Blast dampers are used in ventilation systems to prevent the blast wave through external walls into the building. They are designed with high ventilation capacity. The dampers can protect people and equipment from explosions or momentary pressure change (e.g. tornadoes, etc.). When an explosion occurs, the valve will close instantly under the action of the shock wave; when the shock wave disappears, the valve will be automatically restored. They are mainly used in refineries, oil & gas, nuclear power plants and some other facilities which are at risk of explosions. They are installed on the air openings (air inlet and air outlet) of the facilities.