Patent ID: 8156699

Claim:
A fire resistant vision panel for assembly in an opening passing through a door, the vision panel comprising: a first and second flange unit each comprising a rectangular frame sized to frame the opening and abut a front and rear face of the door; the rectangular frames of the flange units each having four sides attached at corners by welds; sash elements adapted to extend into the opening from each of the first and second flange units to capture a transparent pane therebetween within the opening; at least one retention member attached to the first flange unit and extending into the opening beyond a position of the transparent pane with respect to the first flange unit when positioned between the sash elements to grip a sill surface of the opening thereby to retain the first flange unit and its sash element in position for assembly the retention member having an end unobstructed by the first flange unit when the first flange unit is in position for assembly; a spike positioned on the first end to affix the first end to a core material of a sill surface of the opening to retain the retention member in the opening wherein the spike is sized, oriented and positioned to be driven into the core material by impact of a hammer; and at least one fastener adapted to draw the first and second flange units and the sash elements together against the pane; and wherein the sash elements include flanges extending generally parallel to the transparent pane when captured therebetween, ends of the flanges flexing to provide inwardly spring-biased sharp edge portions in contact with said pane wherein said sharp edge portions will embed in said pane to grip the pane when said pane becomes semi-molten in fire.