip tube to afford delivery of the extinguishing compound, diluent gas and/or water through a piping system. The extinguishing compound in the cylinder may be super-pressurized in the cylinder using nitrogen or another gas, typically to levels of 360 or 600 psig. In the case of lower boiling extinguishing compounds, the extinguishing compound may be stored in and delivered from the vessel without the use of any super-pressurization. 
     In another aspect, an extinguishing system of the present invention can provide for storing the extinguishing compound as a pure material in vessel  3  to which can be connected a pressurization system (not shown) that may include the diluent gas and/or water. In this case, the extinguishing compound can be stored as a liquid in vessel  3  under its own equilibrium vapor pressure at ambient temperatures, and upon detection of a fire, vessel  3  may be pressurized by suitable means. Once pressurized to the desired level, the delivery of extinguishing mixture  9  can be activated. One method useful for delivering extinguishing mixture  9  to an enclosure is referred to as a “piston flow” method and is described in Robin, et al. U.S. Pat. No. 6,112,822, which is hereby incorporated by reference. 
     Methods according to the present invention include those methods that provide the extinguishing mixtures of the present invention. In one aspect, a method can include delivering water, diluent gas, and the extinguishing compound to a space simultaneously upon detection of the fire. In another aspect, upon detection of the fire the delivery of the water may be initiated first. Delivery of the diluent gas can be initiated at a later time, either during or after the water discharges. Delivery of the extinguishing compound can then be initiated after initiation of the delivery of the diluent gas. 
     In another aspect, methods according to the present invention provide for the delivery of both the water and the diluent gas simultaneously followed by the delivery of the extinguishing compound, either during or after the discharge of the diluent gas and water. In yet another aspect, the delivery of the diluent gas may be initiated prior to the initiation of the delivery of the water. Delivery of the water and extinguishing compound is then initiated either during or after the diluent gas is discharged. 
     The invention will be further described with reference to the following specific examples. However, it will be understood that these examples are illustrative and not restrictive in nature. 
     EXAMPLE I 
     Extinguishing concentrations of the fluoroketone CF 3 CF 2 C(O)CF(CF 3 ) 2  were determined using a cup burner apparatus, as described in M. Robin and Thomas F. Rowland, “Development of a Standard Cup Burner Apparatus: NFPA and ISO Standard Methods, 1999 Halon Options Technical Working Conference, Apr. 27–29, 1999, Albuquerque, N.Mex.” and incorporated herein by reference. The cup burner method is a standard method for determining extinguishing mixtures, and has been adopted in both national and international fire suppression standards. For example NFPA 2001 Standard on Clean Agent Fire Extinguishing Systems and ISO 14520-1: Gaseous Fire-Extinguishing Systems, both utilize the cup burner method. 
     A mixture of air, nitrogen and CF 3 CF 2 C(O)CF(CF 3 ) 2  was flowed through an 85-mm (ID) Pyrex chimney around a 28-mm (OD) fuel cup. A wire mesh screen and a 76 mm (3 inch) layer of 3 mm (OD) glass beads were employed in the diffuser unit to provide thorough mixing of air, nitrogen and CF 3 CF 2 C(O)CF(CF 3 ) 2 . 
     n-Heptane was gravity fed to a cup from a liquid fuel reservoir consisting of a 250 mL separatory funnel mounted on a laboratory jack, which allowed for an adjustable and constant liquid fuel level in the cup. The fuel was ignited with a propane mini-torch, the chimney was placed on the apparatus. The fuel level was then adjusted such that fuel was 1–2 mm from the ground inner edge of the cup. A 90 second preburn period was allowed, and a primary flow of air and nitrogen was initiated at 34.2 L/min. 
     Primary and secondary air flows were monitored by flow meters (240 and 225 tubes, respectively). Nitrogen flows were monitored with a flow meter (230 tube). Oxygen concentrations were calculated from the measured air and nitrogen flow rates. The flows were maintained until the flames were extinguished. The primary flow of 34.2 L/min was maintained in all the tests. The secondary flow of air was passed through CF 3 CF 2 C(O)CF(CF 3 ) 2  contained in a 1150 ml steel mixing chamber equipped with a dip-tube. The secondary flow, containing air saturated with CF 3 CF 2 C(O)CF(CF 3 ) 2 , exited the mixing chamber and was mixed with the primary air flow before entering the cup burner&#39;s diffuser unit. 
     Immediately following flame extinction, a sample of the gas stream at a point near the lip of the cup was collected through a length of plastic tubing attached to a Hamilton three way valve and multifit gas syringe. The sample was then subjected to gas chromatographic analysis (G.C.). G.C. calibration was performed by preparing standards samples in a 1 L Tedlar bag. 
     A summary of test parameters and results are shown below in Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames with CF 3 CF 2 C(O)CF(CF 3 ) 2   
               
