A fire-resistant, aluminum, cementitious-material-free, insulation-free door adapted to prevent the spread of fire and heat passing therethrough, consists of: a door frame; a door hingedly mounted on the door frame, the door having a bottom wall, a top wall, and side walls, the bottom wall, top wall...http://www.google.de/patents/US6615544?utm_source=gb-gplus-sharePatent US6615544 - Fire-resistant door
