CLASS 1 UNINSULATED FLEXIBLE DUCT CONSTRUCTED OF POLYMER MATERIAL, HELICAL WIRE, FIRE RESISTANT BARRIER MATERIAL, AND FLAME RESISTANT YARN AND METHOD OF USE
An uninsulated flexible duct includes a duct wall, the duct wall having an outer surface and an inner surface, the duct wall forming a channel for fluid flow therethrough and including a helical wire as a part thereof. The uninsulated flexible duct also includes a fire resistant barrier material forming a part of the duct wall. The fire resistant barrier material includes an overlap zone, wherein a first surface of the fire resistant barrier material faces a second surface of the fire resistant barrier material, the first and second surfaces of the overlap zone being bonded together. The duct also includes a flame resistant yarn adhered to an outer surface of the duct in a path that crosses or at least partially covers the overlap zone a plurality of times or is positioned between helical wires of the duct to assist in meeting a flame penetration test.
1 . An uninsulated flexible duct comprising:
a duct wall, the duct wall having an outer surface and an inner surface, the duct wall forming a channel for fluid flow therethrough, the duct wall including a helical wire;
a fire resistant barrier material forming a part of the duct wall, the fire resistant barrier material including an overlap zone, wherein a first surface of the fire resistant barrier material faces a second surface of the fire resistant barrier material, the first and second surface of the overlap zone bonded together, the overlap zone running along a length of the uninsulated flexible duct; and
a flame resistant yarn adhered to an outer surface of the duct in a path that crosses or at least partially covers the overlap zone or in a path wherein the yarn is centrally positioned between adjacent helical wires so that the yarn would be generally aligned with a weight placed between helical wires in a flame penetration test.
2 . The duct of claim 1 , wherein the fire resistant barrier layer forms the outer surface of the duct.
3 . The duct of claim 1 , wherein the overlap zone runs generally longitudinally along a length of the duct and the path of the flame resistant yarn crosses the overlap zone a plurality of times along a length of the duct.
4 . The duct of claim 2 , wherein the overlap zone runs generally longitudinally along a length of the duct and the path of the flame resistant yarn crosses the overlap zone a plurality of times along a length of the duct.
5 . The duct of claim 1 , wherein the overlap zone runs in a spiral path along the length of the duct.
6 . The duct of claim 5 , wherein the path of the flame resistant yarn is one of:
a) a spiral path having a helix angle that is different than a helix angle of the spiral path of the overlap zone so that the flame resistant yarn crosses over or intersects the overlap zone; and
b) a spiral path having a helix angle the same as the spiral path of the overlap zone and wherein the spiral path of the flame resistant yarn is parallel to the spiral path of the overlap zone so that the flame resistant yarn runs along the overlap zone.
7 . The duct of claim 1 , wherein the overlap zone is bonded by chemical welding.
8 . The duct of claim 2 , wherein the overlap zone is bonded by chemical welding.
9 . The duct of claim 1 , wherein the overlap zone is bonded with one adhesive, or a combination of adhesives, the combination comprising either:
(i) a combination of at least first and second adhesives between in the overlap zone, 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
(ii) a combination of at least first and second adhesives in the overlap zone, 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.
10 . The duct of claim 1 , wherein the fire resistant barrier material includes a coating thereon.
11 . The duct of claim 1 , wherein the duct wall includes at least one polymer layer as a part thereof, the at least one polymer layer and the fire resistant barrier material forming a laminate construction for the duct wall.
12 . The duct of claim 11 , wherein the fire resistant barrier material forms an outer surface of the uninsulated flexible duct.
13 . The duct of claim 11 , wherein the fire resistant barrier material forms an inner surface of the uninsulated flexible duct.
14 . The duct of claim 1 , wherein the flame resistant yarn is adhered to an outer surface of the fire resistant barrier material by one of:
a) a high temperature adhesive;
b) a polyvinylchloride coating on the yarn and tetrahydrofuran applied to the coated yarn to chemically weld it to the outer surface of the duct;
c) a coating applied to the yarn and fire resistant barrier material, and
d) a stitching of the flame resistant yarn to the outer surface of the duct.
15 . The duct of claim 1 , wherein the fire resistant barrier material is coated and forms both an inner and outer surface of the duct, the overlap zone runs generally longitudinally along a length of the duct, and the path of the flame resistant yarn is a spiral path that crosses over or intersects the overlap zone.
16 . In a method of flame penetration testing of a duct, wherein an outer surface of a section of uninsulated flexible duct is configured to face a furnace with an open flame, the improvement comprising providing the section of duct from the duct of claim 1 .
17 . In a method of moving conditioned or unconditioned fluid, preferably air, using an uninsulated flexible duct, the improvement comprising providing the duct of claim 1 as the uninsulated flexible duct to move the conditioned or unconditioned fluid.
18 . The duct of claim 9 , wherein the one adhesive is one of the hot melt adhesive, the cold glue, or the high temperature adhesive.