Abstract:
An air handling system adapted especially for drop ceiling gridwork employs a shroud and a grille. The grille is made of a material meeting UL Standard 94 or 181 and rests on the drop ceiling gridwork. The shroud is made of a material meeting at least UL Standard 94HB, and at least its inner surface is non-reflective to hide the shroud structure when viewed through openings in the grille. The shroud interconnects the grille openings to an air handling duct above the gridwork using the appropriate fasteners.

Description:
[0001]    This application claims priority based on provisional patent application No. 60/391,036 filed on Jun. 25, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to an air handling shroud and grille combination, and in particular, to a shroud made of a fireproof lightweight material for use in a cold air return systems.  
         BACKGROUND ART  
         [0003]    In air handling systems it is common to employ metal boxes or shrouds to direct air in a desired direction. Metal structures provide the fire retardancy or fireproofing that is often-times mandated by local building codes.  
           [0004]    While metal structures allow building codes to be easily met, installing such structures can be problematic, and installation costs can be significant. Further, because of the weight of these structures, installation in drop ceilings requires support beyond that provided by the drop ceiling grids. Consequently, additional wiring must be utilized to support the metal pieces used in the air handling system located above the ceiling tiles.  
           [0005]    Metal materials in air handling applications are also undesirable due to their poor corrosion resistance, poor dampening characteristics (they tend to reflect sound rather than absorb it), and high reflectivity (they detract from a wall or ceiling appearance.) Accordingly, a need exists for improved air handling components that do not suffer from the inadequacies of metal materials, but are still able to meet building codes requirements, particularly with regard to resistance to burning.  
         SUMMARY OF THE INVENTION  
         [0006]    Therefore, it is a first object of the invention to provide an improved air handling component, particularly a cold air return shroud for use in a drop ceiling.  
           [0007]    Another object of the invention is a method of handling air in a drop ceiling that utilizes an air handling component that lacks reflectivity and is lightweight for ease of installation.  
           [0008]    A further object of the invention is a system and method that uses the shroud in combination with a grille in a drop ceiling support structure.  
           [0009]    Other objects and advantages will become apparent as a description of the invention proceeds.  
           [0010]    In light of the foregoing objects and advantages, the present invention is an improvement in air handling system positioned above a drop ceiling grid system and having an air handling header. The improvement comprises a shroud and a grille, the grille sized to rest on grid sections forming an opening in the drop ceiling and being made of a material meeting either UL standard 181 or UL standard 94. The shroud has a shroud body forming a first opening that is sized to mate with the grille, and a second opening sized to mate with the air handling header. The shroud body is made of a material meeting at least UL standard 94HB and wherein an inner surface of the shroud disposed between the first and second openings is non-reflective. The shroud is preferably made of one of a polystyrene, a high impact polystyrene, and an ABS, and the grille is preferably made of glass-fiber reinforced polypropylene. The shroud is preferably configured with walls and body sections to form a nesting fit when a number of shrouds are nested together.  
           [0011]    The invention also entails improvements in methods of handling air in a drop ceiling that uses an air handling system header disposed in a space between the drop ceiling gridwork and a ceiling. According to the invention, a grille is provided that has a number of air inlet openings therein within a section of the drop ceiling gridwork, the grille made of a material meeting UL Standard 94 or 181. The air inlet openings are connected to an opening in the air handling system header using a shroud. The shroud has a shroud body with a first inlet opening and a second outlet opening smaller in size than the first opening. The first inlet opening mates with the grille, and the second outlet opening is sized to mate with an opening in the air handling header. The shroud is preferably made of a material meeting at least UL standard 94HB, and an inner surface thereof disposed between the first inlet opening and the second outlet openings is non-reflective. Because of the lightweight of the shroud and/or grille, the drop ceiling gridwork does not require extra supporting hardware.  
