Abstract:
A hydrant valve assembly including a spool member having at least one spool seal which is at times under extremely high pressure tending to cause the seal to be displaced from an associated recess, the spool member forming venting passages in the seal recess to alleviate seal pressure, the invention also including a new wet pipe design and a new collar design.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to yard hydrants and more particularly to a hydrant including a spool design which reduces the possibility of a spool seal being displaced from the spool. 
     A yard hydrant is installed on water systems to provide a frost resistant source of water remote from a heated building. An exemplary hydrant includes a hydrant valve, a dry pipe, a wet pipe and an activation handle. The hydrant valve includes both a valve housing and a spool member positioned within the housing. The housing forms an inlet or supply port, a drain port, and an opening to accept the spool and seals. The spool member forms an inlet opening or passage, an outlet opening and a passageway between the inlet and outlet openings. The hydrant valve is buried below the frost line and a water supply line runs below the frost line to the supply port. 
     The dry pipe is secured to the housing below the frost line and extends up to a comfortable operating position above ground level. The wet pipe is positioned within the dry pipe and is secured and sealed at a lower end to the spool member so that the member outlet opening opens into the wet pipe channel. The handle is mounted to the top end of the dry pipe via a collar and is linked to the upper end of the wet pipe for forcing the wet pipe and spool member secured thereto between open and closed positions via a lever handle action. The upper end of the wet pipe is also linked to a hydrant outlet spigot. 
     Referring to FIG. 1, an exemplary collar  10  for mounting the handle (not illustrated) to a dry pipe  12  is typically generally cylindrical. To enable easy collar casting the cross section of a collar wall has a frusto-conical shape (i.e. is essentially cone shaped). The angled wall sides are required to allow necessary draft in a sand casting process. The collar  10  is mounted to the dry pipe  12  by sliding the collar  10  onto the top end of the dry pipe  12  and threading a locking set screw  14  through a threaded collar aperture  16  which is perpendicular to a central collar axis  18 . The inner end  20  of the screw contacts an external surface  22  of the dry pipe  12  and clamps the pipe  12  between the inner end  20  and a point  26  on a facing portion  24  of the collar opposite the collar aperture  16 . The handle is linked to the collar via a collar extension (not illustrated). 
     The hydrant valve is a 2-position, 3-way valve having closed and open positions. In the open position the spool member is positioned such that the inlet passage is closed to the drain port and is open to the housing inlet or supply port to supply water flow to the spool member outlet, the wet pipe and the hydrant outlet. 
     To turn off the hydrant, an operator causes the valve to assume the closed position by forcing the handle downward to force the wet pipe and spool member downward. In the closed position the spool member is positioned such that the inlet passage is closed to the supply port and is open to the drain port. This allows any water in the wet pipe to drain below the frost line, and prevents water from freezing within the hydrant in cold climates. 
     To provide watertight seals, the hydrant valve is equipped with elastic seals, typically elastomeric O-rings, which seal the inlet closed when the valve is in the closed position and seal the drain port closed when the valve is in the open position. To this end the housing includes an internal surface and the spool member includes an external surface. The external surface forms recesses for receiving the seals which seal between the internal and external surfaces and move along the internal surface as the valve is opened or closed. 
     To ensure that the valve is opened and closed as the activation handle is manipulated, the wet pipe is formed of a rigid metallic material which essentially does not bend under the force required to manipulate the valve even when the hydrant must be over 10 feet long. 
     Unfortunately, while the hydrant design described above does perform he basic functions required of a yard hydrant, the design does have several shortcomings. First, this hydrant design cannot be used with water systems which provide high supply pressure without the use of an expensive pressurereducing valve. Water system pressures have been climbing because high pressure is desirable for many reasons. For example, often high pressure is required to fight fires. In the industrial and agricultural industries, including irrigation, high pressure water systems are advantageous for rapidly supplying water. Often, water system pressure is not controlled by an end user but is rather controlled by a water utility. Water utilities are often required to supply high pressure water at lower elevations or geographically immediate locations to have any reasonable pressure available at high elevation or geographically remote locations. When a high pressure supply line is linked to a hydrant valve often the valve seals can be inadvertently forced from their recesses. For example, while a valve is opened the hydrant outlet may be blocked causing pressure to build within the wet pipe and valve. If the valve is closed prior to relieving the wet pipe pressure, the pressure in the wet pipe is placed on one of the seals during the closing process. This extreme pressure often causes the seal to become unseated. 
     While a seal may fortuitously find its way back into its recess, often the seal does not and the entire spool member has to be removed to reseat the seal. Typically the seal is lost in the drain. The reseating task is time consuming and in many cases is exacerbated in frigid weather. 
     Second, the metal wet pipe is relatively expensive and therefore objectionable as the pipe costs increase the overall costs of the yard hydrant. 
     Third, it should be appreciated from FIG. 1 that the collar  10  provides very little resistance to collar rotation generally and specifically about an axis from the inner end  20  to a contact point  26 . This minimal resistance results in handle rocking and can affect the stroke length required to open and close the valve. 
     Therefore, it would be advantageous to have a new hydrant design which minimizes the possibility of unseated seals, which has a secure handle mounting collar, and which is relatively inexpensive. 
     BRIEF SUMMARY OF THE INVENTION 
     It has been recognized that venting passages can be provided in at least one of the spool member recesses to substantially reduce the likelihood of an unseated seal. Specifically, according to the present invention during valve movement from the open to the closed positions one seal is moved from a sealing position to an unsealed position (i.e. the seal is spaced from the internal housing wall). The recess associated with this seal includes a land of recess surface behind the seal which is proximate (i.e. closest to) the drain port. According to the present invention, the spool member forms a venting passage behind the seal between the lower corner of the recess and a spool member external surface proximate the drain port. If pressure causes the seal to lift away from the land, this pressure is relieved through the venting passage and the drain port. Thus pressure in the recess behind the seal drops thereby reducing the force pushing the seal out of the recess. When the pressure subsides the seal drops back into the recess, water under pressure is free to flow around the seal and pressure no longer pushes the seal out of the recess. 
     With respect to the wet pipe, according to the present invention the wet pipe is designed to have an external surface having a width dimension which is less than, but similar to, the width dimension of an internal surface of the dry pipe. In this manner the wet pipe is guided by the dry pipe such that the wet pipe will not buckle or substantially bend under a typical activation force. Thus, the wet pipe can be formed of a rigid, yet still bendable, material such as PVC or the like. PVC is appreciably less expensive than metal pipe and therefore, by designing a wet pipe in this manner the overall hydrant costs can be reduced appreciably. 
     With respect to the collar two improvements have been made. First, the threaded collar aperture has been formed to be perpendicular to the internal surface of the collar opposite the aperture. In this manner, when the screw forces the dry pipe against the opposite collar surface, the surface and pipe contact along essentially the entire length of the collar. 
     Second, instead of being cylindrical, the shape of the collar inner surface is revised to provide a relief in the inner diameter which is large enough that the inner diameter contacts the outer diameter of the pipe along two lines of contact. In this way, the collar inner surface contacts the dry pipe along two lines of contact, a significant distance apart and along the full collar length. The set screw still contacts the dry pipe at a single point positioned roughly half way between the contact lines. The resistance to turning is increased substantially using the same economical manufacturing processes, and without applying any higher assembly loads to the dry pipe. 
     These and other objects, advantages and aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefor, to the claims herein for interpreting the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a is a cross sectional view of a prior collar design; 
     FIG. 2 is a partial cross sectional view of a yard hydrant according to the present invention; 
     FIG. 3 is a side elevational view of the spool member of FIG. 2; 
     FIG. 4 is a cross sectional view of the portion of FIG. 2 identified by numeral  4 ; 
     FIG. 5 is a top perspective view of the collar of FIG. 2; and 
     FIG. 6 is a cross sectional view taken along the line  6 — 6  of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein like reference characters represent corresponding elements throughout the several views and, more specifically, referring to FIG. 2, the present invention will be described in the context of an exemplary yard hydrant  30 . Hydrant  30  generally includes a valve assembly  32 , a pipe assembly  34  and a handle assembly  36 . 
