Importance

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Abstract

A damper for an air handling system in which the blade or blades are normally positioned to permit air to flow through the damper by a pneumatic cylinder which, when pneumatically actuated, overcomes the force of a spring within the pneumatic cylinder which would otherwise position the blade or blades to close the damper to air flow. The pneumatic cylinder normally receives air through a primary outlet of a three-way valve, the three-way valve also having a vent outlet and a valve member which is movable to permit pneumatic flow either from a source of pneumatic fluid through the primary outlet or from the pneumatic cylinder back through the three-way valve for venting through the vent outlet. The valve member is biased to permit pneumatic flow only through the vent outlet, but it has a portion which extends beyond the valve body and which is restrained by a mechanism that includes a fusible link to restrain the movement of the valve member so that it normally only permits pneumatic flow through the primary outlet. In the event of a fire or other condition of excessive temperature the fusible link will fail, the valve member will move to its venting position, and the spring within the pneumatic cylinder will close the damper to air flow.

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First Claim