JP2006133075A - Leakage liquid detection sensor and leakage liquid detection system equipped with sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leakage liquid detection sensor and a leakage liquid detection system equipped with the sensor enabling detection of leakage liquid in a wide area by a small number of the leakage liquid sensors, and resultantly capable of performing leakage liquid detection in the wide area without performing a large capital investment. <P>SOLUTION: Concerning leakage liquid on a spot separated from a leakage liquid detection domain of the leakage liquid sensor, a liquid guide route for guiding to the leakage liquid sensor is provided, to thereby enable detection of the leakage liquid in the wide area by a small number of leakage liquid sensors. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a leak detection sensor capable of detecting a leak from a location away from a leak detection area and a leak detection system including the sensor.

Although it is limited to liquids having conductivity such as water (excluding pure water), the most basic idea of a device for detecting leakage is disclosed in Utility Model Registration No. 3094002. In other words, wrap two conductors with paper or the like, and then bundle the two conductors and set them in a place where liquid leakage is detected. Since the electrical resistance is lowered during this period, this is electrically detected and an alarm is issued.

  Various other leak detection sensors have been proposed, but in principle, they are on the extension of the technical idea of the above-mentioned utility model. As such, if the leak detection part is taped and electrodes are attached to both ends of the tape to sense this change in electrical resistance, or a condenser type with insulating paper sandwiched between them and water penetrates into the insulating paper Examples include sensors that detect the change in capacitance. These are basically intended to detect liquid leakage in a limited place where sensors are installed.

  As described above, the conventional technology is limited to a limited place where the sensor is installed, that is, a sensor that basically detects a leak at a point, but semiconductor manufacturing using a large amount of cooling water, etc. In devices and the like, water leakage does not always occur at the sensor installation point. Therefore, in order to observe around the apparatus as widely as possible, it is necessary to install a large number of water leakage sensors.

  For example, the leak sensor disclosed in FIG. 4 as a conventional example of Japanese Patent Application Laid-Open No. 5-79941 is provided with a large number of leak detection sensors, and wiring according to the number of leak detection sensors is provided. In the invention of JP-A-5-79941 itself, there is no change in that a large number of water leakage detection sensors are provided.

  The leak detection sensor of the conventional example disclosed in Japanese Patent Laid-Open No. 5-79941 basically measures a change in electrical resistance due to water leak, but there is a problem that a false alarm is generated due to the type of water leak. This is also described in Japanese Patent Laid-Open No. 5-79941.

  The invention described in Japanese Patent Application Laid-Open No. 5-79941 can reduce such false alarms by adjusting detection sensitivity twice according to detection confirmation and on-site condition (humidity, etc.), environment, type of water leakage, etc. It was solved by doing. As can be seen from this ingenuity, it is inevitable that conventional leak detection sensors will generate false alarms due to various factors such as environmental changes and types of leaks without detailed monitoring and adjustment. However, leaks in semiconductor production lines are not limited to conductive liquids such as cooling water, but may be extremely high resistance pure water or insulating organic solvents. On the other hand, the above prior art is powerless.

  The present applicant has developed an extremely excellent leak sensor that can solve such a false alarm or can cope with any liquid. That is, although not shown, the principle is that the light from the light emitting diode is applied to the surface of a paper that is simple and has good liquid absorption, and the scattered light intensity is measured. This is because the scattering of light on the surface of the paper decreases when the paper gets wet with the liquid, and the output of the semiconductor photodetector decreases. Because it monitors the scattering of light caused by water getting wet with water, it can be reliably detected whether it is pure water with high resistance or an insulating organic solvent. It can be reused.

  In this method, if the size of the paper to be sensed is increased, the leakage detection area increases, but the amount of liquid penetration increases and the penetration length increases according to the amount of paper, so the response speed decreases. . Therefore, in reality, the size of the paper is about 30 mm in diameter, but the actual leakage detection region, that is, the place where the light scattering intensity is monitored is about 2-3 mm in the vicinity of the center of the paper.

  If leakage occurs on the outer periphery of the paper, it can be detected because the liquid penetrates and wets the vicinity of the center of the paper. The detection area is expanded to the size of the paper compared to the actual detection area. It is a sensor. Although this sensor is extremely superior in that it can detect leaks regardless of the type of leak, it is different from the prior art in that it can only detect leaks in limited places where the sensor is installed. It doesn't change.

  The present invention has been made in view of the above points, and does not detect leakage at a limited place where the sensor is installed. The number of leakage sensors in a wide area is small. An object of the present invention is to provide a leak detection sensor capable of detecting leaks and, as a result, capable of detecting leaks in a wide area without investing a large amount of equipment, and a leak detection system including the sensor.

  In order to achieve the above object, as a result of intensive research, the present inventor has established a surface liquid impervious liquid conduit that guides the liquid leak from a location away from the liquid leak detection area of the liquid leak sensor to the liquid leak sensor. It has been found that leak detection in a wide area is possible by coupling to a leak detection sensor, and the present invention has been achieved. Conventionally, it is not known that a liquid leakage path is provided in the liquid leakage sensor, and such an idea is not known at all.

That is, the present invention is characterized in that a surface liquid impervious liquid guide passage is provided for guiding the liquid leak from a location away from the liquid leak detection area of the liquid leak sensor to the liquid leak sensor.
It is preferable that the liquid introduction path has a length that is at least 10 times the liquid leakage detection area of the liquid leakage sensor.

  It is preferable that the surface of the liquid impervious material is formed to be hydrophilic, and it is particularly preferable that the liquid guide path is formed to be super hydrophilic. Here, hydrophilic means a contact angle of 30 degrees or less, and superhydrophilic means a contact angle of 5 degrees or less.

  It is particularly preferable that the liquid guide path contains a substance having a photocatalytic action, and the substance is formed to be hydrophilic by irradiating the substance with ultraviolet rays.

  It is preferable that the center of the liquid introduction path serving as the liquid passage is made of a surface hydrophilic material and both sides are made of a surface hydrophobic or water repellent material.

  It is preferable to provide a second hydrophilic surface that is vertically opposed to each other through a space serving as a hydrophilic surface of the liquid guide path and a flow path for liquid leakage.

  It is preferable that the liquid leakage sensor measures the intensity of scattered light by applying light from a light emitting diode to the surface of paper having good liquid absorbency.

  Further, the liquid leakage detection system of the present invention comprises a liquid leakage detection sensor in which the liquid flow path contains a photocatalytic substance, and ultraviolet rays that hit the photocatalytic substance in the liquid flow path of the liquid leakage detection sensor. (Claim 8).

  It is preferable that a light source that emits ultraviolet light is disposed in the liquid guide path or that the ultraviolet light hits it.

According to the present invention, since the liquid introduction path is provided, it becomes possible to detect a leak in a wide area with a small number of leak sensors, and a large capital investment is required for detecting a leak in a wide area. This kind of conventional leakage sensor has a remarkable effect which is not seen at all. Moreover, since the present invention only couples the liquid introduction path to the conventional liquid leakage sensor, the conventional liquid leakage sensor can be used as it is.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is drawn to illustrate the principle of the system of the present invention, and is close to a normal leak sensor (leak sensor) 1 that can only detect leaks at limited locations where sensors are installed. The liquid guide path (water guide path) 2 is made of a material that does not penetrate liquid at least on its surface and has a hydrophilic coating layer formed on the surface.

  When there is a leak on the end face of the liquid introduction path 2 close to the liquid leakage detection sensor (leakage sensor) 1, the liquid leakage is conveyed to the liquid leakage sensor 1 through the liquid introduction path 2 and the leakage is detected. Is.

