Abstract:
A pendent residential fire prevention sprinkler has a frame structure extending from the sprinkler body, and a system for blocking an outlet to prevent fluid from passing through the outlet until occurrence of a predetermined condition and for unblocking the outlet in response to occurrence of the condition. A deflector is supported by the frame structure at a predetermined distance from the outlet, at a position to be impinged upon by the fluid leaving the outlet. The deflector has a central portion and a peripheral portion, and slots formed in the periphery, defining tines therebetween. The slots include a first plurality of slots, each of which extends inward from the deflector periphery with a uniform width, a second plurality of slots, each of which has a first portion and a second portion between the deflector periphery and the slot&#39;s closed end, where the first portion has a width that varies at different points, while the second portion has a uniform width.

Description:
RELATED APPLICATION 
       [0001]    This application claims benefit under 35 U.S.C. § 119(e) of A.N. 60/954,072, filed 6 Aug. 2007, the entire disclosure of which is hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to pendent residential fire protection sprinklers, and relates more particularly to pendent residential fire protection sprinklers suitable for the protection of even relatively large residential spaces, through having the ability to provide the required coverage of even a large space with the required evenness and required throughput (flow, measured, e.g., in gallons per minute) at relatively low water pressures. The invention also relates to residential fire protection systems utilizing such sprinklers. 
         [0004]    2. Related Art 
         [0005]    Fire protection sprinklers conventionally are connected to a conduit to receive pressurized fire-extinguishing fluid, such as water. A typical sprinkler has a base with a threaded portion for connection to the conduit and an output orifice to output the fluid to provide fire control and/or suppression. The output orifice is sealed by a seal cap, which is held in place by a release mechanism. The release mechanism is designed to release the cap under predetermined conditions, thereby initiating the flow of fire-extinguishing fluid. A typical release mechanism includes a thermally-responsive element, e.g., a frangible bulb, and may include a latching mechanism. 
         [0006]    Certain conventional sprinklers have a pair of arms that extend from the base portion and meet at a hub portion to form a frame. The hub portion is spaced apart from the output orifice of the base portion and lies on the longitudinal axis thereof (the axis, roughly, along which the stream of fluid flows through the orifice). The hub portion may have a set-screw configured to apply a pre-tension force to the thermally-responsive element and latching mechanism. A deflector may be mounted on the hub, transverse to the output orifice, to provide dispersion of the output fluid. 
         [0007]    Fire protection sprinklers may be mounted on a fluid conduit running along a ceiling and may either depend downward from the conduit, which is referred to as a “pendent” configuration, or may extend upward, which is referred to as an “upright” configuration. The area to be protected may extend across an entire room, in which case the relevant fire protection standards, e.g., Underwriters&#39; Laboratories® Standard 1626 (the substance of which is incorporated herein by reference in its entirety), require the fluid flow to reach the four walls surrounding the coverage area, and to impinge on the coverage area evenly, among other requirements. (The true application of these sprinklers having larger K-factors is for 0.1 density, per NFPA 13. NFPA 13D—one and two family dwellings (0.05 density, 2-head design for hydraulic calculation); NFPA 13R—residential occupancies up to and including 4 stories in height (0.05 density, 4-head design for hydraulic calculation); NFPA 13—residential occupancies greater than four stories in height (0.1 density, 4-head calculation); these standards, also, are incorporated herein by reference.) To provide a sprinkler that meets these requirements for residential installations is especially difficult, because the available water pressure in residences is generally below what can be utilized in a commercial space. To this end, it is desired to increase the ability of the sprinkler to deliver fluid per unit time, as a function of available water pressure. This ability is generally measured by the K factor of the sprinkler, defined as the ratio of the fluid throughput per unit time in gallons per minute, to the square root of the water pressure in gauge pounds per square inch. 
         [0008]    In addition to achieving the ability to spray fluid at the required rate, a sprinkler must also meet certain standards pertaining to the evenness with which that fluid is delivered over the surfaces of the space being protected. 
         [0009]    Both of these requirements make the design of a residential sprinkler a challenge. Moreover, although data has been compiled and tabulated on the characteristics of sprinklers based on K factor and the water pressure used, it is frequently found that an actual sprinkler does not perform as predicted based on the known data. Frequently, it is found that a sprinkler requires a higher-than-expected water pressure to deliver an acceptable amount of fluid per minute. 
         [0010]    As a result, the task of designing a sprinkler having a given K factor and that not only will provide the required coverage but will do so at a particular water pressure, is a very challenging one. Depending on the particular parameters that it is desired to achieve, there is no guarantee in fact that it will actually be possible to create a design that will provide the desired level of performance. 
