Patent Publication Number: US-2011064587-A1

Title: Low waste pump follower

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority of U.S. Provisional Patent Application Serial No. 61/243,267, filed on Sep. 17, 2009 (pending), the disclosure of which is incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to pump followers of the type used for removing viscous material from a container. 
     BACKGROUND 
     Pump followers used in conjunction with pumps to remove viscous material from containers may generally include a circular plate or platen coupled to the inlet end of a pump. Such followers are inserted into the open end of a drum, barrel, or other container of highly viscous material. The viscous material is often stored in 55-gallon drums. The platen is driven toward the bottom of the drum. The viscous material is thereby forced into a cavity on the bottom side of the platen and through a pump intake passage in the center of the platen. The material is then pumped to a suitable dispenser. 
     There are shortcomings with the conventional pump followers. First, significant waste can occur as the pump follower is unable to capture all of the material within the drum. It is estimated that as much as 2-3 gallons of material per 55 gallon barrel can be lost due to this inefficiency. In a large scale operation, this translates into substantial material loss. Further, the leftover or residual material at the bottom of the barrel can pose disposal problems 
     For environmental reasons, liner bags are now frequently used to hold the material in the container. When the follower enters the container, it extracts the viscous material within the liner bag. The follower typically must remain spaced far enough from the bottom of the container that the liner bag does not become suctioned into the follower and pump intake passage. For example, in many applications of this type, the follower must be stopped at about 3″ from the bottom of the drum or container, leaving the material in this 3″ space as waste material in the liner bag. 
     SUMMARY 
     In one illustrative embodiment of the present invention, a pump follower is provided that includes a perforated member, such as a screen or grid, attached across the bottom side of a platen. The perforated member covers a cavity of the platen that receives the viscous material and communicates with an intake passage in fluid communication with a pump. The perforated member is configured such that when the platen is inserted into a container of viscous material, the viscous material will flow through holes in the perforated member and into the cavity. The hole size(s) is/are chosen in conjunction with the viscosity of the material such that when the platen is retracted from the container, residual material will be trapped in the cavity and the intake passage by the perforated member. That is, the viscous material will not fall back through the holes in the perforated member into the container. Instead, it will be suctioned from the pump follower during the process of removing material from a subsequent container. In this manner, when the follower reaches the bottom of each container, it is able to capture almost all of the material stored within the container and reduce wasted material. 
     In another exemplary embodiment of the present invention, a method of capturing viscous material in a follower includes driving a platen into the viscous material. The viscous material flows through a perforated member and into a cavity of the platen. The platen is then retracted, and the material remaining in the cavity is retained in the cavity by the perforated member. 
     Various additional features and aspects of the embodiments and scope of the invention will be more readily appreciated upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a bottom perspective view of a pump follower constructed in accordance with an illustrative embodiment of the invention. 
         FIG. 2  is a cross-sectional view of the follower, taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is an exploded bottom perspective view of the pump follower. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
       FIGS. 1-3  illustrate a pump follower  10  including a platen  12 , a perforated member  14 , and a mounting ring  16 . The perforated member  14  is securely attached to the mounting ring  16 , such as by welding. As another option, the perforated member and mounting ring may be substituted with a one- piece structure comprised, for example, of a plate having an outer, solid ring portion and an inner area of perforations. The perforated member  14  is mounted to a bottom side or face  20  of the platen  12  and is situated in a mounting rim or recess  26  ( FIGS. 2 and 3 ) of the platen  12 . Optionally, the recess  26  may be eliminated and the perforated member  14  secured to the bottom face of the platen  12 . The mounting ring  16  is secured to the bottom face  20  of the platen  12 , within recess  26 , by threaded fasteners  22 . Fasteners  22  may each comprise any element suitable for rigidly anchoring the mounting ring  16  to the mounting rim  26 . Alternatively, any other manner of fastening the perforated member  14  to the platen  12  may be used. The perforated member  14  includes a plurality of holes  30  and comprises a perforated flat plate in this example, but may instead comprise any other suitable perforated member, such as a flat screen or grid of intersecting wire-like elements or the like. 
     As depicted in  FIG. 2 , the platen  12  has an internal cavity  32  located on the bottom side  20  of the platen  12 . A pump intake passage  34  is located centrally within cavity  32  and communicates with a pump  36 . The pump  36  communicates with at least one dispenser  38  for dispensing the fluid in any desired manner. 
       FIG. 3  illustrates an exploded view of the perforated member  14  and platen  12 . The follower  10  is assembled as a unit by rigidly attaching the mounting ring  16  to the platen  12 . The perforated member  14  positioned over and covers the entirety of the internal cavity  32  of the platen  12  and the mounting ring  16  is fastened to the platen  12  as discussed above. The mounting ring  16  includes plurality of mounting holes  48 , each of the mounting holes corresponding to one of a plurality tapped mounting holes  50  formed in the mounting rim  26  of the platen  12  for receiving the fasteners  22 . 
     The follower  10  is designed for use with viscous materials, such as glues, sealants, mastics, caulks, epoxies or other viscous material. A material pumped with follower  10  may have a viscosity of at least about 10,000 centipoise at room temperature. The holes  30  in the illustrated embodiment, are 1″ diameter holes staggered on 1¼″ centers. The diameter of the platen  12  is approximately 22″ to fit within and seal against the inner walls of a 55 gallon drum. For sealing purposes, two O-rings  60  are attached to the outer periphery of the platen  12 . The internal cavity  32  is generally funnel shaped and converges toward the intake passage  34 , which has a diameter of 2¾″. This illustrative example is suitable for pumping silicone, at a viscosity of 300,000-400,000 centipoise and room temperature, from a 55 gallon drum. 
     In operation, the follower  10  is inserted into a vertically oriented drum (not shown) to extract the viscous material. The follower is driven down into the drum by a suitable actuator  70  with the perforated member  14  facing into the open end of the drum. The actuator  70  may take any suitable form, such as a pneumatic, hydraulic, electric or gravity driven actuator, for example. As schematically shown with arrows  72 , the actuator  70  can move the pump follower in either direction. The viscous material is thereby forced through the material openings or holes  30  in the perforated member  14 , into the cavity  32  and through the intake passage  34  to the pump  36 . The pump  36  directs the material to a dispenser  38 . 
     When the follower  10  reaches the bottom of the drum and is extracted from the drum, the pump  36  will be stopped and the cavity  32  will be filled with residual or leftover viscous material. The drum may or may not contain a liner bag which holds the viscous material. If the drum includes a liner bag, the perforated member  14  provides the added advantage of preventing the liner bag from being suctioned into cavity  32  and pump intake  34 . The platen  12  may be lowered into the lined or unlined drum such that the perforated member is very close to the bottom of the drum, e.g., about ½″. The residual viscous material will not drop back through the material openings  30 . Instead, the viscosity of the material will cause it to be retained within the cavity  32  and against the upper side or inside face  14   a  of the perforated member  14 . Thus, there will be very little residual material left in the drum or container upon withdrawal of the follower  10 . After the platen  12  is withdrawn, a second, filled container of the viscous material may be placed beneath the pump follower and the pump follower with the retained material of the first container is placed into the second container. The process then repeated with the retained, residual material being initially pumped as the pump follower is driven into the second container. Therefore the holes  30  of the perforated member need to be sized such that the material can pass through them as the platen  12  is forced towards the bottom of the container, but will prevent the material from flowing back through by gravity as the platen  12  is withdrawn from the container. In one embodiment, the perforated member  14  is a screen. 
     While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims. What is claimed is: