JPH08327490A - Leakage detecting device for underground tank - Google Patents

Abstract

PURPOSE: To improve the workability at the time of installing a leakage detecting device by closing the upper end side of a leakage detecting pipe with a lid body integrally formed with a joint box in an airtight state and reducing the numbers of parts and fitting (connecting) spots and, at the same time, to reduce the possibility of breakage of sealing by simplifying the sealing structure, etc. CONSTITUTION: A lid body 19 detachably attached to the upper end side of a leakage detecting pipe 5 is formed to a bottomed pipe-like shape by die casting aluminum, and so on, and a large-diameter flange section 19A which is butted with the flange 6 of the pipe 5 through an annular packing 20 is integrally formed with the lower end side of the lid body 19. In addition, a joint box 23 and pipe-like inspection port 24 are integrally formed with the lid body 19 so that the box 23 and port 24 can be arranged in parallel in the lateral direction on the flange section 19A and a cap 28 is detachably attached to the upper end side of the port 24 with screws. Then the box 23 is isolated from the port 24 and, at the same time, closed with a lid plate 25 so that lead wires 12 from a leakage detector 7 can be led out from the lid body 19 in an airtight and liquidtight state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detection device for an underground tank, which is suitable for detecting whether or not liquid has leaked from an underground tank such as a gasoline filling station, and more particularly to a double shell structure. The present invention relates to a leak detection device for an underground tank.

[0002]

2. Description of the Related Art Generally, in gasoline filling stations,
Multiple underground tanks (oil storage tanks) formed as a cylindrical closed container made of a rigid material such as iron are buried underground in the gas station, and oil liquids such as gasoline, light oil, and kerosene are individually stored in these underground tanks. I try to store it.

By the way, since oil liquid such as gasoline is a dangerous substance, it is obliged to take special measures against leakage of oil liquid. For example, a concrete frame or the like is provided around the underground tank. The so-called concrete pit type which is surrounded by is adopted.

However, in this concrete pit type,
Prior to burying an underground tank (oil storage tank) underground in a gas station, etc., it is necessary to assemble a concrete frame, etc., into a sturdy structure, which is a drawback that a great deal of labor and time are required to bury the underground tank. is there. Therefore, for example, Japanese Patent Laid-Open No. 6-345183 proposes that the underground tank has a double-shell structure in order to simplify the operation of burying the underground tank.

That is, an underground tank having a double shell structure is formed of a steel inner shell containing an oil liquid such as gasoline therein and a fiber reinforced plastic (FRP), and at least the bottom side of the inner shell is formed. A detection space for detecting leakage of oil liquid is defined between the outer shell and the inner shell.

Further, a leak detecting pipe extending vertically through the inner shell is integrally provided, and the lower end side of the leak detecting pipe is communicated with the detection space at the bottom outer surface side of the inner shell.
The upper end side of the leak detection tube is configured to project upward from the inner shell.

A float type leak detector or the like is provided in the leak detection tube from the upper end side thereof toward the detection space so that liquid leaks from the inner shell into the detection space or the outer shell. When groundwater, etc. intrudes (leaks) into the detection space from the outside of the tank, it can be detected early by a leak detector to prevent oil liquid (dangerous substances) from leaking around the underground tank at the gas station. I try to prevent it.

Further, a tubular body with a flange is provided on the upper end side of the leak detection tube, and a connection box (joint box) for signal lines is fixed to the upper end side of the tubular body by means of screws or the like, and the connection is made. At the bottom of the box, etc., the leak detection tube is sealed to the outside together with the detection space. The junction box is provided with an inspection port for airtightness inspection.When performing an airtightness inspection of the underground tank, this inspection port is connected to an external pressure air source, etc., and air is introduced into the leak detection pipe (detection space). It is inspected whether or not it is sealed and can secure the rise of pressure.

Furthermore, in the prior art, in order to check the operation of the leak detector, for example, one end of a wire or the like is connected to the float of the leak detector, and the other end of the wire is connected to the leak detector tube. It is attached to the upper end side of the via a plug or the like. When checking the operation of the leak detector while it is installed in the underground tank, pull up the other end of the wire from the upper end side of the leak detection tube, and manually operate the float through the wire. The leak detector is closed and opened (ON, OF
F) The operation can be checked.

[0010]

By the way, in the above-mentioned prior art, a tubular body with a flange or the like is connected to the upper end side of the leak detection tube, and a connection box (joint) for signal lines is attached to the upper end side of the tubular body. Since the connection is made by screwing the bottom side of the box), the connection box and the tubular body will largely protrude from the upper end side of the leak detection pipe, and these cannot be made compact by being downsized. When an external force acts on the upper end side of the connection box, the connecting portion (screw portion) between the tubular body and the connection box is likely to be damaged early, and the connection box for signal lines (joint box) is always maintained with high strength. There is a problem that you cannot do it.