     Valve assembly  32  includes an elongated housing  38 , a spool member  40  and first, second, third and fourth seals  44 ,  46 ,  42  and  92 , respectively. Housing  38  forms an internal surface  48  which forms a chamber  49  about a housing axis  51 . Internal surface  48  in turn forms first and second sealing surfaces  50 ,  52 , respectively, a first expanded section  54  between sealing surfaces  50  and  52  and a second expanded section  56  adjacent a housing end wall  58 . 
     Referring to FIGS. 2 and 4, at the points where the sealing surfaces  50 ,  52  merge into the expanded sections  54 ,  56 , lead-in chamfers are provided to guide the seals  42 ,  44 ,  46  into and out of engagement with internal surface  48  without catching a sharp edge under pressure. As all chamfers are essentially identical, only one is shown in FIG. 4 as  204 . 
     Referring still to FIG. 2, housing  38  also forms an inlet  60  into first expanded section  54  and forms a drain port adjacent end wall  58  which extends into second expanded section  56 . Moreover, housing  38  also forms an opening  66  opposite end wall  58  which faces upwardly. 
     Referring now to FIGS. 2 and 3, spool member  40  is an elongated cylindrical member which forms an external surface  68  and an internal surface  70  which defines a passageway  72  from an outlet opening  74  at a top end to one or more inlet passages  76 ,  78  at an end opposite opening  74 . Passages  76  and  78  open laterally through external surface  68 . 
     External surface  68  also forms first, second, third and fourth recesses  81 ,  82 ,  80  and  90 , respectively, which are annular and circumferential about surface  68 . Surface  68  between recesses  80  and  81  is closed and is therefore referred to as a closed surface  86 . Surface  68  between recesses  81  and  82  forms passages  78  and  76  and is therefore referred to as an open surface  87 . In addition, surface  68  defines a diameter which is slightly less than internal surface  48  of housing  38 . An axial extension  84  extends from the end of spool member  40  opposite opening  74 . 
     Each seal  42 ,  44 ,  46  and  92  is preferably an elastomeric O-ring, although seals with a variety of cross sections are used, including rectangular section, lobed sections, cup-shaped sections, etc. Seals  42 ,  44  and  46  are received within recesses  80 ,  81  and  82 , respectively and, when received therein, extend slightly radially therefrom so that, as seen in FIG. 2, when spool member  40  is positioned within housing  38 , when a seal is within the area defined by either the first or second sealing surfaces  50 ,  52 , respectively, the seal is compressed between external surface  68  and internal surface  48  providing a watertight seal thereat. Similarly, seal  92  is received within recess  90  such that when a lower end of a wet pipe (described below) is secured therearound, a watertight seal is formed between the external surface  68  of spool member  40  and the internal surface of the wet pipe. 
     A female port  88  for receiving a water supply line (not illustrated) is formed about inlet  60 . It is contemplated that a pressurized water supply line is linked to female port  88 . 
     Referring to FIGS. 2 and 4, one and preferably a plurality of venting passages  166  are formed between a back lower edge of recess  46  and a portion of external surface  68  adjacent drain port  62 . Operation of passages  166  will be described below. 
     Referring still to FIG. 2, pipe assembly  34  generally includes a dry pipe  93  and a wet pipe  94 . Dry pipe  93  has an internal diameter D1 which is slightly greater than the external diameter D2 of wet pipe  94 . Dry pipe  93  is formed of a rigid relatively nonflexible material such as steel whereas wet pipe  94  is formed of a less expensive and more flexible, although relatively rigid, material such as PVC. Dry pipe  93  includes a top end  95  and a bottom end  96 . Bottom end  96  is securely attached to the upper end of housing  38  and is aligned with axis  51 . Attachment of bottom end  96  to housing  38  can be done in any manner well known in the art and therefore is not explained here in detail. 
