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BACKGROUND AND FIELD 
       [0001]    A method and apparatus for filtering debris; and more particularly relates to a novel and improved method and apparatus for separating fish from debris and allowing water passage for all ranges of liquid flow. 
         [0002]    Rotational drum screens for filtering water and separating debris are known in the prior art. Typical rotating drum screens require frequent maintenance and are difficult to clean as well as being costly. The drum filter typically includes a rotating drum positioned in a filter container. Water flows into and through the container, passing through the filtering screen of the drum. Debris typically lodges on the face of the drum screen filter, requiring a screen cleaning device to prevent complete obstruction of water flow. Currently, drums have been turned using one of three traditional methods; overshot, undershot and gear motor. The overshot drum relies upon the passage of water through the top 45% of the drum face. The lower 55% of the drum face is protected by a shroud that covers this portion of the drum. The lower 55% of the drum face is protected by a shroud that covers this portion of the drum. While this rotation is effective in providing a clean drum, the quantity of flow is severely limited due to the drum surface area that the water can flow through, and the requirement that the water level on the downstream side of the drum must be substantially lower than on the upstream side of the drum. 
         [0003]    The undershot drum utilizes the full face of the drum for water to pass through. The rotation of this drum is accomplished with a paddle wheel on the inside of the drum and a gear train to drive the rotation of the drum member. As the water flows through the drum, the momentum and mass of the water flow drive the rotation of the paddle wheel. The drum rotation is in the opposite direction of the rotation of the paddle wheel. As is common with any mechanical gear driven device, maintenance may be difficult and costly. Where there is insufficient differential head across the drum, the drum will fail to rotate and typically become congested with debris. Low flows and low differential head severely impact the rotation of the drum and operation in a self-cleaning mode. 
         [0004]    Where commercial power is available, or where solar panels and battery storage is provided, it is possible to drive a drum utilizing a gear motor, sprockets and a chain drive mechanism. The drums can be effectively rotated and the flow-through capacity can be high or low, although external electric motors, chains and sprockets provide a degree of liability and maintenance that often is not desirable. 
         [0005]    An important application for rotational drum screens includes the filtration of water in rivers, lakes and streams whereby fish are retained in a designated area while debris is removed and filtered water is allowed to pass through the drum into an outlet. This is especially important to prevent endangered species of fish from passing through into agricultural diversions. The rotating drum is positioned perpendicular to the flow of water and rotation of the screen allows for filtration of the water while preventing fish from passing into an outlet. 
         [0006]    Accordingly, there is a serious need for a self-cleaning rotating drum screen that also effectively acts as a fish deterrent while providing drum rotation irregardless of the flow rate of the water as well as providing a state-of-the-art filtration device that does not require an electric motor to provide for rotation of the drum. 
       SUMMARY 
       [0007]    The embodiments and methods set forth are exemplary and not for purposes of limitation. 
         [0008]    Accordingly, there is disclosed a novel and improved method and apparatus for separating fish from debris and allowing water passage without the need for electric motors and without concern for water flow. 
         [0009]    In accordance with the present embodiments, apparatus is provided for separating fish from debris over all ranges of liquid flow having a drum member rotatably mounted on a frame housing, the drum member having an exterior screen in the path of flow of the water passage, a plurality of circumferentially spaced chamber members secured within an interior of the drum member, and an air pressure system for distributing air throughout the chamber member. 