       SUMMARY OF THE INVENTION 
       [0011]    The present inventors have provided a new residential pendent sprinkler having an unexpectedly high K factor, and that operates with excellent results at an unexpectedly low water pressure. 
         [0012]    In one aspect of the invention, a pendent residential fire prevention sprinkler has a frame structure extending from the sprinkler body, and a system for blocking an outlet to prevent fluid from passing through the outlet until occurrence of a predetermined condition and for unblocking the outlet in response to occurrence of the condition. A deflector is supported by the frame structure at a predetermined distance from the outlet, at a position to be impinged upon by the fluid leaving the outlet. The deflector has a central portion and a peripheral portion, and slots formed in the periphery, defining tines therebetween. The slots include a first plurality of slots, each of which extends inward from the deflector periphery with a uniform width, a second plurality of slots, each of which has a first portion and a second portion between the deflector periphery and the slot&#39;s closed end, where the first portion has a width that varies at different points, while the second portion has a uniform width. 
         [0013]    Another aspect of the invention is a pendent residential fire prevention sprinkler has a frame structure extending from the sprinkler body, and a system for blocking an outlet to prevent fluid from passing through the outlet until occurrence of a predetermined condition and for unblocking the outlet in response to occurrence of the condition. A deflector is supported by the frame structure at a predetermined distance from the outlet, at a position to be impinged upon by the fluid leaving the outlet. The deflector has a central portion and a peripheral portion, and slots formed in the periphery, defining tines therebetween. In this aspect of the invention, the residential fire sprinklers each provide a fluid flow of 40 gallons per minute at a gauge fluid pressure of 27.7 psi. 
         [0014]    Another aspect of the invention is a residential fire protection system utilizing such sprinklers. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0015]      FIG. 1  is a side view, partly in section, of a first embodiment of the present invention. 
           [0016]      FIG. 2  is a sectional view of that embodiment, taken from section line  2 - 2  in  FIG. 1 . 
           [0017]      FIG. 3  is a detail, in section, of the circled portion of the structure shown in  FIG. 2 . 
           [0018]      FIG. 4  is a view end-on of the deflector of the embodiment of  FIG. 1 . 
           [0019]      FIG. 5  presents, in tabular form, the results of tests that were performed, comparing the performance of the embodiment of  FIG. 1  with that of some commercially available residential sprinklers. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    In one aspect, the present invention provides a pendent fire protection sprinkler  10 , shown in  FIG. 1 . Since the major parts of the preferred embodiment are common to many sprinklers, it is not deemed necessary to describe them in full detail (reference may be had to U.S. Pat. No. 6,516,893, assigned in common herewith, for additional views). 
         [0021]    The sprinkler  10  of this embodiment has a body  11  having an inlet orifice  12 , an output orifice  13  and an axial passage  21  (see  FIG. 2 ) through the body joining the inlet and outlet orifices. The exterior of the body adjacent the inlet  12  is threaded, to permit the sprinkler to be connected to a piping system that delivers a fire extinguishing fluid to the sprinkler. That fluid is often water, and for simplicity, the fluid will generally be referred to hereinafter as being water; it should nonetheless be understood that other fluids can be substituted without departing from the scope of the invention. The pendent sprinkler  10  is installed with the inlet  12  upwards, and the rest of the sprinkler depending therefrom. It is within the invention for the sprinkler  10  to be mounted either with a cover or exposed to view; both arrangements are well known, and do not require description. 
         [0022]    Two co-planar frame arms  14  extend from the sprinkler body  11 , and are joined together at a distance from the body  11 . A seal cap  15  blocks the outlet  13  so as to prevent the flow of any fluid from the output orifice  13 , and a thermally-responsive element  16  holds the cap  15  in place. Element  16 , which may be for example a glass container in which is a thermally-responsive liquid that upon being heated sufficiently will cause the glass to break, has one end positioned against the cap  15 , and its other end supported by a load screw  17  that is mounted in a hub  18  that is supported by the frame arms  14 . (The load screw and the hub are together referred to as a “hub assembly” for convenience herein.) The thermally-response element  16 , cap  15  and hub assembly together serve to block the outlet  13 , until occurrence of a sufficient temperature condition to cause element  16  to break as described above. When this occurs, as is well known, the cap  15  is no longer held in place, and the water pressure in the piping system and gravity remove the cap, allowing the water to issue from the outlet  13 . (This can be visualized most easily from  FIG. 2 .) 
