Abstract:
A concealed sprinkler head is mounted above the ceiling of a fire protected zone. The sprinkler head includes a housing within which a valve and other operative parts are contained. A decorative cover plate is secured to the housing to conceal the sprinkler head within the ceiling so that none of the operative parts is visible. The cover assembly includes a thin metallic cover plate made of a heat conductive material such as copper, and a metallic skirt including a cylindrical wall threaded on the housing, an annular flange extending outwardly from one end of the cylindrical wall, and a plurality of tabs extending downwardly from the flange. A plurality of heat insulative elements are disposed between the tabs and the cover plate. A metallic layer is attached to the lower surface of each of the insulative elements. A layer of fusible material is disposed between the metallic layer and the cover plate to secure each of the insulative elements to the cover plate through the metallic layer.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to automatic sprinkler heads and more particularly, to a decorative cover assembly adapted to conceal a pendent sprinkler head within the ceiling of a fire protected enclosure. 
   Sprinkler systems are used extensively to provide automatic fire protection for residential, commercial and public buildings. There are two types of pendent sprinkler heads for ceiling applications, one referred to by the term “concealed” and the other referred to by the term “flush”. A concealed sprinkler head has its entire body located above the lower surface of the ceiling of an enclosure in which it is installed. A flush sprinkler head has the majority of its body located above the lower surface of the ceiling, but a thermally responsive element and its related elements are partly or wholly located below the ceiling. Thus, the concealed sprinkler head is less obstructive and more aesthetical than the flush sprinkler head. 
   U.S. Pat. No. 4,014,388 issued to Anderson discloses a concealed sprinkler head wherein a cylindrical housing is located above the ceiling of a fire protected enclosure and surrounds a thermally responsive element and all the other operative parts. A metallic cover plate is connected to the cylindrical housing through a metallic connecter ring and mounted flush against the ceiling so that none of the operative parts is visible. Solder is used to attach the metallic connector plate to the metallic connector ring. One problem arises with this arrangement. In the event of a fire, heat is readily transferred from the metallic cover plate through the solder to the metallic connector ring. As a result, the solder may not melt as quickly as it should be. This results in a reduction in the response time of the thermally responsive element. 
   U.S. Pat. No. 4,105,076 issued to Simons discloses a sleeve adapted to connect a cover plate to a cylindrical housing and made of a thermosetting resin or other heat insulating material. The sleeve has feet around which metal rings fit. The metal rings are attached to the cover plate by means of solder. The heat insulating material reduces the rate of heat transfer from the cover plate to the housing and facilitates melting of the solder. However, such a resinous sleeve is not durable. 
   Accordingly, it is an object of the present invention to provide a decorative cover assembly for a concealed sprinkler head, which is durable and can minimize the response time of the sprinkler head. 
   SUMMARY OF THE INVENTION 
   A concealed sprinkler head is mounted above the ceiling of a fire protected enclosure. The concealed sprinkler head includes a housing within which a valve and other operative parts are contained. A decorative cover assembly is secured to the housing to conceal the sprinkler head within the ceiling so that none of the operative parts is visible. According to the present invention, the decorative cover assembly includes a metallic cover plate made of a heat conductive material such as copper and copper alloy, and a metallic skirt including a substantially cylindrical wall, an annular flange extending outwardly from one end of the cylindrical wall, and a plurality of tabs extending generally downwardly from the flange. The cylindrical wall of the skirt is threaded on the cylindrical housing of the sprinkler head. 
   A plurality of heat insulative elements are disposed between the tabs and the cover plate. The upper surface of each of the insulative elements is adhesively attached or otherwise secured to a corresponding one of the tabs. A metallic layer is attached to the lower surface of the insulative element. A layer of low melting point fusible material or alloy is disposed between the metallic layer and the cover plate. Upon application of heat, the insulative element is secured to the cover plate through the metallic layer. The use of the heat insulative elements allows heat to be focused on the fusible alloy in the vent of a fire and facilitates melting of the fusible alloy and thus, release of the cover plate from the rest of the cover assembly. 
   In a preferred embodiment, the upper surface of the insulative elements may be secured to the tabs in a manner identical to the manner in which the lower surface of the insulative elements is secured to the tabs. To this end, a second metallic layer is attached to the upper surface of each of the insulative elements, and a second layer of low melting point fusible material or alloy is disposed between the second metallic layer and each of the tabs. A protective layer, made of a water resistant material such as wax, may surround the layers of fusible alloy, the metallic layers, the insulative elements and the tabs to prevent corrosion of the elements of the decorative cover assembly. 
   The upper end of the insulative elements may be secured to the tabs by mechanical means. In one embodiment, each of the tabs has a substantially vertical leg, and a foot extending outwardly from the lower end of the leg. Each of the insulative elements includes a rectangular plate and opposite side walls extending upwardly from opposite sides of the plate. The insulative element defines a space between the plate and the side walls to receive the foot of the tab. As an alternative, the foot of the tab has a recess, and the insulative element includes a plate and a projection formed on the plate. The projection is engageably received within the recess to secure the insulative element to the tab. Still alternatively, the foot of the tab has a circular opening. The insulative element includes a cylindrical shank and a head connected to one end of the shank. The shank is snugly fit in the opening to secure the insulative element to the tab. The insulative element may alternatively include a round base, and a semispherical head connected to the base with a diametrical slit. The semispherical head is inserted through the opening to secure the insulative element to the tab. 
   The cover plate may partly or wholly be made of a shape-memory alloy so that its peripheral edge may be bent in a downward direction when the ambient temperature reaches a predetermined level in the event of a fire. To increase the rigidity, a plurality of ribs may be formed in one side of the cover plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present invention will become more apparent from a reading of the following detailed description when taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a vertical sectional view of a concealed sprinkler head mounted above the ceiling of a room and covered by a decorative cover assembly made according to one embodiment of the present invention; 
       FIG. 2  is a bottom view of the sprinkler head with a cover plate removed for clarity; 
       FIG. 3  is an enlarged section, in part, of the decorative cover assembly shown in  FIG. 1 ; 
       FIG. 4  is an enlarged perspective view, partly broken away, of the decorative cover assembly shown in  FIG. 1 ; 
       FIG. 5  shows the manner in which the cover plate is released from the rest of the decorative cover assembly in the event of a fire; 
       FIG. 6  is a view similar to that of  FIG. 3 , but showing a modified form of the decorative cover assembly; 
       FIG. 7  is an enlarged perspective view, partly broken away, of the decorative cover assembly shown in  FIG. 6 ; and 
       FIGS. 8  to  11  are perspective fragmentary views of further modified forms of the decorative cover assembly according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , there is illustrated a concealed sprinkler head, generally designated by the reference numeral  10 , mounted in a hole  12  in the ceiling of a room such that the bottom of the sprinkler head is substantially flush with the ceiling. 
   In the illustrated embodiment, the sprinkler head  10  includes a vertically extending tubular body  14  with a threaded upper or inlet end  14   a  adapted to be connected to a water line  16 , and a lower or outlet end  14   b . The water line  16  is communicated with a supply of pressurized water or other fire extinguishing fluid (not shown). An internal passage  14   c  is defined in the tubular body  14  and extends between the inlet end  14   a  and the outlet end  14   b . An annular flange  18  extends around the outer periphery of the tubular body  14  and is located midway between the inlet end  14   a  and the outlet end  14   b . A generally cylindrical housing  20  depends from the annular flange  18 . A generally cylindrical casing  22  is secured around the lower end of the tubular body  14  and is located within the housing  20 . 
   The outlet end  14   b  of the tubular body  14  is normally closed by a valve assembly  24 . The valve assembly  24  includes a valve element  26  normally seated on the outlet end  14   b  of the tubular body  14 , and a valve holder  28  configured to hold the valve element  26 . A deflector assembly  30  and a thermally responsive assembly  32  are operatively associated to normally urge the valve element  26  in its closed position. The deflector assembly  30  includes a deflector holder  34  located immediately below the valve assembly  24  and shaped to receive the valve holder  28 . A deflector  36  is secured to the deflector holder  34 . Also, an upper heat collector element or disk  38  is secured to the bottom of the deflector holder  34 . As shown better in  FIG. 2 , the deflector  36  includes a plurality of tines  40  to alters the trajectory of water in an optimum pattern when the water is discharged from the outlet end  14   b  of the tubular body  14 . A pair of diametrically opposite struts  42  are connected at their lower end to the deflector  36  and at their upper end to a guide ring  44 . The guide ring  44  is slidably moved within the housing  20 . A compression spring  46  is disposed between the lower surface of the flange  18  and the upper surface of the guide ring  44 . The thermally responsive assembly  32  includes a fuse holder  47  secured to the valve holder  28  and adapted to hold a fusible alloy  48  therewithin. The fusible alloy  48  has a melting point of from 70° C. to 90° C. A lower heat collector disk  50  is secured to the bottom of the fuse holder  47 . An annular ring  52  is located within the casing  22  and disposed between the valve holder  28  and the deflector holder  34 . 
   A decorative cover assembly, designated generally by the reference numeral  60 , is secured to the housing  20  to conceal the sprinkler head  10  within the ceiling. Illustratively, the decorative cover assembly  60  includes an annular skirt  62  secured around the housing  20  and a generally circular, thin cover plate  64  secured to the skirt  62 . The skirt  62  has a helically corrugated cylindrical wall  62   a  and an annular flange  62   b  extending outwardly from the lower end of the cylindrical wall  62   a . The skirt  62  is vertically adjustable by rotation of the skirt  62  relative to the housing  20 . To this end, the housing  20  is formed on its outer peripheral surface with a plurality of conical projections  66  for engagement with the corrugated cylindrical wall  62   a  of the skirt  62 . The conical projections  66  are arranged on a helical path around the circumference of the housing  20 . The skirt  62  is threaded on the housing  20  until the flange  62   b  of the skirt  62  comes into engagement with the ceiling. 
   Referring to  FIGS. 2  to  4 , three tabs  68  extend downwardly from the flange  62   b  and are spaced 120 degrees about the circumference of the flange  62   b . Each of the tabs  68  has a substantially L-shape and includes a short leg  68   a  and a foot  68   b  extending radially outwardly from the lower end of the leg  68   a . Three insulative elements  70  are disposed between the corresponding tabs  68  and the cover plate  64 . More specifically, each of the insulative elements  70  is adhesively attached or otherwise secured to the lower surface of the foot  68   b  of each tab  68 . The insulative element  70  has a thickness of approximately 1.0 mm and is made of a material with a low degree of heat conductivity, such as epoxy resin, phenolic resin, polyester resin and acrylic resin. A metallic layer  72  is adhesively attached or otherwise secured to the lower surface of the insulative element  70 . The metallic layer  72  has a thickness of from 10 to 200 microns and is preferably made of copper or copper alloy to provide good solderability. The metallic layer  72  may alternatively be made of brass, bronze, gold, silver, nickel, tin and similar materials. The lower surface of the metallic layer  72  is coated first with flux and then, a layer of a low melting point fusible alloy  74 . The layer of fusible alloy  74  has a thickness of from 20 to 200 microns and has a melting point of from 45° C. to 65° C. To ensure melting of the fusible alloy  74  before the fusible alloy  48  of the thermally responsive assembly  32  melts, the fusible alloy  74  should preferably have a lower melting point than the fusible alloy  48  of the thermally responsive assembly  32 . Upon application of heat, the metallic layer  72  is soldered to the cover plate  64 . The cover plate  64  is preferably made of copper, aluminum and similar materials to provide a high degree of heat conductivity. As shown best in  FIG. 3 , a protective layer  76  surrounds the insulative elements  70 , the feet  68   b  of the tabs  68 , the metallic layer  72  and the fusible alloy  74 . The protective layer  76  is made of wax, fluoroplastic and similar water resistant materials to prevent corrosion. 
   When the ambient temperature exceeds a predetermined value by the heat from a fire, the fusible alloy  74  melts. As shown in  FIG. 5 , this causes the cover plate  64  to be quickly released from the rest of the decorative cover assembly  60  since the use of the insulative elements  70  allows the heat to be focused on the fusible alloy  74  and retards heat transfer from the cover plate  64  to the annular skirt  62 . Upon release of the cover plate  64 , the thermally responsive assembly  32  is exposed to an elevated temperature where the fusible alloy  48  melts. Melting of the fusible alloy  48  causes the compression spring  46  to urge the deflector assembly  30  and thus, the annular ring  52  in a downward direction. As a result, the valve assembly  24  is released from the outlet end  14   b  of the tubular body  14 . With the valve assembly  24  in its open position, water is discharged from the outlet end  14   b  of the tubular body  14 . The water then strikes the deflector tines  40  and is deflected outwardly in the desired pattern. 
   Referring next to  FIGS. 6 and 7  wherein like elements are given like reference numerals, there is illustrated a modified form of the decorative cover assembly according to the present invention. The lower surface of the insulative element  70  is secured to the cover plate  64  in the same manner as in the previous embodiment. In this alternative embodiment, the upper surface of the insulative embodiment  70  is secured to the corresponding tab  68  in a manner identical to the manner in which the lower surface of the insulative element  70  is secured to the cover plate  64 . Specifically, a metallic layer  77  is attached to the upper surface of the insulative element  70 . As in the metallic layer  72 , the metallic layer  77  is preferably made of copper or copper alloy to provide good solderability. The upper surface of the metallic layer  77  is coated first with flux and then, a layer of fusible alloy  78 . The fusible alloy  74  has a lower melting point than the fusible alloy  78 . However, the fusible alloys  74 ,  78  may have the substantially same melting point. Upon melting of the fusible alloy  74 , the cover plate  64  is released from the rest of the decorative cover assembly  60  in the same manner as in the previous embodiment. 
   The insulative elements may be secured to the corresponding tabs by mechanical means as shown in  FIGS. 8  to  11 . As shown in  FIG. 8 , an insulative element  80  is composed of a rectangular plate  80   a  and opposite side walls  80   b  extending upwardly from opposite sides of the rectangular plate  80   a . The side walls  80   b  have an inverted L-shape such that a space  82  is defined between the plate  80   a  and the side walls  80   b . A tab  84  has a vertical leg  84   a  and a generally rectangular foot  84   b  extending horizontally from the lower end of the leg  84   a  and having a slightly round edge  84   c . The foot  84   b  is inserted through the space  82  between the side walls  84   b  to mount the insulative element  80  to the tab  84 . The lower surface of the insulative element  80  is secured to the cover plate (not shown in  FIG. 8 ) in the same manner as in the embodiment shown in  FIGS. 1  to  4 . 
   In the embodiment shown in  FIG. 9 , an insulative element  90  has a rectangular plate  90   a  and a generally triangular projection  90   b  formed on the plate  90   a  and extending along the length of the plate  90   a . A tab  92  has a vertical leg  92   a  and a U-shaped foot  92   b  extending horizontally from the lower end of the leg  92   a . A rectangular recess  92   c  is formed in the foot  92   b  and has opposite beveled sides  92   d . The projection  90   b  of the insulative element  90  is inserted into the recess  92   c  to mount the insulative element  90  to the tab  92 . The lower surface of the insulative element  90  is secured to the cover plate (not shown in  FIG. 9 ) in the same manner as in the embodiment shown in  FIGS. 1  to  4 . 
   Turning to  FIG. 10 , an insulative element  100  is in the form of a bolt and has a cylindrical shank  100   a  and a circular flat head  100   b  connected to the upper end of the shank  100   a . A tab  102  has a vertical leg  102   a  and a rectangular foot  102   b  extending horizontally from the lower end of the leg  102   a  and having a circular opening  102   c . The outer diameter of the shank  100   a  is slightly greater than the inside diameter of the opening  102   c  so that the shank  100   a  is snugly fit into the opening  102   c . The lower end of the shank  100   a  is secured to the cover plate (not shown in  FIG. 10 ) in the same manner as in the embodiment shown in  FIGS. 1  to  4 . 
   In  FIG. 11 , an insulative element  110  is composed of a round base  110   a , and a semispherical head  110   b  connected to the round base  110   a  through a neck portion  110   c . A diametrical slit  110   d  is formed in the semispherical head  110   b . As in the embodiment shown in  FIG. 10 , a tab  112  has a vertical leg  112   a  and a rectangular foot  112   b  extending horizontally from the lower end of the leg  112   a  and having a circular opening  112   c . The maximum outer diameter of the semispherical head  110   b  is slightly greater than the inside diameter of the opening  112   c . With this arrangement, the semispherical head  110   b  is inserted through the opening  112   c  so that the neck portion  110   c  is located in the opening  112   c . The lower end of the round base  110   a  is secured to the cover plate (not shown in  FIG. 11 ) in the same manner as in the embodiment shown in  FIGS. 1  to  4 . All the insulative elements in the embodiments shown in  FIGS. 8  to  11  are made of a material with a low degree of heat conductivity, such as epoxy resin, phenolic resin, polyester resin and acrylic resin. 
   The present invention has been described with respect to its preferred embodiments, it is to be understood that various modifications and changes may be made without departing from the scope of the invention as defined by the appended claims.