Abstract: The proximate ends of spaced apart sections of duct systems for fluid media are interconnected by expansion joints having a sleeve of flexible material surrounding and isolating the flow path in the area between the sections. The flexible material consists of at least one reinforcing substrate to which surface layers of a media resisting material having a degree of elasticity are fused and bonded. Each substrate in one embodiment consists of two series of strands oriented to present a criss-cross pattern with the strands of both series diagonally disposed with with respect to the flow path when the material is formed into a sleeve. In another embodiment, there is an additional series of strands which are longitudinal.

Abstract: A guillotine damper for use in exhaust or like duct systems which must be entered by men for servicing has its frame provided with guides extending about the flow path from one end of the opening by which the blade enters an air tight bonnet to the other end thereof and enclosed by resiliently flexible metal seals. The blade has marginal channels coextensive with the guides with the channels closely fitting the guides and compressing the sides of the seals with zero leakage attained by sealing air discharged along the channels during movement of the blade and while the damper is closed.

Abstract: 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.

Abstract: A guillotine damper for a duct is provided with a thrust frame upstream of the path of a blade that is movable into and out of an operative position in sealing engagement with a seat downstream of the blade path when the flow path is not obstructed by the blade and in sealing engagement with and seating the blade against the seat when the blade is positioned to block the duct. Devices are provided with each utilizing resilient components to thrust the frame into its sealing positions and a hydraulic component to retract the frame when the blade is to be moved into or out of its duct blocking position. Each device exerts the force of either component to the frame through a series of mechanical elements spaced a substantial distance apart along the sides of the frames and connected thereto.