The smoke damper is constructed of standard hot-dip pre-galvanised steel frame and blade.  The blade is constructed of double-skinned steel plates with stainless steel blade edge seals.  The vertical frame is constructed of ‘C” channel with 38 or 50 mm flanges for duct connection.  Stainless steel jamb seal is installed on the vertical frame to minimise leakage between blade and frame.  Damper blade design enables bi-directional airflow.  Each blade is equipped with square stainless steel stub shaft and pivot on two-parts bearing.  Interconnecting blade linkages are located outside the air stream and pivot on two parts bush.  Damper may be constructed of stainless steel blade and frame.  As a standard, on-off spring-return electric actuator is provided to each damper, number of actuator required depend on the torque required to meet pressure and flow requirement.  The electric actuator is fast acting and able to close or open the damper over 90 degrees travel in 20 seconds.  Pneumatic actuator with a fast acting time of less than 10 seconds may be supplied upon request.