Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2002-09-30
2003-10-28
La, Anh V (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S604000, C137S312000
Reexamination Certificate
active
06639517
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of water leak detection systems utilizing a pair of electrical conductors or probes to detect the presence of an undesirable accumulation of water by changes in the electrical impedance between the two electrodes.
2. Description of the Related Art
Water leakage from various appliances and plumbing fixtures in residential and commercial buildings has often been a problem and has caused significant damage to a building's structure, trim and cabinetry. Many appliances in the home use or contain water. These include washing machines, dishwashers, hot water heaters, refrigerators, including those equipped with ice makers, and air conditioners. Any water leakage from these appliances could flow onto the underlying floor surface and thence down into the underlying floor structure. Flooring and floor support structures manufactured of wood are susceptible to rot if left in a wet or damp condition for an extended length of time. Even a slow or intermittent leak of water from under an appliance can, over enough time, cause sufficient damage to require the replacement of the flooring, subfloor, and supporting joists. These leaks, especially smaller ones, often cannot be detected visually due to the low clearance between the bottom of the appliance and the floor.
In addition to appliances, certain plumbing fixtures and devices located within cabinetry or vanities under kitchen and bathroom sinks are susceptible to leakage and are not readily visible. These may include compression joints used in drain fittings, garbage disposals and water filters. Slow or intermittent leakage from these joints and devices may go unnoticed and cause damage to expensive cabinetry as well as to the floor systems. Even a large, substantial leak may not be apparent from outside the sink cabinetry.
Several leak detection systems to detect and warn of water leaks are available in the prior art. These include systems utilizing a pair of electrodes which detect the presence of water by a means which utilizes a change of electrical resistance between the two electrodes. The presence of water or moisture, which is capable of conducting electricity, between the two electrodes lowers the electrical resistance between the two electrodes. The reduced resistance can be detected by an appropriate electrical circuit and used to activate an audible or visual alarm.
These leak detection systems generally work well for certain applications, particularly those for protecting large areas against large volumes of water leakage. However, their ability to detect slow or intermittent leaks is limited. For example, some systems utilize short lengths of electrodes, which are posited vertically and capable of detecting a volume of water of at least a minimum height located at the electrodes. Small leaks, or leaks which do not produce pools of water which reach the electrodes, will not be detected.
Other systems use a length of paired conductors or electrodes, mounted in parallel on a long substrate, such as a strip or tape. Some of these type incorporate an absorbent layer between the electrodes which aids in the detection of smaller volumes of leakage. To use these systems to protect a certain area, the strips must be manually positioned either in a circumferential pattern around the perimeter of the area or in an anfractuous or sinuous pattern across the area. The former pattern would not detect small or intermittent leaks which did not flow laterally from under the appliance. The latter requires the appliance first to be moved and then the strip or tape is manually configured and posited in the desired pattern. Moving the appliance is often impractical or inconvenient, while bending, folding and otherwise manipulating the tape or strip into the desired pattern may damage the tape or short-circuit or break the electrodes, as might happen as well when the appliance is moved back into its original position. In either case a qualified professional, rather than the homeowner, would usually be required to properly lay out and install the system.
SUMMARY OF THE INVENTION
The present invention is directed to a leak detection mat and system which satisfies the need for detecting slow or intermittent leaks from under appliances with limited accessibility and which may be installed quickly and easily. The leak detection mat comprises a thin base substrate of dimensions proportional to the area to be monitored or the size of the appliance, upon which a pair of electrodes is affixed in a pattern, such that substantially all points of the base substrate area are located between some point on each of the two electrodes. A layer of an absorbent, porous material is posited on top of the pattern of electrodes and is adhered to the base layer.
The leak detection system includes the leak detection mat, wherein one end of each electrode is connected to a sensing means which utilizes the electrical resistance between the two electrodes. When a leak occurs, water dripping on the absorbent layer would diffuse through the absorbent layer and reach the two electrodes, reducing the resistance between the two electrodes and thereby creating an electrically conductive path. The sensing means, comprised of an electrical sensing and transmitting circuit, is connected to the ends of each of the electrodes which could detect the change in resistance between the two electrodes and transmit a signal. The sensing and transmitting circuit may be posited directly on the base substrate. In one embodiment of the invention, the sensing and transmitting circuit would be powered by a small battery. The signal is transmitted to an alarm means, being a remote receiving and alarm station in the preferred embodiment, either by wires in one embodiment or by wireless means, such as radio waves, in the preferred embodiment. The receiving and alarm station is mounted in a more visible and accessible location, thereby giving timely notice to the building's occupants of a potentially destructive leak.
One object of this invention is to provide a leak detection device which can be easily installed under home appliances having a narrow clearance between its bottom surface and the floor.
Another object of this invention is to provide a leak detection device capable of detecting a small leak originating from anywhere under an appliance.
Another object of this invention is to provide a leak detection device capable of monitoring the entire area under an appliance, but which can be installed simply by sliding the detector under the appliance.
Another object of this invention is to provide a leak detection system capable of monitoring a plurality of leak detection devices located in various locations in the building.
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patent: 5188143 (1993-02-01), Krebs
patent: 5192932 (1993-03-01), Schwab
patent: 5440917 (1995-08-01), Smith et al.
patent: 5557263 (1996-09-01), Fisher et al.
patent: 6147613 (2000-11-01), Doumit
patent: 6175310 (2001-01-01), Gott
patent: 0342905 (1989-11-01), None
Chapman Clifford J.
Chapman James
Bowles Rice McDavid Graff & Love, PLLC
Giblin, Jr. John J.
La Anh V
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