Fire extinguishers – Apparatus which isolates flames from non-burning area
Patent
1993-09-27
1996-03-05
Pike, Andrew C.
Fire extinguishers
Apparatus which isolates flames from non-burning area
48192, A62C 400
Patent
active
054958946
DESCRIPTION:
BRIEF SUMMARY
A comprehensive system of air intake and exhaust channels must be installed nowadays in major building complexes, e.g., hospitals, industrial buildings, office buildings, apartment complexes, and underground garages, but also in tunnels and shelters. The main runs in particular of such ventilation systems penetrate fire control sectors and thus facilitate quite considerably the spread of a blaze in the event of fire. To prevent this, devices are installed in ventilation systems of this type at the boundaries between fire control sectors, which devices are activated in case of fire to seal the ventilation system at these junctures.
These may be mechanical dampers or bulkheads, or they may be closures of another type, such as, for example, the so-called fireproofing plates that have the property of expanding to a multiple of their original volume when exposed to the effects of high heat (e.g., from about 80.degree. C. on up). A large number of these plates, parallel to each other, are installed in a cross section of the air intake or exhaust ducts by means of a frame, holder, or other suitable structures, in such a way that the planes of the plates coincide will or lie parallel to the direction of flow. In this manner, air can continue to flow through between the plates unhindered when they are in their original condition, thus when their thickness is small. In case of fire or other occasion of heat, on the other hand, these fireproofing plates expand so strongly that they contact each other and even fuse, thus leading to complete interruption of the flow cross section.
Such ventilation duct closures do have the advantage that their mechanical functioning need not be checked at regular intervals, but on the other hand have disadvantages: among them, that these fireproofing plates do not expand until a relatively high threshold temperature upwards of 80.degree. C. (as a rule, 150.degree. C.), and, furthermore, that once this threshold temperature has been reached it takes several minutes for the material to expand to its fullest extent. It can therefore happen, especially in the case of rapidly spreading fires, that, for example, after the threshold temperature has been attained at the closure, the flame front advances on this closure so rapidly that the flame front, for example a flame vortex, has already passed or broken through this closure before the fireproofing plate has expanded completely, thus after the reaction time necessary to seal off the closure has passed. In this case such a closure would be ineffective until the seal were complete, since the flame front would have been able to pass to the next fire control sector prior to establishment of the final seal.
It is therefore the object of the present invention to improve, in such a way that the flames are prevented from breaking through and/or a deflagration is prevented into the next fire control sector, a closure of the type described, said closure consisting of a material that expands strongly under the effect of heat.
To attain this object, it is proposed that fine-meshed lattices one or more layers thick and consisting of material with good thermal conductivity be placed in the cross section of the ventilation ducts in addition to the fireproofing plates. Since good thermal conductivity is afforded primarily by metals, such lattices are known by the name expanded metal in various thicknesses; for example, expanded metal packages consisting of metal foil only a few 1/100 mm thick, or tanks onto which such an expanded metal is added by processing, are used for explosion protection in containers holding flammable and highly volatile liquids.
Especially when a large number of expanded metal layers is placed in sequence in the direction of flow in the ventilation ducts, even such a .small thickness is enough to prevent breakthrough of the flames, at least for the time required for the closure to seal off completely. It is herewith obviously recommended that the individual layers of expanded metal be disposed transverse to the direction of flow in
REFERENCES:
patent: 2420599 (1947-05-01), Jurs
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