Patent Publication Number: US-2007108223-A1

Title: Dry pellet dispensing device for wells

Description:
BACKGROUND OF THE INVENTION  
      The invention is directed generally to dry pellet dispensing devices and, more particularly, to a device for dispensing dry chemical pellets for the treatment of water pumped from a well.  
      There are many homes and farms which rely on private wells as the sole source of water for both people and animals. Not infrequently, the wells are contaminated with undesirable bacteria and other microorganisms. Some, such as red rust or iron bacteria, are merely a nuisance, causing the water to be unsuitable for washing clothes and resulting in excessive mineral deposits in pipes through which the water flows. Other organisms transmit water-borne diseases that infect both people and livestock ingesting the water. Careful treatment of the water with the appropriate chemicals can frequently alleviate the most typically found contaminations.  
      Devices for treating wells with chemicals are known. Examples include U.S. Pat. Nos. 3,785,525 and 4,235,849. Both patented devices rely on rotating plates to meter the dispensing of solid pellets from a supply reservoir into the well. The known devices suffer from several problems. One problem is the difficulty of metering precisely and adjustably the amount of chemical dispensed into the well. The chemical pellets are subject to breakage, and pieces of the pellets can jam the metering or delivery parts of the known devices. Satisfactory performance of the devices also depends on the reliability of the metering parts to select a single pellet each dispensing cycle. As a result, either over-or under-treatment of the water can occur.  
      An improved device is described in U.S. Pat. No. 4,694,900. A rotating drum is used to meter solid pellets into the well. The surface of the drum included recessed portions in a generally V-shape adjacent dispensing openings in the drum that assisted in proper metering of the pellets. It has been found that performance of the metering device can be improved by adding a recess in a wall portion adjacent the outlet from the pellet reservoir to the metering drum.  
     SUMMARY OF THE INVENTION  
      The dry pellet dispensing device of the present invention includes a pellet supply reservoir divided by a pair of reversely inclined partitions. A metering drum is located at the outlet of the lower partition. A vertical wall portion extends from the underside of the upper partition to the top of the drum. The periphery of the drum contains one or more pellet receiving indentations. Each indentation consists of a central, substantially cylindrical well the axis of which is aligned with a radius of the drum. Flared outwardly from each pellet receiving indentation is a pair of indentations forming a generally V-shape with a vertex at the pellet receiving indentation. The improvement of the present invention is in the addition of a recess in the vertical wall adjacent the periphery of the drum.  
      The metering drum is rotated by motor drive means. The drive means is controlled by an adjustable timer which can be set to run the motor any desired portion of the amount of time water is being pumped from the well. As the metering drum rotates, a single pellet is received in the central well of one of the indentations. The V-shaped indentations, the legs of which flare outwardly and forwardly in the direction of rotation of the drum, assist in the capture of a pellet in the pellet receiving indentation. In addition, the pellet shifting indentations in the lower partition assists in moving pellets toward path on which the wells travel as the drum rotates and thus improved the reliability of the metering device. A captured pellet is carried by the rotating drum until the carrying indentation is at the bottom of the drum. Gravity causes the pellet to be released into a pellet discharge tube which directs it into the reservoir of water to be pumped from the well. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a partially sectional perspective view of the dry pellet dispensing device of the present invention;  
       FIG. 2  is a partially sectional plan view of the metering drum and drive motor;  
       FIG. 3  is a sectional elevational view of the metering drum and pellet discharge tube; and  
       FIG. 4  is a sectional view of the dry pellet dispensing device installed on a well. 
