JPH0453556Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is designed to add hydrocarbons, alcohols,
This invention relates to a device for detecting leakage of insulating fluids such as ketones, ethers, and esters.

(Prior Art) A sensor for detecting leakage of insulating fluid such as oil is disclosed in, for example, Japanese Patent Publication No. 47256/1983. This sensor includes a conductor made of conductive porous polytetrafluoroethylene resin (PTFE) and a pair of electrodes arranged through the conductor. When this conductor is penetrated by insulating fluid, its electrical conductivity decreases significantly (electrical resistance increases)
By detecting this change with a detector, leakage of the insulating fluid can be detected.

The above sensor can also be applied to detect insulating fluid floating in water, such as oil leakage into groundwater.

The above publication also discloses the use of a sensor in which the conductor and electrode are surrounded by a selectively permeable coating such as continuous porous PTFE, in order to detect an insulating fluid floating in water. . This coating almost completely prevents water from entering and allows selective penetration of insulating fluid.

(Problems to be solved by the invention) In the case of the former detection device using the sensor, there were the following drawbacks. In other words, the conductor is continuous porous.
Although it is made of PTFE and can repel water and selectively allow insulating fluid to penetrate, a small amount of water penetrates and changes in the water level change the electrical resistance of the conductor. For this reason, it may not be possible to distinguish between changes in electrical resistance due to changes in water level and changes due to leakage of the insulating fluid, making accurate detection impossible.

In the case of a detection device using the latter sensor, since the coating prevents water from penetrating into the conductor, changes in electrical resistance due to changes in water level can be prevented.
However, this coating makes it difficult for highly viscous insulating fluids such as OF oil and C heavy oil to penetrate into the conductor, making it impossible to detect them. As a result, it could only be applied to insulating fluids with low viscosity. Therefore, an object of the present invention is to provide a device that can accurately detect even highly viscous fluids on water.

(Means for solving the problem) The present invention was made to solve the above problem, and its gist is that each device is placed so that a part of it is submerged under the water surface, and water or leakage is detected. A pair of sensors whose electrical characteristic values change due to penetration of an insulating fluid, one of which is used as an insulating fluid detection sensor and the other a comparison sensor; An isolator which allows the flow of the insulating fluid but prevents the flow of the insulating fluid, and which houses the comparison sensor of the pair of sensors inside, detects and compares each electrical characteristic value of the pair of sensors, and and a detector that detects leakage of the insulating fluid when the difference between the electrical characteristic values of the sensors is equal to or greater than a certain value.

(Function) The comparison sensor of the pair of sensors is housed in an isolator that prevents the insulating fluid from flowing inside, so its electrical characteristic values are based on the fact that the insulating fluid is floating on the water surface. Regardless of whether there is water or not, the characteristic value will correspond to the water level.

On the other hand, sensors for insulating fluids are not housed in an isolator, so their electrical characteristic values correspond to the water level when there is no insulating fluid floating on the water surface. If the fluid is floating, the characteristic value will be different from the characteristic value corresponding to the water level.

Electrical characteristic values of the pair of sensors are detected by a detector. The detector detects the presence of the insulating fluid that has arrived at the water surface if the difference between the electrical characteristic values of the sensors is greater than or equal to a certain value.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 1 to FIG. 5. 1A, 1 in Figure 1
B is a pair of sensors having the same shape. One sensor 1A is for detecting an insulating fluid, and the other sensor 1B is for comparison.

As shown in FIG. 2, each sensor 1A, 1B has a sheet-shaped conductor 2 and a pair of parallel electrodes 3 disposed on both sides of the conductor 2. The conductor 2 is made of unfired or incompletely fired continuous porous PTFE containing a conductive substance such as carbon powder or metal powder. Conductor 2
A permselective coating 5, 6 in the form of a wider sheet is provided on both sides of the membrane. These coatings 5 and 6 are made of continuous porous PTFE, and prevent the penetration of water and allow the penetration of an insulating fluid with relatively low viscosity easily. An opening 6a is formed in one of the coverings 6, and most of one surface of the conductor 2 is exposed (the exposed surface is indicated by 2a in the figure). The electrodes 3 are covered by coatings 5, 6 and are not exposed.

Both sensors 1A and 1B are supported at the same height,
A part of it is submerged in the groundwater surface. The comparison sensor 1B is housed in a separator 7 having a selective distribution function. This separator 7 has a cylindrical shape and is open at the lower end, allowing water to flow through it, but the insulating fluid floating on the water surface X and flowing is blocked by this separator 8 and cannot enter the inside. do not have.

Each electrode 3 of the sensors 1A, 1B is connected to a detector 9 via an electric wire 8.

Next, the operation of the detection device having the above configuration will be explained. In each sensor 1A, 1B, the electrical resistance and electrical characteristic values of the conductor 2 between the electrodes 3 are relatively small when no fluid has penetrated into the pores of the conductor 2. When water or an insulating fluid permeates into the pores of the conductor 2, the electrical resistance increases.

First, the operation up to time _t0 when the insulating fluid is not floating on the water surface X, that is, in FIGS. 3 to 5, will be described.

The conductor 2 of each sensor 1A, 1B has an exposed surface 2a
receives some water infiltration. For this reason, the third
As shown in FIG. 4, the electrical resistance of the conductor 2 of each sensor 1A, 1B changes depending on the change in water level. Since the sensors 1A and 1B have the same shape and are arranged at the same height, the level and manner of change of the electrical resistance of the conductor 2 are almost the same as shown in FIGS. 3 and 4. Therefore, as shown in FIG. 5, the difference in these electrical resistances is almost zero.
The detector 9 automatically switches the connection to each sensor 1A, 1B, detects the electrical resistance of each conductor 2 as a voltage, and further compares the voltages to detect the differential pressure. As described above, when the difference in electrical resistance is approximately zero, the differential voltage detected is also approximately zero. Therefore, even if the electrical resistance changes as the water level changes, no detection signal is output.

When a highly viscous insulating fluid such as heavy oil C leaks into groundwater, this insulating fluid floats on the water surface X and flows. When the insulating fluid reaches the sensor 1A, it permeates into the conductor 2 from the exposed surface 2a. The penetration of this insulating fluid causes a large increase in electrical resistance compared to the case of water (see t ₀ onwards in Figure 3). This electrical resistance is the sum of a portion due to the water level and a portion due to the insulating fluid. On the other hand, since the sensor 1B is housed in the separator 7, no insulating fluid reaches the conductor 2 and the electrical resistance is due to the water level. Since the detector 9 calculates the difference in electrical resistance (voltage difference) as described above, the change in electrical resistance due to the change in the water surface X is erased,
Only the change in electrical resistance caused by the insulating fluid floating on the water surface X can be detected as a voltage difference. Then, when this voltage difference reaches a predetermined level, an insulating fluid detection signal is output.

Note that the electrical resistance of the conductor 2 of each sensor 1A, 1B varies somewhat depending on the temperature, but since the detector 9 detects the difference in electrical resistance of the pair of sensors 1A, 1B as described above, the temperature The change in electrical resistance due to the change is canceled out in the same way as the change in water level,
Also from this point of view, the insulating fluid can be accurately detected.

Even if a low viscosity insulating fluid such as gasoline leaks into groundwater, it can be detected in the same way as above. In addition,
In the case of an insulating fluid with low viscosity, it permeates not only from the exposed surface 2a but also from the entire surface of the conductor 2 through the coatings 5 and 6, which greatly contributes to the change in electrical resistance and has very high detection sensitivity.

FIG. 6 shows another embodiment of the sensor. In this example, an electrode 3 is placed in a conductor 12 made of the same material as the conductor 2 described above.
is arranged, and the conductor 12 is not covered and the entire surface is exposed.

The present invention is not limited to the above embodiments and can be modified in various ways. For example, it is preferable for information processing that the sensors have the same shape and the same height, but even if the sensors have different shapes and are located at different positions, the object of the present invention can be achieved by adding a correction circuit to the detector.

Further, the function of the sensor is not limited as long as it detects the insulating fluid while being affected by changes in water resistance.

The detection device of the present invention can be used to detect not only oil but also insulating fluids such as organic solvents used in chemical factories and the like.

(Effects of the invention) As explained above, the detection device of the invention has the following effects:
Insulating fluid can be accurately detected without being affected by changes in water level.

[Brief explanation of the drawing]

The drawings from FIG. 1 to FIG. 5 show one embodiment of the present invention, and FIG. 1 is a schematic diagram showing a detection device of the present invention partially in section, and FIG. 3 is a diagram showing the change in electrical resistance over time of the insulating fluid detection sensor, and Figure 4 is a diagram showing the change over time in the electrical resistance of the comparative sensor at the same time as in Figure 3. , FIG. 5 is a diagram showing the change over time in the difference in electrical resistance between both sensors. FIG. 6 is a sectional view showing another embodiment of the sensor. 1A... Sensor for insulating fluid detection, 1B... Sensor for comparison, 2... Conductor, 3... Electrode, 5, 6
...Coating, 7...Separator, 9...Detector, X...
water surface.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A pair of sensors, each of which is arranged so that a portion thereof is submerged under water, and whose electrical characteristic values change due to the penetration of water or an insulating fluid whose leakage is to be detected. A pair of sensors, one of which is used as an insulating fluid detection sensor and the other is a comparison sensor; An isolator that accommodates a comparison sensor among the sensors detects and compares each electrical characteristic value of the pair of sensors, and if the difference between the electrical characteristic values of the pair of sensors is more than a certain value, the isolation is performed. 1. A detection device for an insulating fluid, comprising: a detector for detecting leakage of an insulating fluid. (2) The insulating fluid detection device according to claim 1, wherein the pair of sensors have the same shape and are arranged at the same height from the water surface. (3) The pair of sensors includes a conductor made of a continuous porous resin containing a conductive substance, and a pair of electrodes arranged through the conductor, and the detector includes a pair of electrodes for each sensor. The insulating fluid detection device according to claim 1 or 2, which is an electrical resistance detector for detecting electrical resistance between electrodes. (4) The insulating fluid detection device according to claim 3, wherein the conductor is made of a continuous porous tetrafluoroethylene resin containing a conductive substance.