Butterfly valve having a collapsible seal

摘要

A valve comprises a valve member in a duct having a collapsible seal. The collapsible seal includes a sealing ring around the valve member. The seal may be pressurized to contract the sealing to engage the valve member. Conversely, a control vent releases the pressure to expand the sealing ring away from the valve member. To open the valve, the seal expands into the wall of the duct to eliminate friction and initiate fluid flow around the perimeter of the valve member. To close the valve, the valve member is pivoted to the closed position and the seal is activated to engage the perimeter of the valve member. The seal is further configured to withstand high temperature applications. <IMAGE>