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT  
      A dry pellet dispensing device of the present invention is illustrated in  FIG. 1  generally at  10 . The pellet dispensing device  10  is shown mounted on a ground support post  12 , which illustrated only in part in  FIG. 1 . Mounted on post  12  is a base  14  which includes an enlarged rim at  16  to engage a cover ( 17  in  FIG. 4 ) as will be described in detail below. The base  14  supports a pellet reservoir or chamber  18  which is subdivided into several smaller volumes. The upper portion of the chamber  18  is partially divided by a pair of reversely inclined floor portions, upper floor portion  20  and lower floor portion  22 . Pellets  23  for dispensing by the device  10  are introduced into the chamber  18  through the raised collar  40  which is ordinarily sealed shut with a threaded plug  42 . The floor portions  20  and  22  are positioned to direct by gravity pellets  23  in the upper portion of the chamber  18  down toward the lower end of floor portion  22 . The pair of lower corners  24  of floor portion  20  are accordingly inclined toward lower floor portion  22  below the opening in upper floor portion  20 .  
      Narrowing the lower floor portion  22  are a pair of interior side walls  26  and  28  which extend across the chamber  18  from the base  14  upwardly to the upper floor portion  20 . Interior side walls  26  and  28  receive a cylindrical sleeve  30  which also extends to the exterior of the chamber  18 . Received for rotation within sleeve  30  is a metering drum  32 . The drum  32  is exposed through the sleeve  30  in two areas, as is most clearly shown in  FIG. 3 . The first area is between the top of the sleeve  32 , where a wall portion  34  extends upwardly to a point above the opening in the upper floor portion  20 , to where the drum  32  is adjacent the lower floor portion  22 . The second area is a full-width slot at the bottom of the sleeve  30  where the drum  32  is exposed to a lower chamber  36  the walls of which extend from the sleeve  30  downwardly to the base  14  wholly enclosing the second enclosed area. Pieces of broken pellets and fines picked up by the drum  32  are, accordingly, discharged through the full-width slot. Communicating from the lower chamber  36  and to outside the base  14  is a pellet receiving tube  38 . All parts of the device  10  which may be exposed to the pellets  23  or their released gasses should be made of a material resistant to the strong oxidizing effects typically exhibited by the pellets.  
      Referring now to  FIG. 2 , the metering drum  32  has a plurality of indentations about its circumferential periphery. One is a circumferential ring  44  of a shallow concave cross-section and roughly centered with respect to the lower partition or floor portion  22 . Spaced about the ring  44  is one or more pellet receiving indentations  46  of a size to receive a single pellet such that the captured pellet will not extend past the radial confines of the drum  32 . Also included are a pair of outwardly flaring indentations  48  which form a generally V-shaped indentation  51  as best shown in  FIG. 2 . The indentations  48  deepen, as will be described in more detail below, from the outer end thereof to where they meet the pellet receiving indentation  46 .  
      The bottom edge of the wall portion  34  includes a pellet shifting indentation  70  that is positioned above the ring  44 . The pellet shifting indentation  70  is similar in shape to the flaring indentation  48 . The pellet shifting indentation  70  acts to shift pellets in their path toward the ring  44  and thereby improve the reliability in performance of the drum  32  at capturing a pellet in each pellet receiving indentation  46  every time so that the same number of pellets as pellet receiving indentations are dispensed for each full rotation of the drum  32 .  
      Operatively connected to the drum  32  is drive shaft  50  which, in turn, is rotated by motor  52 . Operation of the motor  52  thereby rotates the drum  32  within sleeve  30 . The motor  52  in a preferred embodiment is a 1/250 horsepower electric gear reduction motor that turns at one revolution per minute when connected to 120 volt, 60 Hz current. The 1/250 horsepower gear reduction motor used as motor  52  is sufficiently powerful to shear the calcium hypochlorite pellets described above. Accidental lodging or a pellet of a broken piece of a pellet, therefore, does not cause a malfunction of the device. Electrical power to the motor  52  is controlled by an interval timer  54  ( FIG. 1 ) which, in turn, is supplied with power and runs only during the time water is being pumped from a well on which the device  10  has been installed. The interval timer  54  can be set to operate the motor  52  any proportion of the time that water is pumped from the well.  
