Stock material or miscellaneous articles – Sheet including cover or casing – Foamed or expanded material encased
Patent
1989-02-13
1990-06-05
Van Balen, William J.
Stock material or miscellaneous articles
Sheet including cover or casing
Foamed or expanded material encased
428 72, 428122, 428188, 4283055, 4283191, 428358, 428921, B32B 104, B32B 106, B32B 900
Patent
active
049313398
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to intumescent seals.
The intumescent seals comprise intumescent material which on being subjected to elevated temperature intumesces (i.e. undergoes substantial expansion) to produce a foam of fire-resistant intumesced material, often referred to as "puff".
Known intumescent seals comprise intumescent material which produces either a hard foam or a soft foam.
By a "hard foam" we mean a foam which, although not necessarily rigid, has a relatively high expansion force i.e. will not deform unless substantial pressure is applied to it. A hard foam acts as a pressure seal.
"Palusol" is an example of an intumescent material based on sodium silicate and which produces on heating, a hard foam. It has been claimed that Palusol is fully intumesced within three minutes of activation.
By a "soft foam" we mean a foam which has a relatively low expansion force. A soft foam acts as a gap-filling foam.
Intumescent materials which produce soft foams on heating are supplied by Sealmaster Limited and are described in British Pat. No. 1,601,131. The soft foam tends to be produced copiously by the intumescent material.
Intumescent materials which produce hard foams and soft foams in general intumesce at similar temperatures on heating. In the event of a fire, where an intumescent material produces a hard foam between a door and its associated frame, the hard foam may exert considerable pressure between the door and the frame, helping to control warping of the door in the early stage of a fire. However, this type of foam, at least when produced from known sodium-silicate based intumescent materials, becomes less and less rigid in performance as the fire progresses and finally becomes relatively soft in practice. A consequence of this is that any further dramatic warping or possibly even minor warping cannot be accommodated. Where the intumescent material produces a gap-filling soft foam, the soft foam is (as compared with a hard foam) less able to accommodate severe early warping although the copious foam produced will readily follow the warped surfaces for a prolonged period e.g. 60-70 minutes.
Accordingly, it will be understood that hard foams may be advantageous in certain situations. E.g. they may be useful to restrain doors from warping under fire conditions. Soft foams may be advantageous in certain other situations. E.g. they may be useful for providing sealing between parts which will inevitably undergo relative movement under fire conditions and may fill irregular gaps better than hard foams.
Hard foams may also be disadvantageous under certain circumstances, e.g. since these are less voluminous than soft foam, and thus may not be sufficiently gap filling where there is warping or where large air gaps are present. Soft foam, equally may be disadvantageous under certain circumstances, e.g. they are insufficiently firm to prevent door warping.
Also some known intumescent materials are subject to atmospheric degradation or exposure to air and in particular on exposure to atmospheric moisture.
The invention aims to provide intumescent seals which combine the advantages of seals which produce hard foam, and of seals which produce soft foam but do not suffer from the disadvantages of either type of seal.
The invention is based on the concept of providing an intumescent seal comprising separate bodies or masses of intumescent material which produces a hard foam on heating and intumescent material which produces a soft foam on heating, the seal being for disposition at or adjacent a gap to be sealed by the foams produced by the intumescent materials under fire conditions.
The intumescent material may be accommodated in at least one holder or may be mounted (without any holder) on or in members or parts which, at least in a predetermined relative position, define the gap.
Such members or parts may be a door or window and an associated fixed frame, the leaves of a pair of double doors or partitions.
In accordance with a broad aspect of the invention, there is provided an intumescent seal comprising
REFERENCES:
patent: 4581866 (1986-04-01), Malcolm-Brown
patent: 4839223 (1989-06-01), Tschudin-Mahrer
Dixon International Limited
Van Balen William J.
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