           [0012]    While the interior of the shroud is made reflective, the entire shroud can be made non-reflective. The connector section forming the second outlet opening can include spaced apart dimples that protrude outwardly of an outer surface of the connector section. The dimples act as stops for travel of a rigid takeoff of the air handling system when being secured to the shroud, or as stops for travel of a flexible takeoff once attached to the connector section. The edges of the shroud where body sections meet are preferably rounded to provide greater impact resistance and strength. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    Reference is now made to the drawings of the invention wherein:  
         [0014]    [0014]FIG. 1 is a side view of the one embodiment of the shroud of the invention;  
         [0015]    [0015]FIG. 2 is a top perspective of the shroud of FIG. 1;  
         [0016]    [0016]FIG. 3 is a side view of an alternative shroud configuration;  
         [0017]    [0017]FIG. 4 is a schematic view of the shroud and grille in use in a drop ceiling structure and an air handling system;  
         [0018]    [0018]FIG. 5 is a partial plan view of an exemplary grille for use with the shroud;  
         [0019]    [0019]FIG. 6 is a sectional view along line VI-VI of FIG. 5; and  
         [0020]    [0020]FIG. 7 is a perspective view of an alternative shroud;  
         [0021]    [0021]FIG. 8 is a perspective view of an adapter for the shroud of FIG. 7;  
         [0022]    [0022]FIG. 9 is a perspective view of another embodiment of the shroud of the invention;  
         [0023]    [0023]FIG. 10 is a plan view of the embodiment of FIG. 9; and  
         [0024]    [0024]FIG. 11 is a cross sectional view along the line XI-XI of FIG. 10. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    The present invention offers significant improvements in air handling components, particularly those employed in drop ceilings. The air handling shroud is made of a material that meets at least Underwriters Laboratory Standard 94HB. Using this material for the shroud construction produces a number of benefits beyond the material&#39;s ability to resistance to burning that the UL Standard specifies. The material is black in color or non-reflective so that when the shroud is positioned over a drop ceiling grille, light is not reflected and the ceiling appearance is not compromised by a view into the shroud itself. The material is also more sound absorbent that metal material and sound that is typically generated by air turbulence mechanical, equipment or ambient room noise is significantly dampened. The material is lightweight so that additional support of the shroud is not needed when using in a drop ceiling system. The material is corrosion resistant and does not rust like metal components.  
         [0026]    [0026]FIGS. 1 and 3 show exemplary shrouds as reference numerals  10  and  10 ′. The shroud  10  of FIG. 1 has a shroud body  1  which extends between a first opening  3  and a second opening  5 . In this embodiment, the shroud body has four side walls  7 , edges  9  of each wall defining the first opening  3 . Four body sections  11  link the side walls  7  with a cylindrical section  13 . The cylindrical section  13  is depicted with a step  15  thus forming a first diameter zone  17 , and a smaller diameter zone  19  that terminates in the second opening  5 . The size of the second opening  5  can vary depending on the air handling application. While a circular opening is depicted, the body sections  11  could merge into a section with a square or rectangular cross section, or other cross sectional shape that would suit connection to an air handling system.  
         [0027]    The first opening  3  is generally the inlet side of the shroud, and generally faces the area being treated by the air handling system, e.g., providing a passageway for return of cold air.  
         [0028]    [0028]FIG. 3 shows the alternative shroud configuration  10 ′ wherein a single section  17 ′ is used to transition from the first opening  3  to the second opening  5 .  
         [0029]    The second opening  5  is adapted to connect to ductwork for an air handling system such as a cold air return. The attachment can be by any means such a tape, clips, adhesives or combinations thereof.  
         [0030]    An exemplary use of the shroud  10 ′ in an air handling system is illustrated in FIG. 4. The air handling system is a cold air return system employing a header  21 , with a takeoff  23 . The takeoff links or connects with the cylindrical section  17 ′ using any known means such as adhesives, fasteners, clips, or a combination thereof.  
         [0031]    The air handling header  21  is disposed above a drop ceiling system. Two grids  25  of the ceiling system are shown supporting a grille  27  and tiles  29 . An example of the grille design in shown in FIGS. 5 and 6, but virtually any type of grille or grid that would meet local building codes can be employed in combination with the shroud  10 ′.  
         [0032]    The peripheral edges  31  of the grille  27  rest on the grid flanges  33 . The edges  9  of the first opening  3  of the shroud  10  sit on the grill  21  and are shown surrounding an upstanding peripheral wall  35  of the grille  27 .  
         [0033]    A partial view of specific grille design is depicted in FIGS. 5 and 6. The grille  40  has a peripheral flange  41 , and a wall  43 . The surface  45  of the flange separates the grille peripheral edge  47  from the grille openings  49 . The individual grille openings  49  are formed by the intersecting gridwork  53 .  
         [0034]    The shrouds  10  and  10 ′ can be secured to the grille  27  using any types of fasteners, clips or the like. FIG. 4A shows the use of a fastening screw penetrating through the walls  7  and  35  to keep the shrouds secured to the grille  27 . However, clips, adhesives, other types of fasteners or combinations thereof could be employed to attach the shroud and grille together. In another mode, the shrouds could merely rest on the grille  27  without the use of any fastening or attaching means.  
         [0035]    As noted above, the shroud is made of a material that meets at least the UL 94HB flammability testing. This standard is well known and a further description is not necessary for understanding of the invention. In brief, the standard specifies a horizontal burn rate in terms of mm/min. The UL 94 standard also has a number of other categories such as V-0, V-1, V-2, SV, 5VB, and 5VA. These other categories measure other features such as the time in which burning stops, whether a burn hole is tolerated, etc. The HB category is the least severe of the categories, and the material for the shroud and the grille (if the grille is made according to this standard) should meet at least this category.  
         [0036]    One material that meets this UL 94HB standard is polystyrene, including high impact polystyrene, commonly referred to as HIPS. Blending of particulate rubber with polystyrene improves the impact strength of the polystyrene, thus resulting in the high impact designation. These rubber modified vinyl aromatic polymers can be prepared by polymerizing a vinyl aromatic monomer in the presence of a predissolved rubber to prepare the impact modified, or grafted rubber containing products. Examples of these are described in U.S. Pat. Nos. 3,123,655, 3,346,520, 3,639,522, and 4,409,369, which are herein incorporated by reference. Conventional high impact polystyrene is available from both The Dow Chemical Company and BASF Corporation.  
         [0037]    Another material that also meets this standard is NORYL GTX GTX626 made by GE Plastics. Polyphenylene oxide resins also readily available from commercial sources, including General Electric (“Noryl” resins). “Noryl GTX” resins, which are alloys of poly(2,6-dimethyl-1,4-phenylene ether) and a polyamide such as nylon 6 or nylon 6,6, are also suitable for use as the polyphenylene oxide component, see U.S. Pat. No. 5,635,556 for example. This material is more costly than the polystyrene or HIPS, but it does provide a HDT (heat deflection temperature) of 355° F., whereas a typical HDT value for polystyrene is 183° F. with HIPS having a similar value. Heat deflection temperature is a relative measure of a material&#39;s ability to perform for a short time at elevated temperatures while supporting a load. The test to determine the temperature measures the effect of temperature on stiffness. The test involves giving a standard test specimen a defined surface stress and the temperature is raised at a uniform rate. Thus, in instances where resistance to higher temperatures is required, the GE Plastics material would be preferred.  
         [0038]    Yet another example of a material meeting the UL 94 HB standard is an ABS (acrylonitrile-butadiene-styrene copolymer). This material is similar to the HIPS in that its HDT temperatures are in the range of 166-201° F. (at 264 psi loading), depending on the particular type of ABS selected. Primex Plastics Corporation of Richmond, Ind. offers a number of different types from a general purpose to a weatherable type (which is preferred.)  
         [0039]    The grille material can meet either the UL 94 standard, i.e., at least the 94HB category, or, the UL standard 181. Underwriters Laboratory (UL) Standard 181 dated Aug. 17, 1981 is for factory-made air duct materials and air duct connectors, Section 8, Flame Penetration Test. According to this UL Standard 181, material must not burn through before 30 minutes have elapsed from exposure to an open flame. An example of a grille material that meets this specification is a glass-fiber reinforced polypropylene. These materials, see U.S. Pat. No. 4,379,801 to Weaver (incorporated by reference) as an example, are known for their heat resistance and are available commercially from a large number of sources. Weaver discloses that such a material can have a heat distortion temperature of 327° F. As with the shroud, any material that meets the UL standard and can be fabricated into a grille configuration is adapted for use with the inventive shroud.  
         [0040]    Referring again to the shroud, it is made so that its interior surface  45  (see FIG. 4) is non-reflective. This is accomplished in one mode by the fact that the material used to make the shroud is black, and all surfaces, including the interior surface  45  would be black or non-reflective. Alternatively, the interior surface alone could be made black. Further, and referring again to FIG. 1, the walls  7  are slightly angled with respect to the plane of the first opening  3 . This allows a number of shrouds  10  to nest together or be stacked vertically/horizontally at a job site, thus saving space and providing a compact arrangement to access a shroud for installation. The stackable shroud is vastly superior to the box like structures used in the prior art which were not stackable and were not easily stored for installation.  
