Two round backdraft dampers, models WDR-53 and SSWDR-53, can be installed horizontally for vertical up/down airflow or mounted vertically for horizontal airflow. Model WDR-53 features a galvanized steel frame with aluminum blade; Model SSWDR-53 is constructed with a 304 stainless steel frame and blade. Both models are available with an optional top frame extension. They are rated for velocities up to 2,000 fpm and pressures up to 2-inches water gauge, in diameter sizes from 4-24 inches.
Greenheck, P.O. Box 410, Schofield, WI 54476-0410; 715-359-6171; 715-355-2399 (fax); www.greenheck.com