            
           
           
               
               
               
               
               
            
               
                 Total Air Flow 
                   
                   
                   
                   
               
               
                 [Primary + 
               
               
                 Secondary] 
                 N 2   
                 N 2   
                 O 2   
                 CF 3 CF 2 C(O)CF(CF 3 ) 2   
               
               
                 (L/min) 
                 (L/min) 
                 % (v/v) 
                 % (v/v) 
                 % (v/v) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 38.7 
                 0.0 
                 0.0 
                 20.6 
                 4.1 
               
               
                 39.0 
                 2.1 
                 5.2 
                 19.5 
                 3.8 
               
               
                 37.7 
                 3.3 
                 8.0 
                 18.9 
                 3.4 
               
               
                 37.7 
                 4.5 
                 10.6 
                 18.4 
                 3.1 
               
               
                 36.8 
                 5.7 
                 13.5 
                 17.8 
                 2.8 
               
               
                 36.3 
                 7.0 
                 16.2 
                 17.3 
                 2.4 
               
               
                 36.3 
                 8.3 
                 18.6 
                 16.8 
                 2.1 
               
               
                 35.9 
                 9.6 
                 21.1 
                 16.3 
                 1.8 
               
               
                 35.8 
                 10.9 
                 23.4 
                 15.8 
                 1.5 
               
               
                 35.4 
                 12.2 
                 25.6 
                 15.3 
                 1.2 
               
               
                 34.2 
                 15.4 
                 30.6 
                 14.3 
                 0 
               
               
                   
               
            
           
         
       
     
     EXAMPLE II 
     Example I was repeated, substituting, in once instance the bromofluoropropene CF 3 CBr═CH 2 , alone (under ambient oxygen conditions) for CF 3 CF 2 C(O)CF(CF 3 ) 2 , and, in another instance, CF 3 CBr═CH 2  in combination with diluent gas (reduced oxygen conditions) for CF 3 CF 2 C(O)CF(CF 3 ) 2 . A summary of test parameters and results are shown below in Tables 2 and 3 respectively. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames with CF 3 CBr═CH 2   
               
            
           
           
               
               
               
            
               
                   
                 Total Flow (L/min.) 
                 CF 3 CBr═CH 2  % (v/v) 
               
               
                   
                   
               
               
                   
                 35.42 
                 3.7 
               
               
                   
                 42.66 
                 3.7 
               
               
                   
                 42.32 
                 3.5 
               
               
                   
                 42.54 
                 3.6 
               
               
                   
                 42.54 
                 3.9 
               
               
                   
                 42.54 
                 3.6 
               
               
                   
                   
                 Avg. = 3.7 
               
               
                   
                   
                 STDEV = 0.2 
               
               
                   
                   
                 High = 3.9 
               
               
                   
                   
                 Low = 3.5 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane flames with CF 3 CBr═CH 2  and N 2 * 
               
            
           
           
               
               
               
               
               
            
               
                 Total Flow 
                 N 2   
                 N 2   
                 O 2   
                 CF 3 CBr═CH 2   
               
               
                 (L/min) 
                 (L/min) 
                 % (v/v) 
                 % (v/v) 
                 % (v/v) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 35.4 
                 0 
                 0.0 
                 20.6 
                 3.7 
               
               
                 35.7 
                 2.1 
                 5.7 
                 19.4 
                 3.0 
               
               
                 38.5 
                 3.5 
                 9.2 
                 18.7 
                 1.9 
               
               
                 40.8 
                 6.0 
                 14.7 
                 17.6 
                 1.4 
               
               
                 41.6 
                 7.0 
                 16.9 
                 17.1 
                 1.0 
               
               
                 44.9 
                 10.6 
                 23.6 
                 15.7 
                 0.4 
               
               
                 46.5 
                 12.2 
                 26.2 
                 15.2 
                 0.2 
               
               
                 49.0 
                 14.8 
                 30.2 
                 14.4 
                 0.0 
               
               
                   
               
               
                 *Primary air flow 34.2 L/min. 
               