In order to keep the inside of the leak detection tube (detection space) airtight, it is necessary to hermetically seal between the upper end side of the leak detection tube and the cylindrical body with the flange. It is necessary to similarly seal between the cylindrical body and the connection box, and there is a problem that the sealing structure becomes complicated and the possibility of airtight leakage increases.

Further, since the cylindrical body and the connection box, which are separately formed, are connected to the upper end side of the leak detection tube with sealing, the number of parts and the connection points are increased, and the connection (installation) is performed. There is a problem that the workability at the time cannot be improved.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can close the upper end side of the leak detection tube in an airtight state with a lid body integrated with a joint box, and the number of parts and mounting (connection) To provide a leak detection device for an underground tank, which can reduce the number of locations and greatly improve the workability at the time of installation, can also simplify the seal structure, etc., and can reduce the possibility of airtight leak. It is an object.

[0014]

In order to solve the above-mentioned problems, the invention according to claim 1 is formed into a double shell structure from an inner shell and an outer shell, and the inner shell and the outer shell are An underground tank defining a detection space therebetween, a lower end side of the leakage detection pipe provided at the underground tank so as to communicate with the inside of the detection space, and an upper end side of the leakage detection pipe protruding outside the underground tank, A float type leak detector, which is inserted from the upper end side into the detection space, and has a float provided at the lower end side of the sensor holder to detect the leakage of the liquid into the detection space, and the leak detection tube. It is composed of a lid body provided on the upper end side and holding the inside of the leak detection tube in a hermetically sealed state, and a joint box for the signal line that draws out the signal from the leak detector to the outside in a gas-liquid tight manner on the lid body. The structure that is formed integrally is adopted.

Further, in the invention according to claim 2, a flange portion fixed to the lid body at an upper end side of the leak detection tube in an abutting state, and the sensor holding body located on the flange portion. Formed integrally with a cylindrical inspection port through which the upper end side is inserted,
The joint box and the inspection port are arranged side by side on the flange portion.

Further, in the invention as set forth in claim 3, a lock mechanism for restricting upward and downward movements of the sensor holder to position the sensor holder at the inspection opening of the lid, and the inspection opening of the inspection opening. A cap that is detachably attached to the upper end side and that seals the inspection port is provided.

Furthermore, in the invention described in claim 4,
A scale portion is provided on the outer peripheral surface of the sensor holder to extend from the upper end side to the lower end side of the sensor holder and to measure the vertical movement amount of the sensor holder.

[0018]

With the above construction, in the invention described in claim 1,
Since the joint box for the signal line that draws out the signal from the leak detector to the outside in a gas-liquid tight manner is integrally formed with the lid that holds the inside of the leak detection tube in a sealed state, the joint box and the lid are united. It can be configured as one part (integrated structure), and when the lid is mounted on the upper end side of the leak detection tube, the joint box can be assembled at the same time. Then, the inside of the leak detection tube can be reliably sealed by the lid, and the signal line from the leak detector can be drawn out to the outside in a gas-liquid tight manner by the joint box.

According to the second aspect of the present invention, a flange portion fixed to the upper end side of the leak detection tube in an abutting state is integrally formed with the lid, and the joint box is provided on the flange portion. By arranging the cylindrical inspection port and the cylindrical inspection port side by side, the joint box and the cylindrical inspection port can be set to reinforce each other, and the joint box and the cylindrical inspection port can be set on the flange portion of the lid. The inspection port can be integrated with high strength.

Further, as in the invention described in claim 3,
By providing a lock mechanism for positioning the sensor holder and a cap that seals the inspection port on the inspection port of the lid, the inspection port can be reliably sealed with the cap and the cap is removed from the inspection port. Then, while confirming the upper end side of the sensor holder from the inspection port, an operation of moving the sensor holder up and down (for example, operation check of the leak detector) can be easily performed. Further, by operating the lock mechanism, upward and downward movements of the sensor holding body can be regulated at arbitrary positions, and the sensor holding body is appropriately fixed (positioned) to the lid body at the upper end side of the leak detection tube. )can do.

Further, as in the invention described in claim 4, by providing a scale portion extending from the upper end side to the lower end side of the sensor holding body on the outer peripheral surface of the sensor holding body, the sensor holding body is provided. The amount of movement when moving up and down can be accurately measured via the scale portion, and thus the amount of leakage of the liquid that has entered the detection space can be measured.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A leak detection device for an underground tank according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 9 as an example in which it is applied to an underground tank of a gas station.

