Isolating/pressure relief damper

摘要

Described herein is a damper for controlling the passage of hot gases through a duct. The damper has a frame through which are passages. Along these passages coolant is passed to cool the frame and so reduce its thermal expansion as a result of the passage of hot gases through the duct. One or more damper blades are positioned within the opening in the frame, these blades being mounted on shafts rotatably journalled in a bearing cooled by the coolant passing through the frame, a seal being provided where the shafts extend through the frame to allow flow of coolant from the frame into the duct and prevent flow in reverse. The edges of the damper may be provided with seals which include a first resilient sealing element having a free end arranged to engage and be deflected by contact with the blade or other component when the blade is in its closed position and a second resilient element arranged to be engaged by and give additional stiffness against further deflection to the first resilient sealing element when the latter has become deflected to a predetermined extent.