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DUCTWORK <br />Section 15890 <br />15-1207 <br />d. Minimum Acoustical Performance shall be as follows: <br />Absorption Coefficients @ Octave Band Frequencies Hz <br />125 <br />250 <br />500 <br />1000 <br />2000 <br />4000 <br />NRC <br />0.10 <br />0.32 <br />0.66 <br />0.84 <br />0.91 <br />0.91 <br />0.70 <br />e. Liner to be CertainTeed, ToughGard R Duct Liner, Type 150, or equal. <br />3. Internal duct liner for ducts exposed to weather or installed installed over un- <br />conditioned spaces to be as follows: <br />a. 2" thick, 1.5 -pound density (minimum) with matt facing. <br />b. Thermal Performance - C Value — 0.24 BTU / (h * FT * °F) — minimum <br />C. Thermal Performance - R Value — 8.3 (h * FT * °F) / BTU — minimum <br />d. Minimum Acoustical Performance shall be as follows: <br />Absor tion Coefficients @ Octave Band Frequencies Hz <br />125 <br />250 <br />500 <br />1000 <br />2000 <br />4000 <br />NRC <br />0.24 <br />0.79 <br />1.09 <br />1.05 <br />1.02 <br />1.01 <br />1.00 <br />e. Liner to be CertainTeed, ToughGard R Duct Liner, Type 150, or equal. <br />4. Cement duct liner in place with nonflammable, non -hardening duct adhesive. Seal <br />up all raw edges of insulation inside ductwork with adhesive. <br />5. Provide sheet metal weld pin fasteners and washers on all duct work on 12 -inch <br />intervals with the first row within 3 inches of the leading edge of each piece of <br />insulation and 4 inches from corners. No substitutions on fastening method will be <br />allowed. <br />6. Duct liner and adhesive shall not exceed flame -spread rating of 25 and <br />smoke -developed rating of 50, all in conformance with NFPA 90A. <br />7. Provide metal nosing at all locations where liner is preceded by unlined metal. <br />Ductwork Support: Provide hot -dipped galvanized steel fasteners, anchors, rods, straps, <br />trim, and angles for support of ductwork, unless noted otherwise. <br />J. Miscellaneous Ductwork Materials: <br />Duct Joints: Install duct sealers, pop rivets, or sheet metal screws at each fittings <br />and joint. Use a minimum of #10 galvanized sheet metal screws. <br />2.04 2" W.G. RECTANGULAR DUCT CONSTRUCTION/FABRICATION: <br />A. Shop fabricate ductwork of gauges and reinforcement complying with the more stringent of <br />the following standards, except as noted herein. <br />1. California Mechanical Code (CMC) <br />2. SMACNA HVAC Duct Construction Standards, latest Edition. <br />