     Wet pipe  94  has an upper end  110  and a lower end  112 . Lower end  112  is secured around the upper end of spool  40  so that seal  92  is sealed against an internal surface of wet pipe  94  to form a watertight seal therewith. Upper end  110  forms a recess  114  for receiving a seal (e.g. another elastomeric O-ring) which forms a watertight seal between the external surface of wet pipe  94  and an internal surface of an outlet spigot described below. 
     Referring still to FIG. 2, housing assembly  36  includes a handle  97 , a collar  98 , a lever  99  and an outlet spigot  100 . Spigot  100  defines an internal surface  102  which forms a cylindrical inlet  104 , a flow channel  106  and a spigot or hydrant outlet  108 . 
     Inlet  104  is sized and formed such that it securely receives upper dry pipe end  95 . This constrains motion of the outlet spigot  100  to move up and down axis  51 . Wet pipe end  110  is secured within inlet  104  in any manner well known in the art. Thus, wet pipe  110  moves along axis  51  as handle assembly  36  is moved there along. To form a watertight seal between upper end  110  and flow channel  106 , seal  116  seals between the internal surface of inlet  104  and the external surface of end  110 . Top end  95  of dry pipe  93  terminates within inlet  104  also, but is not securely linked within inlet  104  (i.e., pipe  93  does not move with other handle assembly components). A handle mounting extension  148  extends from output spigot  100  opposite flow channel  106  and forms a mounting aperture  154 . 
     Referring now to FIGS. 2,  5  and  6 , collar  98  includes a lateral wall  118  which traverses between first and second collar ends  120 , 122 , respectively, forming oppositely facing internal and external surfaces  124 ,  126 , respectively. Internal surface  124  forms a passageway for receiving dry pipe  93 . As illustrated, at any section through wall  118 , the cross section has a frusto-conical shape which is wider at second end  122  than at first end  120 . This shape is required for casting purposes. A threaded collar aperture  130  extends between the internal and external surfaces  124 ,  126 , respectively, along an aperture axis  132 . Aperture  130  is formed such that axis  132  is perpendicular to an opposing section  134  of internal surface  124 . 
     In addition, referring specifically to FIG. 5, opposing section  134  forms a relief  136  which forms two edges  138 , 140  which are perpendicular to axis  132 . When pipe  93  is positioned within passageway  128 , a locking set screw  142  is threadably received within aperture  130  such that a distal or inner end  144  of screw  142  contacts an external pipe surface  146  and forces an opposite side of the pipe against the two edges  138 , 140  along essentially the entire lengths of the edges  138  and  140 . It should be appreciated that by providing aperture  130  perpendicular to opposing section  134 , screw  142  can be used in conjunction with collar  98  with relief  136  to provide a relatively large amount of friction impeding collar  98  rotation about pipe  93  and other collar movement. Referring to FIGS. 2 and 5, a collar extension  150  extends radially from collar  98  perpendicular to axis  132  and forms an extension aperture  152 . 
     Referring again to FIG. 2, lever  99  includes a first end  156  which is linked to collar  98  via a pin which passes through aperture  152  and a second end  158  which forms an aperture  160 . Handle member  97  includes a handle extension  162  which is linked to handle mounting extension  148  by a pin which passes through aperture  154 . Member  97  also includes a cam extension  164  which extends opposite handle extension  162  and is linked to the second end of lever  99  by a pin which passes through aperture  160 . 
     Referring still to FIG. 2, when assembled spool member  40  is positioned within housing  38  with dry pipe  93  extending upwardly from housing  38  and wet pipe  94  extending upwardly from spool member  40  to handle assembly  36 . The lower end  112  of wet pipe  94  forms a watertight seal about the upper end of spool member  48  while the inlet of spigot  100  forms a watertight seal about the upper end  110  of wet pipe  94 . Thus, there is an unbroken flow path from passages  76  and  78 , through passageway  70 , wet pipe  94  and channel  106  to hydrant outlet  108 . Collar  98  is secured about the external surface of pipe  93  with lever  99  extending upwardly from extension  150  to extension  164 . Handle member  97  is linked to extension  148 . When installed valve assembly  32  is positioned below a frost line  200  and handle assembly  36  is positioned a suitable/comfortable distance (i.e. 2-4 feet) above a ground level  202 . 
