The Model FSD-331 is a three-hour rated combination fire-smoke damper with Class I leakage. Featuring a high-strength airfoil-style blade, the damper operates with velocity ratings up to 4,000 fpm (20.3 meters per second) and a pressure rating up to 4 inches wg (1 kPa). The steel airfoil blade combined with the profile frame design results in the industry’s lowest pressure drop, claims the manufacturer. Model FSD-331 is available in a vertical mount with a maximum size of 120 inches wide by 96 inches high. Frames are constructed with reinforced corners. A low-profile head and sill are used on sizes less than 17 inches high (432 mm). Blades are reinforced with three longitudinal structurally designed vees. Factory-mounted accessory options include retaining angles, quick-connect breakaway connections, S and drive connections, and access doors.

Greenheck, P.O. Box 410, Schofield, WI 54476-0410; 715-359-6171; 715-355-2399 (fax);

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