US 3538975 A
Description (OCR text may contain errors)
I United States Patent 1 1 3,538,975
 Inventors Sam S. Metti  References Cited Glenvie and UNITED STATES PATENTS Shem Tmfimmhbmk' mind 790,632 5/1905 11611 160/1 2&1 1968 3,401,734 9/1968 McCabe 160/1x 1 e 01!. 9 4s Patented NOV. 10, 1970 FOREGN PATENTS  Asian By mesne assignments, to Air Balancelnu 81,863 6/1895 Germany 160/235 Chm, minis Primary Examiner-Peter M. Caun m of Dehwa" Attrney-- Anderson, Luedeka, Fitch, Even and Tabin ABSTRACT: A fire damper assembly comprises a rigid frame having a pair of parallel side walls with a flange and a rail on v each wall defining a channel and a slat assembly mounted in 4 DAMPER the channels. The slat assembly is formed of a succession of a Chlmss Drawing Figs impervious metal slats with their edges interfitting to permit  U.S.Cl 160/1, the slats to be rotated relative to one another from a folded 160/5, 160/207, 160/235,E05f /20, position to an extended position. Extensions from respective [5 l] Int. Cl. E05d 15/26 edges of each slat straddle the rails. Retainer rings on the ex- Field Search. /1, 5, 6, tensions hold the edges of the slats together and act as 229. 235, 207 bearings in closing the damper.
Patented; Nov. 10, 1910 3,538,975
INVENTORS 3 SAM METTI SHE N 5. TA
FIR E'DA'MPER i The present invention relates to fire dampers and more particularly to fire dampers formed of metal slats where successivesla'tsare' hinged to permit the slats to be rotated relative to one another from arevcrsely folded position to an extended position.
Fire dampers and fire doors are well known for the preventionof the spreadof fires. Such fire dampers have been made of metal slats fastened together in such a way as to permit them to be rolled up or folded out of the way when open and not in operative position. One of the requirements of a fire *da'mper isthat when it is in its operative, or closed, position, it should exhibit no openings permitting direct passage of flame or heat through the effectivelpart of the damper. To this end it has be'en known to construct impervious successive slats of a fire damper with interfitting edges overlapping one another when the fire damper is in its operative position, the interfitting edges 'holding-the-successive slats together. A difficulty "with suchfire dampers was that they required a very complex configuration of the interfittingedges or they could not both b'e folded up and extendedwithout coming apart.
In accordancewith the present invention, a simple retainer "means is provided for hingingsuccessive slats together while permitting interfittingedges of simple configuration to move between a foldedposition and an operative position where the "edges overlap without comingapart. More particularly, in accordance'with apreferred embodiment of'the present invention, thisretainer'means is in theform of rings carried at the ends of the slatsoutside the effective area ofthc fire damper.
To assure full closure of thc l'ire damper, with no openings therethrough, the assembly ofslats is mounted in a rigid frame havingchannels oneachside, each channel being formed by a As illustrated in FIG. I, a preferred embodiment of the fire damper assembly of the present invention may comprise a slat assembly 10 mounted in a frame 12. The fire damper is shown in FIG. I in its operating position, i.e., closed.
7 The frame 12 may be made of sheet metal bent to the desired shape and held together by tabs 14 cut out of the sheet. Mounting holes 16 are drilled through the frame in suitable places for the insertion of bolts or other mounting means for fastening the frame in place, as by attaching it to ad jacent duct work. The slat assembly 10 is formed of a succession of metal slats 18. The top slat is pivotally mounted along one edge to the frame 12 by a pivot pin 20. As shown, successive slats 18 are preferably pivotally secured together at their ends by retaining rings 22. The retaining rings form a hinge between successive slats 18 so that the slat assembly 10 may move freely between the closed position shown in FIGS. 1 to 3 and the open position as shown in FIG. 4. In point of fact, of course, the fire damper is normally positioned in its open position as shown in FIG. 4 and is held in such position by a strap 7 24 containing a fusible link 26 which, upon occurrence of excessive heat as occasioned by afire, melts and thereby permits the fire damper I0 to fall to its closed position to confine the fire.
In order to be fully effective, the fire damper is made so that it exhibits no opening therethrough when in the closed position as shown in FIG. 2. To this end, the frame 12 includes a flange 28 extending inwardly from the frame at least on both rail andaflangeexten'ding from a side wall of the frame. The
rail is shorter than thefflange, and the slats themselves are made longer'than the distance between flanges and shorter than the distance between rails so that, when the damper is closed,-the slatsmay fit between the rails while coveringall of the area between the flanges. There are then no visible openings through the damper. This assures that hot gases and fire notpass directlythrough the closeddamper. At the very least itrequiresthe hot. gases and fire to take a tortuous path.
