The seal may not be penetrated for isolator adjustment. Metal or combination metal and elastomer seals are not permitted. The seal shall be Class A, as tested in accordance with approved Underwriter’s Laboratories, Inc., provisions. The seal shall extend down past the wood nailer of the lower support assembly and flash over the roof material at the wood nailer on the lower support curb. The vibration isolation curb shall be air and weather tight using an elastomeric seal, which is attached to the upper support frame with a galvanized steel clip. Resistance to higher loads or for ratings on extended height curbs or units attached to wood or concrete will require analysis by KNC, but can in most cases be met with only minor modification. Standard units are designed to withstand a 43 psf horizontal and 25 psf vertical wind load. There shall be no metal-to-metal contact. Restraint components shall include neoprene snubbers at all contact points for energy absorption. Seismic and wind load restraints shall be designed to limit movement in all directions. Spring coils shall rest on minimum 0.25 inch (6 mm) neoprene noise pads. All springs shall have an polyester powder coated finish and be color coded to indicate load capacity. Springs shall have a lateral stiffness greater than 1.2 times the rated vertical stiffness and shall be designed for a typical 50% overload to solid. Spring components shall be (1 inch/25 mm) (2 inch/51 mm) (4 inch/102 mm) deflection, free-standing, unhoused, laterally stable steel springs. The lower support curb shall have a minimum elevation of 14 inches (356 mm) from the top of the wood nailer to the base of the curb. The isolation support pedestal, which includes the seismic and wind load restraints, shall be bolted or welded to the building support steel to suitably transfer seismic and wind load forces to the building structure. The lower support curb shall be a formed channel fabricated of heavy gauge galvanized steel with a continuous 1-1/2 inch x 1-1/2 inch (38 mm x 38 mm) nominal wood nailer attached to the isolation support pedestals. Support of the RTU by weather seal attachment bolt heads is not permitted. The upper support rail shall consist of a structural channel with sufficient elevation above the spring to preclude interference with the rooftop equipment and permit access to inspect the isolation system after placement of the rooftop equipment. The upper support rail shall provide continuous structural support for the rooftop equipment and shall be designed to provide isolation against casingradiated vibration in the rooftop equipment housing and structure borne vibration from rotating and mechanical equipment in the rooftop package. The isolation curb shall consist of an upper support rail with supply and return duct supports on which the equipment and duct openings rest and a lower support curb which is attached to the roof structure, separated by free-standing, unhoused, laterally stable steel springs. The vibration isolation curbs shall be complete assemblies designed to resiliently support equipment at the specified elevation and shall constitute a fully enclosed air- and weather-tight system. All rooftop air-handling units shall be supported by vibration isolation curbs as manufactured by Kinetics Noise Control.
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