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[0001]    This application claims the benefit of U.S. provisional application No. 60/937,503, filed Jun. 28, 2007. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The invention relates to suspended ceilings. Particularly, the invention relates to sealing systems for sealing between panels of the suspended ceiling. 
       BACKGROUND OF THE INVENTION 
       [0003]    Suspended ceilings that are used extensively in building construction include a grid of intersecting beams forming a frame suspended by wires from a permanent structural ceiling. The frame supports ceiling panels or ceiling tiles which are simply supported on the frame substantially within grid openings of the frame. 
         [0004]    The beams are generally formed of rolled steel and formed into an inverted T-shape or L-shape. The panels are supported on the flanges of the T or L-shaped beams, with the hanging wires anchored above into the structural ceiling, and connected below to holes in the webs of the beams. 
         [0005]    The panels and the upper side of the flanges of the beams on which the ceiling panels rest have relatively smooth surfaces that form a seal sufficient in effectiveness for most ceiling installations. 
         [0006]    However, in some situations, the seal between the beams and the individual ceiling panels must be sufficiently tight to prevent air and/or dust and/or germs passing between the ceiling panels and the beams. Particularly, an enhanced sealing system for suspended ceilings is useful for clean rooms, operating rooms, hospital rooms, rooms for sensitive manufacturing operations, and rooms where the atmosphere is desired to be contained, such as for indoor swimming pool areas. 
         [0007]    There have been various attempts to form such tight sealing systems for suspended ceilings. Foam strips have been adhesively secured to the upper sides of the beam flanges for sealing against the ceiling panels. 
         [0008]    According to another method a flexible tape is used along the edges of the lower surface of the ceiling panels to seal against the frame. 
         [0009]    Still another method used to seal suspended ceiling panels against the frame has been to create a U-shaped edge around the flanges with soft plastic fins extending downward, as shown in U.S. Pat. Nos. 4,967,530 and 5,033,247. 
         [0010]    Yet another method used to seal suspended ceilings comprises the use of a resilient flap that is biased to extend upward and outward from the upper surface of the flange of the beam at each side of the beam web to form a seal by pressing upwards against the underside of the ceiling panel as disclosed in U.S. Pat. No. 6,701,686. 
         [0011]    The present inventor recognizes that the need exists for a suspended ceiling panel grid system having a sealing effectiveness that is easily installed and is able to easily accommodate the intersection of ceiling beams of the grid system during installation without losing the sealing effectiveness, and which is cost-effectively manufactured. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention provides a sealing system for a suspended ceiling that is cost-effectively installed and provides an effective sealing between the ceiling panels and the support grid of the suspended ceiling. 
         [0013]    The present invention provides strips of sealing material that are compressed between grid beam flanges and ceiling panels to create a sealing system therebetween. 
         [0014]    The present invention provides a strip of sealing material that, in the preferred embodiment, has a V-shaped cross-section, and is hinged on the top surface of the flange, has a bottom leg that lays flat and is stuck with adhesive on a top surface of the flange, and a top leg that presses against the bottom of the ceiling panel when installed. The V-shaped cross-section is compressed by the weight of the ceiling panel and the top leg and the bottom leg are flattened together. 
         [0015]    The present invention provides strips of sealing material that can be supplied in rolls or in strip stocks of stock length, and can be easily cut to length to fit ceiling beams. 
         [0016]    The present invention provides segmented strips of material providing versatility to the placement arrangement of strips. 
         [0017]    The preferred embodiment of the present invention provides sealing strips that are segmented by being weakened or cut along lines at regular intervals. 
         [0018]    The present invention provides segmented strips that, according to the preferred embodiment, are cut-to-length to fit the ceiling main beams. 
         [0019]    The present invention provides segmented strips that according to the preferred embodiment allow for the intersection of the ceilings main beams with perpendicular ceiling tee beams and also allow for the intersection of the ceiling tee beams with perpendicular secondary tee beams 
         [0020]    The present invention provides a strip of sealing material that has protrusions on ends thereof which when installed overlap an adjacent sealing strip that is perpendicular in elongation and enhances the sealing effectiveness at these points of intersection. 
         [0021]    The present invention provides strips of material that have protrusions on the ends which, according to the preferred embodiment, are pre-sized in length to fit the ceilings tee beams and also the secondary tee beams. 
         [0022]    The present invention provides strips of material that, according to the preferred embodiment, may be pre-sized to fit the ceiling tee beams and also the secondary tee beams and can be segmented for accommodating obstructions. 
