Abstract:
A yard hydrant has an elongated wet pipe with a plunger that seals against the inside of a well casing. Lifting a pivoting handle at the top of the wet pipe lowers the wet pipe which opens a normally closed supply valve. Pressurized water can then flow up the wet pipe and out of a nozzle head mounted to the upper end of the wet pipe. Lowering the handle pulls the wet pipe upward, thereby clearing it from the supply valve which is spring biased to shut off the water supply. The handle has a cam that positively actuates a normally closed anti-siphon valve so that water left in the wet pipe can fall under gravity to a collection chamber within the well casing beneath the piston. Lifting the handle again lowers the wet pipe and forces the water in the collection chamber back up the wet pipe. At the same time, the anti-siphon valve will close and the wet pipe re-opens the supply valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not applicable. 
   STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to hydrants and more particularly to freeze-resistant in-ground sanitary yard hydrants. 
   Yard hydrants are installed in water systems to provide water sources remote from buildings. In low temperature climates, such as the mid-west and east coast of the United States, the water lines are buried below the frost line to prevent them from freezing and bursting. Similarly, the lower ends of the hydrants are buried below the frost line to prevent damage to the hydrant arising from freezing. Because the water must reach above ground, the upper part of the hydrants extends up through and above the ground (above the frost line), and is thus subject to the adverse effects of low temperatures. 
   Typical yard hydrants have a main water supply valve, a dry pipe, a wet pipe and an activation handle. The dry pipe is secured to the main valve housing where the water line is connected below the frost line. The dry pipe then extends up through the ground to a comfortable operating position above ground level. The wet pipe is positioned within the dry pipe and its lower end activates the main valve to turn off and on the water supply. The handle is mounted to the top end of the dry pipe and is linked to the upper end of the wet pipe to raise and lower the wet pipe and thereby control the valve from above ground. The upper end of the wet pipe has a spigot which can connect to a hose or spray out the water directly. To turn off the hydrant, an operator moves the handle to move the wet pipe and close the valve. Any water in the wet pipe will drain out of the hydrant below the frost line, and thereby prevent water from freezing within the hydrant. U.S. Pat. No. 6,178,988 discloses one such hydrant design. 
   One problem with such hydrants is the presence of the drain to evacuate the water in the hydrant. The drain opening raises two concerns. First, if water is drained from the hydrant it may be necessary to create a drain field so that the water does not accumulate around the hydrant. This makes installation much more labor intensive, time consuming and costly. Also, dispensing water underground may be regulated in certain areas. Second, the drain opening provides an entry point for underground contaminants into the hydrant, which can make the water dispensed by the hydrant less sanitary. This second issue is particularly a problem when valve seals become worn, dislocated or less resilient. 
   U.S. Pat. No. 6,047,723 discloses a hydrant that collects the water left in the hydrant after it is turned off in a cylinder installed below the frost line. The water collected in the cylinder is purged by a piston back up through the hydrant when the water supply is turned on again. The disclosed hydrant includes a drain opening that is ordinarily isolated from the water collected in the cylinder by one or more o-rings such that normally no water is drained underground. However, should an o-ring fail the water collected water would leak underground. If the o-ring failed while the water supply was on, supply water could be diverted from the hydrant, which could not only flood the area underground surrounding the hydrant but also reduce the water pressure leaving the hydrant above ground. 
   To avoid these concerns, no-drain hydrants have been devised (see e.g., U.S. Pat. Nos. 3,936,207 and 5,701,925). In such no-drain hydrants, water left in the upper part of the hydrant is collected in a well chamber of the hydrant below the frost line. This chamber is enclosed with no openings (other than for the supply water inlet) that could cause leakage or be an entry point for contamination. Since the chambers are enclosed it is possible for a vacuum to form inside the hydrant which can cause two problems. First, the vacuum can pull water back into the hydrant from a hose or other attachment, which can impact the sanitization of the water and may be prohibited by regulation in certain areas. Second, the vacuum can impede or prevent all of the water left in the hydrant from draining into the well chamber. Water can thus remain above the frost line and freeze, thereby leading to damage or failure of the hydrant. 
   U.S. Pat. No. 3,926,207 discloses a hydrant having a pair of check valves located in the head of the hydrant (above ground) that will vent the collection chamber to ambient. The check valves are normally open so that the hydrant is vented when off. Water pressure closes the valves when the hydrant is on. One problem with this design is that there is no positive actuation of the valves to ensure they open to vent the hydrant. The check valves in the disclosed hydrant are spring flapper type valves that are biased open. The spring force is overcome by the force of the pressurized water, which when shut off allows the check valves to re-open. Such a valve arrangement is prone to failure, particularly when the air temperatures are below freezing, in which case water on and around the check valves can freeze causing ice to build up on or around the valves, which can disrupt the seal or hold them closed. The result of this is that the water either sprays through the check valves or the check valves fail to vent the collection chamber causing the aforesaid back siphon problems. 
