Patent Publication Number: US-2007116518-A1

Title: Self-sealing internal manhole chimney seal

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      Not Applicable  
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
      Not Applicable  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to articles for internally sealing a chimney of a manhole against ground water infiltration, and more particularly to mechanisms by which the seal is attached to the manhole.  
      2. Description of the Related Art  
      A typical manhole includes a main chamber or barrel section to which the sewer pipes connect. That section is topped with a conical riser in which the diameter reduces going upward to a size needed to fit a metal frame for the manhole surface opening. The metal frame receives the manhole cover and either sits directly on top of the riser or there may be one or more vertical adjusting rings there between, as needed to raise the top of the frame level with the surrounding surface. Adjusting rings usually are formed by annular precast concrete sections or courses of bricks or blocks. This combination of components is referred to as a “chimney”.  
      During construction of the manhole, the joints between the chimney components are sealed with mortar or other material to prevent surface water infiltration. Nevertheless, movement of the metal frame, resulting from expansion and contraction due to seasonal temperature changes and from vibration as vehicles pass over the manhole, causes cracks to form at those joints. As a result, ground water from rain and snow is able to enter the manhole through these cracks. Such ground water infiltration is undesirable for sanitary sewers, as it increases the volume of effluent which has to be processed by a sewage treatment plant. Municipalities go to great lengths to minimize the inflow and infiltration of ground water into sanitary sewers.  
      As a consequence, different external and internal sealing systems have been devised to prevent ground water infiltration into manholes. One type of an internal sealing system is described in U.S. Pat. No. 4,469,467 and utilizes a resilient sleeve that is inserted into the manhole chimney and held against the inside surface by upper and lower metal fastening bands.  
     SUMMARY OF THE INVENTION  
      An assembly is provided to internally seal a manhole against infiltration of water, wherein the manhole includes an inwardly projecting flange.  
      The assembly comprises a sleeve made of a resilient material which includes a first sealing section and a second sealing section. The first sealing section has a recess for receiving the flange to attach the sleeve to the manhole. In a preferred embodiment, the first sealing section is formed with a hook-like lip that creates the recess and the resiliency of the sleeve enables the lip to engage the flange in a manner that provides a watertight seal.  
      A fastening device engages the second sealing section of the sleeve and presses an outer surface of the sleeve against a surface of the manhole, thereby providing another watertight seal. The preferred embodiment of the fastening device comprises a fastening band that has first and second end portions which overlap and a mechanism that adjustably secures those end portions together to form a loop. For example, the first end portion has a tab and the second end portion has a plurality of slots that cooperate with the tab to connect the first and second end portions together in the loop.  
      Another aspect of the assembly provides a pleated section between the first and second sealing sections to allow the sleeve to expand and contract with movement of the parts of the manhole without breaking the watertight seals. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross sectional view of the upper section of a manhole having an internal chimney seal according to the present invention;  
       FIG. 2  is an enlarged portion of  FIG. 1  showing details of how an upper end of the internal chimney seal is secured to the manhole;  
       FIG. 3  is another enlarged portion of  FIG. 1  that illustrates how a lower end of the internal chimney seal engages the manhole;  
       FIG. 4  is a fastening band that secures the lower portion of the internal chimney seal to the manhole;  
       FIG. 5  is a cross section through the fastening band along line  5 - 5   FIG. 3 ; and  
       FIG. 6  shows an installation tool being used to expand the fastening band inside the manhole chimney. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      With initial reference to  FIG. 1 , a manhole  10  has a chimney  14  that comprises a conical riser  12  typically formed of precast concrete, but which may be laid bricks or blocks. Above the riser  12  are two precast concrete, plastic or rubber adjusting rings  16  on top of which is a metal manhole frame  18 . The number of adjusting rings  16  varies so that the chimney  14  has a height that places the upper end of the frame  18  level with the ground surface  20 . The conical riser  12 , adjusting rings  16 , and manhole frame  18  are held together by mortar  15  or a suitable adhesive.  
      The metal frame  18  has an opening  22  by which a person gains access to the interior of the manhole  10 . An interior, annular flange  24  extends around the interior of the opening  22 . A manhole cover  26  is shown closing the upper portion of the opening  22  above the annular flange  24 . The cover  26  is dropped in place and the annular flange  24  prevents the cover from falling completely through the opening  22 .  
