Abstract:
The invention relates to a device and method for sealing a manhole structure. An elastomeric band with at least two different peripheries is sealingly engaged to at least two corresponding peripheries of the manhole structure. Adhesives and supplemental retaining bands may also be used to secure the elastomeric band to the manhole structure.

Description:
FIELD OF THE INVENTION 
   This invention relates to manhole sealing devices and methods. In particular, it relates to a method and device for applying a tapered seal to a manhole structure with at least two peripheral dimensions. 
   BACKGROUND OF THE INVENTION 
   Manholes are used to provide street-level access to sewer lines and other underground structures. Most often, the top portion of the manhole has the form of a cylindrical frame with a lid. The lower portion of the frame, which is not generally seen after installation, often resembles a hat with a brim that rests on a concrete cone leading to a sewer. The upper portion of the frame holds a lid. The elevation of the manhole frame and lid may be raised to the level of the surrounding surface grade by placing one or more concrete adjusting rings between the bottom of the frame and the cone. A manhole structure is thus created by stacking a number of components on top of each other. After the manhole structure is installed, the space around it is filled in so that only the lid at the top portion of the manhole frame is conveniently accessible at street-level. 
   Manholes created by such stacking of components are vulnerable to leaks. Water and other contaminants may enter the manhole through gaps between the stacked components after installation. Once the manhole structure has been installed and the earth around it filled in, gaps below the ground level become difficult to reach. It is thus desirable to seal the manhole structure during installation to prevent further leaks at the interfaces between the stacked components. 
   Various methods and devices are known for sealing the external surfaces of manhole structures. One method employs an elastomeric band positioned around the top portion of the cone and extending over the adjusting rings to the base of the manhole frame. Because the cone and the adjusting rings have generally the same outer perimeter, a single sealing band may be used to provide a seal for the gaps between these components. Although such a method provides an adequate seal for the portions of the manhole structure with a periphery corresponding to the band&#39;s periphery, i.e., lower portion of the manhole structure from the cone to the bottom of the frame, they do not adequately seal the upper portion of the frame, which has a periphery that is generally narrower than the periphery of the manhole frame&#39;s base. 
   Manhole structures, however, often have structural gaps in the region between the two peripheries where conventional sealing bands do not reach. For example, some manhole-frame designs have holes in the horizontal portion of the frame base that are used to retain bolts or anchors for securing the frame to the stacked components below it. Another example is the “floating” casting. A floating casting is a two-piece manhole frame with a narrower upper frame resting on a wider base flange. For such manhole frames, and for other manhole frame designs with similar leakage points, existing methods are inadequate to provide a complete seal. It is thus desirable to extend the seal from the larger outer periphery generally shared by the cone and adjusting rings to the narrower periphery of the upper frame and lid. 
   What is needed in the industry is a device and method for better sealing a manhole structure that can seal both the larger lower external periphery of a manhole structure and any potential leaks that may originate between the lower periphery of the manhole structure and the narrower periphery of the upper portion of the manhole frame and lid. 
   SUMMARY OF THE INVENTION 
   The problems outline above are in large part solved by the present invention. In particular, the resilient band of the present invention may be used to provide a seal extending from the lower larger external periphery of a manhole structure up to the smaller upper periphery of the manhole frame. The sealing band has a first portion that fits around the first larger periphery of the manhole structure. A second tapered portion of the band extends from the first portion to the second smaller periphery of the manhole frame. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an elevational view of a manhole structure with the manhole frame shown in cross section and with phantom lines depicting the intersection of the manhole structure with a sewer. 
       FIG. 2  is a fragmentary cross section of a view of the invention in place on a manhole structure. 
       FIG. 3  is a fragmentary cross section of the invention in place on an alternative manhole structure. 
   

   DETAILED DESCRIPTION 
     FIG. 1  depicts a manhole structure  10  made up of vertically stacked components connected to a sewer  12 . The stacked components include a cone  14 , adjusting rings  22 , and frame  16 . Cone  14 , at the bottom of manhole structure  10 , is connected directly to sewer  12 . Adjusting rings  22  rest on the top of cone  14 . Frame  16  rests on adjusting rings  22 . Frame  16  has a base portion  24  and an upper portion  26  and supports a lid  30 . 
   A resilient band  18  in accordance with the invention is positioned around the upper portion of the manhole structure  10 . The resilient band  18  covers the top of cone  14 , adjusting rings  22 , and part of frame  16 . The resilient band  18  includes a first portion  36  and a second tapered portion  38 . The first portion  36  of resilient band  18  is secured around a periphery of the manhole structure  10  defined by the upper portion of cone  14 , the adjusting rings  22 , and the lower portion of frame  16 . The second portion  38  of resilient band  18  extends from the first portion  36  and surrounds the manhole structure  10  from the base portion  24  of frame  16  to the upper portion  26  of frame  16 . Second portion  38  of resilient band  18  tapers, becoming narrower until it reaches the narrower periphery of the upper portion  26  of frame  16  of manhole structure  10 . Second portion  38  is secured around manhole structure  10  at the upper portion  26  of frame  16  of manhole structure  10 . 
     FIGS. 2 and 3  depict in greater detail the resilient band  18  fitted to different kinds of manhole frames. 
     FIG. 2  depicts resilient band  18  in place over frame  16 . Frame  16  has a base portion  24  and an upper portion  26 . Adjusting rings  22  at the top of cone  14  support one-piece frame  16 . The base portion  24  has a larger periphery than upper portion  26 . A lid  30  with drop handles  32  rests on upper portion  26 . 
   As shown in  FIG. 2 , resilient band  18  has a first portion  36  and a second tapered portion  38 . The first portion  36  is attached to a periphery defined by the upper portion of cone  14  and the adjusting rings  22 . The second tapered portion  38  of resilient band  18  extends upward from the first portion  36  and surrounds varying peripheries of manhole structure  10  including the top of adjusting rings  22  and the base and upper portions  24 ,  26  of frame  16 . The second tapered portion  38  of resilient band  18  is attached to the periphery of the upper portion  26  of frame  16 . 
     FIG. 2  also shows two supplemental retaining bands  42  over resilient band  18 . One supplemental retaining band  42  surrounds the resilient band  18  at the top of cone  14  below adjusting rings  22 . Another retaining band  42  surrounds the resilient band  18  at the upper portion  26  of frame  16 . 
     FIG. 3  shows retaining band  18  positioned around a two-piece manhole frame  16   a . The lower portion of frame  16   a  includes a flange  44  with engagement member  46  and fasteners  48 . Fasteners  48  engage the upper portion  46  of frame  16   a . The first portion  36  of resilient band  18  is attached to the periphery defined by the upper portion of cone  14  and the adjusting rings  22 . The second portion  38  of resilient band  18  surrounds the region including adjust rings  22 , flange  44 , and upper portion  46  of two-piece frame  16   a . The second portion  40  of resilient band  18  surrounds the upper portion  46  of two-piece frame  16   a.    
   Resilient band  18  may be used to seal manhole structure  10  in a variety of ways. The resilient band  18  may be placed over gaps in manhole structure  10  such as those found between the cone  14  and the adjusting rings  22 , between individual adjusting rings  22 , between adjusting rings  22  and the base portion  24  of frame  16 , between adjusting rings  22  and the flange  44  of two-piece frame  16   a , between the flange  44  and upper portion  46  of two-piece frame  16   a . The resilient band  18  may also be used to provide a seal for holes (not shown) for bolts or anchors in the base portion  24  of frame  16  or flange  44  of frame  16   a . The application of resilient band  18  can also be used to protect those portions of manhole structure  10  that do not present structural gaps, such as the upper portion  26  of frame  16  and the upper portion  46  of two-piece frame  16   a.    
   When used to seal a manhole structure with frame  16 , resilient band  18  is placed around the upper portion of the frame  26  and pulled down into the position shown in  FIG. 2 . In this embodiment, resilient band  18  is positioned around manhole structure  10  from the top of cone  14  to the upper portion  26  of manhole frame  16  so that an effective seal is formed. Resilient band  18  may also be positioned so that first portion  36  surrounds one or more adjusting rings  22  and second portion  40  surrounds the upper portion  26  of frame  16 . 
   In the embodiment shown in  FIG. 3 , resilient band  18  is positioned around the top of cone  14  up to the upper portion  46  of two-piece manhole frame  16   a.    
   When used to seal a manhole structure with a two-piece manhole frame  16   a , resilient band  18  is pulled down over the upper portion of the frame  46 . Optionally, either the first portion  36  or the second portion  38  or both may secured to the manhole frame  16  or  16   a  by applying an adhesive (not shown) to the inner surfaces of resilient band  18 . 
   In an embodiment, the adhesive (not shown) is applied to resilient band  18  at the lower edge the first portion  36  and the upper edge of second portion  38 . A variety of adhesives could be used to secure resilient band  18  to manhole structure  10 . A butyl mastic adhesive, for example, is well-suited to secure resilient band  18  to manhole structure  10 , especially when used in connection with a primer (not shown) for preparing the surfaces of the manhole structure  10  proximate the resilient band  18  to better receive the adhesive applied to the first and second portions  36  and  48  of the resilient band  18 . The primer may be delivered in number of ways, including in aerosol form. The butyl mastic adhesive may be applied to the resilient band  18  before the resilient based  18  is positioned on the manhole structure  10 . The primer may then be applied to the surface of manhole structure  10  so that when the resilient band  18  is positioned over manhole structure  10  the butyl mastic adhesive and the primer work together to keep the resilient band  18  in place. 
   The use of resilient band  18  for sealing manhole structure  10  may include the additional step of securing one or more supplemental retaining bands  42  around at least one external periphery of the resilient band  10  to form a supplemental seal. Supplemental bands  42  may be positioned over those external portions of the resilient band  18  whose internal portions have been treated with an adhesive. For example, two retaining bands  42  may be used, one around the lower edge of the first portion  36  of resilient band  18  and one around the upper edge of the second portion  38  of resilient band  18  as depicted in  FIG. 2 . The retaining band  42  may be chosen from those made of any material suitable for long-term exposure to moisture, such as stainless steel or plastic. 
   Resilient band  18  may be constructed of various polymers having the elastic properties of natural rubber. A plurality of pieces of such material may be joined together with seams to make resilient band  18 . As will be appreciated by those of skill in the art, resilient band  18  could also be made from a single piece of material, without seams.