The slats each have edge extensions extending beyond the rails on each end of the respective-slat and on each side of the rail sothat when the damper is closed the edge extensions engage the rail and hold the slat assembly-in place, the edge extensions on one side ,of the rails being held in the respective channels.
In the preferred embodiment of the invention, alternate rings are disposed on opposite sidesof the rails and act as roller bearings to facilitate the movement of the fire damper from its folded toits operative position.
The primary'ohject of this invention'is to provide an improved fire .dampcr formed of metal slats having intcrfitting edge portions hinged together and mounted in a frame in such rmannerthat thereare no openings through the damper when closed. A furtherinvention is to provide a fire damper in which separate retainer means hinge the slats together permitting bothreverse foldingof the slats and full closing of the t damper'without falling apart. Afurther object of the invention is to provide such fire damper wherein retainer rings function as rollerbearingsguided by a rail toguide the tire damper into its operating position.
Other objects of the inventionwill be made apparent from the following descriptiontaken in connection'with the accompanying drawings in which:
FIG-l is aperspective view showing the fire damper of the present invention inits closedposition;
FIG. 2is a front view, partly in section, of the fire damper t shown in FIG.3.
sides so that-when the fire damper is in its closed position the slatassemhly l0 covers the entire opening within the flange 28. Further, the slats 18 are made individually impervious and longer than the distance between the flanges 28, and the adjacent edges of successive slats 18 are made overlapping. At
the same time,'the adjacent edges are made so that the slats 18 are free to move from the folded to the open position. To this end, the adjacent edges are made to be interfitting, as shown particularly in FIG. 4.
To guidethe closing of the damper and to hold the closed damper in place, a rail 30 is provided along each side of the frame 12. As shown particularly in FIG. 2, the rails 30 are shorter, than the flange 28 so that the slats 18 may extend beyond the edges of the flanges 28 while still clearing the rails 30. The slats have portions 31 extending longitudinally beyond the ends of the slats so that the edge extensions on I each end of a slat straddle a respective rail 30. The edge extensions 31 are therefore guided by the rails 30.
The retaining rings 22 are relatively loosely disposed upon the edge extensions 31 and serve to hold the edges together and to permit relative rotation of the successive slats. The rings 22 permit easy assembly of the slat assembly 10, as the edges of adjacent slats are easily interfitted, and they are then held in place merely by slipping the retaining rings 22 over the edge extensions 3].
Theretainingrings 22 also serve as roller bearings as the fire damper is moved from its open to its closed position. More particularly, the retaining rings 22 that are disposed between the rails 30 and the flanges 28 rotate in channels 32 defined by the flanges 28 and the rails 30 and thus guide the slat assembly 10 in its movement from the open to the closed position, while at the same time providing rolling friction so that the fire damper moves freely. As the slat assembly moves toward its closed position, the retaining rings 22 on the other side of the rails 30 away from the flanges 28 also engage the rails 30 and serve as roller bearings guiding the'slats 18 to the closed position where each edge extension 31 of each slat 18 engages a rail 30, which thus holds the fire curtain in the desired closed position, inhibiting movement of the slat assembly 10 in either direction away from the rails 30 so that the slat assembly remains in position even upon exertion of pressure from either side ofthe damper as by a fire hose.
The configurations of the respective interfitting edges may be generally as shown in greater detail in FIG. 5. The configurations of the two edges are generally semicircular with the radius of one circle being smaller than the radius of the other in order that when the slats are in their folded position, the
edge with the smaller radius nests in the other. At the same time, the edges preferably extend slightly beyond a semicircle so that when the slats are in their extended position, as shown in FIG. 5, the edges overlap.
