Abstract:
A fire resistant wall includes a frame assembly utilizing tubular steel studs having at least one opening at the bottom and at the top, a stratum of fire resistant material disposed in the inter-stud space, and a trim assembly structured to protect the gaps between adjacent panels. The openings in the studs allow hot fluid within the studs to be exhausted in a remote location and cool fluid to be drawn in from another remote location. The stratum of fire resistant material disposed in the inter-stud space resists heat and flames contacting the lateral sides of the studs when the inner stratum of the firewall collapses, or when gaps appear between adjacent inner stratum panels. The trim assembly preferably includes a metal bar with a concave back surface disposed over the gap between adjacent panels and an intumescent caulk disposed at least partially within the gap. An intumescent caulk expands when exposed to heat and fills the gap between inner stratum panels.

Description:
FIELD OF INVENTION 
     This invention relates to fire resistant walls and, more specifically to a fire resistant wall having a thinner profile than prior art fire resistant walls. 
     BACKGROUND OF THE INVENTION 
     Fire resistant walls typically include a frame assembly formed from a plurality of steel channel studs and cross members as well as a stratum of gypsum disposed on both the inner side and the outer side of the frame assembly. The fire resistant wall typically has a stratum of insulation disposed between the studs. The use of gypsum, which is fire resistant, on both the inner side and the outer side of the frame assembly is a relatively inexpensive construct that is capable of passing standard fire resistance tests. That is, in this configuration, the spread of fire from one side of the wall to the other is resisted for a set period of time. During the test, fire is applied to an “inner” side of the wall, and temperature measurements are taken at a number of points on the “outer” side of the wall. During the test, the inner stratum of gypsum is consumed by the fire over a period of time. Typically, a gypsum stratum, or a portion thereof, remains in tact until water and the gypsum, vermiculite and/or similar material fibers within the stratum are destroyed at which time the gypsum stratum, or a portion thereof, crumbles into dust. The destruction of the inner stratum of gypsum has two detrimental effects. First, and most obvious, with the inner stratum gone, the fire may spread to the insulation and outer stratum of gypsum. Second, when the inner stratum is destroyed, structural support for the frame assembly is removed. To pass the test, a fire resistant wall must both delay the spread of the fire for a set period of time (as measured by sensors on the outer side of the wall and which must detect a temperature above a predetermined limit) and ensure that the elements of the frame assembly can survive a fire hose test. That is, after the test, elements of the frame assembly must be able to withstand the force created by a fire hose. 
     The use of both an inner and outer stratum of gypsum held ensures that the frame assembly will not collapse when the stratum layer of gypsum is consumed by the fire. That is, the outer stratum of gypsum adds rigidity to the frame assembly even when the inner stratum of gypsum is destroyed. Further, as noted above, gypsum is fire resistant and helps delay the spread of the fire. This construct, however, tends to be thick. Thus, each wall occupies a set amount of floor space that could be used for other purposes. 
     Further, the use of steel channel studs, while sufficient for supporting a fire resistant wall, does not have sufficient strength to create a blast resistant wall. Blast resistant walls are required in certain types of construction such as, but not limited to, hazardous material storage. Tubular steel studs increase the strength of the frame assembly, but are known to trap heat within the members. Given that the most elements of the fire resistant wall are coupled directly to the frame assembly, this allows heat to be transferred via conduction from one side of the wall to the other. This is not a desirable effect. 
     The insulation used in the intra-stud spaces has not necessarily been a fire resistant material. For example, fiberglass insulation melts at about 1000 degrees Fahrenheit. Typically, the insulation is selected for the insulative qualities of the material. Thus, during a fire, before the inner stratum of gypsum is breached, the insulation burns. Thus, when the inner stratum of gypsum is heated, the heat is passed into an, essentially, empty space. This heat is then transferred to the inner side of the outer surface and may cause the outer layer of gypsum to overheat. 
     Further, it is noted that the gypsum strata is typically composed of a plurality of panels. During a fire these panels tend to shrink and gap. That is, as water and other materials within the panel are consumed, a gap may appear between adjacent panels. Such a gap allows the fire to pass into the fire resistant wall and consume the insulation and/or heat the frame assembly. Again, this is not a desirable effect. 
     SUMMARY OF THE INVENTION 
     The concept disclosed below, and as recited in the claims, provides for an improved fire resistant wall that addresses these issues. The fire resistant wall includes a frame assembly utilizing metal plates welded to the outer surface of tubular steel studs having at least one opening at the bottom and at the top. In this configuration, fluid, which is typically air, within the stud will circulate when heated. That is, hot fluid will naturally rise and exit the stud via the upper opening. Further, cooler fluid will enter the lower opening and move into the stud thereby slowing the rate of heating within the stud. Preferably, the studs are coupled to a horizontal top member and bottom member. The top and bottom members are also hollow and have openings in fluid communication with the stud openings. In this configuration, the hot fluid may be exhausted and cool fluid may be drawn in. Because heat exits the wall via exhausting hot fluid through the tubular members, the heat is not passed to the outer wall. 
     The fire resistant wall further includes a stratum of fire resistant material disposed in the inter-stud space. That is, unlike the prior art which only had an insulation between the studs, the firewall has a gypsum stratum, or other fire resistant material, extending between the studs. In this configuration, when the inner stratum collapses, or when gaps appear between adjacent inner stratum panels, heat and flames do not contact the lateral sides of the studs and the collapsed stratum is pressed against the inside surface of the outer metal plate. Rockwool insulation bats are preferred to hold the gypsum against the plate. Thus, heat transfer is reduced and little heat is passed to the outer surface of the metal plate. 
     The fire resistant wall further includes a trim assembly structured to protect the gaps between adjacent panels. The trim assembly preferably includes a metal bar member, having a concave back surface, disposed over the gap between adjacent panels and an intumescent caulk disposed at least partially within the gap and under the bar. An intumescent caulk is a caulk that expands when exposed to heat. Thus, the trim assembly bar initially resists heated air and flames attempting to pass through the gap and, after the panels shrink, the intumescent caulk expands to fill the gap and continues to substantially seal the gap. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top cross-sectional exploded view of a firewall. 
         FIG. 2  is a side cross-sectional exploded view of a firewall. 
         FIG. 3  is a schematic broken line view of the frame assembly. 
         FIG. 4  is an isometric broken line view of the firewall according to a first embodiment. 
         FIG. 5  is an isometric broken line view of the firewall according to a second embodiment. 
         FIG. 6  is an isometric broken line view of the firewall according to a third embodiment. 
         FIG. 7  is an isometric broken line view of the firewall according to a fourth embodiment. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As used herein, a “stratum” is a layer of specific type of material. The stratum may be comprised of one or more panels of that material. 
     As used herein, a “strata” shall mean a construct having two or more stratums. The different stratums may be mechanically coupled together, e.g., by fasteners, adhesives, or other devices, may be formed together, e.g. two stratums of foam poured against each other or a stratum of foam poured on a rigid panel, or may simply be placed adjacent to, or in contact with, each other. 
     As used herein, “steel” is understood to include steel alloys. 
     As used herein, a “fire resistant board” shall mean a board made from gypsum, vermiculite, or similar materials and any combination thereof. 
     It is understood that the phrase “internal side” means the side of the firewall wherein a fire occurs, or is likely to occur. Conversely, the “external side” is the side of the firewall opposite where a fire occurs, or is likely to occur. 
