JP2005291917A - Tank leakage detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately perform leakage inspection of a liquid phase domain regardless of a physical property of the liquid stored in a tank. <P>SOLUTION: An inspection pipe unit 38 has a sensor unit 40, a detection pipe holding part 54, a detection signal output part 55, an upper cylinder part 56, a lower cylinder part 58 and a fixed member 60. When a pinhole is generated by corrosion or the like on the wall surface of an underground tank 12, a gas phase domain 50 is depressurized to a prescribed pressure, and ground water enters the inside of the underground tank 12. Hereby, the liquid in the underground tank 12 flows into a lower chamber 78b of a liquid storage chamber 78 through the small hole 62a, and a diaphragm 80 is swelled by a volume change of an entering microflow. Resultantly, the liquid 82 injected into an upper chamber 78a of the liquid storage chamber 78 is pushed upward by the volume expansion of the diaphragm 80, and enters the sensor unit 40 through a micro-passage 84. Hereby, a flow velocity measured value is outputted from a flow velocity sensor 44. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a leakage detection device for a storage tank, and more particularly to a tank leakage detection device configured to detect the presence or absence of leakage in a liquid phase region in a state where a storage liquid in a tank is contained.

  For example, in a gas station that supplies fuel such as gasoline to a fuel tank of an automobile, an underground tank for storing the fuel is buried in the ground, and the fuel is sucked up by a measuring machine installed on the ground to Refueling the fuel tank. This type of underground tank is required to be inspected for leaks by the Fire Service Act, and the leak inspection accuracy is defined as being able to detect leaks from holes with a diameter of 0.3 mm.

  The leak from the hole having a diameter of 0.3 mm corresponds to a leak of about 0.8 L / h with a 1 m water column. An underground tank having a capacity of about 10 kl is often used, but a large one has a capacity of 100 KL. In addition, liquids stored in underground tanks, for example, gasoline, light oil, kerosene, heavy oil, chemical liquids, solvents, waste oils, etc. having low to high fluid viscosity, those having corrosive components, and constant components There are various types of liquids, liquids whose components are not constant, and liquids mixed with foreign substances.

  The following method is generally performed as a conventional leakage inspection method performed in a state where the stored liquid is still contained. As a method of detecting the presence or absence of leakage in the gas phase region of the underground tank, the presence or absence of leakage is confirmed by sealing the underground tank and monitoring the pressure change by pressurizing or depressurizing the space (gas phase region) above the liquid. Was inspecting. In addition, for leak inspection of the liquid phase area of the underground tank, for example, the pressure in the underground tank is reduced to a certain value or more by a vacuum pump so that the negative pressure is reached to the bottom of the underground tank. A method for detecting entry into the tank and a method for detecting the sound of ambient air entering the underground tank are employed.

  This leakage inspection in the liquid phase area is configured to insert various sensors in the underground tank to detect the rise in liquid level caused by the intrusion of a small amount of groundwater or the upward flow accompanying the rise in liquid level. The tank leakage detection device is used. For example, a hot-wire anemometer is used as a sensor that detects the rising flow of liquid accompanying the ingress of groundwater into the underground tank (see, for example, Patent Document 1).

  This hot wire type anemometer has a configuration in which a heating resistor and a temperature sensitive resistor are provided in a pipe line, and the heat that is heated by the flow velocity of the liquid flowing through the pipe is increased and the amount of heat that propagates increases. It measures the flow velocity.

In addition, as a sensor other than the hot-wire anemometer, a capacitance type that detects the position of the liquid level by measuring the capacitance that changes as the liquid level rises due to the amount of water flowing into the underground tank There are sensor methods.
JP 2003-185522 A

  In the case where the liquid phase region is inspected for leakage, for example, when infiltration of ground water of about 0.8 L / h occurs, the liquid level rising speed is 0.01 mm / h when the capacity of the underground tank is 10 kL. Since this is a very small change, the sensor performance used for the detection means needs to be highly sensitive.

  In such a sensor having high sensitivity detection performance, in order to increase the detection sensitivity, the flow rate in the minute pipeline and the amount of liquid existing in the minute gap are measured. For example, when the viscosity of the detected liquid such as gasoline, kerosene, light oil, or solvent is low, there is no problem because the liquid can pass through a minute pipe or minute gap without resistance.

  However, when the viscosity of the liquid to be detected, such as heavy oil, waste oil, or chemical liquid, is high, the viscosity resistance in a minute pipe line or minute gap increases and the flow velocity decreases to detect an increase in liquid level. There is a problem that it takes a long time.

  In addition, when contaminants exist in the liquid, the contaminants adhere to minute pipes or minute gaps and block the flow path, and it is impossible to accurately detect minute liquid level rise. There is also.

  In addition, when various waste liquids are mixed like waste oil, the physical properties (dielectric constant, etc.) of the waste oil change. There is also a problem that cannot be determined.

  Moreover, when the liquid which has a corrosive component is stored in the underground tank, there exists a possibility that the material which comprises a micro pipe line and a micro clearance gap may corrode and a leak test cannot be performed.

  Therefore, an object of the present invention is to provide a tank leak detection device that solves the above-described problems.

  According to a first aspect of the present invention, there is provided a detection device main body inserted into a tank, and a liquid provided in the detection device main body, isolating the interior of the detection device main body from the tank and stored in the tank. An isolation member provided so as to move up and down according to the increase / decrease of the liquid, a liquid isolated by the isolation member and enclosed in the detection device body, and provided in the detection device body, A sensor that detects the movement of the liquid that occurs along with the movement, a communication part that communicates the upper part of the main body of the detection device and the upper space of the tank, and outputs the presence or absence of leakage of the tank by a detection signal from the sensor. And an output means.

  The invention according to claim 2 is characterized in that the sensor detects a flow of a liquid moving inside the detection device main body.

  The invention according to claim 3 is characterized in that the isolation member is made of a diaphragm that moves up and down in accordance with increase or decrease of the liquid.

  The invention according to claim 4 is the tank leak detection device according to claim 1, wherein the detection device main body is provided with a sound detection means for detecting a sound generated due to leakage from the leak location of the tank. Features.

  A fifth aspect of the present invention is the tank leak detection device according to the first aspect, further comprising a determination unit that receives the output result of the output unit and determines whether or not there is a leak.

  According to the present invention, the movement of the liquid accompanying the vertical movement of the isolation member that isolates the inside of the detection device main body inserted into the tank and the tank is detected by the sensor, and the presence or absence of leakage of the tank is detected. By detecting the flow of liquid that accompanies the expansion and contraction of the isolation member without directly detecting the liquid in the tank, it is not affected by the viscosity or physical properties (dielectric constant, corrosivity, etc.) of the liquid in the tank. In addition, the flow of liquid due to leakage can be detected with high accuracy. In other words, it becomes possible to accurately detect the movement of the liquid passing through the micropipe or the minute gap in response to the flow of the stored liquid accompanying the leakage, and the tank leakage inspection can be performed efficiently in a short time. .

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a tank leakage detection apparatus according to the present invention.
As shown in FIG. 1, the tank leak detection apparatus 10 is used as an apparatus for inspecting whether there is a leak in an underground tank 12 installed in a gas station that supplies fuel such as gasoline to a fuel tank of an automobile, for example.

  On the ground of the filling station, there are provided a measuring machine 14 for refueling, a manhole 16 communicating with the underground tank 12, an oil filling port 18 of the underground tank 12, and a vent 20 communicating with the upper space of the underground tank 12. In the underground tank 12 buried underground in the fueling station, an oil supply line 22 communicated with the oil supply system of the measuring machine 14 and an oil supply line 24 communicated with the oil supply port 18 are inserted.

  In addition, the air duct 26 communicated with the air vent 20 communicates with the upper part of the underground tank 12. This vent pipe 26 is a pipe that closes the vent to the atmosphere and also serves as a decompression pipe at the time of leakage inspection. The vent 20 has a suction port (see FIG. (Not shown) communicates with each other via the decompression hose 30. An exhaust pipe 32 opened to the atmosphere is communicated with a discharge port (not shown) of the vacuum pump 28.

  The decompression hose 30 is provided with a thermometer 34 for measuring the temperature of air from the underground tank 12 and a pressure gauge 36 for measuring the decompressed state.

