Abstract:
A main drain safety grate apparatus utilizes an elongate drain, frame and grate that distribute the suction flow of water over a large surface to avoid full blockage of the grate, and also utilizes a bendable or deformable, upwardly releasable grate that has a section slotted to permit water to drain therethrough. The grate is ordinarily restrained from upward movement by a slot in each end of the frame into which the ends of the grate fit, and from downward movement by two shelves on which the grate may be supported. The grate may be released from the frame by an upward force applied at the section provided for drainage, which bends, or bows, the grate in an arcuate shape, and acts to shorten the length of the grate relative to the slots into which it is fitted. The bowing effect also serves to rotate a rounded surface and a corner of the end of the grate so as to reduce the effective length by rotating the corner away from the point of contact of the slot and the grate, and permitting that contact point to move over the rounded surface.

Description:
This application is a continuation-in-part of the present applicant&#39;s co-pending provisional application Serial No. 60/049,772, filed Jun. 16, 1997, and claims priority therefrom. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a device to prevent injuries and deaths associated with the main drain of a swimming pool or spa. Pools and spas use a pump to permit the water to circulate both within the spa or pool, through conditioning or heating apparatus and the like, and back to the spa or pool. The point or points from which the pump draws water from the structure, often known as the main drain, can be very dangerous to persons within the structure because of the risks associated with the possibility that a person, or a part of their body might cover, or blind off, that main drain. By covering all or part of that drain, greatly increased suction may result at that point, acting to trap the person. If the person&#39;s face is below water at that time, they may drown. Another risk is that of a person (often a child) placing their buttocks over, and covering, the drain. This occurs most frequently on drains where the grate is missing, but may also occur on flat drain covers that can be so covered and collapse with the increased suction. In this case, the greatly increased suction can act to eviscerate the person through their anus, permanently injuring them. Another risk is of a person&#39;s hair becoming entangled in a grate, trapping the person next to the drain, resulting in drowning. 
     Conventional drain systems have used “anti-vortex” covers, which lack holes at the top, preventing or discouraging a person from covering that hole, and which reduce flow rates (to perhaps less than 6 ft./sec.) to reduce turbulence. Covering the drain with a grate, often having ½ inch openings, have also been used. 
     Other conventional drain systems have used dual or multiple main drains, separated by sufficient distance to prevent both from being covered, ideally reducing the pressure should one become covered, or a plumbing design that prevents any single drain becoming connected exclusively to a suction pump. Further ways include gravity-fed collector sumps, and vent stacks, which attempt to limit total suction to about 8 ft.-H 2 O. 
     One disadvantage of conventional systems is that they often involve extra components, adding complexity and cost to the system. Another disadvantage is that the grates or other covers may fail, permitting a person to cover that drain, and become entrapped, or disemboweled. Another is that even grates designed to be anti-vortex may still permit hair entanglement in the drain cover support attachment points or in the cover openings themselves. Further, it is not clear that multiple drains per pump provide sufficient protection because of the potential for dynamic hydraulic imbalance, which may still permit a large increase in suction at the drain. 
     Previous drains and suction entrapment devices for pools or spas disclosed in patents include the following: 
     U.S. Pat. No. 5,734,999 discloses a floor drain grate that including two or three separate regions through which water can flow into the drain. The regions are spaced-apart, preferably one to two feet, to effectively prevent a swimmer from covering all openings simultaneously, preventing suction entrapment. One or more elongate channel portions are used to create a flow passage structure to space apart the inflow regions, and a central portion overlies the drain, and provides a further inflow region. The floor drain grate, including the channel portions, is disclosed as overlying the pool floor. The central portion is disclosed as being securely attached to the drain, using screws, and the channel portions are disclosed as being integrally formed with the central portion, or as being attached thereto using screws or adhesives. 