            
           
         
       
     
     As indicated in Table 2, under ambient oxygen conditions the concentration of CF 3 CBr═CH 2  required to extinguish n-heptane flames averages 3.7% (v/v). Table 3 demonstrates that when used in combination with nitrogen, CF 3 CBr═CH 2  extinguishes the n-heptane flames at a much lower concentration, as low as about 0.41% (v/v), while maintaining human-safe oxygen levels. 
     EXAMPLE III 
     Example I was repeated, substituting the fluoroether CF 3 CHFCF 2 OCHF 2  for CF 3 CF 2 C(O)CF(CF 3 ) 2 . A summary of the test parameters and results are shown below in Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames 
               
               
                 with CF 3 CHFCF 2 OCHF 2  and N 2   
               
            
           
           
               
               
               
               
               
            
               
                 Total Flow 
                 N 2  Flow 
                 N 2   
                 O 2   
                 CF 3 CHFCF 2 OCHF 2   
               
               
                 (L/min.) 
                 (L/min) 
                 % (v/v) 
                 % (v/v) 
                 % (v/v) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 31.7 
                 0 
                 0 
                 20.6 
                 5.7 
               
               
                 31.2 
                 2.89 
                 8.5 
                 19.9 
                 4.8 
               
               
                 31.0 
                 4.16 
                 11.8 
                 18.2 
                 4.3 
               
               
                 29.9 
                 6.00 
                 16.7 
                 17.2 
                 3.3 
               
               
                 29.6 
                 7.34 
                 19.9 
                 16.5 
                 2.8 
               
               
                 28.6 
                 8.71 
                 23.4 
                 15.8 
                 1.8 
               
               
                 27.8 
                 10.80 
                 28.0 
                 14.8 
                 0.9 
               
               
                 27.3 
                 12.80 
                 31.9 
                 14.0 
                 0.0 
               
               
                   
               
            
           
         
       
     
     EXAMPLE IV 
     Example I was repeated, substituting the hydrofluorocarbon CF 3 CH 2 F for CF 3 CF 2 C(O)CF(CF 3 ) 2 . A summary of the test parameters and results are shown below in Table 5. 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames with CF 3 CH 2 F and N 2   
               
            
           
           
               
               
               
               
               
            
               
                 Total Flow 
                 N 2  Flow 
                 N 2   
                 O 2   
                 CF 3 CH 2 F 
               
               
                 (L/min.) 
                 (L/min) 
                 % (v/v) 
                 % (v/v) 
                 % (v/v) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 41.1 
                 0 
                 0 
                 20.6 
                 9.6 
               
               
                 41.1 
                 3.29 
                 7.4 
                 19.1 
                 7.9 
               
               
                 41.1 
                 6.58 
                 13.8 
                 17.8 
                 6.2 
               
               
                 41.1 
                 9.66 
                 19 
                 16.7 
                 4.5 
               
               
                 41.1 
                 12.2 
                 22.9 
                 15.9 
                 3.3 
               
               
                 41.1 
                 14.8 
                 26.9 
                 15.1 
                 1.6 
               
               
                 41.1 
                 18.4 
                 30.9 
                 14.2 
                 0 
               
               
                   
               
            
           
         
       
     
     EXAMPLE V 
     n-Heptane fires where extinguished utilizing an extinguishing mixture according to the present invention. The fire extinguishing tests were conducted according to the test protocol described in UL-2166. More specifically, Class B fire extinguishing tests were conducted using a 0.23 m 2  square test pan located in the center of a room. The test pan contained at least 5.08 cm of n- heptane with at least 5.08 cm of free board from the top of the pan. The pan was made of steel having a thickness of 0.635 cm and liquid tight welded joints. The pan also included a 3.81 cm (1½″) ( 3/16″ thickness) angle to reinforce the upper edge. 
     The internal dimensions of the test facility (room) were 8m×4m×3.6m (height); precise measurement of the test portion of the facility yielded a total volume of 115m 3 . The enclosure walls were constructed of standard concrete cinder block, filled with insulation and covered on the interior with 1.59 cm plywood. The ceiling and floor both consisted of two layers of 1.91 cm plywood on wooden 5.08 cm×15.24 cm joists, with alternate layers of plywood staggered so that no joints overlapped. The ceiling was also covered with 1.59 cm gypsum wallboard, and the walls and ceiling were finished with tape and joint compound and painted with two coats of primer (Kilz). The windows consisted of standard units employing safety glass and were covered on the interior with Lexan sheets. The enclosure door was of standard solid core construction. 
     A 45.72 cm×45.72 cm hinged positive pressure vent installed in a recess in the ceiling was kept open during testing. The ventilation inlet to the enclosure, through an underfloor duct, remained closed during this evaluation. A 3.5 ton commercial heat pump unit provided temperature control of the room. The inlet and outlet ducts were equipped with closable shutters. The exhaust system was also fitted with a closable shutter. 
     Water spray was discharged at 45 seconds from ignition and continued until extinguishment. The water spray flow rate is shown in Table 5. Water spray was provided using 6 “90 degree solid cone nozzles”. These nozzles were installed approximately 150 cm from the ceiling and were installed to cover the whole area of the floor. In some part of the space, there was an overlap of the spray. Heptafluoropropane was discharged 60 seconds from the beginning of water spray discharge (105 seconds from ignition). Each test was conducted at least three times and the parameters and results are summarized in Table 6. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames 
               
