Leak detection mat and system

• US 6,639,517 B1
• Filed: 09/30/2002
• Issued: 10/28/2003
• Est. Priority Date: 09/30/2002
• Status: Active Grant

• Current Assignee: Matthew E. Uhrich
• Original Assignee: Chapman, Clifford J., James Chapman
• Inventors: Chapman, James, Chapman, Clifford J.
• Primary Examiner(s): La, Anh V
• Application Number:
  US10/260,165
• Time in Patent Office: 393 Days
• Field of Search: 340/603, 340/604, 340/605, 340/634, 340/525, 340/534, 340/693, 137/312, 73/40, 73/405.R, 73/492, 324/557
• US Class Current: 340/605
• CPC Class Codes: G01M 3/16 using electric detection means G01M3/045, G01M3/06, G01M3/12, G01M3/20, G01M3/24, G01M3/26 take precedence
• CPC Class Codes: G08B 21/20 responsive to moisture
• CPC Class Codes: Y10T 137/5762 With leakage or drip collecting

Abstract

A water leak detector system with alarm can be used to monitor inaccessible areas under various household appliances and warn of water leaks. A leak detection mat, having base layer of varying and appropriate sizes has disposed on it one or more pairs of electrodes arranged in a pattern around the upper surface of the base mat such that the two wires of each pair are parallel to the other and generally separated at a constant distance, and together the pair is positioned in a pattern across the surface. An absorbent layer is affixed to the base layer, covering and in contact with the electrodes. The absorbent layer may be impregnated with a soluble ionic salt to increase electrical conductivity when the adsorbent layer is wetted. A sensing and transmitting circuit having two input connections is affixed to the base substrate, with one end of each electrode attached to one of the input connections of the sensing and transmitting circuit. A plurality of leak detection mats may be used in a single system, each mat located under a potential water leak source. Upon water falling upon and being adsorbed by the adsorbent layer, the electrical resistance between the two electrodes at points nearest the leak will decrease. This decrease in resistance is detected by the sensing and transmitting circuit, which transmits a signal. An alarm unit receives the signal and activates an audible and/or visual alarm, the signal being sent either by radio waves or by an electrical signal through wires. The alarm unit is capable of monitoring a plurality of leak detection mats.

Claims

1. A leak detection mat, comprising:

(a) a base substrate, having an upper surface and a first edge;

(b) a pair of electrodes, each having proximal and distal ends and an upper surface, wherein each electrode is rigidly affixed to the upper surface of the base substrate and the electrodes are arranged in a two dimensional pattern across the upper surface of the base substrate wherein any point on the upper surface of the base mat within the pattern is situate between either electrode and the proximal ends of each electrode are located adjacent to the first edge of the base substrate;

(c) an absorbent layer, affixed to the upper surface of the base substrate and substantially in contact with the length of the upper surface of each electrode, except within a length adjacent to the proximal and distal ends of each electrode as necessary or desired to facilitate connection of electrical circuits or jumpers to other leak detection mats;

(d) means for attaching an electrical circuit to the proximal ends of each electrode.

2. The leak detection mat of claim 1, whereby the base substrate is a sheet made of a flexible polymeric resin, plastic, rubber or a composite of laminar films.

3. The leak detection mat of claim 2, whereby the flexible polymeric resin is plasticized polyvinyl chloride.

4. The leak detection mat of claim 1, wherein the absorbent layer is impregnated with an aqueous soluble salt.

5. The leak detection mat of claim 1, wherein the absorbent layer is constructed of woven fibers, felted fibers or polymeric foam.

6. The leak detection mat of claim 5, wherein the fibers are cotton, wool, linen, flax, jute, synthetically produced fibers, or blends of two or more of the preceding fibers.

7. The leak detection mat of claim 1, whereby the pattern of each electrode comprises a main lead traversing the upper surface of the base substrate from its proximal end along the first edge in a direction opposite the other main lead, thence along an edge adjacent to the first edge and opposite the edge of the other main lead, to the distal end of each electrode posited along the edge of the base substrate opposite the first edge, each main lead having a plurality of branches emanating at regular intervals, traversing across the upper surface perpendicular to and away from the edge of the mat, and running between two branches emanating from the other main lead, and terminating before the other main lead.

8. A leak detection system, comprising

(a) a leak detection mat, comprising

(i) a base substrate, having an upper and a lower surface and a first edge;

(ii) a pair of electrodes, each having proximal and distal ends and an upper surface, wherein each electrode is rigidly affixed to the upper surface of the base substrate and the electrodes are arranged in a two dimensional pattern across the upper surface of the base substrate wherein any point on the upper surface of the base mat within the pattern is situate between either electrode and the proximal ends of each electrode are located adjacent to the first edge of the base substrate;

(iii) an absorbent layer, affixed to the upper surface of the base substrate and substantially in contact with the length of the upper surface of each electrode, except within a length adjacent to the proximal and distal ends of each electrode as necessary or desired to facilitate connection of electrical circuits or jumpers to other leak detection mats; and

(iv) means for attaching an electrical circuit to the proximal ends of each electrode;

(b) sensing means for sensing a decrease in electrical resistance between the two electrodes and then transmitting a signal, wherein the sensing means is in electrical communication with the means for attaching an electrical circuit, and;

(c) alarm means in communication with the sensing means for receiving the signal transmitted by the sensing means and annunciating an alarm upon receipt of the transmitted signal.

9. The leak detection system of claim 8, wherein the transmission of the signal from the sensing means to the alarms means is by radio waves.

10. The leak detection system of claim 8, further comprising:

(a) a plurality of leak detection mats, each with sensing means, wherein the signal transmitted by the sensing means contains a unique identification code; and

(b) wherein the alarm means further comprises a display means for displaying the unique identification code received from any one of the sensing means.

11. The leak detection system of claim 10, further comprising a silence means for automatically terminating the annunciation of the alarm after a fixed time period while continuing the display means.

12. The leak detection system of claim 10, wherein the number of sensing means in the leak detection system monitored by one alarm means is less than or equal to ten.

13. The leak detection system of claim 10, further comprising reset means for manually resetting and clearing the display means.