     U.S. Pat. No. 3,940,807 discloses an outlet drain for a spa including channels extending radially substantially in all directions from the central drain aperture through which water can enter the drain. The channels extend approximately two feet, from the ends of opposing channels, to effectively prevent a swimmer from covering all of the channels simultaneously, preventing suction entrapment. It also discloses an anti-vortex plate covering the drain sump. The drain is disclosed as being able to be integrally molded with or bonded to the bottom of the pool, or to replace the existing drain in a pool or spa. The vortex plate is disclosed as being held in position by screws, and the retrofittable drain is held in place by spring clips that apply a downward force to provide a secure fit and to prevent unintended removal. 
     U.S. Pat. No. 4,658,449 discloses an adapter for pool drains that uses an upper ring raised from the surface of the pool floor, and arms radiating downward therefrom to a lower ring, or perimeter frame, that rests on the floor of the pool, to define a raised screening surface above the pool drain. The larger surface area provides a greater area for suction to reduce the suction at any given point. The adapter is also disclosed to use either a heavy metallic mesh or plurality of metallic arms among the radiating arms and the top of the upper ring to reduce the whirlpool effect. The perimeter frame is disclosed as having mounting arms that run across it, intersecting the pool drain, to permit the adapter to be bolted or screwed to the drain. 
     U.S. Pat. No. 4,121,307 discloses a pool having an open gutter around its perimeter, including therein a suction pipe providing positive withdrawal of water in the gutter. The bottom of the pool is shown to have a main drain utilizing an elongated grate. The grate is not described as being removable. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention provides a single device that eliminates the three basic hazards associated with swimming pool main drains: suction entrapment, disembowelment and hair entrapment. It does so by preventing the great increases in pressure associated with a suction inlet being covered by a person&#39;s body, thus preventing a person&#39;s limb or body from being entrapped, or the person from being disemboweled. It also provides a “breakaway” grate that allows a person whose hair is entrapped to rise to the surface safely, but does not ordinarily permit the removal of the protective grate without tools. 
     To accomplish the first object, the entire main drain system is configured into a long narrow device which, by its shape, precludes it from being covered by a swimmer&#39;s body, because a person&#39;s body simply can not conform to blind off this grate. By using this long, or elongate, shape, even should a person press up against the drain, some part of the grate will be left uncovered, permitting the water to continue to enter the drain and preventing the sharp pressure increase associated with the stopping of water flow. It also avoids concern regarding potential suction increases resulting from hydraulic imbalance because water flow continues at that drain and need not shift elsewhere. Thus by being unable to be closed off by a body, the mere design thereby precludes the suction entrapment of a bather due to increased pump suction. 
     The second object is met by using a “breakaway”, deformably releasable, grate. This grate serves as an effective means of eliminating the hazard of hair entrapment (usually young girls with long hair playing in the spa). Should hair become entrapped in the grate, an upward pull on the hair, as by a person seeking to escape, will cause the grate to bow and thus release from its slots in the frame (about a 7 pound pull at the outer ends), allowing the bather to safely return to the surface where the entanglement can easily be removed. Further, due to the length of the slotted design grate (and the increase in flow area), the water velocity through the grate is significantly reduced so that the usual turbulence associated with hair entanglement is significantly reduced. 
     In a preferred embodiment, the drain comprises three parts: the sump, the frame and the grate. The sump serves as the forming shell to provide a water tight water gathering void for the water being drained from the pool at this location. It serves to hold the concrete from occupying this area when pouring or guniting a pool. In other forms of pool construction it serves to prevent either the dirt, sand, or other construction materials from occupying this area. The sump has a suction pipe connection at either end thus facilitating dual suction lines from the single unit. 
     The frame fits snugly into the sump around the edges and serves to provide a means of leveling the top of the drain with the finished pool floor. It will slide within the sump to provide this leveling effect. It is generally held in place by the plaster coat in concrete/gunite type pools, and can be held in place in other types of construction with either a flange attached to the liner or fiberglass for these types of construction. The frame also has a slot at either end to receive the grate. 
