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TECHNICAL FIELD 
     This invention relates in general to wastewater handling, and in particular, the invention relates to an improved deck drain pipe having features to promote simple and reliable mounting to a planar surface such as a wooden beam. 
     BACKGROUND OF THE INVENTION 
     Prefabricated plastic drain conduit is commonly used for drainage of decking around swimming pools. The typical conduit has a complex, often asymmetrical cross section that requires specialized connectors for attaching standard lengths of conduit together to span the entire length of a particular installation. To reduce the need for specialized connectors, the drain channel can be formed with a circular cross section adapted to couple with standard pipe. 
     When a concrete wall or other vertical surface forms the edge of a pool deck, the drain conduit is often secured to the vertical surface using concrete nails. These nails have to be driven into the concrete with greater force than nails driven into wood, which often results in cracking of the conduit, or deformation or misalignment of the conduit. Excessive deformation can lead to premature loss of the conduit&#39;s structural integrity and reduces draining capacity. Misaligned conduit forms a tripping hazard, prevents complete drainage, and is unsightly. 
     A need remained for a deck drain conduit that can be coupled with standard pipe, and has provisions to permit nailing the conduit to a support without unacceptable deformation or misalignment. As always, a deck drain that is reliable and long-lasting and can be made at minimal expense was also desired. 
     SUMMARY OF THE INVENTION 
     In general, a deck drain having the desired features and advantages is achieved by a main channel having a circular cross section, a top section having a top face designed to mount flush with the decking surface, and a mid section interconnecting the top section and the main channel. Nail guiding means attach to the mid section for accepting and directing a nail, preferably a concrete nail, through the mid section to secure the conduit to a support. Preferably, the nail guiding means comprises a pair of parallel planar projections extending away from the mid section, with each projection terminating at the end distal to the mid section in a flange to strengthen the projection and provide a surface for the nail head to press against. 
     A base plate extends out tangentially from the bottom of the main channel, allowing the conduit to stand unaided on a leveled surface. In addition, for each side of the conduit, the end of the base plate, the flanges on the nail guide projections, and a vertical wall of the top section are all aligned along a vertical axis to permit the conduit to be stably secured against a vertical surface without rocking. The base plate additionally acts as an anchor plate in installations where concrete is poured into the space on one or both sides of the conduit. 
     The main channel, mid section and top section are arranged along a major axis transverse to and intersecting with the main channel centerline. The advantages already discussed can be achieved with an asymmetrical conduit, i.e. one having the nail guiding means and the base plate located on only one side of the cross-sectional profile of the conduit. However, a symmetrical cross-sectional profile is preferred. 
     Additional features and advantages of the invention will become apparent in the following detailed description and in the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a section of deck drain according to the invention. 
     FIG. 2 is an end-on cross-sectional elevation thereof, as seen along line  2 — 2  in FIG.  1 . 
     FIG. 3 is an end-on elevation illustrating the use of the nail guiding means. 
     FIG. 4 is a cross-sectional elevation of the deck drain of the invention in a typical installation. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The deck drain  11  of the invention is an elongated conduit  13  as seen in FIG. 1, having a cross-sectional profile (FIG. 2) that defines three connected sections: a main channel  15 , a mid section  17  and a top section  19 . The deck drain  11  is preferably fabricated from extrusion molded polyvinyl chloride or polyethylene, but other materials can be used, including fiberglass and aluminum. The main channel  15 , the mid section  17 , and the top section  19  are aligned along a major axis  21  running transverse with and intersecting the main channel centerline  23 . The cross sectional profile of the conduit  13  does not need to be symmetrical about the major axis  21 , but symmetry is preferred and shown. It should be understood that discussion of the elements on one side of the major axis  21  will apply to corresponding elements on the other side of the major axis  21  as well. 
     The main channel  15  is circular in shape, with an opening  25  at the top to allow water to enter from the mid section  17 . The main channel&#39;s inside diameter is sized to accept and couple snugly with a piece of one-and-one-half inch Schedule  40  nominal size pipe, and can be varied to fit other pipe sizes. The mid section  17  is made up of two parallel sidewalls  27  and  29  connected to and extending vertically from the main channel opening  25 . 
