Abstract:
A pressure relief cap for a water supply comprises an outer portion defining a front face for generally covering an outlet of the supply. The outer portion includes a seal for being urged against and sealingly engaging a periphery of the outlet. An inner portion includes a connector for coupling and decoupling to an outlet. The inner portion is rotatably coupled to the outer portion such that upon at least partial rotation of the outer portion in a first direction relative to the inner portion the seal is moved axially inwardly relative to the inner portion from a disengaged position to an engaged position to sealingly engage a periphery of an outlet, and upon at least partial rotation of the outer portion in an opposite direction the seal is moved axially outwardly from the engaged position to the disengaged position to thereby permit back pressure within an outlet to vent.

Description:
FIELD OF THE INVENTION 
     The present invention relates to pressure relief caps for water supply systems, and more particularly relates to a pressure relief cap for an outlet of a water supply such as, for example, a fire hydrant, which safely vents back pressure within the water supply during the removal of the cap from the water supply outlet. 
     BACKGROUND OF THE INVENTION 
     Couplings of the Storz type are employed for quick connect and disconnect operations and which are widely used in fire fighting as for example in connecting fire hoses to fire hydrants, pumps and other hoses. Examples of Storz type couplings are found in my U.S. Pat. No. 6,102,444, the disclosure of which is herein incorporated by reference in its entirety. Storz type caps are similar to Storz type couplings, but are used for sealing a fire hydrant connection when the fire hydrant is not in use. 
     A drawback with prior caps is that any back pressure in the water supply system could potentially cause the cap to blow off an outlet of the water supply while being removed therefrom and thereby injure someone such as, for example, a firefighter when removing a cap from a fire hydrant. 
     It is therefore a general object of the present invention to provide an improved cap for a water supply which overcomes the drawbacks and disadvantages of prior caps. 
     SUMMARY OF THE INVENTION 
     A pressure relief cap for a water supply system in accordance with the present invention comprises an outer portion defining a front face for generally covering an outlet of a water supply such as, for example, a fire hydrant. The outer portion includes a seal for being urged against and sealingly engaging a periphery of the outlet. Preferably, the seal is annular, and the outer portion defines an annular groove for receiving and retaining at least a portion of the seal. 
     The pressure relief cap further comprises an inner portion including a connector, such as a Storz type connector, for coupling and decoupling to an outlet. The inner portion is rotatably coupled to the outer portion such that upon at least partial rotation of the outer portion in a first direction relative to the inner portion the seal is moved axially inwardly relative to the inner portion from a disengaged position to an engaged position to sealingly engage a periphery of an outlet, and upon at least partial rotation of the outer portion in a second direction opposite to that of the first direction the seal is moved axially outwardly relative to the inner portion from the engaged position to the disengaged position to move the seal away from a periphery of an outlet, and thereby permit any back pressure within an outlet to vent past the seal prior to decoupling the inner portion. 
     Preferably, the inner portion is threadedly coupled to the outer portion to permit rotation of the outer portion relative to the inner portion. Specifically, the inner portion can define radially inwardly facing threads, and the outer portion can define radially outwardly facing threads for threadedly engaging the radially inwardly facing threads of the inner portion. 
     In an exemplary embodiment, the outer portion includes a plug member connected to a seal holding member for supporting the seal. The plug member defines the front face, and is rotatably coupled to the inner portion for movement of the seal between the disengaged position and the engaged position. Moreover, the plug member preferably is threadedly engaged with the inner portion for movement of the seal between the disengaged position and the engaged position. For example, the inner portion can define radially inwardly facing threads, and the plug member can define radially outwardly facing threads for threadedly engaging the radially inwardly facing threads of the inner portion. 
     The outer portion includes at least one projection for facilitating rotation of the outer portion relative to the inner portion. In one aspect of the present invention, the projection extends outwardly from the front face of the outer portion, and defines a shape, such as a pentagon, for being engaged with a correspondingly shaped tool such as a wrench. In a second aspect, the at least one projection includes a plurality of radially outwardly extending handles disposed about a periphery of the outer portion. Specifically, the plurality of handles can each be generally in the shape of a knob or elongated in configuration. 
     The foregoing and other advantages of the present invention will become more apparent in light of the following detailed description of the exemplary embodiments thereof, as illustrated in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 . is a partially exploded, cross-sectional, side elevation view of a pressure relief cap in accordance with the present invention. 
         FIG. 2  is an front view of the pressure relief cap of  FIG. 1 . 
         FIG. 3  is a cross-sectional, side elevation view of a seal holding member of the pressure relief cap of  FIG. 1 . 
