JPS60338A - Liquid leakage detector - Google Patents

Abstract

PURPOSE:To improve a characteristic on the basis of the heating of a sensor and to attain measurement using an economical voltage detector by impressing a heating voltage and measuring voltage to a liquid leakage sensor independently. CONSTITUTION:A pair of power supply electrodes 3 are electrically contacted with both ends of a porous conductive resin layer 2 of a liquid leakage sensor and a pair of measuring electrodes 4 are also contacted with a porous conductive resin layer 2 at the insides of the electrodes 3. Both electrodes 3, 4 and the porous conductive resin layer 2 are surrounded and sealed with a liquid permeable sheathing 5. A power supply 6 alternately outputting a heating voltage for heating the liquid leakage sensor 1 and discharging inner humidity or gas and measuring voltage is connected to the power supply electrodes 3, 3. The heating voltage is higher than the measuring voltage by several times, so that a voltage detector 7 connected to the measuring electrodes 4 is actuated only when the power supply 6 outputs the measuring voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid leak detection device that can reliably detect minute liquid leaks.

For example, as a sensor for detecting the leakage of liquids such as liquefied hydrocarbons such as petroleum, gasoline, and heavy oil, or various organic solvents such as carbon tetrachloride, MEK, and toluene, the patent application No. 52-5
No. 9,859 (Japanese Unexamined Patent Publication No. 53-145.697) "Fluid Detection Element" has been proposed.

This fluid detection element has a structure in which at least two conductors are isolated by a continuous porous tetrafluoroethylene resin material containing a conductive substance, and the resistance between the two conductors due to leakage of liquid to the material is The liquid was detected by the change in value. However, since this sensing element uses a porous resin material, the resistance value of the material may change due to moisture or atmospheric gas components entering the pores, or due to a rise or fall in temperature. However, it is difficult to distinguish between these disturbances and the detection of minute liquid leakage, and there is a drawback that it is not possible to effectively detect minute liquid leakage. For this reason, weather resistance can be improved by heating the detection element to drive out moisture and gas components inside the element and remove the effects of temperature changes. If you don't apply a voltage several times higher than the voltage to the detection element, it will not turn on.
This was uneconomical as it required changes to the measurement circuit and an increase in the number of digits in the digital device.

Therefore, an object of the present invention is to provide a liquid leakage detection device that can reliably and economically detect minute liquid leaks. Therefore, according to the present invention, there is provided a porous conductive resin layer filled with a conductor and at least one pair of electrodes in electrical contact with the conductive resin layer, so that liquid leakage to the porous conductive resin layer is prevented. a liquid leakage sensor that detects the resistance value as a change in the resistance value of the resin layer, a voltage detector that detects the resistance value between the electrodes of the liquid leakage sensor as a voltage value, and a heating voltage of the sensor between the electrodes of the liquid leakage sensor. A leakage detection device includes a power source that selectively supplies power to the measurement voltage and the measurement voltage.

According to this configuration, the heating voltage and the measurement voltage are applied to the leakage sensor separately, so the characteristics can be improved by heating the sensor and measurement can be performed using an inexpensive voltage detector.
It is possible to provide a liquid leak detection device that can reliably and economically detect minute liquid leaks.゛In the configuration of this invention, it is convenient for continuous monitoring if the power supply alternately supplies the heating voltage and the measurement voltage, and in this case, the voltage detector is only used when the power supply is supplying the measurement voltage. It can be made to work. Further, in the configuration of the present invention, the porous conductive resin layer of the leakage sensor can be formed by an extruded conductive tetrafluoroethylene resin layer. The material becomes porous after extrusion by vaporizing the lubricating aid. In order to further increase the porosity, foaming or stretching may be performed. When using tetrafluoroethyne resin as the porous conductive resin layer, an unfired material or a semi-fired material is used, and a fired material is not used.

Next, the present invention will be explained in more detail with reference to the embodiments shown in FIGS. 1 and 2.

In FIG. 1, a porous conductive resin layer 20 of a liquid leakage sensor 1 is shown.
A pair of power supply electrodes 3.3 are provided at both ends in electrical contact with each other, and a pair of measurement electrodes 4.4 are further provided in contact with the porous conductive resin layer inside both power supply electrodes 3.3. ing. Both electrodes 3.4 and the porous conductive resin layer 2 are surrounded and sealed by a liquid-permeable jacket 5.5. As this liquid-permeable jacket 5, stretched continuous porous tetrafluoroethinone resin can be suitably used.

Since the stretched continuous porous tetrafluoroethylene resin is highly water repellent, its use as the outer cover 5 is convenient for selectively detecting liquids other than water. Therefore, when detecting an aqueous liquid, it is necessary to use a liquid-permeable outer covering other than tetrafluoroethylene resin or to make it hydrophilic.

Further, as the porous conductive resin layer 2, an extruded conductive filled tetrafluoroethylene resin can be suitably used.

