| 摘要 |
A double louver damper for use in a duct system conveying hot gases and particles in order to permit safe entry to be made therein when servicing is required has a frame to be incorporated in the system. The frame has two parallel seals surrounding the flow path, one spaced downstream relative thereto and to the other. The frame pivotally supports two sets of the same number of blades, one set for each seal and with the axes of the corresponding blades of the two series in the same plane. Each blade is in the form of an elongated, centrally pivoted diamond and is provided with coplanar lengthwise and end sealing portions of the same radial extent. When the damper is closed, the long axes of the blades are substantially in the same plane with the proximate lengthwise sealing portions overlapping and the remaining lengthwise and end sealing portions engaging the appropriate one of the seals. When the damper is open, each pair of corresponding blades partially overlap to establish a streamlined parallelogram of the thickness of one blade but half again as long with its long sides parallel to the flow path.
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