In the simplest case, it is sufficient that the liquid introduction path 2 is lowered toward the sensor 1. Assuming that the inclination is 1 degree, the height of the liquid introduction path 2 at a distance of 1 m from the sensor 1 is about 17 mm, and when the sensor 1 with the liquid introduction path 2 is installed on a horizontal floor or the like, It is possible to detect a large liquid leak at a water level of 17 mm or more 1 to 1 m away.

  However, in this case, the height of the liquid introduction path 2 is 20 mm or more, and it cannot be installed on the floor where water leakage must be detected. The true object of the present invention is to detect leakage at a location away from the sensor 1 without tilting the liquid introduction path 2.

  In the case of an organic solvent or the like, the material for the liquid conduit may be an ordinary metal or plastic such as aluminum, copper or iron as the liquid conduit 2, and the sensor 1 can be used without considering the material. Liquid leakage at a point more than 10 times larger than the size of was easily detected.

  The sensor used in the above experiment monitors the light scattering of the paper described in the paragraph [0008], and is made of Al having a length of 900 mm and a width of 5 mm so as to contact the outer periphery of the paper having a diameter of 30 mm. The experiment was conducted with the road placed horizontally.

  In the experiment using the sensor, 1 ml of ethanol was dropped at various positions in the liquid introduction channel, and the sensor paper could be wetted with ethanol no matter where it was dropped. This is because the organic solvent has a property of getting wet well with various materials. In other words, if it is limited to liquid leakage such as organic solvent, the liquid leakage detection area can be expanded without changing the liquid leakage sensor itself if it is arranged so that at least one end of the liquid introduction path is in contact with the liquid leakage sensor. be able to.

  The problem here is detection of leakage of water or an aqueous solution of acid, alkali, or the like, that is, water leakage. Since the kind of leakage that cannot be smoothly introduced unless the material of the liquid introduction path is selected, water or an aqueous solution of acid, alkali, or the like is indeed, so the following description will be limited to water or aqueous solution leakage detection.

  The essential form of the invention most effective for detecting leakage of water or aqueous solution will be described with reference to FIG. That is, at least the surface of the water conduit 2 is made to have a structure with improved hydrophilicity. As the water conduit 2, a stainless steel plate having a width of about 10 mm and a thickness of about 0.1 mm was thinly coated with a ceramic coating such as silicon dioxide or zirconia, and a titanium dioxide photocatalyst coating was performed thereon.

In this experiment, a titanium dioxide photocatalyst coating was prepared by applying and drying a fine powder of TiO ₂ and SiO ₂ dispersed in water. The reason why the fine powder of SiO ₂ is added is that it is effective in maintaining hydrophilicity even when sufficient ultraviolet light intensity cannot be provided or the ultraviolet light source is damaged. As a photocatalyst coating method, there are various methods such as a sol-gel method, a sputtering method, a chemical vapor deposition method, and a thermal spraying method. It may be selected as appropriate in consideration. In addition, a photocatalyst material that can be applied to visible light is being intensively developed, but if this is put to practical use, an ultraviolet light source for the liquid introduction path will be unnecessary.

Usually, the water repellency and hydrophilicity of the surface are expressed by the contact angle when water is dropped, and classified as the following expression according to the following contact angle.
Contact angle of 150 degrees or more: Super water repellency
90 degrees or more: water repellency
90-30 degrees: hydrophobic
30 degrees or less: hydrophilic
5 degrees or less: Super hydrophilic

When an ultraviolet ray having a wavelength of 380 nm or less is applied to the surface subjected to the titanium dioxide photocatalyst coating, a super hydrophilic surface is obtained. Since the measurement of the contact angle is not always easy, as shown in the schematic diagram of Fig. 2, here isotropically when 0.5ml of tap water is gently dropped on the surface of several materials placed horizontally. The diameter of the spreading water was measured and evaluated. The results were as follows.
Linoleum floor: 17mm
Decora board: 17mm
PVC board: 15mm
Titanium dioxide photocatalyst coating surface (on Si) preserved in the dark: 25 mm
1 hour 50 minutes sun-dried titanium dioxide photocatalyst coating surface: 65mm
From the above results, it was clarified that on the titanium dioxide photocatalyst coating surface exposed to sunlight after coating and drying of the titanium dioxide gel solution, a superhydrophilic surface was realized, so that water spreads significantly.

