Gas generator for expelling halon replacements

Abstract

A gas generator capable of quickly producing a large quantity of substantially solids-free nontoxic gas useful as a propellant in halon replacement fire suppression systems is provided. The double base castable propellant composition is formulated from a major amount of ammonium nitrate, a minor amount of nitrocellulose, at least one selected high energy nitrate ester plasticizer, a thermal scavenger, and at least one burning rate modification and control additive to achieve a burning rate of 0.2 inches per second or greater at 1000 psia. The burning rate is further enhanced by the configuration of the solid propellant, which is formed to have dimensions selected to enhance the burning rate. The gas generator composition and physical arrangement synergistically produce an optimally rapid burning rate.

What is claimed is:  
     
         1 . A quick burning gas generator characterized by the rapid production of a large amount of substantially solids-free nontoxic gas comprising a double base castable propellant composition formulated to produce a flexible solid gas generator having a burning rate of at least 0.2 inches per second or greater at 1000 psia and having a configuration sized and dimensionally positioned to enhance rapid burning of the gas generator.  
     
     
         2 . The gas generator described in  claim 1 , wherein said double base propellant composition formulation comprises a major amount of ammonium nitrate and a minor amount of nitrocellulose, at least one selected high energy nitrate ester plasticizer, a thermal scavenger and at least one burning rate modification and control additive, wherein the components of said formulation are selected to produce a balanced fuel to oxygen ratio, a flame temperature below 2800° K. and a pressure exponent of 0.8 or less at 1000 psia.  
     
     
         3 . The gas generator described in  claim 2 , wherein said at least one high energy nitrate ester plasticizer is selected from the group consisting of butanetriol trinitrate, triethyleneglycol dinitrate, triacetin, diethyleneglycol, dinitrate, trimethylol trinitrate, nitroglycerine liquid analogs of nitroglycerine, and butylnitrate ester nitramine.  
     
     
         4 . The gas generator described in  claim 3 , wherein said thermal scavenger is selected from the group consisting of para-N-methylnitroaniline, 2-nitro-phenylamine, 4-nitrodiphenylamine, and diphenylamine.  
     
     
         5 . The gas generator described in  claim 4 , wherein the said at least one burning rate modification and control additive is selected from the group consisting of carbon, bismuth oxide and bismuth subsalicylate.  
     
     
         6 . The gas generator described in  claim 5 , wherein said at least one high energy nitrate ester plasticizer is selected from the group consisting of butanetriol trinitrate, triethyleneglycol dinitrate and triacetin, said thermal scavenger is para-N-methylnitroaniline, and said burning rate modification and control additive is carbon.  
     
     
         7 . The gas generator described in  claim 5 , wherein said at least one high energy nitrate ester plasticizer is selected from the group consisting of butanetriol trinitrate, triethyleneglycol dinitrate and triacetin, said thermal scavenger is para-N-methylnitroaniline, and said burning rate modification and control additives are carbon and bismuth oxide.  
     
     
         8 . The gas generator described in  claim 5 , wherein said at least one high energy nitrate ester plasticizer is selected from the group consisting of butanetriol trinitrate, triethyleneglycol dinitrate and triacetin, said thermal scavenger is para-N-methylnitroaniline, and said burning rate modification and control additives are carbon and bismuth subsalicylate.  
     
     
         9 . The gas generator described in  claim 6  wherein said high energy nitrate ester plasticizers are butanetriol trinitrate and triacetin and said burning rate modification and control additives are carbon and bismuth oxide.  
     
     
         10 . The gas generator described in  claim 6 , wherein said high energy nitrate ester plasticizers are butanetriol trinitrate and triacetin and said burning rate modification and control additives are carbon and bismuth subsalicylate.  
     
     
         11 . The gas generator described in  claim 6 , wherein said high energy nitrate ester plasticizer is triethyleneglycol dinitrate and said burning rate modification and control additive is carbon.  
     
