Intumescent seals

DETAILED DESCRIPTION I claim: 1.
An intumescent seal comprising a first body or mass of an intumescent material which produces a hard foam on heating and a second body or mass of an intumescent material which produces a soft foam in heating, the intumescent materials being carried by one or more of a plurality of members or parts which at least when they are in a predetermined position relative to each other define a gap, which gap can be sealed by either of the foams produced by the intumescent material under fire conditions, one said body or mass being disposed relatively near one margin of the gap and the other said body or mass being disposed relatively remote from said margin such that the foam produced by said one body or mass separates the other body or mass and the foam produced thereby from said margin.
2.
An intumescent seal according to claim 1, wherein there are a pair of said members or parts.
3.
An intumescent seal according to claim 1, wherein said members or parts comprise a door or movable window and an associated fixed frame, the leaves of a pair of double doors or windows or movable partitions.
4.
An intumescent seal according to claim 1, wherein the two intumescent materials are accommodated in at least one of said parts or members, the two intumescent materials being accommodated separately from each other.
5.
An intumescent seal according to claim 4, wherein a draught and smoke sealing blade or other resilient sealing element is provided between the two intumescent materials.
6.
An intumescent seal according to claim 1, wherein the seal comprises a holder accommodating both the intumescent materials, the intumescent materials being separate from each other.
7.
An intumescent seal according to claim 6, wherein a draught and smoke sealing blade or other resilient sealing element is provided between the two intumescent materials.
8.
An intumescent seal according to claim 7, wherein the sealing element is secured in or on the holder.
9.
An intumescent seal according to claim 7, wherein the sealing element is provided independently of the holder