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Southern Human Services Center Smith Sinnett /2020072 <br />HVAC and Roof Renovations Orange County,North Carolina <br />HVAC Ducts and Casings 23 31 00 - 3 <br />turning vanes of perforated metal with glass fiber insulation. <br />F.Increase duct sizes gradually,not exceeding 15 degrees divergence wherever possible;maximum <br />30 degrees divergence upstream of equipment and 45 degrees convergence downstream. <br />G.Fabricate continuously welded round and oval duct fittings in accordance with SMACNA (DCS). <br />H.Where ducts are connected to exterior wall louvers and duct outlet is smaller than louver frame, <br />provide blank-out panels sealing louver area around duct. Use same material as duct,painted <br />black on exterior side;seal to louver frame and duct. <br />2.04 HANGERS AND SUPPORTS <br />A.Unless otherwise indicated,use straps or Z bar hangers with 3/8”rods to support rectangular ducts <br />48”wide and smaller and trapeze hangers with rods or angles to support rectangular ducts over <br />48”wide. <br />1.Use trapeze hangers to support externally insulated ductwork with weight bearing inserts. <br />B.For round ducts 24"diameter or smaller,use single hanger. <br />1.Cable Suspension System may be used up to 16"diameter <br />2.Round Duct Strap Bracket by Ductmate Industries may be used up to 24"diameter. <br />C.For round ducts over 24"diameter,use 2 hangers with half round trapeze. <br />D.For round ducts over 25”diameter or larger,use 2 minimum 3/8”rods with trapeze. <br />E.The following upper attachments,upper attachment devices,lower hanger attachments,hanger <br />devices,and/or hanger attachments are not allowed except where specifically indicated: <br />1.Hook or loop. <br />2.Nailed pin fasteners. <br />3.Expansion nails without washers. <br />4.Powder charged or mechanically driven fasteners (forced entry anchors). <br />5.Beam or "C"clamps without retaining clips or friction clamps (provide retaining clips <br />6.for "C"clamps). <br />7.Friction clamps for ductwork over 12". <br />8.Non-factory manufactured upper attachments for metal pan deck including wire coil and <br />double circle (Items 16 and 17 of Fig 4-3 of SMACNA HVAC Duct Construction Standards <br />95). <br />9.Wire hanger. <br />10.Trapeze hangers supported by wires or straps. <br />11.Rods,straps or welded studs directly attached to metal deck. <br />12.Drilled hole with attachment to structural steel. <br />13.Lag screw expansion anchor. <br />14.Rivets. <br />F.Supporting devices shall be standard products of manufacturers having published load ratings. <br />G.Unless drawings indicate the required framing,provide angle iron framing around roof opening <br />where duct penetrates through roof decking,to maintain roof decking structural integrity in <br />accordance with roof decking manufacturer's recommendations. This is not required for concrete <br />decking. For concrete decking,consult with Structural Engineer for location and size of opening <br />prior to execution of Work. <br />H.All hangers and supports shall be fully galvanized. <br />2.05 MANUFACTURED DUCTWORK AND FITTINGS <br />A.Double Wall Insulated Round Ducts: Round spiral lockseam duct with galvanized steel outer wall, <br />perforated galvanized steel inner wall;fitting with solid inner wall. <br />1.Manufacture in accordance with SMACNA (DCS). <br />2.Insulation: <br />a.Thickness: 1 inch. <br />b.Material: Fiberglass or elastomeric foam. <br />3.Manufacturers: <br />a.MKT Metal Manufacturing <br />DocuSign Envelope ID: 94E7997D-4F29-42F6-A9B4-0A160438D2A6