Abstract:
A cover for a main drain of a swimming pool has a single arcuate cutout portion to pass water into the main drain housing. The cutout portion extends more than halfway around the cover and is dimensioned and rounded to pass large debris and to avoid entrapping fingers, hair and cloths of swimmers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to covers for swimming pool main drains.  
         [0003]     A swimming pool has one or more main drains that remove water continuously from the bottom of the pool. The removed water is filtered of both suspended particulate and sediment to keep it both clear and clean. From time to time, larger debris, such as water-soaked leaves, will descend to the bottom of the pool and may be drawn into the drain through its cover.  
         [0004]     However, main drains, because of the relatively powerful suction required for normal operation pose hazards to swimmers, particularly small children. The suction can trap swimmers and sometimes hold them to the drain, which is commonly located in the deepest part of the pool. At other times, the configuration of the drain, in combination with the suction, will entangle the swimmer&#39;s hair or clothing. Either of these circumstances can be fatal to the swimmer.  
         [0005]     Drain covers are frequently designed with many small openings to avoid the aforementioned problems. However, they will then not be suitable for draining larger debris and may still cause entrapment and entanglement.  
         [0006]     A drain cover needs to have a total opening area sufficient to allow the pool to drain. It has to admit leaves and other larger debris. And it also has to avoid or at least reduce the possibility of the entrapment and entanglement of swimmers.  
       SUMMARY OF THE INVENTION  
       [0007]     Briefly recited and according to its major aspects, the present invention is a main drain cover for a swimming pool. The present inventive cover has a utilitarian shape, which is characterized by a low dome having a single, arcuate cutout portion with rounded edges. The present invention may also include an adaptor ring to fit it to a main drain housing, and may include the housing of the main drain itself. The housing may be a two-port housing or a three-port housing that includes an entrapment relief port in addition to the bottom suction port and hydrostatic relief port.  
         [0008]     The single arcuate cutout portion is an important feature of the present invention. Because of its arcuate shape and size, the cutout portion is relatively more difficult for a swimmer to block than more compact openings. Because of its smoothly rounded edges, free of corners and projections, it is much less likely to entangle the hair or clothing of swimmers. Importantly, larger debris will be more easily drawn in through the single, larger, rounded opening.  
         [0009]     The arcuate cutout portion in combination with an entrapment relief outlet is another feature of the present invention. The cutout portion and the entrapment relief port are preferably oriented to be on the same side of the main drain so that hair or other entrapable material is not held within main drain upon entering cutout portion. Cutout portion itself is curved and rounded so as to minimize the potential for hair to wrap around any structure of the drain.  
         [0010]     An advantage of the present cover is that it can be used with two and three-port main drain housings and with new and existing housings, so it is readily backfitted on various types of main drain housings.  
         [0011]     Other features and their advantages will be apparent to those skilled in the art of swimming pool water circulation system design from a careful reading of the Detailed Description of Preferred Embodiments accompanied by the following drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     In the drawings,  
         [0013]      FIG. 1  is top view of a cover for a main drain of a swimming pool, according to a preferred embodiment of the present invention;  
         [0014]      FIG. 2  is a cross sectional view of a main drain of a swimming pool taken along lines  2 - 2  of  FIG. 1  with a first embodiment of a main drain housing, according to a preferred embodiment of the present invention; and  
         [0015]      FIG. 3  is a cross sectional view of a main drain of a swimming pool having an alternative main drain housing in combination with the same cover as is shown in  FIGS. 1 and 2 , according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0016]     The present invention has three embodiments: it is a device for covering a swimming pool main drain, a main drain with a cover, and a cover and adaptor ring for covering a main drain. While specifically intended for use in swimming pools, the present cover could be used for any drain of a body or tank of water where entrapment, entanglement, or draining of larger debris are of concern.  
