Flexible heat barrier and fire shelter for wildland firefighters made therefrom

Abstract

A flexible heat barrier is configured to absorb and deflect heat energy and utilizes a multilayer construction wherein each layer provides a specific purpose. An outer layer configured for exposure to a heat flux includes a coating having an intumescent component and an opacifier component. An inner layer includes a foil that may include a high emittance coating to more effectively reflect radiation. A middle layer includes an insulating fabric layer that may include oriented fibers that can effectively polarize radiation and may include a plurality of layers of oriented fibers that are configured at an offset angle to deflect and reduce radiation transmission through the middle layer. A flexible heat barrier may also include a flexible gas barrier that includes a phase change material, such as frits that melt at a predetermined temperature and flow into gaps to reduce the permeability and further block heat flux.

What is claimed is: 
     
         1 . A flexible heat barrier comprising:
 a) an insulating fabric layer comprising high temperature fibers having a melt temperature of at least 800° C.;   b) a coating coupled to said insulating fabric layer and configured as an outer layer of the flexible heat barrier and comprising:
 i) an intumescent component; 
 ii) an opacifier component; 
 iii) a gas barrier component; and 
 iv) a binder component; 
   c) a metal foil coupled to said insulating fabric layer and configured as an inner layer of the flexible heat barrier;
 wherein the outer layer is configured as an exposure side of the flexible heat barrier and configured to be exposed to a heat source or a flame and the inner layer is configured as a shield side away from said heat source or flame; and 
 wherein the flexible heat barrier has an average burst strength of at least 482 kPa (70 psi) according to American Standard Test Method (ASTM) 774 and United States Department of Agriculture (USDA) specification paragraph 4.4.2.7. 
   
     
     
         2 . The flexible heat barrier of  claim 1 , wherein the insulating fabric layer is a polarizing fabric layer comprising a layer or oriented high temperature fibers having a spacing between said oriented fibers of 5.0 µm or less. 
     
     
         3 . The flexible heat barrier of  claim 2 , wherein the spacing between said oriented fibers is 2.0 µm or less. 
     
     
         4 . The flexible heat barrier of  claim 2  wherein the oriented fibers comprise a coating and wherein the coating forms said spacing between the oriented fibers. 
     
     
         5 . The flexible heat barrier of  claim 1 , wherein the insulating fabric layer comprises two layers of oriented high temperature fibers, each having a spacing between said oriented fibers of 5.0 µm or less. 
     
     
         6 . The flexible heat barrier of  claim 5 , wherein a first layer of oriented high temperature fibers is configured substantially orthogonally, within about 20 degrees or less of orthogonal, to a second layer of oriented high temperature fiber. 
     
     
         7 . The flexible heat barrier of  claim 5 , wherein the second layer of oriented high temperature fibers is configured more proximal to the inner layer and has a larger spacing between said oriented fibers by at least 20% than said spacing between said oriented fibers of the first layer of said oriented fibers. 
     
     
         8 . The flexible heat barrier of  claim 7 , wherein the second layer of oriented high temperature fibers has a larger fiber diameter, by at least 20%, than a fiber diameter of the first layer of said oriented fibers. 
     
     
         9 . The flexible heat barrier of  claim 5 , wherein the second layer of oriented high temperature fibers has a larger fiber diameter, by at least 20%, than a fiber diameter of the first layer of said oriented fibers. 
     
     
         10 . The flexible heat barrier of  claim 2 , wherein the insulating fabric layer comprises woven oriented fibers. 
     
     
         11 . The flexible heat barrier of  claim 1 , wherein insulating fabric layer comprises high temperature polymers having a melt temperature of 300° C. or more. 
     
     
         12 . The flexible heat barrier of  claim 11 , wherein insulating fabric layer comprises polyimide. 
     
     
         13 . The flexible heat barrier of  claim 1 , wherein insulating fabric layer comprises fibers having a melt temperature of 800° C. or more. 
     
     
         14 . The flexible heat barrier of  claim 1 , wherein insulating fabric layer comprises inorganic fibers selected from the group consisting of: glass, fiberglass, silicon carbide and mullite, alumina, quartz. 
     
     
         15 . The flexible heat barrier of  claim 1 , wherein the foil comprises a first layer of foil and second layer of foil, wherein the first layer of foil has an emissivity that is at least 20% higher than an emissivity of said second layer of foil. 
     
     
         16 . The flexible heat barrier of  claim 1 , wherein the foil comprises gold layer. 
     
     
         17 . The flexible heat barrier of  claim 16 , wherein the gold layer is a vapor deposition gold layer having thickness of no more than about 1500 µm. 
     
     
         18 . The flexible heat barrier of  claim 16 , wherein the foil comprises titanium foil. 
     
     
         19 . The flexible heat barrier of  claim 18 , wherein the foil comprises a gold layer on said titanium foil. 
     
     
         20 . The flexible heat barrier of  claim 1 , wherein the intumescent component comprises expandable graphite.