     As shown in  FIGS. 1 and 2 , a firewall  10  includes a frame assembly  12  and a wall assembly  50 . The frame assembly  12  includes at least two hollow, tubular steel studs  14 ,  16  extending generally vertically and, preferably, includes a generally horizontal, generally hollow base member  18  and a generally horizontal, generally hollow top member  20 . The studs  14 ,  16  each have an inner surface  15  and an outer surface  17 , as well as two lateral surfaces  19 . Between each pair of studs  14 ,  16  is an inter-stud space  13 . The base member  18  has an upper surface  22  having at least one opening  24  therein. The top member  20  has a lower surface  26  having at least one opening  28  therein. The studs  14 ,  16  each have at least one lower opening  30  and at least one upper opening  32 . The at least one lower opening  30  and at least one upper opening  32  may be located on a longitudinal side, i.e. one of the inner surface  15 , and outer surface  17 , or one of the two lateral surfaces  19  (not shown), but in the preferred embodiment, the studs  14 ,  16  are coupled to, and extend between, the base member  18  and the top member  20 . Thus, in the preferred embodiment, each stud&#39;s  14 ,  16  at least one lower opening  30  and at least one upper opening  32  are on the axial ends of the studs  14 ,  16 . Further, each base member upper surface at least one opening  24  is aligned, and in fluid communication with, each stud at least one lower opening  30 . Similarly, each top member lower surface at least one opening  28  is aligned, and in fluid communication with, each stud at least one upper opening  32 . In this configuration, a fluid, such as air, may circulate from the base member  18 , through the studs  14 ,  16 , and the top member  20 . 
     Further, the base member  18  and the top member  20  preferably extend to locations remote from the studs  14 ,  16 . The lateral ends  34 ,  36  of the base member  18  and the top member  20  have openings  35 ,  37 , respectively, which allow fluid flow communication with the atmosphere. It is noted that the lateral ends  34 ,  36  may be coupled to additional passages between the frame assembly  12  and the atmosphere and/or may include protective devices such as, but not limited to, vent covers, screens, and such (not shown). In this configuration, when the studs  14 ,  16  are exposed to heat, the hot fluid will naturally rise and exit the studs  14 ,  16  via each stud at least one upper opening  32 . The hot fluid will pass into the top member  20  and be exhausted via a lateral end  36 . As the hot fluid is exhausted, cooler fluid is drawn into the studs  14 ,  16  via the base member lateral end  34  and passes through the base member  18  and through the base member upper surface at least one opening  24  and into a stud  14 ,  16 . Thus, a cooling air circuit is created when the studs  14 ,  16  are exposed to heat, such as but not limited to, heat from a fire. 
     The frame assembly  12  may also include at least two horizontal furrings  40 ,  42 . The furrings  40 ,  42  are, preferably, made from steel. A furring  40 ,  42  is, typically, an elongated U-shaped channel having a base  44  with two tines having distal tips  46 ,  48 . The distal tips  46 ,  48  are coupled, preferably by welding, to the inner surface  15  of each stud. Between the furrings  40 ,  42 , as well as between the furrings  40 ,  42  and either the ceiling or the floor, is an intra-furring space  49 . 
     The wall assembly  50  includes various strata and stratums as described below. An inner strata  52  includes a sheet steel stratum  54  and a fire resistant board stratum  56 . The sheet steel stratum  54  preferably includes a porcelain stratum  58  disposed on the outer side of the sheet steel stratum  54 . Thus, the porcelain stratum  58  is the exposed surface on the internal side of the firewall  10 . The wall assembly  50  further includes an outer stratum  60 , which is preferably steel plate. The outer stratum  60  is the external side of the firewall  10 . The inner strata  52  and the outer stratum  60  are both offset relative to the frame assembly  12 . That is, the inner strata  52  and the outer stratum  60  are not disposed within the plane of the frame assembly  12 . The inner strata  52  is coupled to the stud inner surface  15 . Preferably, the inner strata  52  is directly coupled to the furrings  40 ,  42 . The outer stratum  60  is coupled, and preferably directly coupled, to the stud outer surface  17 . 