         [0023]    Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a bottom perspective view of a suspended ceiling; 
           [0025]      FIG. 2  is a top, right side, front perspective view of a strip of sealing material; 
           [0026]      FIG. 3  is a top, right side, front perspective view of a strip of sealing material attached to the flange of a suspended ceiling beam; 
           [0027]      FIG. 4  is a right side view of  FIG. 3  showing an inverted T-shaped ceiling beam, one side with a ceiling panel resting-in place on the sealing strip and the other side without a ceiling panel; 
           [0028]      FIG. 5  is a top view of the intersection of main and secondary ceiling beams equipped with sealing strips; 
           [0029]      FIG. 6  is a top, front, right side perspective view of the intersection of main and secondary ceiling beams with sealing strips applied; 
           [0030]      FIG. 6A  is a top, front, right side perspective view of the intersection of a secondary ceiling beam and L-shaped wall-ceiling corner beam with sealing strips applied; 
           [0031]      FIG. 7  is a schematic view of the ceiling beam structure of a suspended ceiling; and 
           [0032]      FIG. 8  is an end view of an L-shaped wall-ceiling corner beam. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0033]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure to be considered as the exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
         [0034]      FIG. 1  illustrates the structure of a suspended ceiling  10 . The suspended ceiling  10  incorporates main ceiling beams  11  running wall-to-wall in one direction, with tee beams  12  intersecting the main ceiling beams perpendicularly and extending wall-to-wall in the transverse direction. Secondary tee beams  12   a  run perpendicularly between tee beams  12 . 
         [0035]    According to the present description, “main,” “tee,” and “secondary tee” ceiling beams refer to the location of the beams and are explained in  FIG. 7 . In constructing the grid or frame, the main beams tend to be longer and more continuous, whereas the tee beams are shorter and are connected to the main beams at pre-defined positions depending on the size of the ceiling panels, and the secondary tee beams are connected to the tee beams and also vary in size according to ceiling tile size. 
         [0036]    At each wall, an L-shaped wall-ceiling corner beam  13  is used. Ceiling panels  14  are supported on a horizontal leg  13   a  of the ceiling beam  13  which is supported by the adjacent wall using fasteners, The main ceiling beams  11  are supported by suspension wires  15  hung from the permanent ceiling  15   a.    
         [0037]      FIG. 2  shows the sealing strip  16  of the present invention. According to the preferred embodiment of the invention, the sealing strips  16  described herein are composed of a silicone or rubber based material. The sealing strip  16  includes a top leg  16   a  and a bottom leg  16   b . The top leg  16   a  is segmented by lines  17  forming segments  17   a  having a length L and a width W. The lines  17  can be through cuts or slits, or weakened through the thickness of the top leg  16   a , such as by the use of partial cuts or perforations. 
         [0038]      FIG. 3  shows the sealing strip from  FIG. 2  mounted on a flange  18  of an L-shaped wall-ceiling corner beam  13 . The flange  18  extends from a web  19  of the L-shaped ceiling beam  13 . A protrusion  20 , such as a hemp edge or rolled edge, extends along a length of the flange  18  and functions to stiffen the flange  18  and helps to prevent the sealing strip  16  from being displaced off the flange  18 , particularly if the strip  16  is being installed in the field. The sealing strip  16  is adhesively secured to a top surface of the flange  18  by a layer of adhesive  18   a    
         [0039]    The sealing strip  16  for the wall angle  13  has a width W of about 0.75 inch and is segmented with the lines  17  spaced apart at increments L being about 1 inch. At this spacing, the lines  17  will align with the standard connection points for tees and main beams on the wall angle beam  13 . Also, when the wall angle beam  13  is installed, the intersecting tee beams  12  will hold down two segments of the seal  16  thereon, keeping the seal  16  in place. The segmentation of the sealing strip  16  allows the intersecting tee beams  12  to lay flush on wall angle beam  13  or any other intersecting beam. 
         [0040]      FIG. 4  shows a main ceiling beam  11 , which includes a web  21  and a flange  22  forming an inverted T-shape. One panel  14  is shown supported on a sealing strip  16 . The sealing strip  16  is compressed by the weight of the panel  14  with top leg  16   a  pressed against bottom leg  16   b . Two sealing strips  16  are adhesively secured to a top surface of the flange  22  by a layer of adhesive  22   a.    
         [0041]    According to the preferred embodiment of the invention, the sealing strip  16  for the main beam has a width W of about 0.5 inch and is segmented with the lines  17  spaced apart at increments L being about 6 inches. At this spacing, the lines  17  will align with the standard connection points on a main beam for the connection of tee beams. 