  The tank leak detection device 10 includes, in addition to the vacuum pump 28, a detection pipe unit 38 inserted into the underground tank 12 from the manhole 16, a sensor unit 40 provided at a tip portion of the detection pipe unit 38, and a sensor unit 40. The controller 42 is configured to determine the presence or absence of leakage based on the output detection signal. As will be described later, the sensor unit 40 includes a speed sensor 44 that detects the flow of the liquid as the liquid level rises due to the ingress of groundwater, and a sound sensor (sound that detects the sound generated when bubbles enter the inside of the underground tank 12. Detection means) 46. Further, a differential pressure transmitter 47 for detecting a differential pressure between the atmospheric pressure and the underground tank 12 is connected to the upper portion of the detection pipe unit 38.

  In addition, when performing a leak inspection of the underground tank 12, a closing member (blocking the valve device (not shown) of the oil supply line 22 to close the oil supply line 22 and closing the oil supply port 18 in an airtight state) (Not shown) or the like is attached to prevent air inflow from the oil filler port 18.

  Then, before performing the leakage inspection of the liquid phase region 48 of the underground tank 12, the vacuum pump 28 is activated with the detection tube unit 38 inserted into the underground tank 12 from the manhole 16 to decompress the underground tank 12. It is confirmed by the measured value of the differential pressure transmitter 47 that this reduced pressure state is maintained for a predetermined time.

  That is, the leakage inspection of the liquid phase region 48 of the underground tank 12 is performed after confirming that there is no leakage in the oil supply conduit 24, the ventilation conduit 26 and the gas phase region 50 of the underground tank 12.

Here, the configuration of the detection tube unit 38 will be described with reference to FIG.
As shown in FIG. 2, in addition to the sensor unit 40 described above, the detection tube unit 38 is provided on a detection tube holding portion 54 fixed to the insertion port 52 of the underground tank 12 and an upper portion of the detection tube holding portion 54. Attached to the lower end of the lower cylinder part 58, the lower cylinder part 58 attached to the lower end of the sensor unit 40, the upper cylinder part 56 extending downward from the detection tube holding part 54 Fixed member 60. Here, the main body of the detection device is constituted by the upper cylindrical portion 56, the sensor housing 41, and the lower cylindrical portion 58.
The length from the upper cylindrical portion 56 to the tip (lower end) of the fixing member 60 is set to a dimension according to the distance from the insertion port 52 to the bottom of the underground tank 12. The fixing member 60 is formed around the flow path 64 and the upper disk part 62 inserted into the lower end opening of the lower cylinder part 58, the flow path 64 communicating with the plurality of small holes 62 a provided in the upper disk part 62. The plurality of openings 66 and the lower disk portion 68 are formed. As shown in FIG. 3, latching claws 74 are provided at 90 ° intervals on the periphery of the upper surface of the upper disk portion 62. The four latching claws 74 are latched by a hook-shaped latching portion 58 a protruding from the lower end of the lower cylindrical portion 58.

  Further, a screw hole 68a is formed in the lower disk portion 68 of the fixing member, and the shock absorbing member 72 is fixed by a screw 70 screwed into the screw hole 68a.

  The impact absorbing member 72 is formed of an elastic rubber material or the like, and cushions an impact when contacting the bottom of the underground tank 12 during an insertion operation.

  The lower cylinder portion 58 includes a liquid storage chamber 78 formed therein, and a bag-shaped diaphragm (isolation member) 80 that is accommodated in the liquid storage chamber 78 and is mounted so as to cover the upper disk portion 62.

  A liquid 82 for detection is sealed in the upper chamber 78 a of the liquid storage chamber 78. The liquid 82 is a clean oil liquid having a specific gravity substantially equal to that of the liquid (oil liquid) stored in the underground tank 12 and a relatively small viscosity, and having a property suitable for sensor detection. Is desirable. Before the detection tube unit 38 is inserted and installed in the underground tank, the liquid to be sealed encloses an amount that is slightly lower than the liquid level of the stored liquid in the underground tank 12. In addition, liquid (for example, gasoline, heavy oil, waste oil) stored in the underground tank 12 is supplied to the lower chamber 78b through the opening 66, the flow path 64, and the small hole 62a. The upper chamber 78a and the lower chamber 78b of the liquid storage chamber 78 are isolated by the diaphragm 80 so that the liquid 82 to be detected injected into the upper chamber 78a and the liquid supplied to the lower chamber 78b do not mix.