               
                 with Water and Heptafluoropropane 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Heptafluoro- 
                 Heptafluoro- 
                   
                 Average 
               
               
                   
                 propane 
                 propane 
                 Water 
                 Extinguishment 
               
               
                 Test # 
                 % (v/v) 
                 (kg) 
                 (L/min) 
                 Time (sec.) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 8.7 
                 79.83 
                 42.03 
                 1.0 
               
               
                 2 
                 7.0 
                 63.05 
                 19.69 
                 6.4 
               
               
                 3 
                 5.8 
                 51.71 
                 42.03 
                 12.6 
               
               
                 4 
                 5.0 
                 44.09 
                 42.03 
                 16.0 
               
               
                 5 
                 4.5 
                 39.46 
                 42.03 
                 24.53 
               
               
                   
               
            
           
         
       
     
     EXAMPLE VI 
     Extinguishment testing was performed as described in Example IV above with the exception that the extinguishing mixture included nitrogen. Nitrogen was discharged from cylinders, pressurized to 13.79 mPa, corresponding to 5.18 m 3  of nitrogen at 1 atmosphere and 21.1° C. The cylinders were connected to an end draw manifold via 1.59 cm high pressure flex hoses and cylinder actuation was accomplished via a remote manual lever release actuator. A 3.18 cm orifice union with an orifice plate connected the manifold to the remaining pipe network. This system was designed to afford a 60 second discharge of nitrogen at a concentration of 30% (v/v) and employed a centrally located 2.54 cm (1″), 360° Ansul ® (Marinette, Wis., USA) nozzle with an orifice of 1.43 cm2. The same nitrogen piping system was employed for all tests and hence discharge times varied with the amount of nitrogen employed. 
     Water and nitrogen were discharged into the test enclosure 30 seconds after n-heptane ignition, and continued to discharge until flame extinguishment. The water spray was discharged at the rate of 62.47 L/min. At 50 seconds from the beginning of the nitrogen discharge (i.e., 80 seconds from n-heptane ignition), heptafluoropropane was discharged through a separate pipe system terminating in a 5.08 cm (2″) 180° Chubb nozzle. Each test was conducted at least three times and the parameters and results are summarized below in Table 7. 
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Extinguishment of n-heptane Flames with 
               
               
                 Water/Nitrogen/Heptafluoropropane 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Heptafluoro- 
                 Heptafluoro- 
                   
                 Average 
               
               
                   
                 propane 
                 propane 
                 N 2   
                 Extinguishment 
               
               
                 Test # 
                 % (v/v) 
                 (kg) 
                 % (v/v) 
                 Time (sec.) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 4.3 
                 37.65 
                 4.4 
                 17.4 
               
               
                 2 
                 4.3 
                 37.65 
                 8.6 
                 22.2 
               
               
                 3 
                 3.5 
                 30.39 
                 8.6 
                 36.6 
               
               
                 4 
                 3.5 
                 30.39 
                 12.6 
                 18.7 
               
               
                   
               
            
           
         
       
     
     EXAMPLE VII 
     The test in Example V was repeated using n-Heptane alternative fuels, namely PMMA (polymethyl methacrylate), PP (polypropylene), ABS (acrylonitrile-butadiene-styrene polymer) or wood and permitting a longer preburn. Water spray and nitrogen were discharged into the test enclosure at 210 seconds after ignition (360 seconds in the case of wood), and continued to discharge until flame extinguishment. Heptafluoropropane was discharged at 260 seconds (420 seconds in the case of wood) from ignition and continued for between 8 and 10 seconds. A summary of the parameters and results are shown below in Table 8. 
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Extinguishment of Alternative Fuel Flames 
               
               
                 with Water/Nitrogen/Heptafluoropropane 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Heptafluoro- 
                 Heptafluoro- 
                   
                   
               
               
                 Fuel 
                 propane 
                 propane 
                 N 2   
                 Extinguishment 
               
               
                 Type 
                 % (v/v) 
                 (kg) 
                 % (v/v) 
                 Time (sec) 
               
               
                   
               
               
                 PMMA 
                 3.5 
                 30.39 
                 12.6 
                 12 
               
               
                 PMMA 
                 3.5 
                 30.39 
                 12.6 
                 27 
               
               
                 PP 
                 3.5 
                 30.39 
                 12.6 
                 64 
               
               
                 ABS 
                 3.5 
                 30.39 
                 12.6 
                 88 
               
               
                 Wood 
                 3.5 
                 30.39 
                 12.6 
                 &lt;1 
               
               
                   
               
            
           
         
       
     
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.