1 to 7 show a first embodiment of the present invention.

In the figure, reference numeral 1 denotes an oil storage tank as an underground tank which is buried underground in a gas filling station. The oil storage tank 1 contains an oil liquid F, such as gasoline, inside to form a tank main body. 2 and an outer shell 3 described later are formed as a tank having a double shell structure. Here, the inner shell 2 of the oil storage tank 1 is formed as a horizontal closed cylindrical closed container by welding (canning) a plurality of plate materials made of a highly rigid material such as steel. On the upper side of the shell 2, an oil injection pipe, an oil absorption pipe (neither shown), etc. are provided so as to project upward together with a leak detection pipe 5 described later.

In the oil storage tank 1, an oil liquid F such as gasoline is supplied (supplemented) into the inner shell 2 through the oil filling pipe, and the oil liquid F is stored in the inner shell 2. The tip end of the oil absorption pipe is connected to a weighing machine (not shown) or the like at a gas filling station, and when the vehicle is filled with an oil liquid F such as gasoline, a pump (not shown) attached to the weighing machine.
The oil liquid F is sucked up from the inner shell 2 via the.

Reference numeral 3 denotes an outer shell provided outside the inner shell 2 so as to surround at least the bottom side of the inner shell 2.
Is formed of, for example, fiber reinforced plastic (FRP) as a container corresponding to the outer shape of the inner shell 2, and the upper end side 3A thereof also covers the upper side surface of the inner shell 2. The outer shell 3 defines a detection space 4 between the outer shell 3 and the inner shell 2 for detecting the leakage of the oil liquid F, and the detection space 4 surrounds the inner shell 2 with a small amount of, for example, about 0.1 mm. It has a structure that surrounds it with a gap.

Reference numeral 5 denotes a leak detection pipe provided so as to penetrate through the inner shell 2 in the vertical direction. The leak detection pipe 5 is formed by a metal pipe made of steel or the like, and the lower end side thereof communicates with the detection space 4. are doing. The upper end side of the leak detection tube 5 projects upward from the inner shell 2, and a flange 6 is integrally provided on the projecting end side. The inside of the leak detection tube 5 serves as an insertion hole for a leak detector 7 which will be described later, and the inside of the inner shell 2 is completely blocked. A punching metal (not shown) having a plurality of small holes is fixedly provided on the lower end side of the leak detection pipe 5, and the lower end side of the leak detection pipe 5 is located inside the detection space 4 via the punching metal. It may be configured to communicate with.

Reference numeral 7 denotes a leak detector provided by being inserted into the leak detecting pipe 5, and the leak detector 7 extends in the vertical direction in the leak detecting pipe 5 as shown in FIGS. A long sensor rod 8 whose side projects upward from the leak detection tube 5 and a tubular guide stem 10 integrally fixed to the lower end side of the sensor rod 8 via a stepped tubular spring receiver 9.
And a sensor unit 1 attached to the lower end side of the guide stem 10 for detecting whether or not a leaking liquid has infiltrated into the detection space 4 when a float 14 described later approaches and separates.
1 and a sensor housing 16 and a protective cover 1 described later.
It is composed of 7 etc. And the sensor rod 8
Together with the spring receiver 9, the guide stem 10 and the sensor portion 11 constitute a sensor holder.

Here, the sensor rod 8 is formed of a resin material in a tubular shape together with the spring receiver 9 and the guide stem 10 and the like, and a lead wire 12 serving as a signal wire from the sensor portion 11 is inserted into the inner peripheral side thereof. ing. Further, the lower end side of the guide stem 10 serves as a sensor mounting portion 10A, and a collar-shaped retaining portion 10B is integrally formed on the outer peripheral side thereof. The sensor unit 11 has a built-in detection element 13 such as a reed switch that serves as a detection unit, and the upper end side thereof is integrally fixed to the sensor mounting portion 10A of the guide stem 10 by means such as screwing or press fitting.

Reference numeral 14 denotes a float attached to the sensor portion 11 via a tubular bracket 14A so as to be relatively displaceable. The float 14 is a resin material or the like having a smaller specific gravity (density) than the oil liquid F or water. Is formed in a thick disk shape, and a cylindrical bracket 14A slidably fitted on the outer peripheral side of the sensor portion 11 is integrally provided on the upper end side thereof. The tubular bracket 14A has a ring-shaped magnet 15 built therein, and the magnet 15 is used as the detection element 1.
Closes the reed switch by approaching and leaving 3
It is opened (ON, OFF), and when closed, a detection signal for detecting liquid leakage is output from the sensor unit 11 via the lead wire 12.