     The top section  19  has a flat top face  31  designed to be set flush with the surface of the pool decking. A number of slot-shaped openings  33  are defined at periodic intervals along the length of the top face  31 . The openings are sized to allow water to drain into the conduit  13  while preventing debris from getting in and clogging the main channel  15 . Other opening shapes and configurations can be used, such as an array of round or square holes. If desired, the top face can be made removable to permit cleaning the conduit interior. Vertical faces  35  and  37  connect the top face  31  to a reducer  39  that in turn connects to the mid section  17 . Other configurations can be used. 
     The mid section  17  serves two main purposes: it interconnects the top section  19  and the main channel  15 , and it provides a point of attachment for the nail guiding means  41  to be described later. Although the term “nail guiding means” is used, it should be understood that the term applies to screws as well. The length of the mid section can vary, and can be the minimum necessary to attach the nail guiding means. The mid section can even be omitted altogether, and the nail guiding means  41  attached to the top section  19 . The nail guiding means  41  are preferably not attached to the main channel, since the nail holes that will inevitably result during installation can provide a path for leakage to the surrounding environment if the nail holes are below the water surface during draining. 
     As shown in FIG. 3, the nail guiding means  41  will retain a nail  42  driven into the conduit  13  in the direction of the arrow  44  in the proper vertical orientation for attachment to a support, and will provide additional structural strength to minimize deformation, misalignment, and cracking of the conduit  13 . Preferably, the nail guiding means  41  comprise a pair of parallel projections  43  and  45  extending away from the walls of the mid section  17 . Each projection  43  and  45  terminates in a small flange  47  and  49  that serves to strengthen the end of the respective projection  43  and  45  and provide a resting surface for the head of a nail. The projections  43  and  45  are preferably of sufficient length and spaced sufficiently close together to ensure that a nail passing through the projections  43  and  45  on one side of the conduit  13  will pass between the corresponding projections on the opposite side of the conduit  13 . 
     The nail guiding means can have other configurations. For example, tubular projections can be formed in the conduit at regular intervals, rather than the parallel planar projections shown. This configuration has the advantages that substantially less plastic is needed to make the nail guiding means, and that tubular guides will orient the nail properly in both the vertical and horizontal planes, rather than just in the vertical plane as with the preferred embodiment. However, tubular projections cannot be fabricated using normal extrusion molding techniques, and the resulting projections would be prone to breaking off during handling and installation, even with reinforcement. 
     A base plate  51  is tangentially attached to the bottom of the circular main channel  15  and permits the conduit  13  to be set upright on a leveled surface. This provides a convenient means for holding the conduit  13  in place prior to driving nails or screws through the nail guiding means  41 . Preferably, the end  53  of the base plate  51 , the projection flanges  47  and  49 , and the top channel&#39;s vertical wall  35  or  37  are all aligned along a vertical axis  55 , so that the conduit  13  will contact a vertical support face without wobbling, as shown in FIG.  4 . If desired, the outer surface  57  of the main channel  13  can also align along the vertical axis  55 . All the elements just listed need not be aligned along the vertical axis  55 , but the top section vertical wall  35  or  37  will always be one of the aligned elements, since the top face  31  must abut the vertical support face in order to prevent water from draining around the conduit  13  into the surrounding environment. FIG. 4 illustrates a typical installation for the deck drain  11  of the invention, where the conduit  13  is secured against a cement block  59  with nails  42  and a concrete deck  61  is then poured in against the exposed side of the conduit  13 . 
     The invention has several advantages over the prior art. The deck drain can be constructed simply and inexpensively using conventional methods. It is extremely rugged and durable. It provides means for the conduit to be secured with nails or screws without the deformation and misalignment of prior designs. 
     The invention has been shown in one embodiment, with alternative embodiments described in the text. It should be apparent to those skilled in the art that the invention is not limited to these embodiments, but is capable of being varied and modified without departing from the scope of the invention as set out in the attached claims.

Summary:
A deck drain is made from extruded plastic with a cross section defining a substantially circular main channel, a mid section, and a top section having a top face with a plurality of openings defined therein. Nail guiding means are attached to the mid section, and direct a nail or screw through the mid section to secure the deck drain to a planar surface. Edges of two or more of the structural elements are aligned vertically to permit the deck drain to contact the planar surface without wobbling when attached.