         [0041]    [0041]FIG. 7 shows another embodiment of the shroud as reference numeral  60 , with FIG. 8 showing an adapter  61  for use with the shroud  60 . The adapter  61  reduces the diameter of the opening  63  to a smaller opening  65  to facilitate connection to an air handling duct (not shown). For example, if the opening  63  is 12 inches in diameter, the adapter  61  can reduce the opening  63  to an 8 inch diameter opening. The edge  67  of the adapter  61  fits over the opening  63  and the adapter can be connected to the shroud wall  69  using any known means such as fasteners, tape, or the like.  
         [0042]    [0042]FIGS. 9 and 10 shows a perspective and plan view of another embodiment of the invention designated by the reference numeral  70 . The shroud  70  has a rectangular configuration in contrast to the square configuration of FIGS. 1 and 3, with long side walls  71 , short side walls  73 , two long body sections  75 , and two short body sections  77 . Similar to FIG. 3, the shroud  70  has a single connecting section  79  to provide attachment to a takeoff of an air handling system.  
         [0043]    The connecting section  79  has a number of spaced apart dimples  85  (two shown). The spacing illustrated is roughly at 90 degrees segments as measured from the center of the section  79 . Other spacings and numbers of dimples can be employed without a departure from their intended functions. The dimples  85  form a protrusion in the form of a convex surface on the outer surface  87  of the section  79 . The dimples  85  can act as stops when connecting a rigid or hard takeoff, i.e., a metal takeoff, to the shroud as shown in FIG. 4. The dimples stop further travel of the takeoff onto the section  79 , such that the takeoff can then be attached to the section  79  using screws or the like. The distance from the edge of the section  79  and dimples  85  can vary depending on the overall length of the section  79 , but 1.5 inches is one example of such a dimension.  
         [0044]    In instances where a flexible takeoff is employed, the dimples can then act as retaining means to help secure the flexible takeoff once in place. In this mode, the takeoff can be pushed over the dimples  86 , such that a terminal edge of the takeoff is positioned between the dimples and the junction of the body sections  75  and  77  and the section  79 . Then, a zip tie or other non-screw type fastening device can be positioned around a portion the takeoff below the dimples for securement purposes. The dimples assist in keeping the zip tie in place by impeding travel over the dimples, and the takeoff can be attached without the need for screws or the like. In either instance, the dimples act as stops. In one mode, the dimples stop or impede travel of the hard takeoff prior to its securement. In another mode, the dimples stop or impede travel of the flexible takeoff once it is secured. In an alternative mode to the dimples, a ridge could be employed that would extend around the circumference of the section  79  and function in the same manner as the spaced apart dimples. In this mode, instead of section  79  having spaced apart protrusions, a single protrusion extends along the outer surface of the section to function as the stop.  
         [0045]    As shown in the FIG. 11, the edge  89  between the body section  75  and  77  is rounded. This provides two advantages over a sharp edge: the shroud is able to absorb impact better when objects are dropped on it; and the durability of the shroud is improved, less tearing at the edges occurs.  
         [0046]    The shroud and grille can be made using any known manufacturing techniques, including extrusion, molding, stamping, combinations thereof, or the like. Further, the shroud and grille can have any dimensions that would interface with the particular air handling system being utilized. For drop ceilings, the grilles could be square or rectangular, e.g., 2′×2′, 1′×1′, or 1′×2′. The shroud opening  3  could match the grille size, and shroud height could be around 8-10 inches, and the second opening could be a 6 or 8 inch in diameter. Of course, other dimensions can be used for the shroud and grille depending on the particular air handling system.  
         [0047]    In use, the shroud  10  is installed with an air handling system such as a cold air return. The shroud  10  is sufficiently light that it can merely rest atop a grille that is positioned in a drop ceiling grid opening. In this way, additional wires or other members for shroud and grille support are eliminated and the time and cost of installing the air handling system components is vastly reduced. Further, because the inner surface of the shroud is non-reflective, the space above the grille is not visible to a person looking at the grille itself and decor of the room below the ceiling is not compromised as it is when a reflective metal component is used.  
         [0048]    It should be understood that the shroud and/or grille could be used in air handling system other than those that are positioned in ceilings.  
         [0049]    As such, an invention has been disclosed in terms of preferred embodiments thereof which fulfills each and every one of the objects of the present invention as set forth above and provides new and improved air handling system including a shroud and a grille, particularly adapted for drop ceiling.  
         [0050]    Of course, various changes, modifications and alterations from the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention only be limited by the terms of the appended claims.