Abstract:
A pool drain safety cover system and method. The system includes a base defining at least one primary fluid aperture and a plurality of secondary fluid apertures. The cover also includes a grating extending across at least the primary fluid aperture for permitting the passage of drain water therethrough. The grating has at least an upper and a lower layer. The upper and lower layers are adjacent, and each is comprised of a plurality of spaced ribs for permitting the passage of fluid in a clearance space between the ribs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Patent Provisional Application No. 60/204,413, filed on May 16, 2000. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     (Not Applicable) 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to drainage systems located on the bottom or along the side of a swimming pool or spa. More particularly, the invention relates to a method and apparatus for preventing the entrapment of a person in the drain of a swimming pool or spa. 
     2. Description of the Related Art 
     Swimming pools and spas typically have systems for draining and recirculating water. Such systems usually have a main drain or sump located at or near the bottom of the swimming pool or spa. Water is normally suctioned out of the swimming pool or spa through the main drain, into an inlet of a suction pump, and then drained or recirculated back into the swimming pool or spa through jets located around the interior wall of the swimming pool or spa. 
     When bathers place their heads or bodies in the vicinity of an active drain, their hair or a portion of their body may become entrapped in a portion of the drain, such as a cover or grating. A sealed drain can develop a strong vacuum within a few seconds. If the vacuum pressure is strong enough, a bather who is entrapped by a drain may not be able to break free of the vacuum and may ultimately drown. 
     Swimming pool and spa safety organizations, such as the United States Consumer Product Safety Commission (CPSC), the National Spa and Pool Institute (NPSI), and various state government entities, have acknowledged the need for devices that protect against swimming pool and spa drain entrapment. Of particular concern are entrapments involving hair entanglement, limb entrapment, body entrapment, and disembowelment. Hair entanglement occurs when a bather dips below a water surface and his or her hair is sucked into and becomes entangled on a drain grate on the main drain of a swimming pool or spa. Body entrapment typically occurs when part of a bather&#39;s torso completely covers an unprotected or damaged drain, thereby creating a vacuum within the drain from which the bather cannot break free. Limb entrapment refers to accidents in which a bather&#39;s arm or leg is sucked into a main drain of a swimming pool or spa. Disembowelment accidents occur where small children, usually three to six years old, sit on a drain. Injury occurs when their lower intestines are sucked out of their body through their anus. 
     Various devices have been used to prevent entrapment. For example, swimming pools and spa have been provided with multiple drains, as opposed to just a single drain, to prevent a vacuum from being formed when one of the drains is obstructed. A system with multiple drains has its drawbacks, however, in that it can be significantly more expensive. Additionally, multiple bathers can cover the multiple drains, permitting the creation of the hazardous vacuum which the system is designed to prevent. 
     Pressure detection systems have also been used to reduce the risk of entrapment. Pressure detection systems shut off a drain system when the vacuum pressure within the system reaches a critical level. Unfortunately, the complexity of such systems raises reliability concerns. Thus, a need still exists for an improved method and apparatus for preventing entrapment. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention relates to a pool drain safety cover. The cover includes a base defining at least one primary fluid aperture and a plurality of secondary fluid apertures. The cover also includes a grating extending across at least the primary fluid aperture for permitting the passage of drain water therethrough. The grating has at least an upper layer and a lower layer. The upper and lower layers are adjacent, and each is comprised of a plurality of spaced ribs for permitting the passage of fluid in a clearance space between the ribs. 
     Another aspect of the invention relates to a method for providing a pool drain safety cover. The method includes providing a base defining at least one primary fluid aperture and a plurality of secondary fluid apertures. The method also includes positioning across at least the primary fluid aperture a grating for permitting the passage of drain water therethrough. The grating includes at least an upper layer and a lower layer. The upper and lower layers are adjacent, and each includes a plurality of spaced ribs for permitting the passage of fluid in a clearance space between the ribs. 
     According to either aspect of the invention, the ribs of the upper layer can be perpendicular to the ribs of the lower layer. The spacing between the ribs can be between approximately one-eighth inch and one-sixteenth inch. The base can include a perimeter portion surrounding the primary fluid aperture, and a plurality of protrusions extending from an underside of the perimeter portion. Adjacent pairs of the plurality of protrusions can define the secondary fluid apertures. A tip portion of the protrusions can extend radially beyond the perimeter portion. The tip portion can have a smoothly contoured curved face. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     There are presently shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
     FIG. 1 is a perspective view of a drain safety cover according to the invention. 
     FIG. 2 is a top view of the cover of FIG.  1 . 
     FIG. 3 is an enlarged cross-sectional view of the cover of FIG. 1, taken along the line  3 — 3  in FIG.  2 . 
