| 摘要 |
A damper for ducts of large cross sectional areas has an upstream seat surrounding the flow path and a blade which consists of upstream and downstream skins of a high quality nickel allow steel and an internal reinforcement. The thickness of the skins is such that, given the size and shape of the seat, they are relatively flexible. The skins are welded to opposite sides of the reinforcement which is in the form of a grid or lattice of substantially the size and shape of the seat and both renders the skins rigid and establishes the wanted blade thickness. Members marginally of the grid and welded thereto are exposed to be operatively engaged by the mechanism by which the blade is reciprocated between positions permitting or blocking flow through the damper.
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