Patent Grant
9302132
The present disclosure relates to fire protection sprinklers, and more particularly to a fire protection sprinkler having a sprinkler skipping shield with improved airflow.
This section provides background information related to the present disclosure which is not necessarily prior art.
Sprinkler skipping is a behavior that is sometimes exhibited by an array of sprinklers during a full scale fire. Typically, a fire will initially set off one to four sprinklers in quick succession depending where the ignition source is in relation to the sprinkler array. These first few activations are usually defined as the first ring of activated sprinklers. As hot gas from the fire spreads radially outward from the center, the hot gas comes in contact with the second ring of sprinklers. The second ring of sprinklers are radially adjacent to the first ring. The next consecutive/adjacent ring would be the third ring, and the next would be the fourth ring and so on. Sprinkler skipping occurs when a sprinkler in the third or fourth ring operates before a sprinkler in the second ring. In more general terms, skipping is when a non-activated sprinkler adjacent to a flowing sprinkler fails to operate before sprinklers that are farther away from the heat source. This behavior results in the sprinkler array not performing to its highest efficiency.
Some members of the fire protection industry have concluded that water impingement is the cause of sprinkler skipping. Water impingement is defined as (1) water flow from an activated sprinkler to an adjacent sprinkler; or (2) water droplets carried by the fire plume on to an adjacent sprinkler and impinging on that sprinklers thermal element. The water impingement absorbs heat from the thermal element preventing or retarding its activation (the water keeps the thermal element below its operating temperature).
In order to prevent water impingement, it has been proposed that a shield be installed such that water traveling from a flowing sprinkler or water carried by the fire plume will not strike the thermal element of an adjacent sprinkler. This, in theory, prevents the thermal element from becoming wetted, thereby preventing skipping. The shield that has been proposed is of a solid cylindrical construction.
There is some concern that the response time of the thermal element will be impeded by the skipping shield. The impeded response time can negatively impact the performance of a sprinkler in a fire and in a “Response Time Index” plunge oven test. Both of these tests are important to the performance of the sprinkler in terms of gaining Approvals and Listings.
The present disclosure provides improvements to the design of the skipping shield to reduce the negative impact that the shield has on the thermal response of the sprinkler. By adding holes, slots, louvers, or mesh to the skipping shield, water from the flowing head can still be blocked from impinging on the thermal element. The improved shield will block water from impinging on the heat responsive element but will allow hot gas from the fire to flow through the shield thereby improving the response time of the thermal element.
The present disclosure also provides a geometrical shape other than the cylindrical shape. The improved geometrical shape is designed in such a fashion to encourage laminar or turbulent gas flow around the shield and onto the thermal element of the sprinkler. The shape is made such that water impinges on the shield, yet provides improvement to the airflow that lowers the response time index as compared to that of previous skipping shield designs.
The present disclosure also includes the combination of holes, slots, louver, or mesh with a geometric shape that promotes improved air flow around the thermal element.
Compared to previously proposed skipping shield designs, the improved skipping shield will yield better sprinkler performance in fires by enhancing the response time. The improved skipping shield will also reduce the RTI (Response Time Index) when tested in a plunge oven.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.).
Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
With reference to
The sprinkler body 12 can be provided with any discharge K factor for a desired application. The heat responsive trigger assembly 26 can have any desired response temperature rating and the sprinkler 10 can be designed to have any desired response time index (RTI) for a desired application.
A shield 40 is mounted to the sprinkler body 12 and can include an interior hub portion 42 which can optionally be threadedly engaged with the external threads on the sprinkler body 12. The shield can be mounted to sprinkler body 12 via the frame arms, via the deflector, or via other exterior structure such as a supply piping or other ceiling structures. A plurality of radial spokes 44 can extend from the hub portion 42 for supporting the shield body 46. The spokes 44 can include spaces therebetween to facilitate airflow therebetween. The shield body can include a cylindrical wall portion 48. The wall portion 48 can have other shapes such as cone shaped and sphere shaped, and can be ellipse, square or rectangle in cross-section and can include continuous or discontinuous wall sections. The shield body 48 can include a plurality of louvers 50 that allow air flow through the shield body 46. The louvers 50 can include an inwardly bent portion 50a that define air passages 52 that allow heated air from a fire to enter the shield 40 while the shield serves to prevent water droplets from entering the shield and contacting the heat responsive trigger assembly 26. It is noted that the louvers 50 can extend around a majority of the shield and the louvers 50 can be connected by one or more web portion 54. The louvers can be vertical or horizontal in an assembled condition. The spaces 52 between louvers 50 can be between 0.01 and 1 inch, and more specifically between 0.02 and 0.5 inches. The shield 40 can be formed in a generally cup-shape and the openings between the spokes 44 additionally provide for air circulation into and out of the shield body 46.
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The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.
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| Number | Date | Country | |
|---|---|---|---|
| 20100243283 A1 | Sep 2010 | US |