That is, the inner shell 2 or the outer shell 3 is damaged or cracked and the oil liquid F in the inner shell 2 leaks into the detection space 4, or ground water, rainwater or the like is detected from the outside of the outer shell 3. When these liquids (oil liquid F, groundwater, or rainwater) collect in the detection space 4 when entering the space 4 or the like, the float 14 floats in the direction of the arrow A in FIG. 2 in the liquid. The magnet 15 comes closer to the detection element 13. As a result, the sensor section 11 closes the reed switch of the detection element 13 and outputs a detection signal for detecting the leakage of the liquid to the outside through the lead wire 12.

Note that a retaining ring (not shown) or the like is provided at an intermediate position of the sensor section 11, whereby the float 14
At the position shown in FIG. 2 (actually the bottom 17 of the protective cover 17
It is held in a retaining state at a position slightly separated from above B).

Reference numeral 16 denotes a sensor housing which is slidably fitted on the outer peripheral side of the guide stem 10 and can be displaced relative to the guide stem 10 up and down. It is formed in a stepped tubular shape from substantially the same resin material, and the upper side thereof is a cylindrical sliding portion 16A, and the lower side thereof is a large-diameter opening 16B. Further, a plurality of reinforcing ribs 16C, 16C, ... Are integrally formed on the inner peripheral side of the sensor housing 16 between the sliding portion 16A and the opening 16B, and the lower end side of each reinforcing rib 16C is formed. The retaining portion 10 of the guide stem 10
By engaging with B, the sensor housing 16 is retained in the guide stem 10 in a detached state.

Reference numeral 17 denotes an opening 16 of the sensor housing 16.
A protective cover removably attached to the B side is shown. The protective cover 17 is made of the same resin material as the sensor housing 16 and has a bottomed cylindrical shape. The float 14 surrounds the float 14 from below and the sensor housing 16 is provided. The sensor section 11 and the float 14 and the like are protected from the outside between and. A plurality of elongated windows 17A, 17A, ... Are formed on the peripheral wall side of the protective cover 17, and
The bottom hole 1 is provided on the side of the bottom portion 17B which is the contact portion with the float 14.
7B1 are formed, and the bottom hole 17B1 and each window portion 17A
Is configured to allow liquid (oil liquid F, groundwater, or rainwater) accumulated in the detection space 4 to flow inside or outside the protective cover 17.

Here, a male screw portion 17C is formed on the upper end side of the protective cover 17, and the male screw portion 17C is screwed to the opening 16B side of the sensor housing 16,
The protective cover 17 is integrated with the sensor housing 16. Then, when the leak detector 7 is completely inserted into the leak detecting tube 5, the bottom 17B of the protective cover 17 is on the bottom side of the oil storage tank 1 (the inner surface of the bottom of the outer shell 3 or the punching metal) as shown in FIG. Abutting against the protective cover 17
The sensor housing 16 is positioned with respect to the outer shell 3 and the like.

Reference numeral 18 denotes a lower end of the sensor rod 8 and a spring receiver 9
A spring as an urging means disposed between the sensor housing 16 and the sensor housing 16 is shown. The spring 18 is a coil spring wound around the sliding portion 16A of the sensor housing 16 and has a larger diameter. 16 is always urged downward together with the protective cover 17. Then, the spring 18 serves as each reinforcing rib 16C of the sensor housing 16.
Is engaged with the retaining portion 10B of the guide stem 10, and the upper end side of the sliding portion 16A is separated from the lower surface of the spring receiver 9 with a certain dimension S (for example, about 10 mm).

The spring 18 has a protective cover 17
As shown in FIG. 2, the sensor rod 8 is indicated by the arrow from the upper end side of the leak detection pipe 5 with the bottom portion 17B of the leak detection tube 5 abutting on the bottom portion side (the bottom inner surface of the outer shell 3 or the punching metal) of the oil storage tank 1. When pushed in the B direction (downward), the spring bearing 9, the guide stem 10, and the sensor portion 11 are allowed to be displaced downward relative to the sensor housing 16 and the protective cover 17 by the dimension S. Then, at this time, the sensor unit 11 is pushed in the direction of arrow B in FIG. 2 with respect to the float 14 that remains in contact with the bottom portion 17B of the protective cover 17, so that the detection element 13 is placed inside the tubular bracket 14A. When the magnet 15 is approached, the reed switch of the detection element 13 is forcibly closed.

Reference numeral 19 denotes a lid body which is detachably provided on the upper end side of the leak detection tube 5, and the lid body 19 is formed into a substantially cylindrical tubular shape by means of aluminum die casting or the like, and is attached to the lower end side thereof. Is an annular packing 20 on the flange 6 of the leak detection tube 5.
A large-diameter flange portion 19A that is abutted through is integrally formed. The lid 19 has the flange portion 19A fastened to the flange 6 of the leak detection tube 5 via the packing 20, bolts 21, nuts 22 and the like, so that the leak detection tube 5 is sealed. It is configured to hold.