  The diaphragm 80 is formed in a bag shape from an extremely thin resin material, and is attached so that the opening faces the upper disk portion 62. Further, the opening peripheral edge 80a of the diaphragm 80 is sandwiched between the lower end portion of the lower cylindrical portion 58 and the upper disk portion 62, and is prevented from falling off and sealed. The liquid storage chamber 78 has a sufficient space above the diaphragm 80, and the diaphragm 80 moves up and down according to the increase and decrease of the liquid supplied through the opening 66, the flow path 64, and the small hole 62a. It is provided as follows.

  Further, since the diaphragm 80 is made of a very soft material, it can move up and down with almost no resistance. When the detection tube unit 38 is inserted into the underground tank 12, the diaphragm 80 is pressed by the upper disk portion 62 due to the weight of the liquid 82 enclosed in the upper chamber 78 a of the liquid storage chamber 78 and is folded. It is stored.

  Therefore, in the state where the detection pipe unit 38 is inserted into the underground tank 12, when the liquid level changes due to the increase in the liquid in the underground tank 12 due to leakage, the liquid stored in the underground tank 12 has the opening 66, the flow path. 64, and flows into the lower chamber 78b of the liquid storage chamber 78 through the small hole 62a. As a result, the diaphragm 80 is raised by a minute volume change flowing through the small hole 62a.

  The sensor unit 40 provided in the upper part of the liquid storage chamber 78 is provided inside the sensor housing 41 as described above, and includes a flow rate sensor 44 that detects the flow of the liquid as the liquid level rises due to the ingress of groundwater, and the sensor housing. And a sound sensor 46 that is provided on the lower surface of 41 and detects a sound emitted when bubbles enter the underground tank 12. The flow rate sensor 44 is a hot-wire flow meter that detects the flow rate of the liquid 82 that flows through the microchannel 84. Since the minute channel 84 is a minute hole with a diameter of 0.8 mm, even if the leakage amount is minute, it can be detected as a minute flow velocity.

  The sound sensor 46 is a microphone and is provided at a position facing the upper chamber 78 a of the liquid storage chamber 78. The sound sensor 46 can detect the generation sound of bubbles when the bubbles enter the inside of the underground tank 12 and the burst sound of the bubbles bursting at the liquid level.

  Since the minute channel 84 penetrates the sensor unit 40 in the vertical direction, the liquid 82 is also stored in the liquid storage chamber 86 formed in the upper part of the sensor unit 40. A communication hole 88 communicating with the gas phase region 50 of the underground tank 12 is provided in the upper part of the liquid storage chamber 86. Therefore, the gas in the gas phase region 50 is supplied to the upper space of the liquid storage chamber 86 through the communication hole 88 and is maintained at the same pressure as the gas phase region 50. Thereby, the liquid level of the underground tank 12 and the liquid level of the liquid storage chamber 78 become the same.

  The injection amount of the liquid 82 needs to be adjusted in consideration of the liquid amount (liquid level) stored in the underground tank 12 and the expansion / contraction amount of the diaphragm 80.

Here, a tank leakage inspection method for the underground tank 12 will be described.
At the time of leak inspection, first, the vacuum pump 28 is activated to depressurize the underground tank 12. Thereby, the inspector confirms whether or not there is a leak in each pipeline communicated with the gas phase region 50 and the underground tank 12. That is, when there is no leakage in each pipeline communicated with the gas phase region 50 and the underground tank 12, the pressure of the gas phase region 50 does not change, but each of the channels communicated with the gas phase region 50 and the underground tank 12 is not changed. When there is a leak in the pipeline, the internal pressure in the underground tank 12 gradually increases.

  When it is confirmed that there is no leakage in the gas phase region 50, the vacuum in the underground tank 12 is further reduced by the vacuum pump 28. When the bottom of the underground tank 12 is depressurized to a specified pressure by suction of the vacuum pump 28 until the negative pressure exceeds a certain level, the liquid phase region 48 is inspected for leakage.