     The grate serves as a slotted cover for the sump, thus preventing entry of hands and feet, and providing a smooth surface for the floor of the pool in this area. The grate is elongate, being approximately six times as long as it is wide, and is deformable. This elongated shape assists the grate to deform by bowing along its longitudinal axis, which it will do when sufficient force is applied in an upward direction. When deformed in this manner, the length of the grate in the plane between the two slots in the frame will decrease, and at least one end of the grate will release from the corresponding slot in the frame that retains it in position. The ends of the grate are tapered to assist in the grate&#39;s release from the frame. This grate is thus deformably releasable. The slots in the grate are of the size to preclude the ability of fingers to fit therein thus to remove the grate will require some type of “tool”. They are also sized to allow the designed quantity of water flow to enter the sump. 
     Further advantages and applications will become apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings referenced therein, the invention not being limited to any particular embodiment. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an exploded view of an exemplary safety grate apparatus constructed in accordance with the present invention. 
     FIG. 2 depicts section A—A of FIG. 1, as the assembled device would be installed in the floor of a pool or spa. 
     FIGS.  3 A-B depict an exemplary grate of the present invention in plan and elevation views. 
     FIGS. 3C and 3D is a detailed view of section B—B of FIG.  3 A. 
     FIG. 3D is a partial, detailed, plan view of the present invention. 
     FIGS.  4 A-C depict an exemplary frame of the present invention in plan, elevation and side views. 
     FIG. 4D depicts section C—C of FIG.  4 A. 
     FIG. 4E depicts section D—D of FIG.  4 A. 
     FIG. 4F depicts section F—F of FIG.  4 A. 
     FIG. 4G depicts an alternate embodiment of one end of the present invention as it would appear in section A—A of FIG. 1, as the assembled device would be installed in the floor of a pool or spa. 
     FIGS.  5 A-C depict an exemplary sump of the present invention in plan, elevation and side views. 
     FIG. 5D depicts section E—E of FIG.  5 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the figures for a more detailed description, FIG. 1 shows an exploded view of safety grate apparatus  1 . Grate  2  is shown in a bowed state as it would be when releasing from frame  15 . In the embodiment in FIGS. 1 and 2, safety grate apparatus  1 , including grate  2 , is constructed of molded ABS, but may be made of any similar material with which the person of ordinary skill is familiar. Grate  2 , in particular, is flexible. The bowing effect on grate  2  results from upward force applied to grate  2  between left and right grate-ends  4   a ,  4   b , and downward forces resisting movement at grate-ends  4   a ,  4   b , because grate  2  is engaged with frame  15  by grate-ends  4   a ,  4   b . Turning to FIGS. 4D and 4E, frame  15  (shown generally in FIG. 4A) engages grate-ends  4   a ,  4   b  of grate  2  of FIG. 3B in left and right slots  18   a ,  18   b  visible in FIGS. 4D and 4F and acts to oppose the downward motion at left and right slot tops  49   a ,  49   b  visible in FIGS. 4D and 4F. Turning to FIGS. 3C and 3D the downward force acts on left and right tapers  14   a ,  14   b  and specifically on one or both of left angle section  28   a  or left convex tab  29   a , and on right angle section  28   b  or right convex tab  29   b . As grate  2  bows, convex tabs  29   a ,  29   b  rotate downward about transverse axis  7  (seen in FIG. 3A) moving the flat side of convex tabs  29   a ,  29   b  that are part of lower surface  9  away from left and right slots  18   a ,  18   b  reducing the length of grate  2  and assisting in its release from frame  15  (all shown in FIG.  4 A). 
     Returning to FIG. 1, Edges  11  of grate  2  (detail shown in FIG. 3C) rest upon shelves  17  (detail shown in FIG. 4D) when not bowing upwardly. Liquid channel  21  (detail shown in FIG. 4B) fits snugly within cavity  31  of sump  30 . Details of the fitting surfaces, end surfaces  32 , and side surfaces  33  of cavity  31 , are shown in FIGS. 5A and 5D. Ledge  36  is cut from outlet assembly  38  to permit insertion of frame  15  of FIG. 4C into sump  30  up to its maximum proper depth. 