     FIG. 4 is a perspective view of a base of FIG.  1 . 
     FIG. 5 is a bottom view of the cover of FIG.  1 . 
     FIG. 6 is an enlarged cross-sectional view of a portion of a protrusion attached to the base of FIG. 2, taken along line  6 — 6  in FIG.  2 . 
     FIG. 7 shows the cover of FIG. 1 positioned over a drain. 
     FIG. 8 is a cross-sectional view of the cover of FIG. 1 attached to a drain. 
     FIG. 9 is a cross-sectional view of the cover of FIG. 1 positioned over a drain, illustrating how fluid can flow through the cover prior to entering the drain. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a drain safety cover  10  according to the present invention. The cover  10  can be positioned over a pool drain to prevent bathers from being trapped by the suction of the drain. The cover  10  includes a grating  12 . The cover  10  can also include a base  14  for receiving the grating  12 . 
     The grating can have a top portion  18  and a side portion  20 . As shown in FIG. 2, the top portion  18  can have at least one upper layer of spaced ribs  24  and at least one lower layer of spaced ribs  26 . The ribs within the upper layer  24  and lower layer  26  can extend partially or completely across the top portion  18 . The upper layer  24  and the lower layer  26  are preferably adjacent to each other, as shown in FIG.  3 . The upper layer  24  and the lower layer  26  define a clearance space  22  through which fluid can pass. 
     As shown in FIG. 3, the ribs in the upper layer  24  are preferably substantially parallel to each other. The ribs in the lower layer  26  are also preferably substantially parallel to each other. In addition, the ribs in the upper layer  24  are preferably substantially perpendicular to the ribs in the lower layer  26 . It should be understood that the invention is not limited to these particular orientations, however, as any suitable angles of orientation are acceptable. 
     Referring again to FIG. 1, the side portion  20  of the grating  12  can include at least one upper layer of one or more ribs  28 , and at least one lower layer of one or more ribs  29 . The upper layer  28  and the lower layer of  29  can be adjacent to each other, and the upper layer  28  and the lower layer  29  can each have clearance space  22  through which fluid can pass. The ribs in the upper and lower layers  28 ,  29  of the side portion  20  can extend partially or completely across the side portion  20 . The ribs in the upper and lower layers  28 ,  29  of the side portion  20  can be oriented in the same manner as the ribs in the upper and lower layers  24 ,  26  of the top portion  18 . Thus, the ribs in the upper layer  28  can be substantially parallel to each other, the ribs in the lower layer  29  can be preferably substantially parallel to each other, and the ribs in the upper layer  28  can be substantially perpendicular to the ribs in the lower layer  29 . It is understood that the invention is not limited to these parallel and perpendicular orientations, however, as any other suitable angles of orientation are also acceptable. 
     Positioning the upper and lower layers of the top portion  18  and/or the upper and lower layers of the side portion  20  in the orientations described above has been found to provide distinct advantages over the prior art. Specifically, hair which is placed in the vicinity of the grating  12  can be substantially or entirely prevented from entering the clearance space  22 . Consequently, such a design can prevent hair entanglements and thereby protect individuals from being trapped by the suction of a drain covered by the cover  10 . Notably, however, a cover  10  in accordance with the inventive arrangements will not significantly interfere with the flow of fluid through the cover  10 . 
     In one arrangement, the ribs in the upper and lower layers  24 ,  26  of the top portion  18  and the ribs in the upper and lower layers  28 ,  29  of the side portion  20  can be spaced approximately one-sixteenth inch apart, approximately one-eighth inch apart, or between approximately one-eighth inch and approximately one-sixteenth inch apart. It should be noted, however, that the invention is not limited to these particular dimensions, as other suitable dimensions are also acceptable. 
     In addition, the top portion  18  of the grating  12  can have a plate  30 . In one arrangement, the plate  30  can be a section of the top portion  18 , and can be substantially centrally located on the top portion  18 . Further, the plate  30  can have a perimeter that is less than the perimeter of the top portion  18  so as not to substantially interfere with the flow of fluid through the grating  12 . Including a plate  30  with the grating  12  can provide extra support to the grating  12 , as the plate  30  can provide a solid surface over a portion of the grating  12 . 
     In another arrangement, any layer of the grating  12  can include one or more ribs  31  having a thickness greater than the remaining ribs, where the greater thickness reduces the spacing between the ribs within the layer. Including one or more thicker ribs  31  in one or more of the layers of the grating  12  can provide extra support to the cover  10 , and can help the cover  10  absorb collisions or impacts. Although FIG. 1 shows the grating  12  as having two thicker ribs  31 , it should be noted that the invention is not limited to this particular arrangement. 
