COVER PLATE AND COVER PLATE ASSEMBLY FOR CONCEALED FIRE

PROTECTION SPRINKLER

BACKGROUND

Field of the Invention

[0001] This invention relates generally to a cover plate and cover plate assembly for concealing a fire protection sprinkler.

[0002] Conventional cover plates for fire protection sprinklers are typically used with deploy able/drop-down deflector assemblies, such as those described in U.S. Patent No. 7,275,603 (Polan). These cover plates are soldered to a skirt. When the solder attaching the cover plate to the skirt reaches the temperature rating of the cover plate, the solder melts and releases the cover plate from the skirt, exposing the sprinkler to the room being protected. These cover plates must be made of a material that is readily soldered. These cover plates are typically made of a metal such as copper. However, when these copper cover plates are used in spaces or rooms such as food processing facilities which are washed down frequently with water and possibly chemicals, the copper surface can become tarnished or corroded over time giving the cover plates a discolored messy appearance. [0003] One conventional method to address the messy appearance of the copper cover plates is to provide a coat of paint over the surface of the cover plate facing the protected room. However, frequent cleaning of the protected room can cause the coat of paint to erode, bubble and/or strip over time, again giving the cover plates a messy appearance.

[0004] In addition, the sensitivity of a sprinkler can be affected by covering the sprinkler with a cover plate. As such, concealed sprinklers are designed and tested to have a predetermined sensitivity when configured with an approved concealed sprinkler cover plate. Conventionally, such concealed sprinklers and cover plates are tested according to relevant standards promulgated by Underwriters Laboratories, Inc. (UL).

[0005] Current UL listing criteria require that quick response (QR) sprinklers and QR extended coverage sprinklers for light hazard occupancies, for example, must achieve complete activation of the cover plate and thermal release element (e.g., bulb or soldered link) within seventy-five (75) seconds when tested in accordance with UL Standard 199, Section 31 - Room heat test for QR and QR extended coverage sprinklers. The current UL listing criteria also require that QR sprinklers and QR extended coverage sprinklers for ordinary hazard occupancies, for example, must achieve complete activation of the cover plate and thermal release element (e.g., bulb or soldered link) within fifty -five (55) seconds when tested in accordance with UL Standard 199, Section 31 - Room heat test for QR and QR extended coverage sprinklers.

SUMMARY

[0006] To address the problems described above, a cover plate for a concealed sprinkler is provided having a first layer of metal on a first side of the cover plate facing the sprinkler and a second layer of metal on a side of the cover plate facing an enclosure to be protected, where the first layer of metal is more thermally conductive than the second layer, and the second layer is more resistant to corrosion than the first layer.

[0007] More specifically, a cover plate is provided which is releasably connected to a concealed fire protection sprinkler configured to conceal the fire protection sprinkler. The cover plate includes a first layer of metal on a first side of the cover plate facing the concealed fire protection sprinkler, and a second layer of metal on a second side of the cover plate. The second layer of metal is more resistant to corrosion than the first layer, and is bonded to the first layer. The first side is opposite the second side, such that the second side faces an enclosure to be protected. The first layer is more thermally conductive than the second layer, and a thickness of the first layer is greater than a thickness of the second layer.

[0008] By virtue of the foregoing arrangement, it is possible to provide a cover plate with corrosion resistance by nature of the second layer of metal on a room side of the sprinkler, while maintaining a response time of the sprinkler due to the high thermal conductivity of the first layer of metal.

[0009] According to an example embodiment, the first layer of metal is comprised of copper, and the second layer of metal is comprised of stainless steel. In one example, the thickness of the first layer is at least 16%of the total thickness of the first and second layers. In another example, the thickness of the first layer is at least 80 % of the total thickness of the first and second layers.

[0010] By virtue of the foregoing examples, it is possible to provide a cover plate that meets the UL criteria, for example, discussed above for QR sprinklers and QR extended coverage sprinklers for light and ordinary hazard occupancies, while also providing a corrosive resistant cover plate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 shows a side section view of a cover plate assembly for a concealed fire protection sprinkler, according to an example embodiment described herein, and Fig. 1 A is a partially exploded detail of a portion of the cover plate assembly shown in Fig. 1 ;

[0012] Fig. 2 shows a back view of the cover plate assembly shown in Fig. 1 ;

[0013] Fig. 3 shows a front view of the cover plate assembly shown in Fig. 1 ;

[0014] Fig. 4 shows a side section view of the cover plate assembly shown in Fig. 1 , including a gasket seal;

[0015] Fig. 5 shows a back view of the cover plate assembly shown in Fig. 4; and [0016] Fig. 6 shows the cover plate assembly shown in Fig. 1 and a concealed fire protection sprinkler installed in a ceiling.

[0017] Any reference numeral that appears in different figures represents the same element in those figures, even if that element is not described separately with respect to each figure.

DETAILED DESCRIPTION

[0018] Fig. 1 shows a side section view of a cover plate assembly 100 for a concealed fire protection sprinkler (not shown), according to an example

embodiment described herein. The cover plate assembly 100 includes a cover plate 110, an escutcheon 120 and a frame 130, all aligning along a central axis. The escutcheon 120 is cylindrical and has a circumferential, annular flange 150 on its outwardly facing end (the lower end in Fig. 1). The escutcheon 120 is formed of metal such as copper or a copper alloy. The escutcheon 120 includes perforations 121 on its outer walls for installation with the fire protection sprinkler. In other example embodiments, the escutcheon 120 can include threading for installation with the fire protection sprinkler.

[0019] The cover plate 110 is flat and circular, and includes a first layer 1 12 and a second layer 11 1. The first layer 1 12 is on a first side of the cover plate 110, which faces the escutcheon 120 and the fire protection sprinkler. The second layer 1 11 is on a second side of the cover plate 1 10, opposite the first side of the cover plate 1 10, facing the room to be protected by the fire protection sprinkler. The first layer 1 12 and the second layer 11 1 are bonded together.

[0020] The first layer 1 12 is formed of a metal having high thermal conductivity such as copper or a copper alloy. The second layer 11 1 is formed of a metal having high resistance to corrosion such as stainless steel. Of course, the cover plate 110 is not limited to the materials copper and stainless steel, and in other example embodiments, the cover plate 110 can include other materials so long as a material of the first layer 1 12 has high thermal conductivity and the second layer 11 1 has high resistance to corrosion.

[0021] Other example embodiments include the first layer 1 12 comprised of bronze, brass, nickel, beryllium nickel, or sterling silver, and the second layer 1 11 comprised of titanium, molybdenum, alloys such as those sold under the trademark incoloy® (examples of such alloys include UNS S67956 and UNS N08020; incoloy® is believed to be a registered trademark of Huntington Alloys Corporation, Huntington, West Virginia) or titanium-zirconium-molybdenum (TZM) alloy.

[0022] The frame 130 is formed of a metal such as copper or copper alloy and includes multiple tabs 131 and a spring 132. The frame 130 is in the shape of a flat ring, and the multiple tabs 131 are formed on the frame 130 by downwardly bending outer sections of the ring of the frame 130 into L-shapes.

[0023] The frame 130 is mounted to the escutcheon 120 around the bottom periphery of the escutcheon flange 150 using, for example, an adhesive. The cover plate 1 10 is attached to the frame 130 with solder between the bottom of each of the multiple tabs 131 and the first layer 112 on the first side of the cover plate 110, using a solder that is designed to melt at a predetermined temperature, for example, 135° F, to allow for release of the cover plate 110 and to expose the fire protection sprinkler. The spring 132 applies a downward force against the cover plate 110 once the cover plate 1 10 is soldered to the frame. The application of force by the spring 132 facilitates the release of the cover plate 1 10 once the solder has melted.

[0024] Fig. 1 A is an exploded view, partly in section, of the cover plate assembly 100 shown in Fig. 1. The view of Fig. 1A provides a detailed look at the first layer 112 and the second layer 1 11 of the cover plate 110. As shown in Fig. 1 A, a proportion of the first layer 112 (in this example, the thickness of layer 1 12) is larger than that of the second layer 1 11. The second layer 11 1 is a material which is more resistant to corrosion than is the material of the first layer 1 12. Also, the first layer 112 is more thermally conductive than the second layer 1 11. In other words, the first layer 1 12 has a higher thermal conductivity than does the second layer 1 11.

[0025] In one example embodiment, the thickness of the first layer 1 1 1 is at least 16 % of the combined thicknesses of the first and second layers (the total thickness of the cover plate 110). In another example embodiment, the thickness of the first layer 112 is at least 80 % of the total thickness of the cover plate. It is within the invention for the thickness of the first layer to be in the range from 16% to 80%, inclusive, of the combined thicknesses of the two layers 11 1 and 1 12. [0026] In one specific example, the first layer of the cover plate is comprised of copper with a thickness of 0.0096 inches, and the second layer of the cover plate is comprised of stainless steel with a thickness of 0.0024 inches. In this example, the cover plate comprised 80% copper and 20 % stainless steel (referring to the relation of the thickness of the layers, not to weight).

The foregoing example cover plate successfully released in under 45 seconds with cover plates having temperature ratings ranging from 135°F to 165°F.

[0027] Fig. 3 shows a view of the second layer 1 11 on the second or exterior side of the cover plate 110, which faces the room to be protected. As shown in Fig. 3, the cover plate 1 10 does not require painting (and in fact must not be painted after installation), and has an aesthetically pleasing look, for example, of stainless steel.

[0028] Figs. 4 and 5 show a side section view and a back view, respectively, of the cover plate assembly 100 shown in Fig. 1 , including a gasket seal 201. The gasket seal 201 is formed around the cover plate 110 along the circumference of the cover plate. The gasket seal 201 limits the infiltration of gases or liquids from the protected room to space above the cover plate 1 10.

[0029] Fig. 6 shows the cover plate assembly 100 shown in Fig. 1 and a concealed fire protection sprinkler 300 installed in a ceiling 430, according to an example embodiment. As shown in Fig. 6, the sprinkler 300 installs within a support cup 320, the escutcheon 120, and the cover assembly 100 to form a concealed configuration. The escutcheon 120 installs with a press or threaded fit into the ridged outer surface (walls 330) of the support cup 320.