         [0023]    The sprinkler  10  also includes a deflector  19  supported by and below the frame arms  14 . The deflector  19  of the sprinkler  10  is, broadly, a disc, as can be appreciated more easily from  FIG. 4 . The deflector  19  has an upper face and a lower face. When the sprinkler is actuated, the stream of water emerging under pressure from the outlet  13  first impinges upon the exposed tip of the load screw and hub, and then onto the upper face of the deflector  19 . The deflector is structured (as described below) to disperse the water so as to achieve the required flow, distributed properly over the area protected by the sprinkler. The load screw tip and the hub direct the flow of water onto the deflector, and in fact, thereby play a key role in the proper operation of the sprinkler. This is because directing the stream of water so that it impinges on precisely the right portion of the deflector has been found by the inventors to be of great importance in achieving the best possible distribution of water over the protected area. The preferred embodiment of the present invention has a K factor of 7.6 or more. 
         [0024]    The inventors have found that to achieve the desired coverage, with the desired evenness, a number of features and relationships among parts are important to critical. The deflector  19  must have the correct total area, and it is necessary to be sure that the water strikes the deflector  19  with the proper velocity. Also, it has been found that it is necessary for the water to impinge on the deflector  19  not only with the right velocity, but also in the right location. Furthermore, to achieve proper coverage of the area to be protected, it is not possible to use a deflector having a conventional structure; rather, the deflector  19  itself must have a number of unconventional features, as described below. 
         [0025]    In the preferred embodiment, the load screw tip is sized, shaped and positioned so as to create a spread in the column of fluid from the orifice onto a disk-shaped area of the correct diameter in the middle of the deflector  19 . It has been found that controlling the size of this area is very important in achieving the desired operational characteristics at the low pressures for which the present sprinkler is intended to be suitable. Moreover, it has been found that the spacing between the outlet orifice  13  and the deflector  19  influences the velocity with which the fluid impinges on the deflector, and is important in achieving an even distribution of the fluid onto the walls of the space without the fluid being deflected up onto the ceiling. 
         [0026]      FIG. 3  shows an enlarged view, partly in section, of the hub assembly. The lower end of the thermally-responsive element  16  is visible, resting on the upper tip  31  of the load screw  17 . The load screw  17  is threaded into a central bore  32  in the hub  18 . The inventors have obtained optimum results with the tip  31  of the load screw  17  protruding a certain distance (in the preferred embodiment, 0.075 inch) from the upper surface of the hub  18 , and with the lateral sides  33  at a slight angle (8.5° in the preferred embodiment) to the axis of the sprinkler  10  (that axis being the line extending from the center of the outlet orifice  13  to the center of the deflector  19 ). The upper surface of the tip should not be excessively small (in the preferred embodiment it is 0.108 inch). Moreover, the hub  18  itself plays an important role, and the size of its upper surface greatly factors into reduction of water column&#39;s dispersion (and its energy or velocity) (this surface in the preferred embodiment has a diameter of 0.285 inch). The same consideration applies to the cross-sectional width of the frame arms  14  at the zone of their convergence with the screw hub  18  (the frame arms are here teardrop-shaped in cross-section). 
         [0027]    The lateral sides  34  of the hub  18  are sloped at a slight angle to the sprinkler axis (in the preferred embodiment, 8.5°). It is not necessary for the entire height of the lateral wall  34  to be sloped, and in the preferred embodiment this slope is provided to the upper 0.285 inch of wall  34 . Finally, the upper edge of the hub  18 , where the lateral sides  34  meet the top surface, should not present a sharp edge to the water flow, but should be radiused (again, a radius of 0.04 inch is used in the preferred embodiment). 
         [0028]    Also, to achieve delivery of the proper amounts of fluid to the walls and to the floor of the area to be protected, and with the correct distribution as between the walls and the floor, the deflector  19  has a number of features that are not conventional. It is known to provide the deflector with slots formed in its circumference, but the present deflector  19  uses slots differing from conventional arrangements in a number of way, as shown in  FIG. 4 . While conventional slots are formed exactly radially, the present deflector is provided with a first group of four slots N that are not exactly radial. These four slots are distributed 90° apart from each other around the circumference, two of them being in the plane defined by the frame arms  14  and the other two lying in a plane perpendicular thereto. These slots N are unconventional in that they deviate from being exactly radial, by a small amount. These slots N also are unconventional in that they are provided with a small amount of chamfering at their edges, on the surface of the deflector  19  that faces toward the floor (the side opposite the outlet orifice  13 ). 
         [0029]    Moreover, a number of other slots are formed in such a way as to define four structures resembling a bent fork (defined by slots c and the tines adjoining those slots), each of which is located about 45° from one of the non-radial slots N. These structures are particularly important in ensuring that the fluid is delivered all the way into the corners of the space that is being protected, which is especially difficult when the sprinkler must operate with a low water pressure. 
