Double dome heat and smoke vent structure

DETAILED DESCRIPTION What is claimed is: 1.
A vent structure for enclosing a heat and smoke vent opening comprising: a first heat softenable and heat shrinkable sheet member having a peripheral edge circumscribing said opening, a second heat softenable and heat shrinkable sheet member having an edge over said peripheral edge of said first member, said second member being positioned spaced from and coextensive with said first member forming a dead space therebetween, the one of said members facing the heat to be vented through said vent opening and having a plurality of spaced holes for providing heat circulation to said dead space for softening the other of said members and the other of said members being continuous in the sense it prevents the escape of heat passing into the dead space prior to its softening, and heat softenable heat shrinkable means which opens said holes in response to said heat applied thereto enclosing said holes for enclosing said dead space to provide thermal insulation in the absence of said heat to be vented.
2.
The structure of claim 1 wherein said sheet memers are formed into a pair of nested skylight members and made of material adapted to shrink and fall into said opening upon softening.
3.
The structure of claim 1 wherein said heat shrinkable means is a thermoplastic film cemented to said one member.
4.
A heat and smoke vent skylight structure comprising: a first heat softenable and heat shrinkable thermoplastic skylight sheet member, a second heat softenable and heat shrinkable thermoplastic skylight sheet member spaced from the first member and secured to the first member at the outer edges thereof to form a dead air space therebetween, the inner one of said members having a plurality of spaced holes for providing circulation of heat to the other outer one of said members so that said outer member will soften when the inner one member is exposed to heat and the other of said member being continuous in the sense it prevents the escape of heat passing into the dead space prior to its softening, and heat-softenable, heat-shrinkable hole closing means enclosing said holes for maintaining said dead air space except when said inner one member is exposed to heat sufficient to soften and shrink said hole closing means and open said dead air space to said heat