Now, the water channel 2 having a width of 10 mm coated with the titanium dioxide photocatalyst in the structure shown in FIG. 1 was sun-dried, and then 0.5 ml of tap water was dropped at the end opposite to the leakage sensor 1 side. As a result, it was found that the water spreads from the place where the tap water was dropped to 290 mm. Since the isotropic spread was 65 mm in diameter, the area where tap water spread was about 3300 mm ² , but the spread of tap water in a 10 mm wide conduit as shown in Fig. 1 was 2900 mm ^2. In both cases, it can be seen that tap water spreads over almost the same area.

  Considering the above logic, if the water channel is made of something like a linoleum floor, the water will only spread about 22 mm. It was also found that when the width of the water conduit on the superhydrophilic surface was changed from 10 mm to 5 mm, water spread over 550 mm.

  Therefore, when the amount of tap water dropped was 1 ml, the tap water reached the leak sensor 1000 mm ahead with a probability of 90%. When the dripping amount was further increased to 1.5 ml, the tap water reached the leak sensor 1 in all cases.

  The arrival time to the leak sensor 1 sometimes took 10 seconds or more when the dropping amount was 1 ml, but it was 5 seconds or less when the dropping amount was 1.5 ml. Even with such a small amount of water, it was found that water dropped 1000 mm away was carried to the sensor. However, if it is desired to shorten the arrival time, the water channel is inclined as shown in FIG. It is effective to keep it. For example, just tilting about 0.1 degree, the arrival time is less than 5 seconds even with a drop volume of 1 ml, and less than 3 seconds with a drop volume of 1.5 ml.

  An inclination of 0.1 degree is only 1.7mm at a height of 1000mm, and even if the height up to the hydrophilic surface is added to this, the hydrophilic surface can be placed 2-3mm from the floor. , It is possible to sufficiently capture liquid leakage that shows rise due to surface tension. The fact that the arrival time is accelerated with the inclination of about 0.1 degree is also the effect that the surface of the water conduit is a superhydrophilic surface. When the surface of the water channel was a PVC plate, depending on the inclination of about 0.1 degree, even if 1 ml of tap water was dropped, it just extended on the water channel, and did not reach the leak sensor even after 10 minutes.

  FIG. 3 illustrates a state in which the water droplet 13 spreads on the hydrophilic surface 3. As shown in FIG. 3A, water is lifted on the hydrophobic surface 4, but the hydrophilic surface 3 touches this. Then, as shown in FIG. 3B, water spreads on the hydrophilic surface 3.

  In the above experiment, in order to give the titanium dioxide photocatalyst coating surface super hydrophilicity, it was exposed to sunlight for 2 hours after coating.

  However, the amount of ultraviolet rays in an actual semiconductor factory is extremely small. Therefore, an ultraviolet ray source is necessary for application as a leak sensor. FIG. 4 shows an example in which an ultraviolet light-emitting diode 6 is arranged on the inner surface of a cover (cover) 5 surrounding the water conduit 2 so as to face the water conduit 2. In the embodiment of FIG. 4, both side surfaces 7, 7 ′ of the enclosure 5 of the water conduit 2 are formed in a mesh structure or formed so that water can enter by vertically slitting. In the above embodiment, the water guide channel 2 contains a substance having a photocatalytic action.

When a material containing a photocatalytic substance is used for the water conduit 2, the following effects can be obtained.
(1) It becomes super hydrophilic when exposed to ultraviolet rays.
(2) Even if the water conduit is soiled with organic matter or the like, the organic matter is decomposed by the photocatalytic action, so that the super hydrophilicity of the water conduit is reliably maintained.