         FIG. 4  is a cross-sectional, side elevation view of a plug member of the pressure relief cap of  FIG. 1 . 
         FIG. 5  is a cross-sectional, side elevation view of an outlet attachment member of the pressure relief cap of  FIG. 1 . 
         FIG. 6  is a front view of the outlet attachment member of  FIG. 5 . 
         FIG. 7  is a partial cross-sectional, side elevation view of the pressure relief cap of  FIG. 1  in a seal engaged position. 
         FIG. 8  is a partial cross-sectional, side elevation view of the pressure relief cap of  FIG. 1  in a seal disengaged position. 
         FIG. 9  is a cross-sectional, side elevation view of a pressure relief cap in accordance with a second embodiment of the present invention. 
         FIG. 10  is a front view of the pressure relief cap of  FIG. 9 . 
         FIG. 11  is a cross-sectional, side elevation view of a plug member of the pressure relief cap of  FIG. 10 . 
         FIG. 12  is a front view of the plug member of  FIG. 11 . 
         FIG. 13  is a partial cross-sectional, side elevation view of the pressure relief cap of  FIG. 9  in a seal engaged position. 
         FIG. 14  is a partial cross-sectional, side elevation view of the pressure relief cap of  FIG. 9  in a seal disengaged position. 
         FIG. 15  is a cross-sectional, side elevation view of a combined seal holding and plug member of a pressure relief cap in accordance with a third embodiment of the present invention. 
         FIG. 16  is a cross-sectional, side elevation view of the combined seal holding and plug member of  FIG. 15  with a handle member attached thereto. 
         FIG. 17  is a front view of the combined seal holding and plug member of  FIG. 16 . 
         FIG. 18  is a cross-sectional, side elevation view of the handle member of  FIG. 16 . 
         FIG. 19  is a front view of the handle member of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1-8  a generally cylindrical pressure relief cap embodying the present invention is indicated generally by the reference number  10 . The pressure relief cap  10  in accordance with the present invention permits someone to relieve back pressure within a water supply system such as, for example, a fire hydrant during the removal of the cap. This pressure relief is achieved during the same motion in which the cap is removed, and not through means of a secondary vent or device. Although the present invention will be explained in connection with relieving back pressure within fire hydrants, it should be understood that the present invention can be employed in other applications for venting potentially dangerous back pressure in a water supply system, and take on other practical shapes without departing from the scope of the present invention. 
     The pressure relief cap  10  comprises an outer portion including a cylindrical plug member  12  having a central axis A, and a cylindrical seal holding member  14  for supporting an annular seal or gasket  16  thereon. Although the plug member  12  and the seal holding member  14  are shown and described as separate components, such components can be of unitary construction. Moreover, the annular seal  16  can take other practical shapes or configurations without departing from the scope of the present invention. 
     The pressure relief cap further comprises an inner portion including a cylindrical outlet attachment member  18 . A front face  20  of the plug member  12  defines a projection or knob  22  disposed on the central axis A and extending axially outwardly from the front face  20  of the plug member  12 . The knob  22  is shaped for being received by a correspondingly shaped end of a removal tool such as a wrench. Although the knob  22  is pentagon-shaped as best shown in  FIG. 2 , the knob may take other practical shapes as shown, for example, in  FIGS. 9 and 10 , without departing from the scope of the present invention. 
     As best shown in  FIG. 4 , the plug member  12  further includes a coupling portion  24  disposed circumaxially about the plug member adjacent to a periphery thereof. The coupling portion  24  extends axially away from an inner face  26  of the plug member  12 . The coupling portion  24  defines radially inwardly facing threads  28  and radially outwardly facing threads  30  for engaging other components of the pressure relief cap  10  as explained more fully below. 
     As best shown in  FIG. 3 , the seal holding member  14  is cylindrical and includes a coupling portion  32  along an outer axial end  34 . The coupling portion  32  preferably defines radially outwardly facing threads  36  for engaging other components of the pressure relief cap  10  as explained more fully below. The seal holding member  14  at an inner axial end  38  defines an open-ended channel or groove  40  for receiving and retaining therein the seal  16 . As shown in  FIG. 1 , the seal  16  has a cross-sectional configuration similar to the cross-sectional configuration of the groove  40  with a radially enlarged end portion  42 , a mid portion  44  which is somewhat narrower radially, and a portion  46  forwardly of the mid portion  44  which is somewhat wider than the end portion  42 . 
