Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Patent
1996-10-30
1998-11-10
Zirker, Daniel
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
428920, 428921, 442136, 252 2, C09K 2102, H01B 734
Patent
active
058341200
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fire protection materials.
In many technical fields, it is important to provide fire protection for equipment and plant. In electrical applications, this can cause difficulties because although an insulating material will protect the plant from fire encroaching onto it, by the nature of the material it will retain the heat generated by the plant within the insulative envelope, and may cause overheating of the plant.
For example, fire protection in areas with a high concentration of power transmission, instrument and communication cables and wires is vital to ensure a systematic and safe control and, if necessary, emergency shut-down of plant. These services are essential to utilities in the petrochemical and power generating fields. It is also vital that control and emergency shut-down valves, valve-actuators and associated switch/junction boxes are also protected against fire.
All the items above dissipate heat under their normal operating conditions. The electrical cables generate heat due to their internal line resistance, valve actuators also generate heat due to internal pressures. Valves themselves dissipate the heat due to the process temperatures involved. Accordingly, a fire protection system, while being a good fire barrier, should also ensure minimal restriction to the heat dissipation from these items. This will cause minimum reduction in the amount of current carrying capacity of electrical cables (ampacity derating) and prevent the overheating of valve actuators.
Previously, inorganic materials in the form of fibre blankets constructed from alumino-silicate fibres, silicate fibres, mineral fibres, or a combination of such fibres, have been used for the fire protection of conduits, cable trays and valve actuators. In order to provide one hour fire protection these are usually fitted around the protected items to a thickness of 3 inches or more. These fibre blankets all have a low thermal conductivity (especially in the ambient temperature range) which not only insulates from the effect of fire but even more effectively retards the dissipation of heat from the protected equipment and requires a substantial reduction in the current carrying capacity of electrical cables, deratings of 56% and greater being typical of such fire blanket systems.
It is also known to provide materials which are designed to retard the spread of fire and heat by an endothermic reaction. For example, it is known from prior art documents to use a hydrate within the insulating material, which dehydrates endothermically in the event of fire and thus absorbs heat from the fire. For example, U.S. Pat. No. 4,315,075 and U.S. Pat. No. 4,600,634 describe the use of alumina trihydrate (Al.sub.2 O.sub.3.3H.sub.2 O) in similar applications to retard combustion by an endothermic reaction. The water vapour also dilutes combustible gases which may be present during a fire, retarding combustion. With this compound, the water of hydration begins to be liberated at about 230.degree. C. with the peak release at about 320.degree. C. and 90% of complete dehydration at around 400.degree. C., resulting in a single endothermic reaction.
A disadvantage of such known materials is that the maximum protection is only up to about 400.degree. C. and only over a fairly restricted temperature range after which the protection is significantly reduced. An object of the present invention is to provide an improved fire protection material.
According to the present invention, a fire protection material is characterized by the addition of an endothermic inorganic compound which reacts endothermically on the application of heat through at least two mechanisms so as to bring about multiple endothermic reactions in the event of fire.
The preferred material is formed into semi-rigid sections either in sheet form or moulded into conduit sections or sections specially shaped to encapsulate particular components.
Preferably the endothermic inorganic compound is an hydrated compound and at least one of the mechanisms may comprise dehydrat
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patent: 4612239 (1986-09-01), Dimanshteyn
WO 9420965 Abstract.
Alumina Trihydrate: Flame-Retarding, Smoke-Suppressing Filler, Joseph Z. Keating, Jul.-Aug. 1980, pp. 23-35.
Chi Frank K.
Lintz Timothy S.
Murray Keith
Paddock Ralph W.
Philpott Clifton
Darchem Engineering Ltd.
Unifrax Corporation
Zirker Daniel
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