[0030] As described above in connection with Fig. 1 , the cover plate 110 is mounted on raised portions (e.g., the multiple tabs 131 of frame 130 in Fig. 1) around the periphery of the escutcheon flange 150. As also described above, the cover plate 110 is attached to the multiple tabs 131 with solder that is designed to melt at a predetermined temperature, e.g., 135°F, to allow for release of the cover plate 1 10. The raised portions result in a gap or space between the cover plate 1 10 and the escutcheon 120, which allows air flow to reach the sprinkler 300. The release of the cover plate 1 10 allows a deflector 340 to drop down into the deployed position. At a second predetermined temperature, e.g., 165°F, a fusible soldered link 350 separates to initiate the flow of fluid from the sprinkler. [0031] To install the sprinkler, the support cup 320, which has a diameter of, e.g., 2.28 inches, is inserted in a cavity in the ceiling 430 having a diameter of, e.g., about 2 5/8 inches, and a threaded base 310 of the sprinkler is connected to an output fitting 435 of a conduit 440. The escutcheon 120 and the cover plate 110 is then installed in the support cup 320 so that the escutcheon flange 150 rests on the outer surface of the ceiling 430 (the outer surface of the cover is about 3/16 inches from the surface of the ceiling due to the gap between the flange and cover).

[0032] The support cup 320 and escutcheon 120 are configured to allow for an adjustment to accommodate variations in the distance between a face 450 of the conduit output fitting 435 and the surface of the ceiling 430, which is referred to as the "field adjustment." The field adjustment is sometimes needed, because the deflector 340 must be properly located below the ceiling 430 in its deployed position, but it is difficult to position sprinkler conduits 440 precisely with respect to the ceiling 430 surface, due to the practicalities of building construction. To ensure the correct positioning of the deployed deflector 340, the distance between the face 450 of the conduit output fitting 435 and the ceiling 430 should not be more than 2 inches.

[0033] The field adjustment is achieved by allowing the escutcheon 120 to be positioned with a varying degree of overlap with the outer walls 330 of the support cup 320. The support cup 320 and escutcheon 120 are configured so that any secure engagement between these components results in a proper position for the deflector 340 upon deployment.

[0034] The amount of field adjustment, which in this example is 0.5 inches, is determined by the length of rods 360 of the deflector support members 370, because the length of the rods 360 determines the amount of variation that can be accommodated in the position of the conduit 440 relative to the ceiling line 430. In other words, the rods 360 may be completely retracted within the housing member 370 before deployment, such as when the conduit 440 and, therefore the sprinkler 300, is positioned as close as possible to the ceiling line 430. Alternatively, the rods 360 may be nearly 3/4 extended before deployment, such as when the conduit 440 is positioned as far as possible above the ceiling line 430. The length of the rods 360, in turn, determines the height of the outer walls 330 of the support cup 320. Thus, the outer walls 330 of the support cup 320 must have a height of slightly more than 0.5 inches in the example described herein.

[0035] Configuring deflector support members 380 such that the rods 360 extend through the housing members 370 and the flange 140 allows for the use of a shallower cup, because the depth of the support cup is primarily determined by the length of the rods 360. This in turn results in the thermally-responsive element being located closer to the ceiling line, thereby improving sprinkler sensitivity. By contrast, in conventional concealed sprinklers, the guide pins coupled to the deflector are generally positioned below the flange, requiring a deeper support cup (because the depth of the support cup is determined by the length of the guide pins plus the flange thickness). Consequently, the thermally-responsive element is located farther from the ceiling line, resulting in reduced sprinkler sensitivity.

[0036] The inventor herein has found that stainless steel is not typically used in cover plates because it has a lower thermal conductivity than copper (stainless steel is more insulating than copper), so using stainless steel instead of copper slows the heating of the solder and the operation of the sprinkler. In addition, the inventor herein has found that stainless steel is more difficult to solder than copper.

[0037] By virtue of the foregoing arrangement, it is possible to provide a cover plate, for example, a composite copper/stainless steel cover plate, that provides corrosion resistance on the room side of the sprinkler, while maintaining the response time of the sprinkler due to the high thermal conductivity of the copper backing.

[0038] More specifically, the foregoing described arrangement meets all of the current UL listing criteria set forth in UL Standard 199, Section 31. For example, the foregoing described arrangement meets the requirement that quick response (QR) sprinklers and QR extended coverage sprinklers for light hazard occupancies, for example, must achieve complete activation of the cover plate and thermal release element (e.g., bulb or soldered link) within seventy-five (75) seconds, and the requirement that QR sprinklers and QR extended coverage sprinklers for ordinary hazard occupancies, for example, must achieve complete activation of the cover plate and thermal release element (e.g., bulb or soldered link) within fifty-five (55) seconds, when tested in accordance with UL Standard 199, Section 31 - Room heat test for QR and QR extended coverage sprinklers.

[0039] While the present disclosure has been described with respect to what is presently considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.