Qualified to pressures as high as 15 psi, Models HBS-430 and HBS-431 protect against blasts and instantaneous pressure changes. These heavy-duty, double-flanged, channel frame-style dampers feature double thickness fabricated airfoil blades and cover applications in UFC and GSA codes and standards, including Charge Weight I at 82 ft. Areas of use include government buildings, mining, oil and gas platforms, refineries, and protection of ventilation systems.