Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-12-15
2002-07-02
Wu, Daniel J. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S539230, C340S636210, C340S691100, C340S691700, C340S693200, C073S308000
Reexamination Certificate
active
06414598
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid detection and alarm system for detecting the presence of oil or water leaks from indoor domestic appliances or domestic furnace oil tanks, for example, or for basement flooding. The invention may also be used for industrial applications where the detection of leaking liquids are desirable to prevent environmental or other unwanted results. The invention is typically placed over a drip pan or low point of a surface where the liquid is likely to collect. The invention uses an electrical circuit with an audible alarm device, enclosed in housing, with an attached float.
Oil leaks from domestic 909 liter steel oil tanks or connections can cause serious damage to a home and create an environmental disaster if the oil finds its way under the building foundation. In most cases the oil must be reclaimed from the soil at a considerable expense. If the ground water becomes contaminated, cost for the clean up is higher, and in most cases the property is devalued. There is no accurate prediction device or method, which will determine with accuracy when a tank will fail, or when fittings will leak. There is therefore a need for an alarm system which will be reliable, compact, and will warn the residents that their oil tank is leaking.
The invention will operate for liquids with a density greater then 775 kg/m
3
and a flash point no less then 38 degrees Celsius. Typical heating oil found in domestic steel tanks would meet or exceed these minimum limitations.
2. Description of the Prior Art
Prior art includes an Oil Alert system designed by Dorlen Products Inc. of Milwaukee, U.S.A., which features “Oil Alert Sensing Modules” which are absorbing cells which after insertion into a housing, are placed on the floor and will activate an audible alarm after the cells have detected oil. This prior art has limitations, which the invention will overcome. For example, this prior art requires cell replacement after triggering and cannot be easily self checked. The unit must be placed on a level surface, thus cannot act as an adjustable level alarm.
There are other oil detection systems used in industrial applications such as detecting a liquid level between double-wall storage tanks. However, this prior art is intended to be used in this specific industrial application. These known devices do not have an easy self-check mechanism, are not portable, and are typically not equipped with an audible alarm.
Other water detection alarm systems use a conducting sensing method which cannot be used to detect the presence of oil due the fact that oil is a poor electrical conductor.
The invention may be distinguished from the other prior water detection alarms in significant respect. Prior art includes a variety of patents pertaining to water leak detection devices which are designed to detect water and automatically shut down an appliance or valve. Many prior art devices use conductivity sensing probes, strips or cells to detect the presence of water from a leaking basement, appliance, or back-up pipe. An audible alarm will sound when moisture is detected. Representatives of this prior art are patents such as:
Canadian patent no. 1261940 Otterhof
Canadian patent no. 2124907 Janesky
Canadian patent no. 1244533 Leblanc
Canadian patent no. 2023376 Shih
Canadian patent no. 2228517 Isaacson
Canadian patent no. 2175005 Leger
U.S. Pat. No. 5,539,383 Chin
U.S. Pat. No. 5,058,421 Alexander
U.S. Pat. No. 5,091,715 Murphy
U.S. Pat. No. 4,297,686 Tom
U.S. Pat. No. 5,898,374 Schepka
U.S. Pat. No. 5,655,561 Wendal
U.S. Pat. No. 5,557,263 Fisher
U.S. Pat. No. 5,550,532 Marshall
U.S. Pat. No. 4,805,662 Moody
U.S. Pat. No. 4,246,575 Purtell
U.S. Pat. No. 5,517,174 Barrows
U.S. Pat. No. 4,800,372 Poteet
U.S. Pat. No. 4,973,947 Tax
Other prior art utilizing conductive type detective systems can easily false alarm when condensation forms on the probes. Absorption type units, which sit on the floor, will become submerged if the water level quickly rises, thus damaging the unit and causing it to malfunction. The invention is intended to be mounted directly above the monitoring surface. The float can rest at any desired height above the monitoring surface, however the component housing should be mounted a minimum distance of 7 cm above the float and up to 807 cm directly above the liquid surface. The minimum distance can be lowered if required, although for most application this is not desired. Most prior art devices are fixed units, which are not adjustable once set in place. The length of the conductivity leads limits the range of these prior art devices.
Other prior art devices generally may not incorporate a fail-safe mechanism, in the event the sensing device becomes disabled for any reason. If a dielectric capacitor, or absorbent cell becomes disabled for any reason, then the unit will not indicate a fault in the alarm unit. Some prior art devices do include a battery low voltage-checking device.
SUMMARY OF THE INVENTION
The invention provides a simple water or oil leak detection alarm system which is capable of producing an audible alarm when the liquid level increases above the point at which the unit is set to trigger. The invention would typically be used in a domestic home application for detecting water flooding, or a leaking oil tank installation. The invention can also be adapted for many industrial applications where the presence of a conductive or non-conductive liquid requires alarming. In combination with its audible alarm, connections preferably are provided for external monitoring, such as a home security system or relay controller. The invention uses a float, which can be adjusted to various heights above the area, which requires monitoring. The invention is portable and can be easily moved from one monitoring position to another, or from one liquid service to another. The invention requires a 9-volt battery, which is checked continuously for sufficient voltage. The unit will sound an alarm when insufficient voltage is detected. A 120 volt ac/9-volt dc external supply can also be used to power the invention. The triggering mechanism of the invention requires a positive liquid level increase of approximately 5 mm after contact with the float to activate the alarm. This ensures the unit does not false alarm with the presence of moisture, like many prior art devices. The invention is ideally suited for monitoring oil leaks from domestic furnace tanks, which can leak at any time. By simply attaching the unit on the side of a pan (located under the tank), with hook and pile fastening material (e.g. Velcro (trademark)) or other commonly known fastening means, the unit will be fixed into position ready to detect a leak. The invention has a simple self-check feature. By the touch of a fingertip, the unit can be self checked to ensure all circuits are fully operational. A fail-safe design ensures that in the event the float becomes disabled for any reason, the unit will sound the alarm.
The invention does not require conductive water detection systems for a triggering mechanism. It uses a float, attached to a lever switch, which upon coming in contact with a rising liquid, will cause the lever switch to rise, activating a spring-loaded switching mechanism.
The invention is portable and can be moved from place to place, or it can be used to service different types of liquid applications. Today when areas become flooded, this alarm will enable a homeowner to set the positioning and height so that the house can be vacated when the alarm sounds. This would be a safety feature in areas under threat of potential flooding. The alarm offers portability and flexibility, along with a reliable simple safety check for operability.
As stated, the invention has a simple self check mechanism. A simple motion of raising the lever switch with a finger will allow the unit to be checked for all operational features. Other prior art devices with self-check mechanisms may require submersion in the water or liquid to be self-checked. This would, typi
Freill Michael R. G.
Freill Peter E.
Armstrong R. Craig
Borden Ladner Gervais LLP
Wu Daniel J.
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