  In the leak inspection of the liquid phase region 48, when there is no leak in the underground tank 12, the ground water around the underground tank 12 cannot enter the underground tank 12, so that the liquid level does not rise. Therefore, since no flow is generated in the micro flow path 84 of the sensor unit 40, the flow velocity measurement value by the flow velocity sensor 44 is also zero.

  However, when pinholes due to corrosion or the like are generated on the wall surface of the underground tank 12, the liquid phase region 48 is depressurized to a specified pressure, and moisture such as groundwater enters the inside of the underground tank 12, The liquid level rises. Thereby, since the liquid of the underground tank 12 flows into the lower chamber 78b of the liquid storage chamber 78 through the small hole 62a, the diaphragm 80 moves upward by the volume change of the inflowing minute flow rate. As a result, the liquid 82 to be detected injected into the upper chamber 78 a of the liquid storage chamber 78 is moved upward along with the upward movement of the diaphragm 80, passes through the microchannel 84, and flows into the sensor unit 40. Is done.

  As described above, since a flow in which the liquid 82 moves upward also occurs in the flow path of the sensor unit 40, the flow velocity measurement value is output by the flow velocity sensor 44.

  When the detection signal of the flow velocity sensor 44 is output, the control device 42 determines the presence or absence of leakage and notifies the determination result. In addition, when there is no groundwater around the underground tank 12, the gas contained in the ground enters the inside of the underground tank 12 and is mixed into the liquid stored in the underground tank 12 as bubbles. Bubbles burst on the surface. In this case, the sound sensor 46 detects a bubble generation sound and a bubble burst sound, and outputs a detection signal to the control device 42.

FIG. 4 is a block diagram showing the control device 42 and each device connected to the control device 42.
As shown in FIG. 4, the control device 42 includes a control circuit 90 that performs calculation processing for leakage inspection, a monitor (notification unit) 92 that displays inspection results connected to the control circuit 90, and various types including leakage inspection results. It has a memory 94 for storing data and a leakage inspection program, and a printer (notification means) 96 for printing the leakage inspection result. The control circuit 90 is connected to a vacuum pump driving circuit 98 for driving the vacuum pump 28, an interface 100 to which detection signals from the flow velocity sensor 44 and the sound sensor 46 are supplied, and a differential pressure transmitter 47. ing.

  In the memory 92, a control program (output means) that outputs the presence / absence of leakage of the underground tank 12 based on the detection signal from the flow rate sensor 44, and the leakage of the underground tank 12 is detected by the detection signal from the flow rate sensor 44 that receives the output result. A control program (determination means) for determining the presence or absence is stored.

Here, the procedure of the leakage inspection control process executed by the control circuit 90 will be described with reference to FIG.
As shown in FIG. 5, the control circuit 90 activates the vacuum pump 28 and starts depressurizing the gas phase region 50. As described above, the inspector confirms whether or not the gas phase region 50 has leaked when the decompression of the gas phase region 50 is started.

  In the next S12, the flow velocity detection signal from the flow velocity sensor 44 is read. In S13, the flow rate detection signal is integrated to calculate the flow rate. In the next S14, it is confirmed whether or not the gas phase region 50 has been reduced to the specified pressure by the detection signal of the differential pressure transmitter 47.

  In S14, when the gas phase region 50 is not depressurized to the specified pressure, the processes of S12 to S14 are repeated. In S14, when the gas phase region 50 is depressurized to the specified pressure, the process proceeds to S15, and it is confirmed whether or not the leak amount calculated in S13 is equal to or greater than a preset specified value (determination means).

  In S15, when the calculated leak amount is equal to or greater than a preset specified value, it is determined that there is a leak in the underground tank 12, the process proceeds to S16, the leak amount is stored in the memory 94, and the leak amount (inspection) in S17. Result) is displayed on the monitor 92, and the leakage amount (inspection result) is printed by the printer 96. In step S18, the decompression by the vacuum pump 28 is stopped.

  In S15, when the calculated leakage amount is smaller than the preset specified value, it is below the measurement accuracy of the flow velocity sensor 44. Therefore, the process proceeds to S19, the bubble detection signal from the sound sensor 46 is read, and the sound sensor It is confirmed whether or not the acoustic detection level of the bubble detection signal detected by 46 is equal to or higher than a preset specified value.

