Laserfiche WebLink
2.03 SEALING MATERIALS <br /> I <br /> A. General: The term sealant used here is not limited to materials of adhesive or mastic nature;but also includes tapes <br /> and combinations of open weave fabric strips and mastics. <br /> B. Joint and Seam Tape: 2 inches wide,glass-fiber-fabric reinforced. <br /> C. Tape Sealing System: Woven-fiber tape impregnated with a gypsum mineral compound and a modified <br /> acrylic/silicone activator to react exothermically with the tape to form a hard,durable,airtight seal. <br /> D. Joint and Seam Sealant: One-part, non-sag, solvent-release-curing, polymerized butyl sealant complying with FS <br /> TT-S-001657,Type I;formulated with a minimum of 75 percent solids. <br /> E. Flanged Joint Mastics: One-part, acid-curing, silicone elastomeric joint sealants, complying with ASTM C 920, <br /> Type S,Grade NS,Class 25,Use O. <br /> 2.04 HANGERS AND SUPPORTS <br /> A. Building Attachments: Concrete inserts, powder actuated fasteners, or structural steel fasteners appropriate for <br /> building materials. Do not use powder actuated concrete fasteners for lightweight aggregate concretes or for slabs <br /> less than 4 inches thick. <br /> B. Hangers: Galvanized sheet steel,or round,uncoated steel,threaded rod. <br /> 1. Hangers Installed In Corrosive Atmospheres: Electro-galvanized,all-thread rod or hot-dipped-galvanized rods <br /> with threads painted after installation. <br /> 2. Straps and Rod Sizes: Conform with Table 4-1 in SMACNA HVAC Duct Construction Standards, 1985 <br /> Edition,for sheet steel width and gage and steel rod diameters. <br /> C. Duct Attachments: Sheet metal screws,blind rivets,or self-tapping metal screws;compatible with duct materials. <br /> D. Trapeze and Riser Supports: Steel shapes conforming to ASTM A 36. <br /> 1. Where galvanized steel ducts are installed,provide hot-dipped-galvanized steel shapes and plates. <br /> 2. For stainless steel ducts,provide stainless steel support materials. <br /> 2.05 DUCT FABRICATION <br /> A. General: Except as otherwise indicated,fabricate rectangular ducts with galvanized sheet steel, in accordance with <br /> SMACNA "HVAC Duct Construction Standards, Tables 1-3 through 1-19, including their associated details. <br /> Conform to the requirements in the referenced standard for metal thickness,reinforcing types and intervals,tie rod <br /> applications,and joint types and intervals. <br /> 1. Fabricate rectangular ducts in lengths appropriate to reinforcement and rigidity class required for pressure <br /> classification. <br /> 2. Provide materials that are free from visual imperfections such as pitting,seam marks,roller marks,stains,and <br /> discoloration. <br /> B. Static Pressure Classifications: Except where otherwise indicated,construct duct systems to the following pressure <br /> classifications: <br /> 1. Supply Ducts: 3 inches water gage; 1 inch of water gage downstream of VAV boxes. <br /> 2. Return Ducts: 3 inches water gage,negative pressure. <br /> 3. Exhaust Ducts: 1%z inch water gage,negative pressure. <br /> i' <br /> 15891-5 No.99132-CP2 <br /> 15891-7 No.99132-CP2 <br />