         [0042]    The cross section of tee beams  12  and secondary tee beams  12   a , including details of the sealing strips are substantially identical to the cross section of the main beam  11  shown in  FIG. 4 .  FIG. 5  illustrates a main ceiling beam  11  intersecting a tee ceiling beam  12 . Protruding, tapered end portions  23  are arranged on each end of a secondary beam sealing strip  24 . The protruding end portions  23  are shaped and sized to overlap the sealing strip  16  on the main beam  11  by a distance P of about 5/16 inches to ensure a more effective seal at the intersection. The secondary sealing strip  24  is mounted to the tee ceiling beam  12  in the same way as the strip  16  is mounted to the main ceiling beam  11  ( FIG. 4 ). 
         [0043]    All sealing strips  16 ,  24  that end at an intersection between two beams can have a protruding end portion  23  to create this overlap, such as whenever a main beam  11  intersects a wall angle beam  13 ; a tee beam  12  intersects a main beam  11  or angle beam  13 ; or a secondary tee beam  12   a  intersects a main beam  11 , a tee beam  12  or an angle beam  13 . 
         [0044]    According to the preferred embodiment of the invention, the sealing strip  24  for the tee beam  12  is identical to the sealing strip  16  for the main beam and has a width W of about 0.5 inch and is segmented with the lines  17  spaced apart at increments L being about 6 inches. At this spacing, the lines  17  will align with the standard connection points on a main beam for the connection of tee beams. 
         [0045]      FIG. 6  shows the action of the segmentation lines  17  at the intersection of two beams  11 ,  12 . At the intersection, the web  21  of the tee beam  12  is attached to the web  21  of the main beam  11 . In order to accommodate the pass through of the web  21 , the sealing strip  16  can be split at a line  17  to allow the web  21  to pass through the sealing strip  16  to be connected to the beam  11 . The upper leg of the strips  16 ,  24  for main beams and tee beams are segmented. The lower leg of the strips  16 ,  24  need not be segmented. 
         [0046]    Secondary tee beams  12  have sealing strips  16  adhesively secured to upper sides of flanges of the secondary tee beams in the same manner as the sealing strips  16  are secured to the main beams  11  ( FIG. 4 ). The upper leg  16   a  of the strips  16  for secondary tee beams is not required to be segmented but can be segmented to allow for accommodating other obstructions. 
         [0047]      FIG. 6A  shows the action of the segmentation lines  17  at the intersection of two beams  12 ,  13 . At the intersection, the flange  22  of the tee beam  12  is set on the flange  18  of the beam  13 , particularly on the sealing strip  16  that is carried by the flange  18 . In order to accommodate the flange  22 , the sealing strip  16  is pre-cut on lines  17  that straddle the flange  22  and allow the flange  22  to set down onto folded flat segments  17   a  present on the flange  18  without pressing down the adjacent segments  17   a  of the upper leg  16   a  of the strip  16  on opposite sides of the flange  22 . The upper leg  16   a  of the strips  16  for corner beams  13  is thus preferably segmented along its length at slits  17 . The lower legs  16   b  of the strip  16  for corner beams  13  need not be segmented. The strip  24  is shown discontinued to show the flange  22  setting on the flange  18 . In practice the strip  24  would continue along the flange  22  until abutting the web  19 . 
         [0048]      FIG. 7  shows two major, main ceiling beams  11 ,  11  extending a certain length, typically 12 feet. Tee beams  12 ,  12 ,  12  intersect and connect the main beams  11 ,  11  perpendicularly, and are typically 4 feet long. Secondary tee beams  12   a ,  12   a  intersect and connect the tee beams  12 ,  12 ,  12  perpendicularly, and are typically 2 feet long. 
         [0049]      FIG. 8  shows an L-shaped wall-ceiling corner beam  13  being installed against a wall  40  with a sealing strip  16  adhesively secured on the outside of the web  19  to form an airtight seal with the wall when fasteners  42  are tightened into the wall. The sealing strip  16  here need not be segmented and the width W is preferably about 0.5 inch. 
         [0050]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.

Summary:
A seal for a suspension ceiling. The seal has a bottom leg is for attaching to a flange of a ceiling beam and top leg for engaging a ceiling panel and compressing between the ceiling panel and the bottom leg. The top leg is resiliently biased away from the bottom leg to form a V-shape when the seal is in an uncompressed state. The top leg of the seal may have one or more slits, cuts, or weakened areas that separate a plurality of segments of the top leg.