  In S19, when the acoustic detection level of the bubble detection signal is equal to or higher than the specified value, it is determined that bubbles are generated, and the process proceeds to S20, where the bubble generation is notified by the monitor 92 and the printer 96.

  If the sound detection level of the bubble detection signal is less than the specified value in S19, the process proceeds to S21, where no leak is stored in the memory 94, and no leak is reported by the monitor 92 and the printer 96 in S22. Then, the process proceeds to S18 and the suction pump 70 is stopped.

  As described above, in the tank leak detection device 10, the flow rate sensor 44 detects the movement of the liquid 82 accompanying the ascending operation of the diaphragm 80 that isolates the interior of the lower cylinder portion 58 inserted into the underground tank 12 and the underground tank 12. Therefore, by detecting the flow of the liquid 82 without directly detecting the liquid in the underground tank 12, the viscosity and physical properties of the liquid in the underground tank 12 are detected. Without being affected by (dielectric constant, corrosiveness, etc.), it is possible to detect the flow rate of water such as groundwater entering the underground tank 12 with high accuracy. Therefore, it is possible to accurately detect the movement of the liquid 82 that passes through the microchannel 84, and the leakage inspection of the underground tank 12 can be performed efficiently in a short time.

FIG. 6 is a longitudinal sectional view showing a first modification of the detection tube unit 38.
As shown in FIG. 6, in Modification 1, a capacitive sensor unit 110 is incorporated in the detection tube unit 38 instead of the sensor unit 40. The sensor unit 110 includes a cylindrical detection unit 112 for detecting capacitance, an upper holding member 114 fitted to the upper part of the cylindrical detection unit 112, and a cylindrical detection unit 112 inside the sensor housing 111. And a lower holding member 116 fitted to the lower part of the lower part.

  As shown in FIG. 7, in the cylindrical detection unit 112, a metal inner cylinder 118 and an outer cylinder 120 are concentrically arranged, and an annular flow path is provided between the inner cylinder 118 and the outer cylinder 120. 122 is formed. In addition, an inlet 124 penetrates in the radial direction at the outer periphery of the lower end of the outer cylinder 120 so that the liquid 82 flows into the annular flow path 122, and the annular flow path 122 is formed at the outer periphery of the upper end of the outer cylinder 120. Outlet 126 through which the liquid 82 to be detected flows out penetrates in the radial direction.

  Further, the inner cylinder 118 and the outer cylinder 120 are connected to a capacitance detection circuit 130 via lead wires 128a and 128b. Since the capacitances of the inner cylinder 118 and the outer cylinder 120 change according to the change in the liquid level in the sensor housing 111, the capacitance detection circuit 130 detects the position of the liquid level from the detected capacitance value. It becomes possible.

  The length in the vertical direction (axial direction) of the cylindrical detection unit 112 is arbitrarily set. For example, it may be set according to the capacity of the underground tank 12 or the amount of liquid stored in the underground tank 12. It is also possible to narrow the measurable range if the height position of the liquid level at the time of leakage inspection is determined.

  The upper holding member 114 and the lower holding member 116 have the same shape and are arranged so as to be symmetrical in the vertical direction. Here, the configuration of the lower holding member 116 will be described, and the description of the upper holding member 114 will be omitted.

  As shown in FIG. 8, the lower holding member 116 is formed in a disk shape, an annular groove 132 is provided on the upper surface thereof, and a flow path 134 penetrating in the vertical direction is provided on the outer periphery at intervals of 90 degrees in the circumferential direction. In four places.

  The annular groove 132 is a guide portion for positioning the mounting positions of the inner cylinder 118 and the outer cylinder 120. The inner periphery of the annular groove 132 is fitted inside the inner cylinder 118, and the outer periphery of the annular groove 132 is the outer cylinder. Fits outside 120. The inner cylinder 118 and the outer cylinder 120 are fitted with an annular groove 132 provided on the lower surface of the upper holding member 114 at the upper end and fitted into an annular groove 132 provided on the upper surface of the lower holding member 116. Being held.

