Fluid handling – Freeze condition responsive safety systems – Low temperature responsive drains
Reexamination Certificate
2000-09-29
2002-04-23
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Freeze condition responsive safety systems
Low temperature responsive drains
C137S218000, C137S557000
Reexamination Certificate
active
06374849
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
This invention relates to a test cock apparatus with freeze protection capability particularly intended not only for monitoring the pressure and flow of fluid through a valve, such as a backflow prevention valve, but also for preventing the fluid traveling therethrough from freezing. The apparatus incorporates a test cock for use in testing pressure and fluid flow with a thermal actuator element like those used in conventional freeze protection elements. Although the invention of the present application may be used in any suitable environment in which the flow of a liquid must be controlled, the invention is preferably intended for use on a backflow preventer.
A backflow preventer is a well known device commonly used to prevent pollutants originating from downstream sources from contaminating potable water supplies. A typical backflow preventer includes two spring-loaded check valves positioned in serial combination within a housing for preventing backflow of a fluid. Thermal actuator elements are likewise well known, and are commonly used in freeze protection elements. A typical freeze protection element is positioned within a housing having inlet and outlet passages through which fluid enters and exits, respectively. The freeze protection element is normally in sealing engagement with a relief port which is defined by the housing for discharging fluid therefrom in response to changes in temperature. Fluid entering the inlet passage and passing through the interior of the housing encounters the thermal actuator element, which in turn contracts in response to decreased fluid temperature. As the temperature approaches freezing, the actuator contracts enough to disengage the freeze protection element from the relief port which allows the near-freezing water to pass through the relief port and out of the housing. As the cold water exits the housing, the corresponding increase in temperature of the water remaining inside causes the thermal actuator to expand and the freeze protection element to close.
The invention of the present application takes advantage of the fundamental principles underlying freeze protection elements to provide a test cock apparatus having unique freeze protection capabilities. The test cock apparatus of the present invention makes use of a thermal actuator element positioned in a bronze housing. The housings of most freeze protection elements include inlet and outlet passages positioned in alignment with each other. In contrast, the housing of the test cock apparatus of the present invention lacks an outlet passage and instead defines an inlet passage which is positioned and extends perpendicularly to a narrow discharge passage. The thermal actuator is positioned within the housing perpendicular to the inlet passage and is in alignment with and upstream from the discharge passage. The thermal actuator includes a thermosensitive element which expands in response to increased ambient air and system fluid temperatures to push a spring-guided plug into sealing engagement with the discharge passage. The thermosensitive element contracts in response to decreased ambient air and system fluid temperatures, thereby causing the plug to disengage the passage for permitting near-freezing fluid to pass through.
The invention of the present application employs inlet and discharge passages which are innovatively positioned relative to each other and to the thermal actuator and test cock. The invention also combines the fluid and pressure monitoring capabilities of a test cock valve with the thermodynamic principles underlying freeze protection elements to provide a unique test cock apparatus for ensuring that adequate fluid temperature, pressure and flow are maintained within a valve housing.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide a test cock apparatus which is not only capable of monitoring fluid pressure and flow within a valve housing, but also of ensuring that the fluid passing through the valve housing does not freeze.
It is another object of the invention to provide a test cock apparatus having components which are not permanently connected to one another or to an external object, thereby allowing ease of access to and repair of the components.
It is another object of the invention to provide a test cock apparatus with freeze protection capabilities which may be directly attached to another valve, such as a backflow preventer valve, or to another test cock which is in turn attached to the backflow preventer valve.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a test cock apparatus with freeze protection capability for controlling fluid pressure and flow in a backflow preventer valve. The test cock apparatus includes a valve housing having interior walls defining a chamber therein and including an inlet port and a discharge port communicating with the chamber for permitting fluid flow therethrough. A temperature-responsive freeze protection element is positioned within the chamber and is axially moveable between a closed position in sealing engagement with the interior walls of the valve housing for preventing fluid flow through the discharge port, and an open position out of sealing engagement with the walls of the valve housing for permitting passage of fluid through the discharge port. A test cock communicates with the chamber of the valve housing for monitoring fluid pressure therein.
According to one preferred embodiment of the invention, the inlet port is positioned perpendicular to the discharge port.
According to another preferred embodiment of the invention, the test cock is positioned in axial alignment with the inlet port and perpendicular to the discharge port.
According to yet another preferred embodiment of the invention, the freeze protection element includes a thermal actuator disposed within the valve housing for moving the freeze protection element to the closed position by expanding in response to increasing fluid temperature and to the open position by contracting in response to decreasing fluid temperature.
According to yet another preferred embodiment of the invention, the freeze protection element further includes a spring captured in the chamber of the valve housing for moving the freeze protection element in and out of sealing engagement with the walls of the valve housing in response to a respective increase or decrease in fluid temperature.
According to yet another preferred embodiment of the invention, the freeze protection element further includes a spring guide plug having a first end adapted for receiving the thermal actuator therein and a second end adapted for moving in and out of sealing engagement with the walls of the valve housing in response to the respective increase or decrease in fluid temperature.
According to yet another preferred embodiment of the invention, the spring is concentrically positioned along the length of the spring guide plug, and the first end of the spring guide plug includes a flange for capturing the spring between the first and second ends, thereby permitting the spring to expand and contract in response to the respective contraction and expansion of the thermal actuator for moving the second end of the spring guide plug in and out of sealing engagement with the walls of the valve housing in response to the respective increase or decrease in fluid temperature.
According to yet another preferred embodiment of the invention, the second end includes a beveled portion. An O-ring is captured in an annular groove extending around the second end adjacent to the beveled portion. The walls of the valve housing define a complementary chamfered shoulder for cooperating with the beveled portion and the O-ring for sealingly engaging the second end of the spring guide plug with the walls.
According to yet another preferred embodiment of the invention, a backflow preventer for protecting fluid sources from pollutants is disclosed. The backflow preventer valve
Adams, Schwartz & Evans P.A.
Conbraco Industries, Inc.
Michalsky Gerald A.
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