     As best shown in  FIG. 5 , the outlet attachment member  18  includes a coupling portion  50  defining radially inwardly facing threads  52  along an outer axial end  54  for engaging other components of the pressure relief cap  10 . The coupling portion  50  of the outlet attachment member  18  further includes a connector such as lugs  56  for coupling to an outlet of a water supply system such as a fire hydrant (not shown). As shown in  FIGS. 1 and 5 , the lugs  56  preferably form part of a Storz type coupling, but may take other practical forms without departing from the scope of the present invention. 
     During assembly of the pressure relief cap  10 , the radially inwardly facing threads  28  of the plug member  12  are threadedly engaged with the radially outwardly facing threads  36  of the seal holding member  14 . Preferably, an adhesive such as, for example, LOCTITE®, is applied to one or more of the threads  28 ,  36  immediately prior to or during assembly in order to permanently secure the seal holding member  14  to the plug member  12  after the adhesive is cured. The radially enlarged end portion  42  of the seal  16  is engaged in the groove  40  defined by the seal holding member  14  to thereby secure the seal to the seal holding member. The radially outwardly facing threads  30  of the plug member  12  are threadedly engaged with the radially inwardly facing threads  52  of the outlet attachment member  18 . 
     With reference to  FIGS. 7 and 8 , in operation the lugs  56  of the outlet attachment member  18  are axially inserted into an opening of a water supply outlet such as a fire hydrant (not shown). The plug member  12  is then rotated in a clockwise direction with the seal  16  in a disengaged position as shown in  FIG. 8 . Rotation of the plug member  12  loosely engages the lugs  56  within the opening of the hydrant and causes the outwardly facing threads  30  of the plug member to be threaded along the inwardly facing threads  52  of the outlet attachment member  18  so as to move the plug member and seal holding member  14  coupled thereto axially inwardly relative to the outlet attachment member. As the seal holding member  14  is moved axially inwardly, the seal  16  supported on the seal holding member is also moved axially inwardly from a disengaged position (shown in  FIG. 8 ) to an engaged position (shown in  FIG. 7 ). In the engaged position, the seal  16  is positioned for sealing engagement with a face of the outlet of a hydrant. Upon further rotation of the plug member  12  in a clockwise direction, a surface  33  of the plug member contacts a first stop surface  35  of the outlet attachment member  18  to prevent the radially outwardly facing threads  30  of the plug member from being further threaded onto the radially inwardly facing threads  52  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the plug member. The rotating outlet attachment member  18  causes the lugs  56  to move into a fully engaged position within the opening of the hydrant to thereby secure the pressure relief cap  10  to the hydrant. 
     When the pressure relief cap  10  is to be removed from a hydrant or other water supply outlet, the plug member  12  is rotated in a counterclockwise direction. The outwardly facing threads  30  of the plug member  12  are unthreaded along the inwardly facing threads  52  of the outlet attachment member  18  so as to move the plug member and the seal holding member  14  coupled thereto axially outwardly relative to the outlet attachment member. As the seal holding member  14  is moved axially outwardly, the seal  16  supported on the seal holding member is also moved axially outwardly from an engaged position (shown in  FIG. 7 ) to a disengaged position (shown in  FIG. 8 ). In the disengaged position, the seal  16  is positioned to be spaced from and no longer in sealing engagement with a face of the outlet of a hydrant. As a result, any back pressure within a hydrant is allowed to escape past the seal  16  while the lugs  56  are still in the fully engaged position within the opening of the hydrant. Because any venting takes place while the outlet attachment member  18  is secured to the outlet of the hydrant, the dangerous possibility of back pressure causing the pressure relief cap  10  to blow off the hydrant and injure someone is eliminated. Upon further rotation of the plug member  12  in a counterclockwise direction, a surface  37  of the seal holding member  14  contacts a second stop surface  39  of the outlet attachment member  18  to prevent the radially outwardly facing threads  30  of the plug member  12  from being further unthreaded along the radially inwardly facing threads  52  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the plug member. The rotating outlet attachment member  18  causes the lugs  56  to move from an engaged position within the opening of a hydrant to a disengaged position to thereby permit the pressure relief cap  10  to be safely removed from the hydrant after the back pressure has been vented. 
     With reference to  FIGS. 9-14 , a pressure relief cap in accordance with a second embodiment of the present invention is indicated generally by the reference number  110 . Like elements with the pressure relief cap  10  shown in  FIGS. 1-8  are indicated by like reference numbers preceded by “1”. 