     Referring now to FIG. 2, it shows safety grate apparatus  1  as installed in pool floor  5 . Sump  30  and frame  15  are embedded within pool structure  6 . Grate  2 , is in the present invention, removable as shown above in FIG. 1, but here is shown in place. Sump  30  is emplaced at a level below pool floor  5 , with step  43 , flange  45 , and suction pipe connections  41  retaining it in position. Outlet assemblies  38  serve to connect sump  30  to piping system (not shown) to remove water from safety grate apparatus  1 . Lower section  23  of liquid channel  21  of frame  15  is inserted within cavity  31  of sump  30 . Because lower section  23  may translate vertically within cavity  31  of sump  30  prior to completion of pool structure  6 , frame face  16  may be adjusted during construction to be level with pool floor  5 . Once frame  15  and sump  30  are in place and pool floor  5  has been finished, grate  2  may be inserted by bowing it slightly (shown in FIG. 1) so that taper  14   b  of right grate-end  4   b  may be inserted into right slot  18   b ,and similarly for the left end. For insertion, right taper  14   b  may be inserted into corresponding slot,  18   b , while grate  2  is at a slight angle to frame  15 . A relatively small force is applied to the other grate end,  4   a , and at that same location, a torque applied tending to bend draining section  3  upward. Grate  2  will bow enough so that taper  14   a  opposite taper  14   b  injected into slot  18   b  will be able to snap into its corresponding slot,  18   a . This process may be reversed to insert grate  2  into slot  18   a  first. 
     In operation, a conventional pump (not shown) applies suction through conventional pipes (not shown) connected to suction pipe connections  41  (also shown in FIG.  5 B). This in turn draws water through drain slots  12  of grate  2  through liquid channel  21  of frame  15  and into cavity  31  of sump  30 . From there it is drawn through outlet assemblies  38  to the conventional piping system (not shown). 
     Referring now to FIG. 3A, grate  2  includes draining section  3 , having drain slots  12  created by the spaces between slot struts  10 . Grate  2  also has left and right grate-ends  4   a ,  4   b  which have left and right tapers  14   a ,  14   b , (shown in FIGS.  3 C and  3 D). Continuing in FIG. 3C, upper surface  8  of grate  2  is substantially level, with right grate-end  4   b  and right taper  14   b  being narrower. Left grate-end  4   a  is similar. Returning to FIG. 3A, transverse axis  7  runs parallel to both grate-ends  4   a ,  4   b  and tapers  14   a ,  14   b . In FIGS. 3C and 3D edges  11  of the long sides of grate  2  extend downwardly and form part of lower surface  9 . The upper part of edges  11  are rounded, as is the transition into right taper  14   b , and corners  13  (shown in FIG.  3 A). In the embodiment in FIG. 3C, drain slot width  59  is 0.2 in., strut height  57  is 0.35 in, strut width  85  is 0.5 in. and grate thickness  56  is 0.26 in., which is less than overall grate height  55  because of the downward extension of edges  11 . Also best seen in FIGS. 3C and 3D are right angle section  28   b  and right convex tab  29   b . The flat underside of convex tab  29   b  also forms part of lower surface  9 . Left taper  14   a  has similar features labeled  28   a  and  29   a  respectively. Also shown are upper taper height  53 , 0.25 in., and lower taper height  54 , 0.15 in. In FIG. 3B, grate height  55  is 0.5 in., and grate length  50  is 29.9 in., and in FIG. 3A, grate width  51  is 4.76 in., while drain slot length  58  is 3.1 in. Draining section length  84  is 24.0 in. 
     Note that as in shown in FIG. 3A, grate  2  is elongate, grate length  50  being approximately 6 times grate width  51 . Notable also is that drain slots  12  run parallel to transverse axis  7 , normal to grate  2 &#39;s long axis, thus assisting in easy bending or deformation about axes substantially parallel to transverse axis  7 . This deformation permits the distance between grate-ends  4   a ,  4   b , and tapers  14   a ,  14   b , to decrease, freeing them (or at least one) from slots  18   a ,  18   b  of frame  15 , the bowing effect being shown in FIG.  1 . 
