Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-09-02
2001-10-30
Hofsass, Jeffery A. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S602000, C340S604000, C338S035000
Reexamination Certificate
active
06310555
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is a system designed to sense leakage in plumbing pipe systems as well as water damage and other intrusions to piping systems at their onset, to locate the source of the leakage, and to promptly alert its operator, so as to prevent flooding, loss of energy or of water, and destruction of plumbing.
To be effective, a water leak detection system requires adaptability as to the placing of the sensor devices, and the microminiaturization necessary in the placing of the sensors in remote locations, as well as simplicity in installing the device. The prime element in the system is the sensor, which, acting by itself or in tandem with numerous sensors, should be able to sound an alarm once there is any evidence of undue increase in moisture in the form of a rise in humidity proximal to the sensor. What is unique in the water leak detector is that it alerts the operator to the source of leakage as soon as the leakage arises, such as the leakage from piping joints, pipe corrosion or stress, or intrusion by burglars. The importance of the current art is that it may be placed a pipe level rather than floor level, and typically responds several hours before any of the prior art will react.
PRIOR ART
Goulbourne's art is based on a series of sensors attached by wire to a central logic control unit. Its use today is limited to the chemical industry where there is a constant internal pressure whose deviation can be monitored.
Hanson's detector is for use in surface water, requiring such a degree of moisture as to physically render a material frangible, and does not reset, until or unless the collected moisture on the material re-evaporates. This is not as reliable method for detecting leaks at or near their source, where the leaks tend to be airborne droplets.
Alexander's system is useful in detecting changes in the level of static liquid tanks and in detecting leaks once there is flooding of ½ inch or more. This is not practical in detecting leaks when they arise, i.e. when a plumbing pipe is ruptured. In residential and business applications, the location of the plumbing pipes will be equipped with drainage. Thus, leaks will not be detectable when they arise.
Hoiberg's device contributes to the art with the conical shielding around the sensor. This is intended to sense liquid deposits on a flat surface and the cone is set into the sensor specifically so as not to respond to humidity. The mists that would signal the beginning of a leak are excluded from the system. Thus, it would require sensors too numerous to be economically practical. Moreover, Hoiberg's device must be operated at floor level. We would then have to wait until there is flooding, to sense the leak.
Furuuchi's device is a humidity sensor with the feature of being sufficiently sensitive to detect fogging, such as water over ½ mm. gaps. The graphs indicate (
FIG. 4
) that the device is intended to measure relative humidity between 80 and 90 percent. Droplets of water caused by leakage require, however, measurements of complete saturation (100% humidity).
Ohsato's sensor measures relative humidity. The average humidity on the surface depicted in his “FIG.
10
” device is adapted for a rise in Relative Humidity from 40% to 100% (i.e. saturation) in 5.4 minutes. The reason is that Ohsato relies on the relative absorbtiveness of the medium. The reactions utilized begin with a physical reaction which is ultimately translated into a reaction of an electrical nature. The instant art, however, does not react to fogging but to jets or streams of water. Accordingly, our device responds within mircroseconds, thus avoiding false alarms arising from fogging in 90% relative humidity. The most common leak in plumbing is that of hot water through seams that connect copper piping. The typical seal in copper piping seams is 1/32″ thick, and a fissure through the pipe and subsequently through the adhesive is evidence through a jet of water droplets with a diameter of or greater than 1/100″. Placing the instant device opposite an adhesive bend in anticipation of likely fracture, the user is then alerted when the first droplet makes contact with the copper electrodes. Conversely, detecting the presence of fogging in the room is not the objective of the instant art.
Unoguchi's art is directed at the detection of various levels of humidity, while the instant art is simply aimed at the detection of saturation by droplets.
Abel's art is an offshoot of Relative-humidity detectors, rather than saturation. Abel attempts to solve the current-drain and ionization drawbacks in relative-humidity detectors. In contrast, the instant device reacts to the deposition of water droplets with a diameter of 0.01″ on the sensor coil. Thus, unlike Abel, the conductivity need not be calibrated or reset. Ionization is prevented by means of a plastic casement. Moreover, in Abel's device, the accumulation of droplets such as in fogging will trigger its alarm, while in the instant device the sensor's surface is limited so as to preclude fog detection.
Wilson's art consists of awater sensor that detects deposits of water 1/67″ in diameter and is connected to a windshield wiper motor. It relies on total capacitor output, which in turn, is influenced by cumulative moisture absorbtion rather than a simple stream of leakage.
Reich's art senses relative humidity through a film whose dielectric constant is altered according to the relative moistness of the sensor medium.
Kronberg's art as an improvement in sensing the presence of liquids is that the detector comes equipped with a “dry”-type sensor that reacts to moisture, as “FIG.
6
”. It measures moisture by contact with a pipe, but does not measure by size, such as water droplets, because Kronberg's art measures total conductivity change over a surface, rather than the bridging of 2 coils by contact with as little a quantity as one droplet.
SUMMARY OF THE INVENTION
A battery-powered liquid and humidity detection and alarm system comprising a transistorized moisture sensor, alarm system, and low-battery alert. The sensor aspect of the device is in the form of an outer and inner ring of copper coils and is positioned in place by a rubber or similarly flexible strip. The presence of moisture on the sensor element causes a forward bias in the transistor, triggering an audible alarm or flashing light. The sensor is sensitive as to detect unwarranted moisture as the presence of human sweat or several molecules of water droplets in contact with the sensor element. the alarm is also capable of being wired to a remote radio-operated control unit, and a landline to notify a plumber.
REFERENCES:
patent: 3864659 (1975-02-01), Furuuchi et al.
patent: 3983527 (1976-09-01), Ohsato et al.
patent: 4449188 (1984-05-01), Unoguchi et al.
patent: 4692752 (1987-09-01), Abel
patent: 4705060 (1987-11-01), Goulbourne
patent: 4831493 (1989-05-01), Wilson et al.
patent: 4888455 (1989-12-01), Hanson
patent: 5058421 (1991-10-01), Alexander et al.
patent: 5153564 (1992-10-01), Hoiberg
patent: 5345821 (1994-09-01), Reich et al.
patent: 5463377 (1995-10-01), Kronberg
patent: 5655561 (1997-08-01), Wendel
Hofsass Jeffery A.
Nguyen Phung
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