Blower

In a conventional pipeline blower, a movable side rack of a frame is a starting rack approximately 180-degree structure, and the bottoms of the movable side racks are pivoted to a free end of a fixed side rack and arranged on an outer periphery of the fixed side rack; a start/stop half-circle structure has disadvantages that the movable side rack is closed in front of another free end of the fixed side rack, i.e., part of a sealing pad of an opening portion of an upper portion of a frame annular rack is displaced in a cross side of the periphery direction; the frame has two openings and is formed by the fixed side rack and the movable side racks connecting/disconnecting the fixed side rack; in the frame, a fan arranged in the frame and a blower driving a motor of the fan, at least part of left-right dual-door forms the movable side racks; the bottom end of each movable side rack is pivoted to two free ends of the fixed side rack, wherein a first connecting point (pivot portion) and a second connecting point (pivot portion) are fixed outside the periphery of the fixed side rack, thus protecting sealing pads of the movable side racks.