     Referring now to FIGS.  4 A-E, depicting frame  15 , which is also made of molded ABS, in FIG. 4A, frame  15  includes frame face  16 , shelves  17 , which are placed below the level of frame face  16  (best shown in FIG.  4 D), flange  19  and flange corners  20 . Referring to FIG. 4B, flange  19  and flange transition  25 , which is rounded, are shown. Liquid channel  21  is visible, including lower section  23 . Better visible in FIG. 4D are upper section  22  of liquid channel  21  and flange transition  25 . Outer surface  26  of liquid channel  21 , visible in FIGS. 4B,  4 C, and  4 D interfaces with end surfaces  32  and side surfaces  33  of cavity  31  of sump  30  (all visible in FIG.  5 A), to retain frame  15  in FIG. 4B within sump  30 , while permitting translation up and down. Referring to FIG. 4D, liquid channel  21  includes upper section  22 , which includes shelves  17 , and shelf transitions  24 . Shelf transitions  24  are rounded as are flange transitions  25 , and corners  27  (better seen in FIG.  4 A). In addition, the safety grate apparatus can have a frame comprising at least two vertically-oriented liquid channels, with the safety grate apparatus comprising a sump substantially enclosing the lower section of the liquid channels, and the apparatus at least two grates, where each liquid channel comprises upper and lower sections, the upper sections adjacent to the draining sections so as permit draining from the draining section through the liquid channels. Remaining with FIG. 4D, slot  18   b  is shown and has a width substantially the same as channel width  63 , but at least greater than grate width  51  (shown in FIG.  3 A), and has slot top  49   b . Channel width  63  (also shown in FIG. 4A) is 4.95 in. adjacent to slots  18 , but narrows to approximately 4.76 in. nearer to the center of frame  15 . Inner channel width  64  (also shown in FIG. 4A) is similarly 3.65 in., narrowing to about 3.35 in. Continuing with FIG. 4D, inner channel width  64  is less than channel width  63 , the result of placement of shelves  17  of upper section  22  of liquid channel  21  to support edges  11  of grate  2  (as shown in FIG.  2 ). Shelf transition height  66 , (shown also in FIG. 4E) 0.55 in., is substantially the same as slot height, but is at least greater than upper taper height  53  (shown in FIG.  3 C). In FIG. 4D, flange  19  has thickness  67 , 0.15 in., and transition height  65 , 0.35 in. FIG. 4B shows frame length  60 , 33.48 in., and FIG. 4A channel length  62 , 29.48 in. and frame width  61  7.0 in. FIG. 4C shows frame height  69 , 2.0 in. Wall thickness  68 , 0.1 in. of liquid channel  21  is shown in FIG.  4 E. Wall thickness  68  is less proximate to right slot  18   b  (and similarly left slot  18   a ) than it is along the length of liquid channel  21 . Slot height  87 , 0.35 in., best seen in FIGS. 4D and 4E, is sufficient to permit entry of at least right convex tab  29   b  into right slot  18   b  (and similarly for the left side shown in FIG.  4 F). Wall thicknesses  68  (in FIG.  4 E), when added to inner channel width  64 , and channel length  62  (in FIG.  4 A)—that is the outer dimensions of liquid channel  21  (in FIGS.  4 B and  4 C)—correspond approximately to the dimensions of cavity  31  of sump  30 , cavity length  70  and cavity width  71  (shown in FIG. 5A) to provide a snug fit between them. In one embodiment, two retainers, left and right slots  18   a ,  18   b , are constructed by cutting or routing out the ABS material from the ends corresponding to channel width  63  and slot height  87 , at each end of frame  15 . However, another retainer serving the same functions as slots  18   a ,  18   b  may be substituted therefor for one of the two of left and right slots  18   a ,  18   b , including structures so formed to retain grate-ends  4   a ,  4   b  (shown in FIG. 3A) from upward movement and movement away from the opposite retainer, and to permit rotation of grate-ends  4   a ,  4   b  about transverse axis  7 . One alternate embodiment is shown in FIG. 4G, in which a section view of an alternate right grate-end  4   b  has bead  88  which is retained by semi-circular retainer  89 . 
