Fluid handling – Hydrant type – Movable riser actuated valve
Reexamination Certificate
1998-12-11
2001-01-30
Walton, George L. (Department: 3753)
Fluid handling
Hydrant type
Movable riser actuated valve
C137S292000, C137S307000, C251S231000, C251S279000, C251S344000, C251S347000, C251S349000, C251S353000, C251S900000
Reexamination Certificate
active
06178988
ABSTRACT:
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
Baker Manufacturing
Quarles & Brady LLP
Walton George L.
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