      The device  10  is shown installed on a well in  FIG. 4 . The well includes an electrical submersible pump  56  connected to a power source by supply line  58 . Of course, any other pump means, such as a jerk rod pump, could be used in place of the submersible pump  56 . The pump  56  is submersed below the surface of an underground source of water  60  and above a filter screen  62 . Water pumped from the well is routed through discharge tube  64 . A well cover  66  covers the top opening of the well and mounts support post  12  for support of the device  10 . Surrounding the pellet reservoir  18 , motor  52  and timer  54  is the cover  17  which seals around the base  14  to keep environmental water and moisture out of the device  10 . Pellet dispensing tube  38  passes inside support post  12  and into the well. Dispensed pellets  67  are dropped from the tube  38  into the water  60 . Dissolving pellets may reside on filter screen  62 .  
      In operation, an electrical pressure switch on a pressurized supply tank attached to the discharge tube  64  actuates the pump  56  to refill the supply tank whenever the pressure therein drops below a predetermined pressure. The pressure switch controlling pump  56  also actuates the interval timer  54  so that timer  54  runs whenever pump  56  is pumping water from the well. Timer  56 , accordingly, operates to measure the volume of flow of water from the well. For human consumption, a ratio of between 0.5 and 1.0 part per million of residual chlorine to water is found to produce the desired bacteriostatic effect without imparting an adverse taste or odor to the discharge water. The level of residual chlorine in water pumped from the well is dependent on the volume of water in the well, the flow of water pumped from the well, the temperature of water in the well, and the degree and type of contamination present.  
      The residual chlorine level in water pumped from the well can be adjusted by appropriately changing the number of chlorine pellets  67  dispensed into the well by the device. This may be accomplished in two ways. First, the interval timer  54  can be adjusted to operate the motor  52  either a larger or smaller proportion of the time water is being pumped from the well. Secondly, the number of pellets dispensed per revolution of the motor  52  and metering drum  32  can be adjusted by increasing or decreasing the number of pellet receiving indentations  46  in the periphery of the drum  32 .  
      The pellets dispensed by the device  10  of the preferred embodiment are oblate spheroids having a minor diameter of 5/16 inches (7.9 mm) and a major diameter of ⅜ inches (9.5 mm). The pellets are compressed out of 70% calcium hypochlorite (Ca(ClO) 2  .2Ca(OH) 2 ) and 30% inert soluble material, and weigh 0.035 oz. (1 gram). It has been determined that one such pellet dissolved in 10 gallons of water will result in a residual chlorine level of approximately 0.5 to 1.0 parts per million. With six pellet receiving indentations in the drum, and the timer set to operate continuously with the pump, a continuous flow rate of 60-70 gallons per minute can be treated by the dispenser.  
      The pellet receiving indentations  46  of the drum  32 , as described above, are of a size to capture a single pellet. The motor  52  rotates the drum  32  so that the surface of the drum  32  adjacent the lower floor portion  22  moves upwardly with respect thereto. The circumferential indentation  44  is centered with the pellet receiving indentations  46 . It acts during rotation of the drum  32  to center a pellet in line with the next pellet receiving indentation  46 . Also assisting the capture of a pellet are the two flared indentations  48 . A pellet off center of the circumferential indentation  44  will be urged toward the pellet receiving indentation  46  by the two flared indentations  48  as they are rotated through the pellets ahead of the pellet receiving indentation. Further assisting the reliable capture of a pellet in each pellet receiving indentation  46  is the pellet shifting indentation  70  of the wall portion  34  which acts to shift pellets that are in the vicinity of the outlet to the metering drum  32  toward the circumferential indentation  44 . In dispensing pellets the size and type described above, it has been found that the following dimensions of the indentations enhance single pellet capture in the pellet receiving indentation  46 : 
          (a) Circumferential indentation 44—width 9 mm, maximum depth 2 mm.     (b) Flared indentations  48  and pellet shifting indentation 70—length 18 mm, maximum width 8 mm, maximum depth 3 mm.     (c) Pellet receiving indentation 46—diameter (edges chamfered) 12 mm, depth 12 mm        

      It should be clear from the foregoing description of the preferred embodiment that other mechanical or electrical means could be employed in accomplishing the broad purposes of the invention. It should be understood this description is intended to illustrate but not to limit the scope of the invention as defined in the following claims.