Fluid handling – Hydrant type – With casing
Reexamination Certificate
1999-02-09
2001-04-17
Walton, George L. (Department: 3753)
Fluid handling
Hydrant type
With casing
C137S301000, C137S334000, C137S340000, C137S375000, C137S801000, C137S849000, C138S032000, C165S045000, C165S104210
Reexamination Certificate
active
06216722
ABSTRACT:
TECHNICAL FIELD
In general, the present invention relates to hydrants employed for intermittently dispensing water. More particularly, the present invention relates to a freeze-resistant hydrant. Specifically, the present invention relates to a yard or building hydrant assembly that employs a regenerative heat-transfer medium to continuously maintain an above-ground valve and water supply pipe at a temperature that precludes freezing.
BACKGROUND ART
Yard hydrants have long been employed to dispense water supplied by underground water pipes at various locations where needed. For the most part, these hydrants can be relatively simple and inexpensive, yet provide reliable service over extended time periods. A problem arises, however, in areas where below-freezing temperatures are encountered because the valve pipes and control valves are commonly located at or a few feet above ground level and thus are fully exposed to outside temperatures. When water in a control valve or water pipe freezes, the expansion of the water in its frozen state often causes damage to a control valve or pipe. Thereafter, when the frozen water thaws, the water uncontrollably escapes, thereby creating the possibility of water damage, besides the loss of valuable water supply.
In some applications, it is possible to merely shut off the water pressure source to the hydrant when there is a chance of freezing temperatures and to drain down the exposed portion of the water line above ground and a distance below the surface of the ground to a depth below the frost line for a particular geographic area. In many other applications, it is not possible to merely shut down the hydrant in this manner during potentially freezing weather conditions due to the necessity to have it continually operable for purposes of watering livestock or the like.
In some instances, electrical heating elements have been employed to prevent water in hydrants from freezing. However, such heating devices are relatively expensive, require substantial work and expense to install and maintain, and tend to consume substantial electrical power in employing relatively inefficient electrical resistance units. In addition, there are a vast number of locations where hydrants are installed that electrical power is not readily available. Further, a loss of electrical power, even for a short time period, can result in the water freezing and the attendant damage to the pipe and/or control valve.
The other approach that has been emplpoyed to prevent freezing besides permanent shutdown or the use of a heat source to maintain the water above freezing involves systems that effect a temporary drain down any time that water flow is discontinued. Some such systems employ a stop cock position led below the freezing line with provision for draining the water from the vertical pipe between the stop cock and the above-ground control valve. In some instances, this is effected by employing a small weep hole in the vertical pipe below ground and normally proximate to the below-ground stop cock. Such weep holes are normally on the order of one-sixteenth of an inch in diameter to permit the water to drain into the ground. Systems of this type do have disadvantages. First, it is possible for contaminated water in the ground to enter the weep hole and contaminate the water when the stop cock is opened and water flow to the control valve is resumed. A common source of such contaminated water arises from usage of a spray nozzle for dispensing insecticides and fertilizers where back flow through the weep hole may result and the water source may be thus contaminated. Another problem with the weep hole approach is that rust may readily form at the weep hole after a period of time and result in blockage of the weep hole. In such instance, the water is unable to drain down, which, upon the occurrence of freezing temperatures can result in damage and breaking of the vertical pipe and/or the control valve.
Another type of temporary drain-down system contemplates connecting the vertical pipe to a tank, which permits water in the vertical pipe to drain down into the tank. In such systems, a venturi is positioned in the line, such that the tank is pumped out when water flow is resumed so that it is then ready to receive drain-down water when water flow is again discontinued. While this system is a closed system that does not permit discharge of water into the ground or possible return flow of contaminated ground water, there is nevertheless a build-up of bacteria in the tank that is expelled when water flow is resumed, particularly when the hydrant stands for substantial time periods without being actuated to clear the tank.
Thus, all known systems for preventing freezing of yard hydrants and the like are subject to limitations and disadvantages that can result in either the water becoming contaminated or in freezing of the water under circumstances that are likely to intermittently occur.
DISCLOSURE OF THE INVENTION
Therefore, an object of the present invention is to provide a freeze-resistant yard hydrant that is a closed system that does not rely upon the egress of water to and possible ingress of water from the surrounding soil. Another object of the present invention is to provide such a yard hydrant that does not rely upon the presence and continuity of electrical power to the yard hydrant assembly. A further object of the present invention is to provide such a yard hydrant that employs a regenerative heat-transfer medium in a sealed heat-transfer tube that migrates within said heat-transfer tube to transfer underground heat to the control valve and a portion of the water delivery for the hydrant.
Another object of the present invention is to provide a freeze-resistant yard hydrant employing a heat-transfer medium in the form of a fluid with a boiling point under vacuum of approximately 30 degrees Fahrenheit in a closed container that, with underground warming, creates a vapor that rises and contacts the cooler water line and control valve that condenses the vapor, such that it returns to the below-ground location in a liquid form. A further object of the present invention is to provide such a yard hydrant assembly wherein the heat-transfer tube enclosing a heat-transfer fluid extends from a position below ground, where the temperature is substantially above freezing, upwardly to encompass the vertical portion of the water line and to a position in proximity to the control valve at the top of the water pipe. A further object of the invention is to provide such a yard hydrant wherein a heat-transfer tube is evacuated prior to the introduction of the heat-transfer fluid to preclude the formation of entrapped air pockets in said heat-transfer tube. A further object of the present invention is to provide such a yard hydrant assembly wherein the heat-transfer tube extends a sufficient distance below the water line and has a sufficient surface area so as to provide a temperature differential whereby the heat-transfer mediumn maintains water in the water line and control valve at a temperature above freezing at the most extreme lower range of air temperature encountered in a geographic area where the hydrant is installed.
Still another object of the present invention is to provide a freeze-resistant yard hydrant assembly that is capable of operating for extended time periods without the necessity for servicing, maintenance, or other attention. Yet another object of the present invention is to provide such a yard hydrant that is relatively inexpensive in terms of material and installation costs and that is essentially cost-free thereafter in operation. Yet another object of the invention is to provide such a yard hydrant that may be readily installed by persons without technical expertise in that the configuration is relatively non-complex and does not require any extent of calibration or other adjustment upon installation or in subsequent operation.
In general, the present invention contemplates a freeze-resistant hydrant extending between a first area having a temperature at leas
Renner Kenner Greive Bobak Taylor & Weber
Walton George L.
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