     As previously indicated, the invention can also include a base  14 . FIG. 4 shows an example of a suitable base  14 . Although FIG. 4 shows the base  14  as having a circular shape, the invention is not so limited, as the base  14  can be any other suitable shape capable of receiving the grating  12  and covering a drain. The base  14  can have a perimeter portion such as a ring  32 , which can enlarge the size of the cover  10  and possibly further reduce the risk of entrapment or injury. The ring  32  can define a primary fluid aperture  34  through which fluid can flow from the grating  12  to a drain. 
     The base  14  can have one or more support members  36  extending partially or completely across the primary fluid aperture  34  upon which the grating  12  can be seated. Alternatively, one or more projections (not shown) placed along an inner perimeter  38  of the primary fluid aperture  34  can be used to support the grating  12 . 
     For purposes of holding the grating  12  in place, the perimeter of the side portion  20  of the grating  12  can be substantially equivalent to the inner perimeter  38  of the primary fluid aperture  34  of the base  14 . Such an arrangement can provide a snug fit between the grating  12  and the base  14 . The invention, however, is not limited to this particular arrangement, as any other suitable structure or process can be used to secure the grating  12  to the base  14 . For example, the grating  12  and the base  14  can be constructed as one component in which the grating  12  can be secured to the base  14  during the manufacturing process. 
     Referring to FIG. 5, the base  14  can have one or more protrusions  40  which can be arranged radially about the underside of a perimeter portion such as a ring  32 . The protrusions  40  can define a plurality of radially spaced secondary fluid apertures  41  beneath the ring  32  for ensuring an unimpeded fluid flow path in the event that an obstruction is placed over the grating  12 . In one arrangement, most of the protrusions  40  do not extend beyond the inner perimeter  38  of the primary fluid aperture  34  of the base  14  so as not to interfere with the fluid flowing through the grating  12 . One or more of the protrusions  40 , however, can be extended across the primary fluid aperture  34 , for example to form the support members  36  for supporting the grating  12 . 
     The ends of one or more of the protrusions  40  can be rounded or tapered. The invention, however, is not so limited, as the protrusions  40  can be any suitable shape. FIG. 6 shows a suitable protrusion  40 , in which a top surface  42  of the protrusion  40  can be tapered such that the top surface  42  slopes substantially downwards towards an end  44  of the protrusion  40 . In addition, the top surface  42  and the end  44  can be rounded. The upper layers  26  of the grating  12  can be positioned above, below, or at the same level as the uppermost surface of the ring  32 . In one arrangement (not shown), a section of the side portion  20  of the grating  12  can extend below the underside of the ring  32  SO that fluid flowing through secondary fluid apertures  41  can also pass through the side portion  20 . 
     FIG. 7 shows the cover  10  attached to a drain  16 . The cover  10  may be attached to a drain  16  in any suitable manner. For example, a portion of the cover  10  may be mounted to the drain  16  with any suitable mechanical or chemical fastening structure, such as screws, bolts, nails, or adhesive. To receive such a suitable fastening structure, one or more holes  46  can be provided in the ring  32  of the base  14 , as shown in FIG.  4 . Although FIG. 4 shows the base  14  as containing eight holes  46 , the invention is not limited to this particular embodiment, as the base can contain any suitable number of holes  46 . As shown in FIG. 5, the holes  46  can be positioned on the base  14  such that the holes  46  pass through one or more protrusions  40 . Such an arrangement can provide extra support to the base  14 , as a greater portion of the base  14  can be engaged by the suitable fastening structure inserted into the holes  46 . Notably, however, the invention is not limited in this regard, as the holes  46  can be located at any other suitable location on the base  14 . FIG. 8 shows one or more fasteners  48  being inserted into the holes  46  to secure the cover  10  to the drain  16 . 
     FIG. 9 shows the path of fluid through the grating  12  and the base  14 . Fluid can enter the top portion  18  of the grating and can pass through the upper layers  26  of the grating (not shown) before entering the drain  16 . Further, fluid can enter and pass through the side portion  20  of the grating  12  before entering the drain  16 . Fluid can also pass through the secondary fluid apertures  41  formed by the protrusions  40  and, if so desired, can pass through a section of the side portion  20  before the fluid enters the drain  16 . The arrangement illustrated in FIG. 9 can prevent a bather from being trapped by the low pressure area created by the drain  16 , yet does not significantly interfere with the flow of fluid through the grating  12  and the base  14 . 
     It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be obvious to persons skilled in the art, and that such modifications or changes are to be included within the spirit and purview of this application. Moreover, the invention can take other specific forms without departing from the spirit or essential attributes thereof.