  However, the material used for the water conduit 2 of the present invention may be a hydrophilic material and does not stick to a material having a photocatalytic action. If a material with excellent hydrophilicity is used, it is possible to conduct water from a place far from the sensor itself. If a material with poor hydrophilicity is used, the water conveyance area to the sensor is only narrowed. If a hydrophilic material having a contact angle of 30 degrees or less is used for the water conduit, it is possible to sufficiently detect liquid leakage at a location 10 times or more away from the moisture detection part of the liquid leakage sensor.

In the above description, in order to show the best mode of the present invention, a water guide channel coated with photocatalyst containing TiO ₂ has been shown for detection of leakage of water or an aqueous solution. In this case, the only recovery after water leakage is drying. However, unless such simple recovery is considered, the water channel is not limited to a photocatalyst-coated water conduit containing TiO ₂ . The same effect can be obtained by coating a well-known surface active agent used for detergent on the surface of the water conduit. However, in this case, the restoration requires work such as coating the surface active agent again after drying the water conduit.

In addition, it has been experimentally shown that a photocatalyst-coated water conduit containing TiO ₂ necessary for water or aqueous solution leakage detection, or a water conduit coated with a surface active agent, can also effectively conduct liquids to organic solvents. It has been confirmed.

FIG. 6 shows another embodiment of the present invention, and shows an example in which non-hydrophilic films 8 and 8 ′ are formed on both sides of the liquid introduction path 2 in the liquid passage direction. The liquid guide path 2 is constituted by forming a hydrophilic film 3 on a liquid guide path substrate (water guide path substrate) 9, and a non-hydrophilic film thicker than the hydrophilic film 3 on both sides of the hydrophilic film 3. 8, 8 'are formed.

  By comprising in this way, a leak can be guide | induced to a leak sensor effectively.

  FIG. 7 shows an example in which the ultraviolet light-emitting diode 6 is fixed by covering the liquid introduction path with an enclosure 5 having a substantially U-shaped cross section and spaced in the length direction inside the upper surface of the enclosure 5. In the above embodiment, the U-shaped enclosure 5 is fitted and fixed to the convex strips 10 and 10 'on both sides of the water guide path substrate 9 with the concave strips 11 and 11' on the inner surface of the U-shaped enclosure 5 below. ing.

  Both sides of the U-shaped enclosure 5 are formed in a mesh or slit region 7 with a predetermined height from the surface of the liquid guide path 2, so that liquid leakage reaches the liquid guide path 2.

  FIGS. 8 and 9 show another embodiment of the present invention, in which the second hydrophilic surface 3 ′ is formed through the hydrophilic surface 3 of the liquid introduction path and the space 12 which becomes the flow path of the liquid leakage. An example of opposing arrangement is shown.

  The liquid leakage moves in the space 12 which becomes the flow path of the liquid leakage, but can be moved more smoothly by configuring as described above.

  A predetermined height is formed in the mesh or slit region 7 from the first hydrophilic surface 3, and when water leaks onto the substrate 9 ′ of the second hydrophilic surface 3 ′, the first hydrophilic surface 3 An opening is formed in the second hydrophilic surface and the substrate so as to fall down.

  In the above embodiment, since the second hydrophilic surface 3 ′ and the substrate 9 ′ are formed of a transparent or translucent material that transmits light, the ultraviolet rays from the light emitting diode 6 can be transmitted without any problem. It hits the hydrophilic surface 3.

  As shown in FIG. 10, a tongue piece 16 is formed at a connecting portion of the liquid leakage sensor 11 with the liquid guide path 2 of the liquid absorbent paper 15, and the tongue piece 16 is formed on the hydrophilic surface 3 of the liquid guide path 2. It is preferable to make it contact.