  As described above, the inner cylinder 118 and the outer cylinder 120 are positioned so that their upper and lower ends are concentrically arranged by fitting into the annular grooves 132 of the upper holding member 114 and the lower holding member 116, and The gap of the path 122 is set to a predetermined dimension suitable for detecting a change in capacitance.

  Further, the upper holding member 114 and the lower holding member 116 are in contact with the restricting portions 111 a and 111 b of the sensor housing 111, and the mounting positions in the vertical direction are restricted. Therefore, the cylindrical detection unit 112 is attached in a state where the inner cylinder 118 and the outer cylinder 120 are held between the upper holding member 114 and the lower holding member 116.

  When the leakage inspection of the liquid phase region 48 is performed, in the cylindrical detection unit 112 configured as described above, if no leakage occurs in the underground tank 12, the underground water cannot enter the underground tank 12. In the annular flow path 122, the liquid level does not rise. Therefore, since no flow is generated in the micro flow path 84 of the sensor unit 40, the flow velocity measurement value by the flow velocity sensor 44 is also zero.

  However, when a pinhole due to corrosion or the like is generated on the wall surface of the underground tank 12, the inside of the underground tank 12 is reduced to a specified pressure and the groundwater enters the inside of the underground tank 12, so that the liquid level rises. Will occur. Thereby, since the liquid of the underground tank 12 flows into the lower chamber 78b of the liquid storage chamber 78, the diaphragm 80 moves upward by the volume change of the flowed-in micro flow rate. As a result, the liquid 82 to be detected injected into the upper chamber 78 a of the liquid storage chamber 78 passes through the micro flow path 84 and moves inside the sensor housing 111 of the sensor unit 110 as the diaphragm 80 moves upward. Is flowed into.

  The liquid 82 to be detected inside the sensor housing 111 passes through the flow path 134 and the inlet 124 of the lower holding member 116 and flows into the annular flow path 122 to raise the liquid level in the annular flow path 122. .

  As described above, since the flow of the liquid 82 moves upward also in the annular flow path 122 of the sensor unit 110, in the capacitance detection circuit 130, the ratio between the liquid phase and the gas phase of the inner cylinder 118 and the outer cylinder 120. The change of the electrostatic capacity accompanying the change of is detected, and the liquid level measurement value is output.

  As described above, the sensor unit 110 detects the displacement (liquid level) of the liquid 82 accompanying the expansion / contraction operation of the diaphragm 80 and determines whether or not the underground tank 12 has leaked, so that the liquid in the underground tank 12 can be directly detected. Without detecting the flow of the liquid 82, the flow rate of the groundwater that has entered the underground tank 12 without being affected by the viscosity or physical properties (dielectric constant, corrosiveness, etc.) of the liquid in the underground tank 12 can be determined. It can be detected with high accuracy. Therefore, it becomes possible to accurately detect the displacement (liquid level) of the liquid 82 passing through the micro flow path 84, and the leakage inspection of the underground tank 12 can be efficiently performed in a short time.

FIG. 9 is a longitudinal sectional view showing a second modification of the detection tube unit 38.
As shown in FIG. 9, in Modification 2, the above-described upper disk portion 62 is removed from the detection tube unit 38, and a metal or resin spherical net member 65 is provided instead. The net member 65 is formed in a hemispherical shape so as to receive the diaphragm 80 pressed downward by the liquid 82 sealed in the upper chamber 78 a of the liquid storage chamber 78 in a state before being inserted into the underground tank 12. In addition, a flange 65 a that is hooked on the ring-shaped protrusion 67 is provided on the peripheral edge thereof.

  Since the cross section of the flange 65a is formed in an L shape, the flange 65a is fitted and locked between the outer periphery of the ring-shaped protrusion 67 and the inner periphery of the lower cylindrical portion 58, and is prevented from falling off.

  Thus, by providing the mesh member 65 instead of the upper disk portion 62, when the detection tube unit 38 is inserted into the underground tank 12, the diaphragm 80 is held in close contact with the spherical mesh member 65. Since it can be brought into the stored liquid in the underground tank 12, air can be prevented from entering the lower part of the diaphragm 80.

  Therefore, the inflow of air into the lower part of the diaphragm 80 is prevented, so that a decrease in the flow velocity detection accuracy accompanying the air inflow is prevented at the time of leakage detection, and the leakage detection accuracy can be ensured.

