1. Field of the Invention
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.
2. Related Art
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.
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.
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' 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.
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.
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.
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.
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.
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's closed end, where the first portion has a width that varies at different points, while the second portion has a uniform width.
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.
Another aspect of the invention is a residential fire protection system utilizing such sprinklers.
In one aspect, the present invention provides a pendent fire protection sprinkler 10, shown in
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
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
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
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.
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.
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).
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 ways, as shown in
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.
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.
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 42a where the direction of the slot is radial, but also another region 42b where the slot b extends in a direction that is visibly at an angle to the radius of the deflector 19.
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).
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.
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 42a, 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 42b 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.
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.
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°).
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.
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.
The attached drawings are to scale, and the contents of those drawings are part of the disclosure of the present invention.
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.
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.
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.
Number | Name | Date | Kind |
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2697008 | Rowley | Dec 1954 | A |
5865256 | Pounder | Feb 1999 | A |
6026907 | Pahila | Feb 2000 | A |
6059044 | Fischer | May 2000 | A |
6276460 | Pahila | Aug 2001 | B1 |
6516893 | Pahila | Feb 2003 | B2 |
Number | Date | Country | |
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20090078432 A1 | Mar 2009 | US |
Number | Date | Country | |
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60954072 | Aug 2007 | US |