         [0010]    The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those skilled in the art upon a reading of the Specification and study of the Drawings. In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the Drawings and by study of the following Description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a side view of a form of drum rotation apparatus; 
           [0012]      FIG. 2  is front view of the drum rotation apparatus of  FIG. 1 ; 
           [0013]      FIG. 3  is a side view of a form of drum rotation apparatus; 
           [0014]      FIG. 4  is a cross-sectional view about lines  4 - 4  of the drum rotation apparatus of  FIG. 1 ; 
           [0015]      FIG. 5  is a cross-sectional view about lines  5 - 5  of the drum rotation system of  FIG. 1 ; 
           [0016]      FIG. 6  is a front view of an air distribution block; 
           [0017]      FIG. 7  is a rear view of the air distribution block of  FIG. 6 ; 
           [0018]      FIG. 8  is a perspective view of the air distribution block of  FIG. 6 ; 
           [0019]      FIG. 9  is a front view of an air supply manifold; 
           [0020]      FIG. 10  is a rear view of the air supply manifold of  FIG. 9 ; 
           [0021]      FIG. 11  is a perspective view of the air supply manifold of  FIG. 9 ; 
           [0022]      FIG. 12  is an exploded view of a partial air distribution system of the present device; 
           [0023]      FIG. 13  is a perspective view of a chamber shown in  FIG. 3 ; 
           [0024]      FIG. 14  is a schematic view of an air distribution system; 
           [0025]      FIG. 15  is an alternate form of drum rotation apparatus; 
           [0026]      FIG. 16  is an alternate form of drum rotation apparatus; and 
           [0027]      FIG. 17  is a schematic of the drum rotation apparatus of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Referring in more detail to the drawings, there is shown by way of illustrative example in  FIGS. 1 to 17  various forms of an air-induced rotation device. The apparatus includes a rectangular frame  11  having four closed sides  13 ,  15 ,  17 ,  19  defining a rectangular support. The side portions  13  and  17  have bosses  21 ,  21 ′ for inserting an axle or shaft  23  therethrough, as shown in  FIG. 4 . The axle  23  extends through each opening  21 ,  21 ′, and a drum member  25  is rotatably mounted on the axle  23 . The drum member  25  is cylindrical having opposite end walls or drum hubs  27  and  29  the axle  23  being mounted in bearings  31  and  33  as shown in  FIG. 3  and  FIG. 4 . A filter screen  35  may be mounted on the exterior of the drum member  25 . The filter screen  35  is preferably a wedge wire screen  37 , as shown in  FIG. 1 , having horizontally extending, vertically spaced, wedge wires traversing the entire width of the drum member  25  between the opposite end walls  27  and  29 . The filter screen  35  aids in removing and transporting debris on the face of the screen while preventing fish from passing through the drum screen. A lifting eye  18  is provided for ease of positioning the frame  11  and drum member  25  in a desired location with a crane or other large machinery. 
         [0029]    Chamber members  41  are mounted in circumferential spaced relation along a perimeter of an interior of the drum member  25 , as shown in  FIGS. 2 ,  3 ,  4 ,  5  and  12 , and are sealed with end blocks or plugs  28  and attached to end caps  26  of the opposite end walls  27  and  29  as shown in  FIG. 5  and  FIG. 12 . Preferably, eight chambers are mounted in the drum member but fewer or greater numbers may also be used. Each chamber member  41  is preferably made of steel or other non-corrosive material and is defined by four side walls  43 ,  45 ,  47  and  49 , forming a squared chamber having four closed joined ends or corners  51 ,  53 ,  55  and  56  as shown in  FIGS. 12 and 13 . Open portion(s)  57  provide for the passage of water and air into and out of each chamber member  41 . The open portion(s)  57  are located along a substantial length of the rectangular chamber  41  as shown in  FIGS. 12 and 13  and may also comprise sectional openings or any other type of opening that allows for water and air passage. The mechanism used to introduce air under pressure into the chambers consists of an air compressor C as shown in  FIG. 1  or from a solar battery powered compressor (not shown). The air compressor C may be located at either end of the frame  11  and has an air line  34  that runs from the air compressor C to the frame  17  and into an angle fitting, not shown, that is threaded into an air distribution manifold  59  at entry bore  61 . Air is then fed through entryway  62  and into a semi-circular slot  63  that is milled into the smooth mating surface of the manifold  59  for about 120 degrees from approximately 6 0&#39;clock to 11 0&#39;clock as shown in  FIG. 9 . The air distribution manifold  59  is mated with an air distribution block  65 , the block  65  and the manifold  59  each having a centrally located bore  67  to accommodate the axle  23  allowing for rotation of the drum, as shown schematically in  FIG. 12 . The air distribution manifold  59  has a milled portion  73  on the outside face of the manifold  59  that fits over the tubular steel drum support frame  11  and keeps the manifold from rotating about the drum axle. An “O” ring seal  75  rests in a slot  77  on the outside perimeter of the manifold  59  insuring a complete seal between the manifold  59  and the block  65 , preventing any air from escaping from between the surfaces of the manifold  59  and the air distribution block  65 . 
         [0030]    The air distribution block  65  has bores, preferably eight,  79 ,  81 ,  83 ,  85 ,  87 ,  89 ,  91  and  93  that are approximately 45 degrees apart and intersect with and are connected to eight threaded openings  79 ′,  81 ′,  83 ′,  85 ′,  87 ′,  89 ′,  91 ′ and  93 ′ located along the perimeter of the block  65 . Fittings (not shown) are then inserted into each of the threaded openings and connected to flexible hoses  101  that feed air to each chamber consecutively around the perimeter of the end wall  27  through a bore fitting  62 . The block  65  is secured to the end wall  27  with bolts  72 ,  74 ,  76  and  78 . The air distribution system may be secured to either the end wall  27  or the end wall  29 , but in this embodiment is preferably secured to just one end wall for air distribution at one end of the chambers  41 . 