     
         12 . The gas generator described in  claim 2 , wherein said double base propellant composition comprises 55 to 74% by weight ammonium nitrate, 10 to 20% by weight nitrocellulose, 13 to 34% by weight high energy nitrate ester plasticizer, 0.9 to 2.0% by weight thermal scavenger, and 0.1 to 2.2% by weight burning rate modification and control additive.  
     
     
         13 . The gas generator described in  claim 12 , wherein said double base propellant composition comprises 61.5% by weight ammonium nitrate, 10.0% by weight nitrocellulose, 26.3% by weight high energy nitrate ester plasticizer, 0.9 to 2.0% by weight thermal scavenger and 1.3% by weight burning rate modification and control additive.  
     
     
         14 . The gas generator described in claims  13 , wherein said high energy nitrate ester plasticizer comprises butanetriol trinitrate and triacetin, said thermal scavenger comprises para-N-methylnitroaniline, and said burning rate modification and control additives comprise carbon and bismuth oxide.  
     
     
         15 . The gas generator described in  claim 1 , wherein said propellant formulation is castable to produce a flexible substantially rectangular configuration having a thickness selected to enhance rapid burning of the gas generator.  
     
     
         16 . The gas generator described in  claim 15 , wherein said selected thickness is 0.050 to 0.500 inches.  
     
     
         17 . The gas generator described in  claim 16 , wherein said selected thickness is 0.060 inches.  
     
     
         18 . A castable solid double base propellant composition comprising 61.5% by weight ammonium nitrate, 10.0% by weight nitrocellulose, 24.3% by weight butanetriol trinitrate, 2.0% by weight triacetin, 0.9% by weight para-N-methylnitroaniline, 0.2% carbon and 1.1% bismuth oxide.  
     
     
         19 . A clean, low temperature gas generator assembly capable of rapidly producing a balanced gas output in excess of 3 moles for each 100 grams of gas generator propellant composition comprising a plurality of axially extending concentric sleeve supports, each of said sleeve supports being mounted a selected radial distance apart and positioned concentrically to support a plurality of gas generator elements sized and positioned adjacent to a surface of each of said sleeve supports to substantially cover said sleeve support, wherein each said gas generator element comprises a flexible substantially rectangularly shaped solid propellant, wherein the longest dimension of the rectangle corresponds approximately to the largest circumference of a sleeve support, and said solid propellant forming said gas generator has a thickness and composition formulated to burn rapidly at a rate of at least 0.2 inches per second or greater at 1000 psia.  
     
     
         20 . The gas generator assembly described in  claim 19 , wherein said propellant thickness is 0.050 to 0.500 inches and said propellant composition formulation comprises a major amount of ammonium nitrate and a minor amount of nitrocellulose, at least one selected high energy nitrate ester plasticizer, a thermal scavenger and at least one burning rate modification and control additive, wherein the components of said formulation are selected to produce a balanced fuel to oxygen ratio, a flame temperature below 2800° K. and a pressure exponent of 0.8 or less at 1000 psia.  
     
     
         21 . A method of making the gas generator described in  claim 2 , including the steps of: 
 (a) adding nitrocellulose to a blend of at least one high energy nitrate ester plasticiser and said thermal stabilizer to produce a solvent-less slurry;    (b) adding to the solvent-less slurry, ammonium nitrate and at least one burning rate modification and control additive;    (c) mixing the mixture formed in step (b) at a temperature sufficiently low to maintain a homogenous mixture until the viscosity of the mixture is greater than about 1.0 kP; and    (d) curing the resulting product to produce a solid, flexible propellant composition.    
     
     
         22 . The method described in  claim 21 , wherein said thermal scavenger comprises para-N-methylnitroaniline, said high energy nitrate plasticizer comprises butanetriol trinitrate and triacetin, and said burning rate modification and control additive comprises carbon and bismuth oxide.