Class 1 flexible uninsulated duct with polymer core and surrounding fire resistant barrier layer and method of use

Abstract

An uninsulated duct for use in interior spaces that do not require insulation includes a polymer core and a fire resistant barrier layer surrounding the polymer core. The barrier layer is made of a material that makes the uninsulated duct one that meet the UL 181 Class 1 duct rating in terms of flame penetration and high temperature testing. The uninsulated duct can be one that includes a longitudinal seam with an adhesive-containing overlap to secure ends of the fire resistant barrier material together or a duct that is spirally wound such that the adhesive-containing overlap exists for wraps of the barrier material to maintain duct integrity. In either duct construction, an adhesive combination is used so that the uninsulated duct can meet testing in connection with the UL 181 Class 1 duct standard, be able to be manufactured easily, and maintain duct integrity for use in moving air applications.

I claim: 
     
         1 . A flexible uninsulated duct that meets at least some or all of Underwriter Laboratories (UL) 181 Class 1 duct standards comprising:
 a polymer core having a helical wire as a part thereof, the polymer core having first and second opposing surfaces; and   a fire resistant barrier layer having opposing first and second surfaces, one of the first and second surfaces of the fire resistant barrier layer facing one of the first and second surfaces of the polymer core, one of the first and second surfaces of the fire resistant barrier layer or one of the first and second surfaces of the polymer core forming an inside surface of the flexible uninsulated duct that forms a channel for conditioned air flow, wherein either the fire resistant barrier layer forms the channel or the fire resistance barrier layer is exposed as an outer surface of the flexible uninsulated duct, and   (1) portions of the fire resistant barrier layer forming an overlap as either a longitudinal seam or a spirally wound seam, a combination of at least first and second adhesives between overlapping portions of the fire resistant barrier layer, the first adhesive as a hot melt adhesive in an effective amount to immediately bond the overlapping portions together, the second adhesive as a high temperature adhesive in an effective amount to maintain the bond between the overlapping portions when the longitudinal seam or spirally wound seam is subjected to a flame penetration test according to the UL 181 Class 1 duct standard; or   (2) portions of the fire resistant barrier layer forming an overlap and either longitudinal seam or a spirally wound seam, a combination of at least first and second adhesives between overlapping portions of the fire resistant barrier layer, the first adhesive as a hot melt adhesive in an effective amount to immediately bond the overlapping portions together, the second adhesive as a cold glue in an effective amount to maintain the bond between the overlapping portions when the longitudinal seam or spirally wound seam is subjected to a high temperature test according to the UL 181 Class 1 duct standard.   
     
     
         2 . The flexible uninsulated duct of  claim 1 , wherein the overlap is in the longitudinal seam of the flexible uninsulated duct. 
     
     
         3 . The flexible uninsulated duct of  claim 1 , wherein the overlap is in the spiral wound seam of the flexible uninsulated duct. 
     
     
         4 . The flexible uninsulated duct of  claim 1 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a sodium silicate adhesive. 
     
     
         5 . The flexible uninsulated duct of  claim 2 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a sodium silicate adhesive. 
     
     
         6 . The flexible uninsulated duct of  claim 3 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a sodium silicate adhesive. 
     
     
         7 . The flexible uninsulated duct of  claim 1 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a cold glue. 
     
     
         8 . The flexible uninsulated duct of  claim 2 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a cold glue. 
     
     
         9 . The flexible uninsulated duct of  claim 3 , wherein the first adhesive is the hot melt adhesive and the second adhesive is a cold glue. 
     
     
         10 . The flexible uninsulated duct of  claim 4 , wherein the hot melt adhesive is in contact with a portion of the sodium silicate adhesive located on at least one portion of the first resistant barrier layer forming the overlap or the hot melt adhesive is adjacent to the sodium silicate adhesive in the overlap. 
     
     
         11 . The flexible uninsulated duct of claim  11 , wherein the hot melt adhesive in contact with a portion of the sodium silicate adhesive has a continuous or discontinuous strip form or a discontinuous form made up of discrete portions of hot melt adhesive dispersed along the overlap. 
     
     
         12 . The flexible uninsulated duct of  claim 3 , wherein the hot melt adhesive and the cold glue are generally separate from each other in the overlap. 
     
     
         13 . The flexible uninsulated duct of  claim 12 , wherein the hot melt adhesive and cold glue are in strip form adjacent to each other. 
     
     
         14 . The flexible uninsulated duct of  claim 4 , wherein the hot melt adhesive covers 20-40% of an area of the sodium silicate adhesive applied to the fire resistant barrier layer, preferably 25-35%. 
     
     
         15 . In a method of supplying conditioned or unconditioned air to a space using a flexible insulated duct, the improvement comprising using the flexible uninsulated duct of  claim 1  for said supplying. 
     
     
         16 . The method of  claim 15 , wherein the flexible uninsulated duct is located within an interior wall of a building.