         [0030]    As can be seen in the drawing, the various slots each have a shape from a total of four different shapes. Taking the relatively deep slot at a location N as a starting point and going counterclockwise, one encounters a relatively wide but shallow (or short) slot a, then a deep and asymmetrical slot b, a slot c that is the widest and also (by a small margin) the shallowest of the four shapes, then another slot of the same shape as slot b, and another having the same shape as slot a. This pattern of six slots is repeated a total of four times around the circumference of the deflector, once in each 90° of the circumference. 
         [0031]    The asymmetrical slots b have an outer portion  41  in which the slot width decreases from the deflector periphery, and then an inner portion  42 , in which the width is constant. This inner portion in addition includes both a region  42   a  where the direction of the slot is radial, but also another region  42   b  where the slot b extends in a direction that is visibly at an angle to the radius of the deflector  19 . 
         [0032]    Thus, one feature of the deflector  19  is that it has a first plurality of slots (slots a, c and N), which are each of constant width (although they are not all of the same width), and which extend at least approximately radially toward the center of the deflector (although not exactly, in the case of slots N), and a second plurality of slots, which each have a portion that is visibly non-radial, as well as a portion that is of variable width (slots b). 
         [0033]    In addition, the root diameter of all four shapes of slots (the width of the slot at its closed end nearest the center of the deflector) is relatively large. 
         [0034]    In the preferred embodiment, the deflector  19  has a diameter of 1.56 inches. The length of slots N is 0.305 inch, and their width is 0.065 inch. Slots a are 0.23 inch in length and 0.08 inch in width, and slots c are 0.22 inch in length and 0.10 inch in width. The asymmetrical slots b have a total depth (distance from the deflector periphery to the root of the slot) of 0.3175 inch. Region  42   a , nearest the deflector center, has a length of 0.118 inch (not including the length of the radiused closed end), and a width of 0.07 inch, region  42   b  extends at an angle of 12.5° to the deflector radius, out to a distance of 0.10 inch from the deflector periphery, and has a width of 0.07 inch, and portion  41  has occupies the last 0.10 inch out to the periphery and has a width that increases linearly. 
         [0035]    Also, in the preferred embodiment, the angular spacing from a slot of type N to the nearest slot b is 32.5°, measured from the center of slot N at the deflector periphery to the radius that intersects the center of the root of slot b. The angular spacing from a slot N to the nearest slot a is 15°, measured from the center of slot N at the deflector periphery to the radius that lies on the nearest edge of slot a, and that from slot N to the nearest slot c is 45.0°, measured from the center of slot N at the periphery of the deflector  19  to the center of slot c. 
         [0036]    In addition to the slots, the deflector  19  is provided with a number of small holes  43  (four in the drawing) that permit additional delivery of fluid to the floor beneath the sprinkler. In the preferred embodiment, these four holes are countersunk, having a larger bore on the lower side of the deflector and a smaller bore on the upper surface. In the preferred embodiment, the holes  43  have a diameter of 0.045 inch on the upper side of deflector  19 , and a maximum diameter of 0.078 inch on the lower side (the counterbore, on the under side of the deflector, is preferably formed with its wall at an angle of 60°). 
         [0037]    The placement of these holes also is unconventional, in that such holes would commonly be placed in line with the frame arms, or along a line perpendicular to the location of the frame arms, while in the present invention, they are placed somewhat offset from the conventional locations (and 90 degrees apart from each other). In the preferred embodiment, the holes  43  are 22.5° from the slots N, measured from the center of slot N at the deflector periphery to the radius that passes through the center of the hole  43 . This placement also has been found to be important in achieving the desired operation. 
         [0038]    These features of the deflector  19  help to ensure that the fluid is distributed in the desired way as between the floor and the walls of the space being protected, and that fluid is delivered into the corners of the space at a sufficient rate. 
         [0039]    The attached drawings are to scale, and the contents of those drawings are part of the disclosure of the present invention. 
         [0040]    It should also be noted that, while one preferred embodiment of the sprinkler is illustrated, it is also contemplated to use this sprinkler in a concealed version, employing a standard cup and cover plate. 
         [0041]      FIG. 6  is a table showing an accurate comparison for 0.1 density (including data for a concealed sprinkler), comparing the preferred embodiment of the present invention (in the columns labeled “RASCO”) with a number of other, conventional residential sprinklers (identified in the table by their respective manufacturers). In each column of data, the first number gives the water flow achieved in gallons per minute, and the second number (in parentheses) give the gauge pressure in pounds per square inch required for that flow. 
         [0042]    These data show that the sprinkler of the present invention achieves the desired operation at lower pressures than can be used with the other sprinklers tested. As is well known, this is advantageous to the end user, since the lower pressure demand in the system reduces the installation cost.