| 摘要 |
A fire collar ( 10 ) including a housing defining an opening ( 18 ) and a passage ( 20 ) adapted to receive a conduit therethrough. A layer of intumescent material ( 43 ) surrounds the conduit and is supported by the housing adjacent the opening. Torsion springs ( 34 ) are mounted between the housing and the intumescent material to surround the conduit and are held in a non-operational position by fusible links ( 41 ). When the heat of a fire melts the links, each torsion spring acts in a longitudinal plane of the passage to assist the intumescent material to collapse the conduit and seal the passage against advancement of the fire.
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