         [0031]    In use, the drum member and frame  11  are submerged, preferably at least 50% in a body of water W as shown in  FIG. 17 . Each chamber begins filled with water, the drum is in equilibrium and the drum member is not rotating. When air is introduced into the manifold  59  and distributed to the air distribution block  65  through the channel  63 , the hoses  101  that feed air to the chambers  41  receive air from the air distribution block  65 . Pressurized air is introduced sequentially into the chambers with the air displacing the water and providing a force equal to the weight of the water that had been displaced. The air flow to the chambers  41  is dependent upon the position of the air hose  101 , and consequently the bores  79 ,  81 ,  83 ,  85 ,  87 ,  89 ,  91  and  93  with respect to the channel  63 . When the bores are in the 6 0&#39;clock to 11 0&#39;clock position with respect to the stationary manifold  59 , the channel provides air through the bores  85 ,  87 ,  89  and  91  to the hoses  101  and consequently the chambers secured to the hoses, within that range. While the manifold  59  remains stationary, the block  65  rotates in a clockwise fashion. As a result, the bores and the air hoses  101  shift positions and air is distributed sequentially to the chambers in the 6 0&#39;clock to 11 0&#39;clock positions. As the chambers  41  fill with air, the water is forced out. Following the physics of flotation, an upward force is created that is in proportion to the weight of the water that is being displaced. Rotation of the drum member  25  is accomplished through the buoyant weight differential of the chambers. As the chambers  41  move over the top of the drum member  25 , the air escapes and is rapidly replaced with water as shown by way of example only and not limitation, in  FIG. 17 . The speed of rotation of the drum member  25  can be controlled by regulating the volume and pressure of the induced air. Because the drum member  25  is supported on low friction bearings, it is possible to turn large drums with a very small compressor. 
         [0032]    When the apparatus is placed in the flow of water, e.g., a stream, typically partially submerged, water flows into the path of the drum screen  35 , and much of the water passes through the screen and exits downstream. Particles and other debris, however, tend not to flow through the openings in the screen but may be carried on the face of the drum screen  35  and deposited at an exit portion with the filtered water while fish are deterred from approaching the drum member  25 . The drum screen is self-cleaning so that the debris is washed off of the screen. This self-cleaning aspect avoids the need for any type of regular maintenance or cleaning device to remove debris from the screen. 
         [0033]    The air lift rotation allows the drum to be large, relatively maintenance-free and economical to construct. This allows for the screening of large agricultural diversions that would be cost-prohibitive if other configurations of drums were used. It will also provide an alternative to large costly plate screens that require raking type cleaners due to debris caught on the screen. The rotation of the drum screen containing the chamber members  41  also acts as a deterrent to fish based on the turbulence zone surrounding the rotating drum screen due to the drum rotation and the internal chambers striking the water. 
       Alternate Forms 
       [0034]    An alternate form of invention is illustrated in  FIG. 15  in which like parts are correspondingly enumerated to those of  FIGS. 1 to 14 . The drum screen  25 ′ is of a cylindrical form and is rotatably mounted upon the axle  23 ′ utilizing modified flotation chambers  42 . The modified chambers  42  are circumferentially mounted along a perimeter of an interior of the drum member  25 ′ and attached to opposite end walls  27 ′ and  29 ′. Each chamber member  42  forms a cubic chamber having an air and water passage portion  57 ′. Sequential air induction occurs in the same manner as described previously with the addition of a manifold  59 ′ and a block (not shown) on each end wall  27 ′ and  29 ′ for air distribution to each chamber  42 . 
         [0035]    Another form of apparatus is illustrated in  FIG. 16  in which like parts are correspondingly enumerated to those of  FIGS. 1 to 14 . The alternate form has chamber members  44  that are circular in shape with an air and water passage area  57 ″. It will be appreciated that the chamber members may take many different forms but accomplish the same end result without departing from the spirit of the apparatus. 
         [0036]    While a number of exemplary aspects, embodiments and methods have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and subcombinations thereof. It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and subcombinations as are within their true spirit and scope.

Summary:
A method and apparatus for separating fish and debris from water, the apparatus being made up of a frame member within which a rotating drum member is mounted, the drum member containing circumferentially mounted, longitudinally extending chamber members with an open side, and an air distribution member for inducing air into the chambers, facilitating rotation of the drum member. The method and apparatus are conformable for use in areas where the flow of water is a concern.