BLAST CONTROL DEVICE

PURPOSE:To prevent the occurrence of the overload of a subsequently starting blower and to enable ensurance of proper operation by a method wherein a damper for parallel branch is provided so that a space between a duct and a blower is divided into two sections, and during the starting of the blower, opening and closing are controlled according to a state. CONSTITUTION:Dampers 4..., 5..., 7..., and 8... are mounted facing a plurality of ducts 6..., 9... and the inlet of a blower chamber, and dampers 31 and 31 for parallel branch are provided in a manner to divide the dampers into two lots. When, during running of a precedingly starting blower, a subsequently starting blower is started and blast is fed to a single duct through the two ducts, the dampers 31 and 31 for parallel branch are closed, and a damper for the duct on the subsequently starting side and a blower chamber damper are opened. After the speed of the subsequently starting blower is increased to a given value, the dampers 31 and 31 for parallel branch are opened, and a damper for the duct on the subsequently starting side is closed.