   SUMMARY OF THE INVENTION 
   The inventors of the present invention have recognized that in-ground hydrants should have an integral positively actuated anti-siphon valve to prevent back siphon from the well casing and better ensure that all the water in the hydrant properly collects in the well casing (below the frost line) when the hydrant is not operating. The hydrants should also be designed so that they can be installed and serviced more readily from above the ground. The inventors determined that this aim can be furthered by avoiding side feed valve arrangements, for example instead using straight or axially aligned feed valves. It has also been recognized that maintenance of the hydrants and underground leakage can be reduced significantly by reducing or eliminating components that tend to fail over time. 
   Consistent with the above, in at least one embodiment the hydrant of the present invention includes a handle, an elongated wet pipe, a well casing, a supply valve and an anti-siphon valve. The wet pipe is movable and defines a flow passage between open ends. One end has a plunger head that slidably seals against the inside of the well casing to define a collection chamber that is in fluid communication with the flow passage of the wet pipe and a supply opening having a supply valve actuated by the wet pipe. The anti-siphon valve is actuated by the handle to vent the collection chamber to ambient. 
   In other preferred embodiments of the hydrant, the anti-siphon valve is normally closed by a spring, but is opened (when the supply valve is closed) by direct contact with the handle when the handle is in an “off” position. More preferably, the handle includes a valve cam positioned to contact and open the anti-siphon valve when the handle is in the off position. The valve cam can be a convex surface of the handle, and can pivot with the handle to release or clear the anti-siphon valve when the handle is in an “on” position. Like the anti-siphon valve, the supply valve can also be spring biased closed. 
   Thus, when the wet pipe is lowered so that the hydrant is in the on position, it will force the supply valve open against the spring to allow water to flow up into the wet pipe. When the hydrant is on, the anti-siphon valve will be in its normally closed state. When the wet pipe is raised up clear of the supply valve so that the hydrant is off, the supply valve will close on its own to shut off the water supply. The valve cam will then contact an unseat the anti-siphon valve and hold it open. This will vent the collection chamber (via the wet pipe) to ambient so that there is no back siphon out of the hydrant or any pressure that would prevent the water in the wet pipe from flowing under gravity to the collection chamber. Note that as the wet pipe moves up off of the water valve, the collection chamber will increase in volume until the wet pipe returns to its highest position when the hydrant is off. In this position, the collection chamber will be large enough to hold all of the water left in the wet pipe. 
   In other embodiments, the wet pipe, well casing and supply valve are all centered along a longitudinal (or vertical) axis. This gives the hydrant a slender profile and a small footprint allowing the hydrant to be installed in a small hole. Preferably, the well casing is a single cylindrical tube with an outer surface defining an exterior of the hydrant and an inner surface defining the collection chamber. The bottom and top of the well casing is capped and the bottom end cap contains the supply valve. Water in the collection chamber is displaced by the plunger head, which preferably includes a pusher plate and a cup seal, back up through the wet pipe when the hydrant is on. Also, the supply valve is preferably a self-contained cartridge that threads in place at the bottom of the well casing. It can be serviced, installed and replaced from above ground using a long socket wrench. 
   In still other embodiments, the hydrant has a nozzle head at the upper end of the wet pipe, which preferably mounts the handle. A pair of links extend between and pivotally connect the handle and a fixed collar member. Lifting (pivoting upward) the grip end of the handle causes the links to push the wet pipe down onto the supply valve to turn the hydrant on. Pushing down (pivoting downward) the handle cause the links to lift the wet pipe up off of the supply valve. As mentioned, in this position the valve cam of the handle engages the anti-siphon valve to vent the wet pipe and collection chamber. The anti-siphon valve is preferably an integral part of the nozzle head. Specifically, it is positioned in a small passage between a vent opening to ambient and the main outlet passage, which communicates with the wet pipe at all times. Any time the hydrant is off, the anti-siphon valve is held open by the cam to vent the wet pipe. 
   These and other advantages of the invention will be apparent from the detailed description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a yard hydrant according to the present invention; 
       FIG. 2  is an exploded assembly view thereof; 
       FIG. 3  is sectional view taken along line  3 — 3  of  FIG. 1  of the hydrant in an “off” position; 
       FIG. 4  is an enlarged sectional view showing a siphon valve opened by a cam when the hydrant is in the off position as shown in  FIG. 3 ; and 
       FIG. 5  is a sectional view similar to  FIG. 3  albeit showing the hydrant in an “on” position; 
       FIG. 6  is an enlarged sectional view showing the siphon valve normally closed as when the hydrant is in the off position shown in  FIG. 5 ; and 
       FIG. 7  is an enlarged sectional view showing a supply valve opened by the lower end of the wet pipe when the hydrant is in the on position shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings wherein like reference characters represent corresponding elements throughout the several views, the present invention will be described in the context of an exemplary yard hydrant  10 . Referring to  FIG. 1 , the hydrant  10  generally includes a pipe assembly  12 , a nozzle head  14  and a handle assembly  16 . 
   As shown in  FIG. 2 , the pipe assembly  12  includes a well casing  18 , a wet pipe  20  and a stand pipe  22  all being generally elongated cylinders concentric with axis  24  made of PVC or galvanized metal. The well casing  18  has the largest diameter and is capped at both ends by end caps  26  and  28 . Lower end cap  26  fits over the bottom end of the well casing  18  and defines a supply opening  30  concentric with the axis  24  to which a water supply line (not shown) is coupled by any suitable means. The lower end cap  26  also defines a threaded pocket  32  in which a supply valve cartridge  34  is threaded. The valve cartridge  34  housing is preferably made of plastic, such as nylon, having good sealing properties. 
   A rubber gasket  35  is disposed at the interface between the valve cartridge  34  and the lower end cap  26 . An upper end of the valve cartridge  34  defines a hex head  37  (best seen in  FIG. 2 ) which fits into the socket (not shown) of an elongated tool for turning the valve cartridge  34 . The socket preferably has detents that snap onto the hex head  37  so that the valve cartridge  37  can be lowered into the well casing  18  and raised up out of the well casing  18  at the end of the socket from above ground through an upper end of the well casing  18 . 
   As best seen in  FIG. 7 , the valve cartridge  34  includes a spring  36  that biases a brass valve head  38  against a valve seat  40 . The valve head  38  has an upper portion  42  that projects axially up through the valve seat  40 , a tapered circumference section  44  and a stem  46  (about which the spring  36  fits) mounting a pair of annular seals  48 . The tapered section  44  of the valve head  38  creates a line seal with the inner diameter of the valve seat  40  and seals  48  create a surface seal (see  FIG. 3 ). The supply valve  34  is normally closed because the spring  36  holds the valve head  38  against the valve seat  40  (as shown in  FIG. 3 ) in the absence of a downward axial force. When the valve head  38  is forced axially downward against the spring  36 , the valve head  38  unseats so that the water supply opening  30  is in communication with the bottom of the well casing  18  (see  FIGS. 5 and 7 ). 
   Referring to  FIGS. 1–3 , the upper end of the well casing  18  is capped by the upper end cap  28  which fits down into the top of the well casing  18  and mounts an o-ring seal  50  sealing against the inner diameter of the well casing  18 . Three fasteners  52  secure the upper end cap  28  to the well casing  18 . These fasteners can be removed to remove the upper end cap  28  and allow access inside of the well casing  18  for service from above the ground. The upper end cap  28  has an axial opening  54  through which the wet pipe  20  slides and a short cylindrical section  56  in which fits a lower end of the stand pipe  22 , secured fixed in any suitable manner. The upper end of the stand pipe  22  is capped by end cap  58  having an axial opening  60  for the wet pipe  20 . A split metal collar  62  is clamped around the end cap  58 . 
   The wet pipe  20  has the smallest diameter, which defines an internal flow passage  64 . The lower end of the wet pipe  20  has a plunger  66  secured thereto which is made up of an annular, preferably PVC, pusher  68 , which has a septum  70  in the middle, and a downwardly opening cup seal  72 , made of a suitable reinforced rubber or other elastomeric material, slidably sealing against the inner diameter of the well casing  18 . The space defined by the cup seal  72 , the well casing  18  and the lower end cap  26  defines a collection chamber  74 , which has a variable volume that expands and contracts as the wet pipe  20  is moved along the axis  24 , as described below. 
   The collection chamber  74  portion of the hydrant  10  must be located below the frost line to avoid freezing of the hydrant  10 . This depth varies by region, however in the mid-west United States for example, it is about 3–6 feet below ground. The length of the well casing  18  is thus a function of this bury depth plus an additional height above ground height, typically 12–18 inches. The length of the wet pipe  20  varies as well and is typically several inches longer than the well casing  18 . The stand pipe  22  is a set length, 10 inches for example. 
   The upper end of the wet pipe  20  mounts the nozzle head  14  and the handle assembly  16 . Referring to  FIGS. 1–4 , the nozzle head  14  is preferably cast iron and defines a right angle outlet passage  76  in communication with the wet pipe flow passage  64 . A suitable connection can be provided at the outlet passage port to connect a hose or other implement, if desired. The nozzle head  14  also has a vent passage  78  opening to ambient air and leading to a short vertical passage  80  in which an anti-siphon valve  82  is disposed. The vertical passage  80  extends between the outlet passage  76  and the vent passage  78  so that when the anti-siphon valve  82  is open, the collection chamber  74  of the well casing  18  is vented to ambient via the wet pipe flow passage  64  and the outlet passage  76 . 
   As shown in  FIG. 6 , the anti-siphon valve  82  includes a spring  84  that fits around a valve member  86  and bears against a surface of the nozzle head  14  and an upper end  88  of the valve member  86 . The spring  84  biases the valve member  86  to seat a valve head  90  against a valve seat  92  and thereby isolate the vent passage  78  from the outlet passage  76 . As shown in  FIG. 4 , the anti-siphon valve  82  is opened by contact of a valve cam  94  formed at the end of a handle member  96 , which is preferably made of metal. The valve cam  94  is a convex surface of the handle  96  near the pivotal connection of the handle  96  to the nozzle head  14 . When the handle  96  is down as shown in  FIG. 4 , the valve cam  94  physically contacts the upper end  88  of the valve member  86  and drives it downward to unseat the valve head  90  from the valve seat  92 . The positive contact of the valve cam  94  ensures that the anti-siphon valve  82  will open and not be stuck closed. When the handle  96  is pivoted upward as shown in  FIG. 6 , the valve cam  94  pivots away from, and preferably clears, the upper end  88  so that the spring  84  can drive the valve member  86  upward to seat the valve head  88  against the valve seat  92 . In the preferred embodiment shown, the valve head includes a rubber seal  93  creating a surface seal against the valve seat  92 . 
   A small spring latch  100  disposed in a pocket in the handle  96  latches the handle  96  in the “off” position shown in  FIG. 4  by engaging a surface of the nozzle head  14 . By pushing the upper end of the latch with a thumb or finger, it can be dislodged from the nozzle head  14  so that the handle  96  can be pivoted upward to the on position shown in  FIG. 6 . The spring latch  100  automatically latches again when the handle  96  is returned to the off position. 
   The handle  96  is connected by a pair of metal links  110  to the collar  62 . The links  110  can pivot as the handle  96  pivots, and because the collar  62  is fixed in place, the links  110  impart an axial motion to the wet pipe  20  and all the components connected thereto. Specifically, as the handle  96  is lifted up to the on position shown in  FIG. 6 , the wet pipe  20  moves vertically downward and as the handle  96  is pushed down to the off position shown in FIG.  4 , the wet pipe moves vertically upward. 
   The hydrant  10  thus operates as follows. The hydrant  10  is off when as shown in  FIG. 3 . In this position, the normally closed supply valve  34  is closed so that no water from the water supply line can flow into the well casing  18  and out of the nozzle head  14 . Any water that would have been left in the wet pipe  20  or the nozzle head  14  will have drained down into the collection chamber  74 , which has a volume equal to or greater than that of the wet pipe  20  and the outlet passage  76  of the nozzle head  14 . The anti-siphon valve  82  is held open by the valve cam  94  to prevent back siphon and relieve any vacuum that may prevent the water from draining freely under gravity to the collection chamber  74 . 
   The hydrant  10  is turned on by lifting the handle  96  upward to the on position shown in  FIG. 5 . Doing so, drives the wet pipe  20  downward. The plunger  66  in turn drives the water in the collection chamber  74  up into the flow passage  64  of the wet pipe  20 . When the wet pipe  20  is all the way down, the septum  70  contacts the upper part  42  of the valve head  38  so as to unseat it and open the supply valve  34 . Pressurized water from the water supply line can thus flow into the hydrant  10 , up through the wet pipe flow passage  64  and out the nozzle head outlet passage  76 . Note that when the supply valve  34  is open, the anti-siphon valve  82  is closed, since the valve cam  94  is moved out of the way. The hydrant  10  is turned off by pushing the handle  96  down, thereby lifting the wet pipe  20  off of the supply valve  34 , allowing it to close. The handle  96  forces the valve cam  94  to open the anti-siphon valve  82  which allows the water in the flow passage  64  and the outlet passage  76  to drain down into the collection chamber  74 . 
   It should be understood that the apparatus described above is only exemplary and does 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: