Abstract:
A silt trap is shown which provides easy access to the end of a valve stem of a valve in a buried water main having a valve box which extends from the valve to the surface. The trap is a tapered bowl having a centrally located I-bolt for removal. The lip of the bowl is covered by a U-shaped gasket which seals around the entire periphery of the bowl lip. The device traps silt and other debris and can be easily removed for dumping without allowing debris to fall into the valve box.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from a provisional application Ser. No. 60/683,326, filed May 23, 2005. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates generally to underground access boxes containing underground valves, such as those being commonly employed in municipal water and gas systems utilizing lines that are buried underground.  
         [0004]     2. Description of the Prior Art  
         [0005]     When underground lines are laid, it is generally necessary to have one or more underground valves in the lines for use in controlling the flow of the material through the lines. For example, in the case of municipal water works distribution system, many miles of water lines are buried in the streets and right of ways in order to serve municipal customers. Included in these miles of pipelines there may be hundreds, if not thousands, of valves. These are typically gate valves to control the flow of water in the pipeline system. The valves are typically installed in pipelines that are buried, for example, from three to ten feet under the surface of the ground. The use of underground valves of this general type has necessitated the use of valve boxes to allow a means of obtaining access to the valves without having to dig down in the earth to uncover the valve.  
         [0006]     Valve boxes of the type under consideration are well known in the relevant industries and are generally tubular casings which may have an enlarged lower bell housing that encompasses the valve. The upper end of the valve box generally includes a cover which is oftentimes located generally flush with the ground surface. By removing the cover or lid on the valve box, and by using a special tool, such as a T-handled socket wrench, a maintenance man can normally quickly gain access to the end of the valve stem of the buried valve and operate it to turn it on and off. This can be done provided that the enclosure, that is, the valve box, is not filled with silt, sand, road-base material, solidified material, or other debris which prevents access to the operating end of the valve stem.  
         [0007]     As well-known in the prior art, when a water line becomes broken, very serious damage can result from water gushing out of the break and flooding adjacent residences or other buildings, doing substantial damage to the surrounding properties. In some cases, emergency crews have difficulty obtaining access to the operating stems of the valves because the valve box or enclosure has become filled up, as has been described. Typically, a good deal of difficulty is experienced in digging out or extracting debris from the underground enclosure which, in turn, delays the time before the emergency can be corrected, and the valve or valves are shut off to stop water coming out of the break.  
         [0008]     The present invention has as one object to provide a simple and inexpensive means to prevent the buildup of silt or other debris in underground valve boxes, so that the valve stem located in such boxes is readily accessible at all times.  
         [0009]     Another object of the invention is to provide such a device which fits most commercially available valve boxes of the type used in the water and gas distribution industries without the need to modify such valve boxes.  
         [0010]     Another object of the invention is to provide such a device which will trap any sediment tending to fall in around a valve nut in a valve box, which device can be simply pulled out and emptied periodically and which will not allow sediment to fall inside the box during removal.  
       SUMMARY OF THE INVENTION  
       [0011]     A silt trap is shown for use with a valve box of an underground valve. The valve box has a valve-operating stem with an operating fitting at an operating end thereof. The valve box forms a circular enclosure with an interior defined by a lower region surrounding the operating end of the valve stem and an upper region extending to a surrounding surface. The silt trap comprises a trap body formed as a tapered bowl having an upper peripheral lip region and downwardly extending tapered sidewalls which terminate in a generally planar bottom region of the bowl. The peripheral lip region of the trap body is sized to have a predetermined diameter which allows it to be received on an internal shoulder provided within the upper region of the circular enclosure. The trap body also has a peripheral sealing element which circumscribes the upper peripheral lip region of the bowl and a centrally located handling element which extends upwardly from the bottom region of the bowl. The trap body can be installed within the interior of the circular enclosure of the valve box on an internal shoulder provided therein by lowering the trap body into position using the handling element. The peripheral sealing element forms a seal with the interior of the circular enclosure which prevents the enclosure from accumulating silt and debris.  
         [0012]     In one preferred form of the invention, the tapered bowl is formed of stainless steel and the handling element is an I-bolt. A U-shaped gasket surrounds the peripheral lip region of the bowl when in place. This version of the device is sized to be received within the existing diameter of a 7  1 / 2  inch cast iron water or gas valve box.  
