Patent attributes
An intumescent structure provides a hermetic-type barrier within a fiber duct through which communications cabling is extended. The structure is formed of a fire-resistant body possessing a plurality of pre-perforated forms that extend through the body. Each of the pre-perforated forms may be sized to have cross-sectional dimensions and geometries that generally correspond to the cross-sectional configurations of communications cabling that are typically placed in a fiber duct to interconnect electronic equipment. Selective removal of the pre-perforated forms establish associated passageways through the body for receiving the appropriately sized cabling therethrough. This facilitates the maintenance of a barrier to gasses and other substances escaping through the duct, while still allowing cabling to freely pass through the duct.