  In the above embodiment, the leakage inspection of the underground tank installed in the fueling station that supplies fuel such as gasoline to the fuel tank of the automobile has been described. However, the present invention is not limited to this, and the ground tank installed in the facility other than the gas station is not limited to this. Of course, the present invention can also be applied to leak inspection.

  Further, in the embodiment, the inside of the underground tank is depressurized and the groundwater is forcibly sucked into the underground tank, but the inside of the underground tank is slightly pressurized to detect a decrease in the liquid level inside. good.

  Furthermore, it is needless to say that the leakage of the underground tank may be detected by constantly monitoring an abnormality in the underground tank as a standard product in the underground tank storing the liquid, not only at the time of tank inspection.

  In the above embodiment, the detection of leakage in the underground tank has been described as an example. However, the present invention is not limited to this, and for example, the presence or absence of leakage in a tank installed on the ground or in a building is detected. Of course, the present invention can also be applied to a tank leak inspection apparatus.

It is a block diagram which shows one Example of the tank leak detection apparatus which becomes this invention. 4 is a longitudinal sectional view showing the configuration of a detection tube unit 38. FIG. 3 is a perspective view showing a configuration of a fixing member 60. FIG. FIG. 3 is a block diagram showing a control device and each device connected to the control device. 3 is a flowchart of a leakage inspection control process executed by a control circuit 90. 6 is a longitudinal sectional view showing a first modification of the detection tube unit 38. FIG. It is a perspective view which shows the state by which the inner cylinder 118 and the outer cylinder 120 were arrange | positioned concentrically. 4 is a perspective view showing a configuration of a lower holding member 116. FIG. FIG. 9 is a longitudinal sectional view showing a second modification of the detection tube unit 38.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tank leak detection apparatus 12 Underground tank 14 Weighing machine 16 Manhole 18 Lubrication port 20 Ventilation port 22 Lubrication pipeline 24 Lubrication pipeline 26 Ventilation pipeline 28 Vacuum pump 36 Pressure gauge 38 Detection pipe unit 40,110 Sensor unit 41,111 Sensor Housing 42 Control device 44 Flow rate sensor 46 Sound sensor 47 Differential pressure transmitter 48 Liquid phase region 50 Gas phase region 54 Detector tube holding part 56 Upper cylinder part 58 Lower cylinder part 60 Fixing member 62 Upper disk part 64 Channel 66 Opening 68 Lower part Disk portion 72 Shock absorbing member 74 Latching claw 78 Liquid storage chamber 80 Diaphragm 82 Liquid 84 Micro flow channel 86 Liquid storage chamber 88 Communication hole 90 Control circuit 92 Monitor 94 Memory 112 Cylindrical detector 114 Upper holding member 116 Lower holding member 118 Inner cylinder 120 Outer cylinder 122 Annular flow path 124 Inlet 126 Outlet 130 Capacitance Detection circuit 132 an annular groove

Claims (5)

A detection device body inserted into the tank;
An isolation member provided in the detection device main body, isolating between the inside of the detection device main body and the tank, and being provided so as to move up and down according to the increase or decrease of the liquid stored in the tank;
A liquid isolated by the isolation member and sealed in the main body of the detection device;
A sensor provided in the detection device main body, for detecting the movement of the liquid caused by the vertical movement of the isolation member;
A communication part for communicating the upper part of the detection device main body and the upper space of the tank;
Output means for outputting the presence or absence of leakage of the tank according to a detection signal from the sensor;
A tank leak detection device comprising:   The tank leak detection device according to claim 1, wherein the sensor detects a flow of a liquid moving inside the detection device main body.   The tank leakage detection device according to claim 1, wherein the isolation member includes a diaphragm that moves up and down in accordance with increase or decrease of the liquid. The tank leak detection device according to claim 1,
A tank leak detection apparatus, wherein a sound detection means for detecting a sound generated due to a leak from a leak point of the tank is provided in the detection apparatus main body. The tank leak detection device according to claim 1,
A tank leak detection apparatus comprising: a determination unit that receives the output result of the output unit and determines whether or not there is a leak.

Images