         [0013]     In the method of the invention, assured access is provided to a valve-operating stem, having an operating fitting at an operating end thereof, of an underground valve. As previously described, the valve has a circular enclosure with an interior defined by a lower region surrounding the operating end of the valve stem and an upper region extending to a surrounding surface. In the first step of the method, a silt trap is provided which is sized to be received within the upper region of the circular enclosure, the silt trap being formed as a tapered bowl having an upper peripheral lip region and downwardly extending tapered sidewalls which terminate in a generally planar bottom region of the bowl. The silt trap also has a peripheral sealing element which circumscribes the upper peripheral lip region of the bowl and a centrally located handling element which extends upwardly from the bottom region of the bowl. The silt trap is installed by using the handling element to lower the trap into position on an internal shoulder provided within the interior of the circular enclosure, the upper peripheral lip region of the tapered bowl being appropriately sized so that peripheral sealing element which circumscribes the upper peripheral lip region forms a seal with the interior of the circular enclosure.  
         [0014]     In the next step of the method of the invention, the silt trap is periodically removed from the enclosure by using the handling element to retrieve the trap from the interior of the enclosure. The trap can then be emptied of any accumulated silt or debris, followed by reinstalling the trap within the interior of the enclosure.  
         [0015]     Additional objects, features and advantages will be apparent in the written description which follows.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is partial, cross sectional view of a typical prior art underground pipeline installation showing a gate valve and valve box and illustrating the general environment of the present invention.  
         [0017]      FIG. 2  is a side view of the silt trap of the invention showing a hidden portion of the handling element of the trap in dotted lines for ease of illustration.  
         [0018]      FIG. 3  is a top view of the silt trap of  FIG. 2 .  
         [0019]      FIG. 4  is side, partial cross sectional view illustrating, in exploded fashion, the installation of the silt trap of the invention on an internal shoulder provided within the valve box interior.  
         [0020]      FIG. 5  is a view similar to  FIG. 4 , but showing the assembled silt trap within the valve box and with the valve box cover in place.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Underground valves of the type under consideration will be well familiar to those skilled in the relevant waterworks and natural gas industries. As has been briefly described, the invention deals with a device and method whereby access to the end of the valve stem at the bottom of the valve box may be more easily assured, as well as for preventing the buildup of silt, debris or other material in the bottom of the valve box with the passage of time.  
         [0022]     Typically, a valve box of the type under consideration may have a size which is in the range of 6 inches to 12 inches in diameter, depending upon the size of the water main and valve with which it is operated. In one embodiment, the silt trap of the present invention is designed to fit a standard 7½ inch cast iron water and gas valve box. However, it will be readily appreciated that the device of the invention can be provided in convenient sizes to fit all standard valve boxes, both water and gas. Typically, the valve in question, such as a gate valve, has an operating stem at the end of which is an operating fitting, typically in the form of a square nut which can receive a square socket at the end of the operating tool, which extends to the surface. From the foregoing, it is to be seen that the tool, as described, can be inserted into the valve box, and then by rotating, the valve can be opened or closed.  
         [0023]     Referring now to  FIG. 1  of the drawings, there is shown in pictorial fashion, a typical prior art buried water pipeline  11 , valve  13  and valve box or enclosure  15 . The valve has a stem  17 , at the upper end of which is a square fitting  19 . The lower end of the valve box or enclosure  15  may be secured to the valve flange  21 , as by welding. The valve box enclosure, as shown, is normally cylindrical and extends to the surface, and the top end is normally closed by a removable cap or cover ( 16  in  FIGS. 4 and 5 ). The enclosure has an internal shoulder ( 23  in  FIG. 1 ). The interior is divided into a lower region surrounding the operating end of the valve stem (generally at  18  in  FIG. 4 ) and an upper region (generally at  20  in  FIG. 4 ) extending to a surrounding surface, as viewed in  FIG. 1 .  
         [0024]     As described in the foregoing, frequently the valve box or enclosure  15  becomes filled with silt, dirt, or other debris so that access cannot be readily had to the fitting  19  without the necessity of digging out any accumulated debris within the interior of the valve box. In some cases, a maintenance crew wishing to gain access to the operating fitting of the valve stem may find that the material within the enclosure has become so solidified that it cannot be extricated without a great deal of effort. Even where the material is loose silt, soil or debris, some effort is required to uncover the valve nut, thereby wasting valuable time and labor.  
         [0025]      FIG. 2  shows a silt trap  25  of the invention which is intended to be installed within the valve box  15 , shown in  FIG. 1 , to prevent the accumulation of silt and debris within the enclosure. The silt trap  25  is sized to be received within the upper region ( 20  in  FIG. 4 ) of the circular enclosure on the internal shoulder  23  which is provided as a part of the valve box. As will be appreciated from  FIG. 2 , the silt trap is formed as a tapered bowl having an upper peripheral lip region  27  and downwardly extending sidewalls  29  which terminate in a generally planar bottom region  31  of the bowl. The angle “α” formed between the horizontal plane  32  of the bottom region of the bowl and the sidewall is approximately 35 degrees in  FIG. 2 . The silt trap is also provided with a peripheral sealing element  33  which circumscribes the upper peripheral lip region of the bowl and a centrally located handling element  35  which extends upwardly from the bottom region of the bowl.  
         [0026]     The tapered bowl can be made of any of a number of convenient materials including various metals and metal alloys and various synthetic plastics. Preferably, the bowl is formed of stainless steel because of its corrosion resistance and relative light weight. The handling element  35  in the embodiment of the invention illustrated is an I-bolt which is centrally mounted for ease of installing and removing the silt trap from within the valve box. The sealing element  33  illustrated in  FIG. 2  is preferably a U-shaped elastomeric gasket which surrounds the peripheral lip region  27  of the bowl on an approximate ⅜ inch wide flange. The tapered bowl has a predetermined bowl depth, the bowl depth being in the range from about 1½ to 3 inches in the embodiment of the invention illustrated, so as to not interfere with the operating end of the valve stem  17  in an existing valve box. Preferably, as has been mentioned, the tapered bowl is sized so as to be received within the existing diameter of a 7½ inch cast iron water or gas valve box with the sealing element  33  forming a seal against the surrounding sidewalls of the valve box enclosure.  
         [0027]     The method of utilizing the device of the invention will now be briefly described. In the method of the invention, assured access is provided to a valve-operating stem  17 , having an operating fitting  19  at an operating end thereof, of an underground valve  13 . The valve  13  has a circular enclosure  15 , as has been described, with an interior  18  defined by a lower region  18  surrounding the operating end of the valve stem and an upper region  20  extending to a surrounding surface ( 22  in  FIG. 1 ).  
         [0028]     In the first step of the method, a silt trap such as the previously described trap  25  is provided which is sized to be received within the upper region  20  of the circular enclosure  15 . The silt trap  25  is installed by using the handling element  35  to lower the trap  25  into position on the internal shoulder  23  provided within the interior  18  of the circular enclosure  15 . The upper peripheral lip region  27  of the tapered bowl is appropriately sized so that peripheral sealing element  33  which circumscribes the upper peripheral lip region forms a seal with the interior sidewalls  18  of the circular enclosure.  
         [0029]     In the next step of the method of the invention, the silt trap  25  is periodically removed from the enclosure by using the handling element  35  to retrieve the trap from the interior of the enclosure. The trap can then be emptied of any accumulated silt or debris, followed by reinstalling the trap within the interior of the enclosure.  
         [0030]     An invention has been provided with several advantages. The trap sidewalls are tapered for several specific purposes. The bowl is tapered so as not to interfere with the existing valve box installation, as has been discussed. The tapered design also directs silt and debris to the center lower portion of the tapered bowl as well as providing added strength to the design so that a light weight metal or metal alloy can be used, in turn reducing costs. The trap is designed to allow silt to settle into the bowl to a depth of about ½ to 3 inches. The sealing element of the design not only forms a silt tight seal when the device is in place within the valve box enclosure, but also prevents additional debris from falling into the interior of the enclosure as the trap is being removed. The trap will work as designed, even if the valve box is filled with water. The trap is simple in design and economical to manufacture.  
         [0031]     While the invention has been shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit thereof.