         [0017]     Referring now to  FIGS. 1, 2  and  3 , there is illustrated a drain cover according to a preferred embodiment of the present invention, and generally indicated by reference number  10 .  FIGS. 2 and 3  are identical except for an entrapment relief port  50 , the function of which will be described presently. Cover  10  is preferably round, gently domed to allow a robotic cleaner to pass over it easily, and has a single, arcuate aperture or cutout portion  12  formed therein. Cover  10  is fitted to a collar  22 , which is in turn fitted to a main drain housing  16  and both collar  22  and main drain housing  16  are set in a pool floor  20  during construction of the pool. Collar  22  is slip fitted to main drain housing  16  by sliding a depending flange  32  inside of main drain housing  16 . Cover  10  is in turn slip fitted on to collar  22  by sliding depending flange  46  of cover  10  inside upstanding flange  42  of collar  22  and may be held in place by screws  44 .  
         [0018]     Collar  22  has a flange  14  for use in securing collar  22  to pool floor  20 . Cover  10  has a depending flange that fits within an upstanding flange  22  of collar  22 . The material of pool floor covers flange  14  of collar  22  during construction to hold collar  22  in place. Housing  16  has two ports: a suction outlet  24  and a hydrostatic outlet  26 . Suction outlet  24  is connected by piping (not shown) to a canister filter located along side the pool (not shown), and hydrostatic outlet  26  will connect to the area below pool floor  20  so that, in the event water collects below the pool, it can be removed through hydrostatic relief outlet  26 . Alternatively, housing  16  instead of being a two-port housing could be a three-port housing, as shown in  FIG. 3 , in which case, the third port  50 , for entrapment relief will lead to a relief port in the wall of the pool below water level (not shown) to provide entrapment relief in the event cutout portion  12  is blocked. Outlets  24  and  26 , to a canister filter and hydrostatic relief port, are well known in the art. Entrapment relief ports are also known but the orientation of cutout portion to coincide with third port  50  is not known in the prior art. In order to assure proper orientation of cover  10  to housing  16 , some convenient, foolproof key such as an asymmetric cover screw pattern ( FIG. 1 ) can be used.  
         [0019]     Cover  10  is gently domed (best seen in  FIG. 2 ) in part for strength and in part so that robotic cleaners will be able to travel over cover  10  easily, and so that swimmers, stepping on cover  10  will not encounter sharp edges or abrupt changes in pool floor elevation. Cutout portion  12  is shaped and formed to allow sufficient water to pass through it without significant change in velocity and without trapping fingers, toes, hair or clothing. Cutout portion  12  is also large enough so that covering all of cutout portion  12  is difficult for a child, yet cover  10  provides the strength required to easily support an adult standing on cover  10 .  
         [0020]     The total area of cutout portion  12  is preferably at least comparable to the area of suction line  24  in order to have the same flow velocity at cutout portion  12  as at suction line  24 . The arc of cutout portion is preferably somewhat greater than 180° to be as large as possible but still provide a sufficiently solid cover  10  for strength. The width of cutout portion should be about as large as the fingers of an adult so as not to trap the fingers of a child. Cutout portion  12  should also be as close to the periphery of cover  12  as possible consistent with the area, width and arc requirements set forth above so that the distance from one end of cutout portion  12  to the other is as large as it can be. Importantly, the large arcuate shape helps to draw leaves and other large debris into main drain housing  16 .  
         [0021]     All edges of cover  10  adjacent to cutout portion  12  are preferably rounded to assure smooth flow of water into cutout portion  12  and prevent the entanglement of hair and clothing. Furthermore, no surfaces or edges inside cutout portion are of a type that is likely to entangle hair or clothing.  
         [0022]     One or more main drains with housing  16 , collar  22  and cover  10  may be provided as part of the water circulation system of a newly constructed swimming pool.  
         [0023]     It will be readily apparent to those skilled in the art of swimming pool circulation system design that many changes and substitutions can be made to the foregoing preferred embodiments without departing from the spirit and scope of the present invention, defined by the appended claims.