BETEC CAD Explosion proof Dampers can stand up to the toughest and most demanding environments and can be custom-built to meet the exact needs of virtually any ventilation or process applications. Ex-D - GB / SB 40, Galvanized / Stainless Steel Construction Aerofoil Blades; Static / Dynamic; Fire Rating : 3 Hrs. Leakage Rating to Class-2, at 250°F. Drive : Electric / Pneumatic.: Ex-D-GB-40B ; Ex-D-GB-40BPn ; Ex-D-SB-40B ; Ex-D-SBPn Ex-D SB-40 Series is a stainless steel high performance 3hr. rating fire damper, to ensure lowest resistance to airflow in HVAC systems with velocities to 3000 fpm (10.2 m/sec.) and 4” w.g. (1000Pa) may be installed vertically or horizontally (with blades running horizontally) and is rated for airflow and leakage class 2 in either direction. Ex-D-GB-40 --- All Steel Heavy Duty Industrial 2’’(50mm) Flanged Frame Damper. Max. System velocity --- 3000FPM ; Max. air leakage ---- 0.4% with seal.