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Orange County Health Department Improvements Smith Sinnett /2024008 <br />Hillsborough,NC Orange County Asset Management Services <br />HVAC DUCTS AND CASINGS 23 31 00 - 3 <br />3.Neoprene gasket must be closed cell rubber based sealing tape and must pass UL 94 HF-1. <br />4.Butyl rubber gasket which complies with UL 723,Mil-C 18969B and TTS-S-001657.This material,in <br />addition to the above,shall not contain vegetable oils,fish oils,or any other type vehicle that will <br />support fungal and/or bacterial growth. <br />5.Surface Burning Characteristics: Flame spread index of zero and smoke developed index of zero, <br />when tested in accordance with ASTM E84. <br />D Hanger Rod: ASTM A36/A36M;steel,galvanized;threaded both ends,threaded one end,or continuously <br />threaded. <br />E Cable Suspension System: <br />1.Suspension system shall be Gripple Hang-Fast as manufactured and supplied by Gripple,Inc.,or <br />Ductmate "Clutcher"cable hanging system. <br />2.Suspension system shall be load rated and verified by SMACNA Testing and Research Institute to be <br />in compliance with SMACNA Standards. <br />3.All suspension systems shall used galvanized hardware. <br />2.03 DUCTWORK FABRICATION <br />A Fabricate and support in accordance with SMACNA (DCS)and as indicated. <br />1.Internal tie rods or bracing are not allowed for ductwork 36"and below.Tie rods shall be 1/2",3/4", <br />1",1-1/4"or 1-1/2"galvanized rods with bolt assembly consisting of rubber washer and friction <br />anchored threaded insert similar to Ductmate Easyrod or PPI Condu-Lock. <br />2.Internal tie rods are not allowed for ductwork in chase and other non-accessible locations. <br />B Where the size for a duct segment is not indicated,the duct segment size shall be equal to the largest duct <br />segment to which it is connected.Transition to smaller size shall occur on the side of the fitting where <br />smaller size is indicated. <br />C No variation of duct configuration or size permitted except by written permission. Size round duct installed <br />in place of rectangular ducts in accordance with ASHRAE (FUND)Handbook -Fundamentals. <br />D Construct T's,bends,and elbows with radius of not less than 1-1/2 times width of duct on centerline. Where <br />not possible and where rectangular elbows must be used,provide air foil turning vanes of perforated metal <br />with glass fiber insulation. <br />E Increase duct sizes gradually,not exceeding 15 degrees divergence wherever possible;maximum 30 degrees <br />divergence upstream of equipment and 45 degrees convergence downstream. <br />F Fabricate continuously welded round and oval duct fittings in accordance with SMACNA (DCS). <br />G Where ducts are connected to exterior wall louvers and duct outlet is smaller than louver frame,provide <br />blank-out panels sealing louver area around duct. Use same material as duct,painted black on exterior side; <br />seal to louver frame and duct. <br />2.04 HANGERS AND SUPPORTS <br />A Refer to the Structural Drawings and Details for the limitations and applications of each type of hanger and <br />weight when attaching to bar joists,trusses,or other building Structural elements.The Contractor shall be <br />responsible for providing additional miscellaneous steel,unistrut,and other components to span multiple <br />joists as required by the Structural Drawings to distribute concentrated loads. <br />B Unless otherwise indicated,use straps or Z bar hangers with 3/8”rods to support rectangular ducts 48”wide <br />and smaller and trapeze hangers with rods or angles to support rectangular ducts over 48”wide. <br />1.Use trapeze hangers to support externally insulated ductwork with weight bearing inserts. <br />C 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 />D For round ducts over 24"diameter,use 2 hangers with half round trapeze. <br />E For round ducts over 25”diameter or larger,use 2 minimum 3/8”rods with trapeze. <br />F The following upper attachments,upper attachment devices,lower hanger attachments,hanger devices, <br />and/or hanger attachments are not allowed except where specifically indicated: <br />Docusign Envelope ID: 2D852F9B-A7CF-462A-9536-444A53AA848A