     Moving to FIGS.  5 A-D, depicting sump  30 , which is also made of molded ABS, in FIG. 5A, sump  30  has cavity  31  extending downwardly into sump  30 . Cavity  31  is formed of end surfaces  32  and sides surfaces  33 , which are at substantially right angles to one another, and bottom section  34 , which is semi-circular in section (best shown in FIGS.  5 C and  5 D). As best shown in FIG. 2, cavity  31  is the watertight enclosure from which a conventional piping system (not shown) draws water through grate  2  and liquid channel  21  and thence through outlet assemblies  38 . Moving to FIG. 5D, step  43  and step transition  44  surround and are below sump face  35  (also shown in FIG.  5 B). Similarly flange  45  and flange transition  46  also surround and are below step  43 . In FIG. 5A, transitions  44  and  46  have rounded corners  48  and flange  45  has corners  47 . Best shown in FIGS. 5A and 5D outlet assembly  38  pierces end surfaces  32  to permit water to be drained into a conventional piping system (not shown). Best shown in FIG. 2, outlet assembly  38  includes ring  37  affixed to end surface  32 , sealed thereto using sealant  42  (shown in FIG.  5 D). Moving outwardly there are inner threads  39  and passing through end surface  32 , there is suction pipe connection  41 , having outer threads  40 . Suction pipe connection  41 , where it penetrates end surface  32  on the outer portion of sump  30 , is also sealed using sealant  42 . Returning to FIG. 5D, ledge  36  is cut from ring  37  to a depth  72  of 1.55 in. Ledge depth  72  permits frame  15  to be inserted fully into cavity  30  (shown in FIG.  2 ). Maximum insertion of frame  15  into cavity  30  occurs when the underside of shelves  17  contact sump face  35 . At maximum insertion liquid channel  21  does not extend far enough into cavity  31  to block outlet assemblies  38 . 
     In FIG. 5A, cavity  30  has cavity length  70  of 29.8 in., and cavity width  71  of 3.85 in., narrowing to about 3.5 in. near the center. End sump face width  83  is 0.9 in, and the side sump face width  86  is 1.0 in. In FIG. 5D, cavity wall thickness  79  is 0.15 in. and overall sump depth  73  is 4.7 in. Sump  30  has step height  74 , 0.35 in., (FIG.  5 C) step width  75  (FIG.  5 D), 0.4 in., and flange height  76 , 0.5 in. (FIG.  5 C). Shown in FIG. 5D are flange thickness  78 , 0.15 in., and flange width  77 , 0.2 in., increasing to 0.3 in. near the center of the length of sump  30 . 
     Referring to FIG. 5D suction pipe connection inner diameter  81  is 1.9 in.; moving to FIG. 5D, its depth is  82  is 2.8 in., and in FIG. 5B, its length  80  is 1.3 in. In this embodiment outlet assemblies  38  are not integrally molded, but are prefabricated and inserted into holes penetrated through end surfaces  32 , and sealed using sealant  42  (best shown in FIG.  2 ). Details of inner threads  39  and outer threads  40  are well known to the art and are the choice of the user to correspond to conventional piping (not shown). 
     In operation, if a bather were to get their hair, or a finger, or other part of the body caught in the grate of the present invention, the bather could release themselves from pool floor  5  to return to the surface in the following manner. Referring to FIG. 2, by pulling upwardly on the caught body part or hair, the bather will apply a force on draining section  3 . While sufficient upward force applied at a position other than draining section  3  will also result in release, it is expected that any such force will be applied at draining section  3  because it is around slot struts  10  in draining section  3  that any body part of hair might get caught. This upward force will bow grate  2 , thereby shortening the distance therebetween sufficiently to permit release of one of the left or right grate-ends  4   a ,  4   b , from slots  18   a ,  18   b  which are a fixed distance apart. Once one of grate-ends  4   a ,  4   b  is free, the other may be removed simply by moving grate  2  away from the remaining slot. Focusing on left and right tapers  14   a  and  14   b , and referring to FIGS. 3C and 3D, the bowing effect also acts to rotate both of convex tabs  29   a ,  29   b  downward, such that their flat undersides, part of lower surface  9 , move away from the top, restraining, surface of slots  18   a ,  18   b . This also effectively shortens grate  2  because the convex surface of convex tabs  29   a ,  29   b  extend less far toward frame  15 .