      An internal chimney seal  30  is attached inside the manhole  10  to provide a watertight barrier at the joints between the manhole frame  18 , the adjusting rings  16 , and the riser  12 , thereby blocking ground water infiltration. The seal  30  consists of a tubular sleeve  32  that preferably is constructed of rubber or a similar resilient material that is extruded as a strip. The extruded strip is cut to a length that corresponds to the circumference of the finished sleeve and the ends then are sealed together with a suitable adhesive, for example. The exemplary sleeve  32  has two central pleats  33  and  34  located in between cylindrical sealing sections  35  and  36  at opposite ends of the sleeve. The pleats  33  and  34  allow the sleeve to expand, thereby accommodating vertical movement of the manhole components. Additional pleats or a straight section may be placed between pleats  33  and  34  to provide a sleeve that is able to span taller manhole chimneys.  
      With reference to  FIG. 2 , the upper sealing section  35  of the sleeve  32  is adapted to engage the interior annular flange  24  of the manhole frame  18 . Specifically a hook-like lip  40  extends around the upper end of the sleeve  32 , thereby forming a recess  38  in the outer circumference of the upper sealing section  35 . The resilient property of the sleeve  32  and the size of the recess  38  provide a tight engagement of the hook-like lip  40  with the annular flange  24  of the manhole frame  18 , that secures the components together with a watertight seam.  
      In addition to providing a watertight seal to the manhole chimney frame  18 , the lip  40  of the sleeve  32  also acts as gasket between the manhole cover  26  and the chimney frame to prevent water infiltration through that seam. As seen in  FIG. 1 , the lip  40  extends over the upper surface of the annular flange  24  in the opening  22  of the chimney frame  18 . Therefore when the manhole cover  26  is dropped into the frame opening  22 , the cover compresses the sleeve lip  40  providing a seal between the cover and the chimney frame  18 . Thus the novel internal chimney seal  30  incorporates an integral cover gasket.  
      Referring to  FIGS. 1 and 3 , the lower sealing section  36  of the sleeve  32  has outer circumferential surface  42  that engages and conforms to the interior surface  44  at the upper portion of the conical riser  12 . That outer circumferential surface  42  is formed by plurality of outwardly projecting annular fins  50  which extend around the sleeve  32  and engage the conical riser&#39;s interior surface  44 . The fins  50  deform when the lower sealing section  36  is pressed against the inner surface of the manhole  10 , thereby conforming to irregularities in that manhole surface to provide a watertight seal. Specifically, each fin  50  has an edge or tip that contacts the interior surface of the manhole and has a section spaced from that edge which is adapted to deform as the fin is pressed against the manhole.  
      The fins  50  of the lower sealing section  36  are held against the inner surface of the manhole  10  by a stainless steel fastening band  48  that is received in an annular groove on the inner circumferential surface  46  of the lower sealing section  36 . The fastening band  48  has overlapping end portions  51  and  52  which are slidable with respect to each other, as shown in  FIG. 4 . After the resilient sleeve  32  is properly located within the manhole  10 , the fastening band  48  is expanded within the sleeve to press the finned outer periphery of the lower sealing section  36  against the inner surface of the manhole riser  12 . The resiliency of the sleeve  32  allows the lower sealing section to expand against the manhole wall and form an annular seal which prevents water flow there between.  
      Referring to  FIGS. 1 and 6 , expansion of the fastening band  48  is performed by a scissors type tool  65  that is placed into apertures  66  and  67  in the fastening band  48 . As the fastening band  48  is expanded by the tool  65 , an angled tab  68  (see  FIG. 5 ) on one end portion  51  sequentially ratchets into a plurality of slots  70  spaced along the other end portion  52 . Specifically a bolt  72  on the tool is turned by a wrench to spread part two legs  74  and  75  that pivot about pin  76  on the tool  65 . The remote ends of the legs  74  and  75  have hooks that fit into the apertures  66  and  67  in the fastening band  48 . After the fastening band  48  has expanded sufficiently to provide the water tight seal, the bolt  72  is turned in the opposite direction to draw the legs  74  and  75  together so that the tool  65  can be disengaged from the fastening band. The fastening band and the expansion tool are described more fully in U.S. Pat. No. 5,496,128, which description is incorporated herein by reference.  
      The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.