A. Standard Quality Casing Fabrication: Factory-fabricated and constructed self-supporting wall, roof and floor double-wall casing panels with 2-inch (R-16) closed-cell injected-foam insulation within formed channel framing or greater. The casing construction shall provide thermal breaks. All joints shall be air-tight and water-resistant sealed. 1. Casing Performance: a. Leakage: Casing shall meet AHRI 1350 Casing Air Leakage Rate CL3 with less than 10 cfm leakage per 100 sqft. at 6.0-inches w.g. positive or negative internal pressure. b. Deflection: Casing shall meet AHRI 1350 Casing Deflection Rate CD3 with less than 0.0042-inches (1/240) deflection per inch of span at 6.0-inches positive or negative internal pressure. Floor deflection shall not exceed 0.0625-inches at 6- inches internal pressure and 300-pound per sqft. live load. 2. Casing Materials: a. Exterior: G90 galvanized-steel, smooth, 20-gauge (0.036-inch thick) minimum. b. Interior: G90 galvanized-steel, smooth, 20-gauge (0.036-inch thick) minimum with galvanized-steel structure, 1) Exceptions: a) Cooling coils sections will be Type 304 stainless steel, smooth, 20-gauge (0.038-inch thick) minimum or aluminum 16-gauge (0.050-inch-thick) minimum with stainless steel screws. 3. Casing Finish: None 4. Casing Section Gaskets: Neoprene gasket around entire perimeter of casing section joints. B. Floor: Each section shall have a 2-inch tall lip at the perimeter to form a water-tight pan. Walking surfaces of floor panels shall have a solid 3/16-inch thick checker-plate aluminum solid lining with water-tight welded seams and reinforcements to support 300-pound per sqft. live load C. Monorail Beams: Each fan section shall include a structural I-beam monorail capable of lifting the fan motor(s) through the fan section access door on the primary service side of the unit...
