JPH09189636A - Method for detecting leakage from dust collecting sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a waterproof sheet flexible to prevent its damage by arranging insulated wires in a grid under the waterproof sheet, and binding their crossing points with electric conductivity sensors. SOLUTION: Insulated wires are arranged lengthwise and crosswise in a grid under a waterproof sheet 3, and electric conductivity sensors 6 each comprising, e.g. a diode and two electrodes, are attached to their crossing points. An electric potential is imparted to each of the vertical and horizontal lines of the wires by scanning circuits S1 , S2 and is measured by the sensors 6 mounted on the crossing points, whereby the presence of waste water 4 at each of the crossing points of the grid can be detected, along with the leakage of water from the sheet 3 and its site. Thus by separating wiring work and sheet stretching work, the sheet 3 can be kept flexible to prevent its damage and to reduce expenses.

Description

Detailed Description of the Invention

[0101]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of leakage of sewage due to breakage of a waterproof sheet which prevents underground infiltration of sewage into a garbage repository.

[0092]

2. Description of the Related Art Conventionally, a parallel electric wire is attached on both sides, and an insulating waterproof sheet is used, which is composed of vertical and horizontal grid electrodes on the front and back sides. The electrical resistance between the vertical and horizontal electric wires due to leakage of sewage was measured to detect the leakage location.

[0093]

However, due to the lack of extensibility of the electric wire, the flexibility of the waterproof sheet is lost, making it difficult to adhere to irregularities on the ground, which may cause the sheet to break. In addition, the sheet was expensive to manufacture, and the construction cost was due to lack of flexibility.

[0093]

[Means for Solving the Problems] By separating a sheet from an electric wire, arranging an insulated electric wire under the sheet in a grid pattern, and attaching an electric conductivity sensor at an intersection thereof, it is possible to maintain the flexibility of the sheet and to prevent waste water. Leaks can be detected.

[0056]

This will be explained with reference to the drawings. FIG. 1 shows a typical example of the basic cross section of a garbage collection base. Although garbage 2 is stored in a depression 1 on the ground, a waterproof sheet 3 is used. Prevents the infiltration of sewage generated there into the underground. However, the waterproof sheet 3 may be damaged due to the projections contained in the garbage 2 or the projections on the surface of the depression 1, and leakage of the dirty water 4 may occur.

Since sewage water contains organic acids and various other ions, it has an extremely high electric conductivity as compared with ordinary rainwater and groundwater, and therefore can be detected electrically using electrodes.

FIG. 2 shows the detection principle, in which the scanning circuits S1 and S2 apply electric potentials to the vertical and horizontal rows of the electric wires 5 arranged in a grid pattern. The electric conductivity sensor 6 shown in FIG. 3 is attached to each intersection, and the presence of waste water at the intersection of the lattice can be detected by measuring the electric resistance thereof.

Conventionally, the vertical and horizontal rows of the grid of electric wires are attached to the front and back of the waterproof sheet 3, respectively, and the electric wires themselves have also been used as sensors. In this method, the electric resistance is infinite and the detection sensitivity is high when there is no leakage of sewage. However, instead, since the electric wire has no extensibility, the sheet itself loses flexibility, and the adhesion to the unevenness existing in the depression 1 on the ground is lowered, and as a result, the sheet is easily broken.

In the present invention, both the vertical and horizontal rows of the grid of electric wires are arranged on the lower side of the waterproof sheet 3, and the electric wires keep the insulation between the ground and the electric wires by the clothes. An electrical conductivity sensor 6 is attached to the intersection. Installation work using only electric wires is easy and at the same time the flexibility of the seat is maintained.

In such a structure according to the present invention, even if there is no leakage of sewage, since there is an electric resistance due to groundwater, use of a nonpolar electrode for the electric conductivity sensor 6 insulates each intersection of the grid. Instead, a sneak circuit is formed between the electric wires forming the grid through the electric conductivity sensor 6, and even if an intersection is selected by the scanning circuits S1 and S2, it is affected by the electric resistance of another intersection.

Therefore, in the present invention, an electric conductivity sensor having polarity is used. FIG. 3 shows the circuit, which is composed of a diode D and electrodes E1 and E2. In this structure, if direct current is used for the scanning signal, the diodes can prevent the electrical conductivity sensors from wrapping around each other.

However, when a direct current is used for the scanning signal, the product of the current and the measurement time must be reduced for many years of use because the electrodes are corroded due to electrolysis. For the purpose of measurement, it is not necessary to always measure, so it is possible to prevent corrosion by performing short-time measurement at time intervals.

Further, in order to eliminate the influence of the electric resistance due to the groundwater at all times, a normal value of the resistance value at each intersection may be stored and a measuring method focusing on the change may be used.

[0142]

As described above, by separating the wiring work and the sheet tensioning work, it is possible to keep the flexibility of the sheet and prevent the damage. Also, the overall cost is reduced. Further, depending on the shape of the depression, it is possible to increase the resolution of detection not only in the vertical and horizontal grids but also in the form of a cobweb or other places of the sheet.

[Brief description of the drawings]

FIG. 1 shows a typical example of a cross section of a basic garbage repository, FIG. 2 shows its detection principle, and FIG. 3 shows a concrete example of an electric conductivity sensor 6 used in the present invention. I will show you a good circuit.

[Explanation of symbols]

 1 ... ・ Grounded ground 2 ・ ・ ・ ・ Fresh garbage 3 ・ ・ ・ ・ Waterproof sheet 4 ・ ・ ・ ・ Sewage 5 ・ ・ ・ ・ ・ ・ Grid of electric wire 6 ・ ・ ・ ・ ・・ Electrical conductivity sensor S1, S2 ・ ・ Scanning circuit D ・ ・ ・ ・ Diode E1, E2 ・ ・ Electrode

Claims (1)

[Claims] 1. An insulated electric wire is arranged in a vertical and horizontal grid pattern on the lower side of the sheet, and the intersections thereof are connected by an electrical conductivity sensor composed of, for example, a diode and two electrodes, and the vertical and horizontal grids are scanned by an electric signal. Therefore, the method for detecting leaks in the dust collection sheet is characterized by detecting the leak of contaminated water from the sheet and its location.