     In operation, with handle extension  162  down (i.e., as illustrated in FIG.  2 ), wet pipe  94  and spool member  40  are in a closed position with second and third seals  44  and  42 , respectively, sealed between external surface  68  and internal sealing surfaces  50  and  52 , respectively. In this position, water at inlet  60  is blocked by closed surface  86  (see FIG.  3 ). In addition, referring to FIGS. 2 and 3, passages  76  and  78  are opened at least partially into second expanded section  56 . Thus, any water within flow channel  106 , wet pipe  94  or passage  70  is free to flow through passages  76  and  78  into expanded section  56  and thereafter out drain port  62 . 
     To turn on the hydrant, an operator grasps handle extension  162  and pulls upwardly and backwardly. When extension  162  is so pulled, cam extension  164  and lever  99  align vertically forcing outlet spigot  100  upward. As spigot  100  is forced upward, because wet pipe  94  is securely attached thereto and spool member  40  is securely attached to lower end  112  of wet pipe  94 , both wet pipe  94  and spool member  40  are forced upwardly. Cam extension  164  and lever  99  are sized such that when they align vertically, spool member  40  travels upward within housing  48  such that passages  76  and  78  are aligned with first expanded section  54  and therefore are aligned with inlet  60 . When so aligned, first and second seals  44  and  46  form watertight seals between external surface  68  and sealing surfaces  50  and  52 , respectively. As passages  76  and  78  are open to inlet  60 , pressurized water at inlet  60  is forced through passageway  70 , wet pipe  94  and flow channel  106  to outlet  108 . 
     Now, assuming hydrant components are in the open position (i.e., passages  76  and  78  are aligned with inlet  60 ), it will also be assumed that outlet  108  is blocked for some reason, (i.e., a hose linked to outlet  108  is closed). In this case, pressure builds up within channel  106 , wet pipe  94 , passageway  70  and expanded section  54 . Now, assuming handle extension  162  is forced into the closed position illustrated in FIG. 2 to close the hydrant, as the handle is pushed downward, second seal  46  slides along sealing surface  52  to a bottom edge thereof just above expanded section  56  (see also FIG.  4 ). In the prior art hydrant design, pressure built up in channel  106  and wet pipe  94  flows through the clearance between surface  48  and surface  68  on the spool and builds up in recess  82  behind seal  46  tending to force seal  46  out of recess  82  and down toward section  56 , seal  46  many times becoming unseated and therefore resulting in an ineffective seal. 
     According to the present invention, venting passages  166  reduce pressure on seal  46  and therefore appreciably reduce the likelihood of seal  46  becoming unseated. In this manner, as the pressure within wet pipe  94  forces seal  46  slightly out of recess  82 , a venting path between seal  46  and a back surface of recess  82  opens allowing the pressure to be released through venting passage  166  into expanded section  56  and then out drain port  62 . Because there is minimal clearance between surface  48  on the body and surface  68  on the spool and this is the only route for water to reach the seal cavity, the pressure built up behind the seal drops quickly with a small flow through the vent. After the pressure has been released, seal  46  springs back into recess  82  and water within channel  106  and wet pipe  94  drains through passages  76  and  78  and around seal  46  to drain out of port  62 . 
     It should be appreciated that the present invention serves three purposes. First, by providing the venting passage(s) seals which are under high pressure are not forced out of their respective recesses. Second, by providing a wet pipe which has an external diameter which is nearly identical to the internal diameter of the dry pipe, a relatively inexpensive material (i.e., PVC) can be used to form the wet pipe, the dry pipe  93  guiding the wet pipe  94  therein. Third, the inventive collar design reduces handle assembly rotation and helps to maintain a constant stroke for turning the hydrant on and off. 
     It should be understood that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. 
     To apprise the public of the scope of this invention, the following claims are made: