Fluid handling – Liquid level responsive or maintaining systems – By float controlled valve
Reexamination Certificate
1999-10-13
2001-07-24
Lee, Kevin (Department: 3753)
Fluid handling
Liquid level responsive or maintaining systems
By float controlled valve
C137S563000, C004S508000
Reexamination Certificate
active
06263906
ABSTRACT:
TECHNICAL FIELD
This invention relates to controllers for maintaining a desired fluid level in a fluid reservoir, and more particularly to a mechanical controller which automatically admits fluid from an auxiliary fluid reservoir into a primary fluid reservoir to maintain the level of the fluid in the primary reservoir at a predetermined level, and which further completely removes the risk of overflow to the primary reservoir.
BACKGROUND OF THE INVENTION
BACKGROUND ART
Fluid level controllers are used in a wide variety of applications to monitor the level of fluids in reservoirs or containers to ensure that a desired fluid level is maintained. Most often, such fluid level controllers are of an electrical type which senses the level of fluid in the reservoir being monitored and determines, electronically, when and how much fluid to add from a supply source to maintain the level of fluid in the reservoir at a desired level. However, such electronic controllers suffer from several drawbacks. For one, such controllers require an external power source to power the electronic components. This limitation makes an electronic controller susceptible to malfunctioning caused by a power outage. When the fluid reservoir being monitored is needed for a manufacturing operation, even temporary malfunctioning of the electronic controller can seriously disrupt a manufacturing process. If the reservoir being monitored is used in a chemical manufacturing process, a fluid shortage can affect the desired composition of the fluid, thereby detrimentally affecting the manufacturing process itself or components manufactured from the process. Conversely, an overflow of the reservoir is equally problematic since the contents of the primary reservoir often comprise a chemical composition which can represent a serious hazard to the environment should the reservoir overflow. Thus, preventing an overflow of the reservoir is just as important as maintaining a proper fluid level therein and, in some instances, even more important.
Electronic controllers are often relatively complicated devices having a number of independent parts that are susceptible to temperature, humidity and other environmental factors. Failure, or even intermittent malfunctioning, of just a single electronic component can often result in malfunctioning of the entire controller and hence overflow of the primary reservoir.
Still another drawback with conventional electronic controllers is their cost. These devices often represent a significant investment to the user. Installation is also not always straightforward and often requires highly skilled technicians to install and calibrate the controller. Frequently re-calibration of an electronic controller is needed to maintain optimum performance.
Another option for maintaining a fluid level within a reservoir at a desired level is simply periodically manually adding fluid as needed. Obviously, this also has a number of drawbacks, not the least of which is the manpower required to continuously monitor the reservoir and to add fluid as needed. This method is also susceptible to human error and does not lend itself easily to those applications where refilling is needed on a highly frequent basis to maintain the fluid level of a reservoir within a narrow predetermined range.
Accordingly, it is a principal object of the present invention to provide a fluid level controller which can be reliably used to maintain the level of a fluid within a fluid reservoir with no risk of overflow to the reservoir, and without the need for an electrically powered circuit for monitoring and adding fluid to the reservoir as needed.
It is another object of the present invention to provide a fluid level controller which is completely mechanical in its operation, and therefore which is not susceptible to the shortcomings of electronic fluid level controllers.
It is another object of the present invention to provide a fluid level controller which is operable to monitor the level of, and replenish if needed, the fluid within a primary reservoir without the need for complicated electronic fluid level monitoring equipment.
It is another object of the present invention to provide an entirely mechanical fluid level controller which operates to monitor and precisely add fluid, as needed, to a primary reservoir, and which eliminates entirely the chance of an overflow of the primary reservoir because of having added too much fluid to the primary reservoir.
It is still another object of the present invention to provide a fluid level controller that requires virtually no periodic maintenance, can be implemented in a variety of operating environments with little or no modification to a reservoir with which it is used, is cost efficient to construct and operate, and is generally not susceptible to variations in ambient temperature, humidity or other environmental factors which could affect conventional electronic controller systems.
SUMMARY OF THE INVENTION
The above and other objects are provided by a fluid level controller in accordance with preferred embodiments of the present invention. The fluid level controller of the present invention is a strictly mechanical fluid level controller that requires no source of electrical power for its operation. As such, it is unaffected by electrical power outages, power surges or “brown outs”. The controller of the present invention, being mechanical in nature, is not affected by temperature, humidity or other environmental factors which limit the effectiveness of electronic controller systems which frequently require a number of sensitive electronic components for their operation, which components can also be significantly affected by the above-mentioned environmental factors.
The controller of the present invention makes use of an auxiliary reservoir which has a fluid outlet coupled to an inlet of a primary reservoir by a conduit. Preferably, this is a U-shaped conduit. The level of the fluid in the primary reservoir is the level which is ultimately controlled by the controller of the present invention. The fluid in the conduit experiences or “sees” the hydrostatic pressure exerted by the fluid in the primary reservoir. Thus, as the fluid level in the primary reservoir drops, such as because of evaporation, the hydrostatic pressure sensed by the fluid in the auxiliary reservoir, at the inlet of the primary reservoir, drops thus causing fluid to flow through the conduit into the primary reservoir in an attempt to maintain the fluid level in the primary reservoir at is former level.
Within the auxiliary reservoir is a float assembly which monitors the level of the fluid therein. The level of this fluid is set during installation of the controller to match the desired upper level of the fluid in the primary reservoir. An inlet of the auxiliary reservoir is coupled to a pressurized fluid source, such as a source of pressurized water. Importantly, the auxiliary reservoir includes an overflow drain conduit near an upper end thereof which is disposed at a lower elevational level than an upper edge of the primary reservoir. In this manner, there is little possibility of an overflow of the auxiliary reservoir and absolutely no risk of overflow at all to the primary reservoir. Additionally, it will be noted that the upper edge of the auxiliary reservoir is disposed at a lower elevational level than the upper edge of the primary reservoir to eliminate any possibility of an overflow of the primary reservoir.
The float assembly functions to admit pressurized fluid through a valve thereof once the float reaches a predetermined lower level. When the float rises to the predetermined upper level its internal valve closes, thus interrupting flow into the auxiliary reservoir. The float assembly thus functions to maintain the fluid level in the auxiliary reservoir at the predetermined upper level. Even a failure of the float assembly cannot cause an overflow of the primary reservoir because of the lower elevational positioning of the upper edge of the auxiliary reservoir, as well as the overflow drain condui
Harness & Dickey & Pierce P.L.C.
Lee Kevin
The Boeing Company
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