The rings 22 are preferably annular to provide a suitable roller bearing surface and to permit free turning of the edges of the slats within the rings 22. The inner diameter of the rings is made large enough so that the interfitting edge extensions 31 are free to rotate between the folded and extended positions of the slats. It is necessary that the fire damper operate effectively even after long periods of nonuse. Since it is impractical to keep the joints clean, or at least unrealistic to expect someone to clean them, the relative dimensions of the edge extensions and the retaining rings preferably provide a loose fit at least while the slats are folded, so that corrosion and dirt do not lock the nesting edges together. This is particularly important under certain conditions of use, as where the damper is disposed in a dirty or corrosive atmosphere for long periods. It is useful under any conditions, for the fire damper is not intended to be used except in the event ofl'ire, which may occur many years after installation. A loose lit also assures closure in cases where the slats have been accidentally bent, as in installation, so that the hinges would not otherwise be free. On the other hand, the rings are not so large that the interfitting edges can come apart and leave open space between slats. The inner diameter of the rings is therefore made less than the sum of the dimensions of the interfitting edge extensions in the direction of the extended slat assembly. Further, the inner diameter of the rings 22 is preferably made only slightly greater than the outer diameter of the edge extension with the larger radius plus the thickness of the other slat so that the slats in the extended position are disposed snugly against one another and are held in place by the retaining rings 28 as shown in FIG. 5. In such condition, the slats l8 fit tightly against one another when the damper is closed, precluding the passage offire therethrough.
When there is a long span between the ends of the slats 18 there is a tendency for the slats to buckle in the presence of fire, which might cause the adjacent edges of the slats to come apart and permit the passage of fire through the damper. To prevent this, auxiliary retainers 34 are fastened to the edge of the slats at some distance from each of the ends. These retainers 34 are affixed to the slats near the edges and are curved to oppose the curvature of the edge of the slat on which it is mounted so that the edge of the adjacent slat is held between the brace and the edge of the slat on which it is mounted, preventing the interfitting edges from coming apart, as when exposed to heat or water pressure.
The fire damper as described so far is suitable for operation vertically whereby gravity closes the fire damper upon the melting of the fusible link 26. There are occasions, however, where it is necessary or desirable to mount the fire damper assembly horizontally, as in a floor. On such occasions means may be provided to close the damper. Such means may be a spring mounted on the frame 12 and affixed at one end to the end slat 18 of the slat assembly 10.
Although a preferred embodiment of the invention has been shown and described, various changes can be made within the scope of the invention. For example, under some conditions the retaining rings 22 may be omitted and the slats hinged together only by the retainers 34.
l. A fire damper comprising in combination, a rigid frame having a pair of parallel side members, a flange and a rail extending from each side member toward the other side member, the flange and rail on each side member being parallel to each other to define a channel therebetween with the flange extending farther from the respective side member than the rail; a slat assembly including a succession of impervious metal slats formed from sheet metal, each slat being longer than the distance between said flanges and shorter than the distance between said rails, each slat except those at the ends of said succession having a pair of parallel side ed e portions each bent to mterfit a side edge portion of the a acent slat along the entire length of the respective slats, and having four edge extensions formed integrally with said bent edge portions and of substantially the same cross section as said side edge portions, each extension extending longitudinally from a respective side edge portion at a respective end of the respective slat, the distance between the extremities of the edge extensions on a respective side edge being greater than the distance between said rails and less than the distance between said side members, the shape of the interfitting side edge poi tions permitting suid sluts to be rotated relative to one another from a folded position where the slats are reversely folded against one another with the side edge portion ofone slat nesting in the interfitting side edge portion of the next slat to an extended position where the respective slats are disposed edgewise with said interfitting side edge portions free to disengage laterally, and retainer members formed separately from said slats disposed adjacent said side edge portions and retaining said interfitting side edge portions in hinging engagement; and means mounting said slat assembly in the frame between said side members with the edge extensions on one side edge portion of each of said slats disposed within said channels and the edge extensions on the other side edge portions of each of said slats disposed on the side of said rails opposite said channels, said mounting means including pivot means for pivotally mounting the slat at one end of said succession on said side members.
2. A fire damper according to claim 1 wherein said retainer members comprise retaining rings disposed about respective edge extensions.
3. A fire damper according to claim 2 wherein said edge extensions are loosely disposed within respective retaining rings in the folded position of said slat assembly.
4. A fire damper according to claim 3 wherein said edge extensions are snugly disposed within said rings in the extended position of said slat assembly.
5. A fire damper according to claim 2 wherein said retaining rings are free to rotate about said edge extensions and function as bearings between said edge extensions and said rails.
6. A fire damper according to claim 2 wherein said retainer rings retain adjacent slats in overlapping relationship in the extended position of said slat assembly.
7. A fire damper according to claim 1 wherein said retainer members retain said interfitting side edges in loose engagement in the folded position of said slat assembly and in snug engagement in the extended position of said slat assembly.
8. A fire damper according to claim 1 wherein said retainer members retain adjacent slats in overlapping relationship in the extended position of said slat assembly.