     The pressure relief cap  110  is similar to the pressure relief cap  10  except that a plug member  112  of the pressure relief cap  110  includes radially outwardly extending handles or knobs  122  disposed about a periphery thereof. As best shown in  FIG. 10 , for example, the plug member  112  includes four handles  122  spaced at 90 degree intervals about the periphery of the plug member. The plug member  112  can also include a projection or knob  123  disposed on a central axis A and extending axially outwardly from a front face  120  of the plug member  112  for gripping when the plug member is being coupled to or removed from a water supply outlet such as a fire hydrant. Although, four handles  122  extending radially outwardly from the periphery of the plug member  112  are illustrated by way of example, it should be understood that a fewer or greater number of handles can be employed without departing from the scope of the present invention. Moreover, other types of handles can be substituted such as, for example, those shown in  FIG. 16 . It should also be understood that although the plug member  112  and the seal holding member  114  are shown and described by way of example as separate components, such components can be of unitary construction without departing from the scope of the present invention. 
     With reference to  FIGS. 13 and 14 , in operation the lugs  156  of the outlet attachment member  118  are axially inserted into an opening of a water supply outlet such as a hydrant (not shown). The plug member  112  is then rotated in a clockwise direction with the seal  116  in a disengaged position as shown in  FIG. 14 . Rotation of the plug member  112  loosely engages the lugs  156  within the opening of the hydrant and causes the outwardly facing threads  130  of the plug member to be threaded along the inwardly facing threads  152  of the outlet attachment member  118  so as to move the plug member and seal holding member  114  coupled thereto axially inwardly relative to the outlet attachment member. As the seal holding member  114  is moved axially inwardly, the seal  116  supported on the seal holding member is also moved axially inwardly from a disengaged position (shown in  FIG. 14 ) to an engaged position (shown in  FIG. 13 ). In the engaged position, the seal  116  is positioned for sealing engagement with a face of the outlet of a hydrant. Upon further rotation of the plug member  112  in a clockwise direction, a surface  133  of the plug member contacts a first stop surface  135  of the outlet attachment member  118  to prevent the radially outwardly facing threads  130  of the plug member from being further threaded onto the radially inwardly facing threads  152  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the plug member. The rotating outlet attachment member  118  causes the lugs  156  to move into a fully engaged position within the opening of the hydrant to thereby secure the pressure relief cap  110  to the hydrant. 
     When the pressure relief cap  110  is to be removed from a hydrant, the plug member  112  is rotated in a counterclockwise direction. The outwardly facing threads  130  of the plug member  112  are unthreaded along the inwardly facing threads  152  of the outlet attachment member  118  so as to move the plug member and the seal holding member  114  coupled thereto axially outwardly relative to the outlet attachment member. As the seal holding member  114  is moved axially outwardly, the seal  116  supported on the seal holding member is also moved axially outwardly from an engaged position (shown in  FIG. 13 ) to a disengaged position (shown in  FIG. 14 ). In the disengaged position, the seal  116  is positioned to be spaced from and no longer in sealing engagement with a face of the outlet of a hydrant. As a result, any back pressure within a hydrant is allowed to escape past the seal  116  while the lugs  156  are still in the fully engaged position within the opening of the hydrant. Because any venting takes place while the outlet attachment member  118  is secured to the outlet of the hydrant, the dangerous possibility of back pressure causing the pressure relief cap  110  to blow off the hydrant and injure someone is eliminated. Upon further rotation of the plug member  112  in a counterclockwise direction, a surface  137  of the seal holding member  114  contacts a second stop surface  139  of the outlet attachment member  118  to prevent the radially outwardly facing threads  130  of the plug member  112  from being further unthreaded along the radially inwardly facing threads  152  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the plug member. The rotating outlet attachment member  118  causes the lugs  156  to move from an engaged position within the opening of a hydrant to a disengaged position to thereby permit the pressure relief cap  110  to be safely removed from the hydrant after the back pressure has been vented. 
     With reference to  FIGS. 15-19 , a pressure relief cap in accordance with a third embodiment of the present invention is indicated generally by the reference number  210 . Like elements with the pressure relief cap  10  are indicated by like reference numbers preceded by “2”. 
     The pressure relief cap  210  is similar to the pressure relief cap  10  except that the seal holding member  14  and the plug member  12  are substituted with a combined seal holding and plug member  215  of unitary construction. Accordingly, the radially inwardly facing threads  28  of the plug member  12  and the radially outwardly facing threads  36  of the seal holding member  14  shown in the first embodiment are not necessary in the combined seal holding and plug member  215 . The seal holding and plug member  215  supporting an annular seal  216  defines an annular portion  260  having an outer annular surface  262 , and a stepped portion  264  extending radially outwardly from the annular portion. The stepped portion defines radially outwardly facing threads  266 . 