When tetrafluoroethylene resin is used, it is convenient for detecting liquids other than water, such as petroleum, because of its water repellency, but other resins can be used depending on the purpose. Examples of the conductor filled in the resin include graphite powder, carbon black powder, carbon fiber, various metal powders, cermets, metal nitrides, metal borides, metal silicides, metal oxides, metal semiconductors, Organic semiconductors and the like can be used. These filling conductors are 5~
The mixture is mixed into a 70% by weight tetrafluoroethylene resin, and a lubricating additive is mixed into the mixture and extrusion molded to obtain a porous conductive resin layer.

Power supply electrode 3.3 of the leakage sensor 1 obtained in this way
A power source 6 that alternately outputs a heating voltage for heating the leakage sensor 1 and a measurement voltage is connected to. In this case, the heating voltage is several times higher than the measurement voltage, so the voltage detector 7 connected to the measurement electrode 4.4 of the leakage sensor 1 operates only while the power supply 6 outputs the measurement voltage. It is done like this.

In this embodiment, a heating voltage is applied by the power supply 6, so moisture and gas inside the sensor are expelled, and the conductive resin layer is kept in a stable state at a constant temperature, resulting in stable characteristics and minimal liquid leakage. can be reliably detected, and since the voltage detector is activated when a low measurement voltage is being supplied from the power supply 6, the detection can be performed with an inexpensive device. Moreover, especially in this embodiment, since the measuring electrode 4.4 is located inside the power supply electrode 3.3, there is an advantage that leakage detection is accurate and quick.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the leakage sensor 8 has only one pair of electrodes 10, 10 that are in conductive contact with the porous conductive resin layer 9, and the electrodes 10, 10 for power supply are Also serves as a measurement electrode. The liquid leakage sensor 8 of this embodiment is also surrounded and sealed by a liquid-permeable jacket 11 as in the embodiment of FIG.

The heating voltage and the measurement voltage are crossed on the electrode 10.10! A power supply 12 that supplies power to the leakage sensor 8 is connected to L, and this electrode 1
0.10 is also connected to a voltage detector 13 which operates only while the power supply 12 supplies the measurement voltage.

The liquid leak detection device according to this embodiment can also detect minute liquid leaks similar to the embodiment shown in FIG.

According to the present invention, the conductor is charged with
.

A leakage system comprising a porous conductive resin layer and at least one pair of electrodes in electrical contact with the conductive resin layer, and detects liquid leakage to the porous conductive resin layer as a change in the resistance value of the resin layer. A liquid sensor, a voltage detector that detects a resistance value between electrodes of the liquid leakage sensor as a voltage value, and a power source that selectively supplies a heating voltage and a measurement voltage of the sensor between the electrodes of the liquid leakage sensor. By configuring the liquid leak detection device, it is possible to provide a device that can reliably and economically detect minute liquid leaks.

Note that this invention is not limited to the above embodiments,
Various modifications and changes can be made within the scope of the idea of this invention.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are conceptual diagrams of a liquid leakage detection device showing different embodiments of the present invention. 1.8: Liquid leakage sensor, 2.9: Porous conductive resin layer, 3: Power supply electrode, 4: Measurement electrode, 5.11: Liquid permeable jacket, 10: Electrode, 6.12:
Power supply, 7.13: Voltage detector.

Claims (1)

[Claims] 1) A porous conductive resin layer filled with a conductor and at least a pair of electrodes electrically in contact with the conductive resin layer, A liquid leakage sensor that detects the arrival of liquid leakage as a change in the resistance value of the resin layer, a voltage detector that detects the resistance value between electrodes of this liquid leakage sensor as a voltage value, and at least one pair of electrodes of the liquid leakage sensor. A liquid leakage detection device comprising a power supply that selectively supplies a heating voltage and a measurement voltage to the sensor between the two. 2. The liquid leakage detection device according to claim 1, wherein the power source alternately supplies a heating voltage and a measurement voltage to the liquid leakage sensor. 3) The liquid leakage detection device according to claim 1 or 2, characterized in that the voltage detector operates only when the measurement voltage is supplied in response to selective power supply of the power source. Liquid leakage detection device. 4) In the liquid leakage detection device according to any one of claims 1 to 3, it is provided that the porous conductive resin layer of the liquid leakage sensor is made of an extruded conductive tetrafluoroethylene resin layer. Characteristic liquid leakage detection device. 5) The liquid leakage detection device according to claim 4, wherein the extruded conductive tetrafluoroethylene resin layer is unfired or semi-fired. 6) A liquid leakage detection device according to any one of claims 1 to 5, wherein the liquid leakage sensor has a liquid-permeable jacket on its outer periphery. 7) In the liquid leakage detection device according to any one of claims 1 to 6, the liquid leakage sensor includes a pair of power supply electrodes that are in electrical contact with the porous conductive resin layer and an inner side of the power supply electrodes. A liquid leakage detection device characterized by having two pairs of electrodes: a pair of measurement electrodes that are in electrical contact with a porous conductive resin layer.