  After using the leak detection sensor of the present invention, as shown in FIG. 12, for example, a rubber pipe 16 is externally fitted to the end of the cover 5, and nitrogen is blown from the other end pipe 17 having a small diameter. What is necessary is just to blow dry.

  Although the liquid leakage sensor itself used in the present invention is not particularly limited, it is possible to irradiate light from a light emitting diode on the surface of paper having good liquid absorption and measure the scattered light intensity, so that the problem of false alarm does not occur. This is preferable.

  FIG. 11 shows another example of the leak sensor.

  The leaked liquid that has moved on the hydrophilic surface 3 of the liquid guide path is sealed from the bottom mesh 18 and enters the water-absorbing polymer 19. The water-absorbing polymer 19 expands in volume, and is conducted through the drop lid 20 and the elastic body 21. The electrode 22 is raised, and the first electrode 24 and the second electrode 25 fixed on the back surface of the insulating plate 23 fixed above are short-circuited. At this time, it is possible to detect a water leak by configuring a buzzer or an electric lamp to turn on.

  In the above embodiment, the cylindrical container 26 of the housing is formed in a shape in which a small diameter portion is connected to a large diameter portion, and the conduction electrode 22 rises in the small diameter portion.

It is (a) top view which shows the Example of this invention, (b) It is a side view. It is a top view which shows the spreading of the water droplet in the super hydrophilic surface of this invention. (A) is a side view which shows the mode of the water droplet on a hydrophobic surface, (b) is a side view of the state which the water droplet touched the hydrophilic surface. It is (a) top view and (b) side view which show the other Example of this invention. It is (a) top view and (b) side view which show the other Example of this invention. It is (a) top view and (b) side view which show the other Example of this invention. It is a front view which shows the other Example of this invention. It is (a) top view and (b) side view which show the other Example of this invention. It is a front view which shows the other Example of this invention. It is a top view which shows the combined state of the liquid introduction path of this invention, and a leak sensor. It is a side view which shows the other Example of this invention. It is the (a) front view which shows the state dried after use of the liquid introduction path of this invention, (b) It is a cross-sectional side view.

Explanation of symbols

1 ... Leak sensor (leak sensor)
2 ... Liquid guide (water guide)
3 ... hydrophilic surface 4 ... hydrophobic surface 5 ... cover (enclosure)
6: Light-emitting diode 7, 7 ': Cover side surfaces 8, 8': Non-hydrophilic coating

Claims (9)

A liquid leakage detection sensor comprising a long liquid-impermeable path for surface liquid impermeability that guides liquid leakage from a location away from a liquid leakage detection region of the liquid leakage sensor to the liquid leakage sensor. The sensor according to claim 1, wherein the liquid introduction path has a length that is ten times or more a liquid leakage detection region of the liquid leakage sensor. The sensor according to claim 1, wherein the liquid guide path has a hydrophilic liquid impermeable surface. The sensor according to claim 3, wherein the liquid guide path includes a substance having a photocatalytic action, and is formed to have a hydrophilic surface by being irradiated with ultraviolet rays. 5. The sensor according to claim 3, wherein a center of the liquid guide path serving as a liquid passage is formed of a surface hydrophilic material and both sides are formed of a surface hydrophobic or water repellent material. The sensor according to any one of claims 3 to 5, wherein the sensor has a second hydrophilic surface that is vertically opposed to each other via a space serving as a hydrophilic surface of the liquid guide path and a flow path for liquid leakage. The sensor according to any one of claims 1 to 6, wherein the liquid leakage sensor applies light from a light emitting diode to the surface of paper having good liquid absorption and measures the intensity of scattered light. A liquid leakage detection system comprising the liquid leakage detection sensor according to any one of claims 4 to 7 and ultraviolet light that hits a photocatalytic substance in a liquid guide path of the liquid leakage detection sensor. The liquid leakage detection system according to claim 7, wherein a light source that emits ultraviolet light is provided in the liquid guide path, or ultraviolet light is applied.

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