     The wall assembly  50  further includes an inter-stud strata  70  within the inter-stud space  13 . The inter-stud strata  70  extends between adjacent studs  14 ,  16  and contacts the lateral surfaces  19  of the adjacent studs  14 ,  16 . In this configuration, the studs  14 ,  16  lateral surfaces  19  are generally not exposed to heat and flames when the inner strata  52  is destroyed by fire. As shown in  FIG. 4 , the inter-stud strata  70  preferably includes a thermax board stratum  72 , a fire resistant board stratum  74  and a thermafiber stratum  76 . The inter-stud strata fire resistant board stratum  74  is disposed between the thermax board stratum  72  and the thermafiber stratum  76 . The inter-stud strata thermafiber stratum  76  is disposed on the internal side, i.e. fire side, of the inter-stud strata  70 . In a second alternate embodiment, shown in  FIG. 5 , the inter-stud strata  70  includes a thermax board stratum  80  and a thermafiber stratum  82 , with the thermafiber stratum  82  disposed on the internal side, i.e. fire side, of the inter-stud strata  70 . In alternate embodiments, shown in  FIGS. 6 and 7 , the inter-stud strata  70  includes a thermafiber stratum  90  and a fire resistant board stratum  92 . As shown in  FIG. 6 , in the third embodiment, the thermafiber stratum  90  is disposed on the internal side, i.e. fire side, of the inter-stud strata  70 . As shown in  FIG. 7 , in the fourth embodiment, the fire resistant board stratum  92  is disposed on the internal side, i.e. fire side, of the inter-stud strata  70 . 
     Further protection of the frame assembly  12  may be accomplished by providing an additional stratum to the inner strata  52  structured to extend into the intra-furring space  49 . That is, the inner strata  52  may further include a thermafiber stratum  100  disposed between the at least two horizontal furrings  40 ,  42 . 
     The inner strata  52  is typically constructed of a series of elongated panels  110 . The inner strata panels  110  preferably have generally straight edges. Preferably, the inner strata panels  110  extend the width of the firewall  10  and, as such, there are preferably only horizontal gaps  112 , or seams, between the inner strata panels  110 . It is noted that for a smooth appearance, the inner strata panels  110  are typically disposed immediately adjacent to each other forming seams; however, as noted above, when heat is applied to the inner strata panels  110 , the panels shrink. Thus, even where a gap  112  did not exist originally, a gap  112  is typically created upon the occurrence of a fire. Accordingly, as used herein, a gap  112  also means a seam between inner strata panels  110 . 
     As shown in  FIG. 2 , a trim assembly  120  is disposed over each gap  112  between adjacent inner strata panels  110 . The trim assembly  120  includes an outer cover  122  and intumescent caulk  124 . The outer cover  122  is structured to form a space between the central portion of the outer cover  122  and the inner strata panels  110 . That is, the outer cover  122  is arcuate, or a similar shape. The intumescent caulk  124  is disposed between the outer cover  122  and the inner strata panels  110  and at least partially fills the gap  112 . The intumescent caulk  124  may couple the outer cover  122  to the inner strata panels  110 , however, it is preferred that a fastener, such as, but not limited to, a nail  126  couples the outer cover  122  to the inner strata panels  110  or to one of the furrings  40 ,  42 . 
     In the event of a fire, the intumescent caulk  124  is structured to expand. As the intumescent caulk  124  expands, the intumescent caulk  124  fills the space between the central portion of the outer cover  122  and the inner strata panels  110  and will fill any portion of the gap  112  that is not filled with caulk  124 . That is, even if the inner strata panels  110  shrink, the intumescent caulk  124  expands to fill the space therebetween. As such, fire and/or heated gas is less likely to penetrate the inner strata  52  via the gap  112 . 
     In view of these features, the firewall  10  disclosed herein has a reduced thickness relative to traditional firewalls having two offset stratums of fire resistant board while maintaining a similar, or having an improved, resistance to the spread of fire and collapse. 
     While particular embodiments of the invention have been disclosed above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details may be made without departing from the invention as defined in the appended claims.