     The pressure relief cap  210  further comprises an annular handle member  268  defining an inner annular surface  270  for being received over the outer annular surface  262  of the seal holding and plug member  215 . The annular handle member  268  includes elongated handles  271  extending radially outwardly therefrom, and a coupling portion  272  defining radially inwardly facing threads  274  for engaging the radially outwardly facing threads  266  of the seal holding and plug member  215 . The coupling portion  272  of the annular handle member  268  further defines radially outwardly facing threads  276  for engagement with radially inwardly facing threads  252  of an outlet attachment member  218 . 
     During assembly of the pressure relief cap  210 , the radially inwardly facing threads  274  of the handle member  268  are threadedly engaged with the radially outwardly facing threads  266  of the seal holding and plug member  215 . Preferably, an adhesive such as, for example, LOCTITE®, is applied to one or more of the threads  274 ,  266  immediately prior to or during assembly in order to permanently secure the handle member  268  to the seal holding and plug member  215 . 
     In operation the lugs  256  of the outlet attachment member  218  are axially inserted into an opening of an outlet of a water supply such as a fire hydrant (not shown). The handle member  268  is then rotated in a clockwise direction with the seal  216  in a disengaged position. Rotation of the handle member  268  loosely engages the lugs  256  within the opening of the hydrant and causes the outwardly facing threads  276  of the handle member to be threaded along the inwardly facing threads  252  of the outlet attachment member  218  so as to move the seal holding and plug member  215  coupled thereto axially inwardly relative to the outlet attachment member. As the seal holding and plug member  215  is moved axially inwardly, the seal  216  supported on the seal holding and plug member is also moved axially inwardly from a disengaged position to an engaged position (shown in  FIG. 16 ). In the engaged position, the seal  216  is positioned for sealing engagement with a face of the outlet of a hydrant. Upon further rotation of the handle member  268  in a clockwise direction, a surface  233  of the handle member contacts a first stop surface  235  of the outlet attachment member  218  to prevent the radially outwardly facing threads  276  of the handle member from being further threaded onto the radially inwardly facing threads  252  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the handle member. The rotating outlet attachment member  218  causes the lugs  256  to move into a fully engaged position within the opening of the hydrant to thereby secure the pressure relief cap  210  to the hydrant. 
     When the pressure relief cap  210  is to be removed from a hydrant, the handle member  268  is rotated in a counterclockwise direction. The outwardly facing threads  276  of the handle member  268  are unthreaded along the inwardly facing threads  252  of the outlet attachment member  218  so as to move the seal holding and plug member  215  coupled thereto axially outwardly relative to the outlet attachment member. As the seal holding and plug member  215  is moved axially outwardly, the seal  216  supported on the seal holding and plug member is also moved axially outwardly from an engaged position (shown in  FIG. 15 ) to a disengaged position. In the disengaged position, the seal  216  is positioned to be spaced from and no longer in sealing engagement with a face of the outlet of a hydrant. As a result, any back pressure within a hydrant is allowed to escape past the seal  216  while the lugs  256  are still in the fully engaged position within the opening of the hydrant. Because any venting takes place while the outlet attachment member  218  is secured to the outlet of the hydrant, the dangerous possibility of back pressure causing the pressure relief cap  210  to blow off the hydrant and injure someone is eliminated. Upon further rotation of the handle member  268  in a counterclockwise direction, a surface  237  of the seal holding and plug member  215  contacts a second stop surface  239  of the outlet attachment member  218  to prevent the radially outwardly facing threads  276  of the handle member  268  from being further unthreaded from the radially inwardly facing threads  252  of the outlet attachment member, thereby causing the outlet attachment member to rotate along with the handle member. The rotating outlet attachment member  218  causes the lugs  256  to move from an engaged position within the opening of a hydrant to a disengaged position to thereby permit the pressure relief cap  210  to be safely removed from the hydrant after the back pressure has been vented. 
     The handle member  268  and the seal holding and plug member  215  are shown and described as separate components by way of example, but can be of unitary construction. Further, the seal holding and plug member  215  can be substituted with separate plug member and seal holding member components. Moreover, other types of handles, such as those shown in  FIGS. 2 and 10 , can be substituted without departing from the scope of the present invention. 
     As will be recognized by those of ordinary skill in the pertinent art, numerous modifications and substitutions may be made to the above-described embodiments of the present invention without departing from the scope of the invention. Accordingly, the preceding portion of this specification is to be taken in an illustrative, as opposed to a limiting sense.