The lid 19 is located on the flange portion 19A and has a joint box 23 and a cylindrical inspection port 24.
3 are integrally formed so as to be arranged side by side in FIG. 3, and a cap 28 described later is detachably screwed to the upper end side of the inspection port 24. The joint box 23 is isolated from the inspection port 24, and is closed by a substantially rectangular lid plate 25 as shown in FIG. 4 to cover the lead wire 12 for outputting a detection signal from the leak detector 7. It is configured to be drawn out of the body 19 in a gas-liquid tight manner.

Here, the lower end side of the lead wire 12 is connected to the sensor portion 11 via the inside of the sensor rod 8 and the guide stem 10 as shown in FIG. It is taken out as shown in. Then, the upper end side of the lead wire 12 is covered with the lid body 19.
Into the joint box 23 of the seal clamp 23A
(See FIG. 4) and the like, and is drawn out to the outside of the joint box 23 in a gas-liquid tight manner via another seal clamp 23B.

On the other hand, on the upper end side of the inspection port 24, as shown in FIG. 6, the male screw portion 24A on the outer peripheral side and the female screw portion 2 on the inner peripheral side are formed.
4B are formed, and the female screw portion 24B is formed as a taper screw. Further, the upper end side of the sensor rod 8 is inserted into the inspection port 24, and the outer peripheral surface of the sensor rod 8 has a scale portion 2 extending from the upper end side toward the lower end side.
6 is formed as a scale in units of millimeters (mm), for example.

Reference numeral 27 denotes a set screw which is screwed into the female screw portion 24B of the inspection port 24 and constitutes a locking mechanism together with the female screw portion 24B. The set screw 27 has a hexagonal head as shown in FIG. The taper screw portion 27B includes a portion 27A and a taper screw portion 27B extending downward from the lower side surface of the head portion 27A in a substantially truncated cone shape. The taper screw portion 27B has cutouts 27C, 27C extending in the vertical direction (axial direction). , ... are formed. Then, in the normal standby state shown in FIG. 6, the set screw 27 separates the head portion 27A from the upper end side end face of the inspection port 24 by a certain dimension, and the taper screw portion 27B is attached to the female screw portion 24B of the inspection port 24. Is screwed onto.

In this standby state, the cap 28 is removed and the sensor rod 8 is lifted from the upper end side of the inspection port 24 in the direction of arrow A or pushed in the direction of arrow B to move the sensor rod 8 in the vertical direction. It is possible to measure the amount of movement of the liquid when it is moved to the position of the scale 27 by using the upper surface 27A1 of the head 27A as a reference surface, and it is possible to measure the amount of liquid leakage into the detection space 4 as described later. .

On the other hand, the taper screw portion 27B of the set screw 27
Is further screwed into the female screw portion 24B of the inspection port 24 and the set screw 27 is set to the lock position.
The lower end side 27D of 7B is tightly fitted to the outer peripheral surface of the sensor rod 8 by reducing the diameter through each notch 27C, and at this lock position, the set screw 27 is provided on the upper end side of the inspection port 24. The sensor rod 8 can be positioned by means of this, and the vertical movement of the sensor rod 8 can be restricted.

Reference numeral 28 denotes a cap that closes the upper end side of the inspection port 24 via an annular packing 29.
As shown in FIG. 6, the reference numeral 8 is formed of a rigid metal material into a cylindrical shape with a lid, and a female screw portion 28A screwed to the male screw portion 24A of the inspection port 24 is formed on the inner periphery of the lower end side thereof. There is. The cap 28 covers the inspection port 24 from the upper side, thereby sealing the inspection port 24 via the packing 29.

Reference numeral 30 denotes a chain whose one end side is attached to the center of the upper end of the cap 28 via a screw 31 or the like, and the other end side of the chain 30 is connected to the lid body 19 as shown in FIG. The cap 28 is prevented from being lost when it is removed from the inspection port 24.

Further, reference numeral 32 denotes a pressure inspection plug screwed to the side surface of the inspection port 24. The pressure inspection plug 32 hermetically closes a pressure inspection hole 33 which is radially branched from an intermediate portion of the inspection port 24. are doing. When the pressure inspection (airtightness inspection) of the oil storage tank 1 is performed, the pressure inspection hole 3
3 is connected to an external pressure air source (not shown) or the like, and it is inspected whether or not air can be sealed in the leak detection tube 5 and the detection space 4 to ensure an increase in pressure.

The leak detecting device for the oil storage tank 1 according to the present embodiment has the above-mentioned structure, and its operation will be described below.

First, when the leak detector 7 is assembled to the oil storage tank 1 having a double shell structure, the leak detector 7 is detected from the upper end side of the leak detection pipe 5 toward the detection space 4 via the sensor rod 8. Insert into tube 5. Then, as shown in FIG. 2, with the lower end side of the protective cover 17 in contact with the bottom side of the oil storage tank 1 (the bottom inner surface of the outer shell 3 or the punching metal), the insertion work of the sensor rod 8 is stopped (finished). Then, the upper end side of the sensor rod 8 is made to project upward from the leak detection tube 5. At this time, the tip (upper end) side of the lead wire 12 is pulled out from the upper end of the leak detection tube 5 to the outside.

Next, the tip (upper end) side of the lead wire 12 is guided into the joint box 23 of the lid 19, and the seal clamp 23A in the joint box 23 (see FIG. 4).
The upper end of the sensor rod 8 while connecting to the inspection port 24
The flange portion 19A of the lid body 19 so as to be inserted into the inside.
Is abutted on the flange 6 of the leak detection tube 5 via the packing 20, and in this state, the nuts 22 are screwed to the bolts 21 to fix the lid body 19 on the leak detection tube 5.

When the operation of the leak detector 7 is checked before the inspection port 24 of the lid 19 is closed by the cap 28, the upper end side of the sensor rod 8 protruding upward from the inspection port 24 is shown in FIG. For example, by pushing in about 10 mm (which can be confirmed by the scale portion 26) in the direction of the arrow B or releasing the pressing force at this time, the spring receiver 9 and the guide stem of the leak detector 7 shown in FIG. The sensor 10 and the sensor unit 11 are displaced relative to the sensor housing 16 and the protective cover 17 through the spring 18 in the directions of arrows B and A.

As a result, the sensor section 11 is provided with the protective cover 1
2 is relatively displaced with respect to the float 14 that remains in contact with the bottom portion 17B of the valve 7, and the sensing element 13 comes closer to and away from the magnet 15 in the tubular bracket 14A. The reed switch or the like of the detection element 13 is forcibly closed or opened, and the detection signal at this time is confirmed outside the joint box 23 to close or open (ON, OFF) the leak detector 7. You can check it easily.

Next, after the operation check is completed, the inspection port 24 of the lid 19 is closed by the cap 28 through the packing 29 so that the leak detection pipe 5 and the detection space 4 are kept airtight. . Then, for example, when injecting (supplementing) the oil liquid F such as gasoline, which has been transported to a gas station by a tank truck, into the inner shell 2, the upper end side of the oil injection pipe whose lower end side extends into the inner shell 2 is It is connected to a hose (not shown) of a tank truck, and the oil liquid F is injected from the tank truck into the inner shell 2 via an oiling pipe or the like.

Further, an oil liquid F such as gasoline is applied to the vehicle through a fueling nozzle (not shown) by a measuring machine or the like provided at a fueling station.
When refueling the oil, the pump in the metering machine sucks up the oil liquid F in the inner shell 2 via an oil absorption pipe or the like, and supplies the sucked oil liquid F to the vehicle from the oil supply nozzle.

By the way, when an unexpectedly large external force acts on the oil storage tank 1 due to an earthquake or the like and the inner shell 2 is damaged or cracked, the oil liquid F in the inner shell 2 leaks into the detection space 4. I have something to do. Further, even if the outer shell 3 is damaged or cracked, groundwater, rainwater, etc. from the outside of the outer shell 3 can be detected in the detection space 4
May invade inside. However, even in this case, since the oil storage tank 1 has a double-shell structure, the inner shell 2 and the outer shell 3 are
It is possible to reliably prevent a situation in which only one of the two is damaged or cracked and both are damaged.

The liquid (oil liquid F, groundwater or rainwater) at this time gradually accumulates in the detection space 4,
The float 14 is indicated by an arrow A in FIG.
As the magnet 15 in the tubular bracket 14A approaches the detection element 13 in the sensor section 11 when it rises in the direction, the sensor section 11 closes the reed switch of the detection element 13 and detects the liquid leakage. It is possible to output a detection signal to the outside through the lead wire 12, and it is possible to promptly notify the liquid leakage by an external notification means (not shown) or the like.

Thus, according to this embodiment, the leak detector 7 is provided with the long sensor rod 8, the spring bearing 9, and the guide stem 1.
0, sensor unit 11, float 14, sensor housing 1
6 and the protective cover 17 and the like, and the sensor portion 11 and the float 14 of the leak detector 7 are connected to the sensor housing 1
6 and a protective cover 17 are surrounded, and a lid 19 integrally formed with a joint box 23 is provided on the flange 6 of the leak detection tube 5, and the inside of the leak detection tube 5 is sealed by the lid 19. Since it is configured to be held at, the following operational effects can be obtained.

That is, the sensor portion 11 and the float 14 can be protected from the outside between the sensor housing 16 and the protective cover 17 when the leak detector 7 is transported or assembled, and the sensor portion 11 and the float 14 are protected. It can be effectively prevented from being damaged during transportation. Then, when the leak detector 7 is inserted from the upper end side of the leak detector tube 5 or the like, the leak detector 7
The protective cover 17 can reliably prevent the float 14 of the above from colliding with the bottom side of the oil storage tank 1 (the inner surface of the bottom of the outer shell 3 or the punching metal) in the detection space 4 side, and the durability of the sensor section 11 and the float 14, etc. The life and life can be greatly extended.

When checking the operation of the leak detector 7, the upper end side of the sensor rod 8 protruding upward from the inspection port 24 is pushed in the direction of arrow B (downward) in FIG. 2 is released by pressing the spring receiver 9, the guide stem 10, and the sensor portion 11 of the leak detector 7 shown in FIG. , A by relative displacement in the direction A
The detection element 13 can be moved toward and away from the magnet 15 in the tubular bracket 14A by relatively displacing the float 14 in the directions of arrows B and A, and the leak detector 7 can be closed and opened (ON, (OFF) Operation can be easily checked.

Further, by disposing the spring 18 between the spring receiver 9 and the sensor housing 16 on the lower end side of the sensor rod 8, the sensor section 11, the guide stem 10 and the sensor cover 16 and the protective cover 17 are provided. The sensor rod 8 can be urged by a spring 18 so as to always push upward, and the float 14 is separated from the detection element 13 of the sensor unit 11 in the protective cover 17 until liquid leakage occurs. The detection element 13 can be held in the open (OFF) state.

A lid 19 for keeping the inside of the leak detecting tube 5 in a sealed state is provided on the upper end side of the leak detecting tube 5, and the lid 19 receives a signal from the leak detector 7 (sensor section 11). Since the joint box 23 for the lead wire 12 that draws out the gas-liquid tightly to the outside is integrally formed by using means such as aluminum die casting, the joint box 23 and the lid 19 are formed as a single component (integrated structure ), It can be formed lightly, and the inside of the leak detection pipe 5 can be reliably sealed by the packing 20 and the like by the lid 19, and the lead wire 1 from the leak detector 7 (sensor section 11) can be formed by the joint box 23.
2 can be drawn to the outside in a gas-liquid tight manner.

Further, since the cylindrical inspection port 24 is integrally formed on the flange portion 19A of the lid body 19 so as to be juxtaposed in the left-right direction with respect to the joint box 23, the joint box 23 and the inspection port 24 are formed. Can be formed so as to reinforce each other on the flange portion 19A, and the strength of the joint box 23 and the inspection port 24 can be effectively increased.

Since the joint box 23 is isolated from the inspection port 24 and the lead wire 12 from the sensor portion 11 is drawn out of the lid 19 in a gas-liquid tight manner, the upper end side of the oil storage tank 1 is closed. Even if a large amount of rainwater or the like flows into the flange 6 of the leak detection tube 5 and the manhole (not shown) provided around the lid body 19, the rainwater or the like enters the joint box 23 (lid body 19). Can be reliably prevented, and the seal structure can be simplified.

On the other hand, the inspection opening 24 of the lid 19 is formed with a tapered female screw portion 24B on the inner periphery of its upper end side as shown in FIG. 6, and the female screw portion 24B is provided with a stopper constituting a locking mechanism. The screw 27 is screwed, and the lower end side 27D of the taper screw portion 27B is reduced in diameter and expanded by each notch 27C according to the screwing amount of the set screw 27. Since the scale portion 26 extending from the upper end side toward the lower end side is formed, the following operational effects can be obtained.

That is, in the standby state in which the set screw 27 is screwed into the female thread portion 24B of the inspection port 24 as shown in FIG. 6 and the head portion 27A is separated from the upper end side end face of the inspection port 24 by a certain dimension, Remove the cap 28 and lift the sensor rod 8 in the direction of arrow A from the upper end side of the inspection port 24, or
The amount of movement when the sensor rod 8 is moved in the up and down direction by pushing in the direction of
The upper side surface 27A1 can be measured as a reference plane.

When the liquid leaks (enters) into the detection space 4 as described above, the sensor rod 8 is lifted from the upper end side of the inspection port 24 in the direction of arrow A in FIG. By pushing the sensor rod 8 in the vertical direction and moving the sensor rod 8 in the vertical direction, the sensor unit 11 can be moved at any movement position.
It can be confirmed whether or not the detection element 13 of is closed (ON), and the moving position at this time is measured by the scale portion 26 of the sensor rod 8 with the upper side surface 27A1 of the head 27A as the reference surface, whereby the detection space 4 It is possible to easily measure the amount of liquid leakage to the.

In this case, the leakage amount of the liquid into the detection space 4 (leakage detection tube 5) is, for example, 2 from the bottom of the outer shell 3.
When the height level of 0 mm is reached, the initial positions of the detection element 13 of the sensor unit 11 and the magnet 15 of the float 14 are set so that the float 14 floats and the detection element 13 of the sensor unit 11 is closed (ON). Assuming a preset case, when the leakage amount of the liquid is in the detection space 4 (leakage detection tube 5) at a height level of, for example, 50 mm, the sensor rod 8 is moved upward by 30 mm from the reference plane. At this time, the detection element 13 of the sensor unit 11 is switched from the closed (ON) state to the open (OFF) state, and when the leakage amount of the liquid reaches 50 mm, the scale unit 26 is turned off. Can be measured through.

Further, the taper screw portion 27B of the set screw 27
Is further screwed into the female screw portion 24B of the inspection port 24 and the set screw 27 is set to the lock position.
The lower end side 27D of 7B can be reduced in diameter through each notch 27C, and can be tightly fitted to the outer peripheral surface of the sensor rod 8, and when the operation of the leak detector 7 (sensor unit 11) is checked or the amount of liquid leakage. While the sensor rod 8 is positioned on the upper end side of the inspection port 24 via the setscrew 27 at the time of measurement or the like, it is possible to regulate the vertical movement of the sensor rod 8. And, even when the worker or the like moves away from the position of the inspection port 24,
The detection element 13 of the leak detector 7 (sensor unit 11) can be held in the closed (ON) state, and the reliability of leak detection can be improved.

Therefore, according to this embodiment, it is possible to reliably prevent the float type leak detector 7 from being damaged during transportation or assembly by the protective cover 17 or the like, and the leak detection is stable for a long period of time. The leak detection tube 5
The joint box 23 can be assembled at the same time by only attaching the lid body 19 to the upper end side, and the workability at the time of attachment can be greatly improved by reducing the number of parts and the location of attachment (connection).

Further, the inside of the leak detecting tube 5 can be sealed by the lid 19 in which the joint box 23 is integrated, and the leak detector 7 (sensor section 11) can be closed by the joint box 23.
Since the lead wire 12 can be drawn out to the outside in a gas-liquid-tight manner, the sealing structure and the like can be simplified, and the possibility of airtight leakage (infiltration of rainwater) and the like can be surely reduced, and the lid body It is possible to reduce the size and weight of the 19 side to make the whole compact.

Further, by arranging the joint box 23 and the inspection port 24 side by side on the flange portion 19A of the lid body 19, they can be integrated with each other with high strength as a mutual reinforcing relationship. The strength can be significantly increased, and the reliability and durability of the leak detection device can be significantly improved, and various effects can be obtained.

Next, FIG. 8 shows a second embodiment of the present invention. The feature of this embodiment is that the operation of the leak detector is checked by pulling up the sensor holder from the upper end side of the leak detection tube. Is configured to implement. In this embodiment, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 41 denotes a leak detector according to the present embodiment which is provided by being inserted into the leak detector tube 5. The leak detector 41 is the same as the leak detector 7 described in the first embodiment. Similarly, although it has a long sensor rod 8, a cylindrical guide 43 is fixed to the leak detector 41 on the lower end side of the sensor rod 8 via a cylindrical flange 42, and the inside of the cylindrical guide 43 will be described later. The movable stem 44 is inserted. here,
The tubular guide 43 constitutes a sensor holding body together with the tubular flange 42 and the sensor rod 8, and the tubular flange 42 has substantially the same shape as the spring bearing 9 described in the first embodiment. Further, the upper end side of the tubular guide 43 serves as a spring receiving portion 43A for a spring 45 described later, and a small diameter insertion hole 43B is formed on the inner peripheral side of the spring receiving portion 43A.

Reference numeral 44 designates a spring 45 in the cylindrical guide 43.
The movable stem 44 has a large diameter sensor mounting portion 44A on the lower end side, and a sensor portion 46 described later is press-fitted into the sensor mounting portion 44A. Have been combined. In addition, the movable stem 44
A small diameter lead tube portion 44B is integrally formed on the upper end side of the
The upper end side of the lead tube portion 44B projects to the outside of the tubular guide 43 through the insertion hole 43B. Then, the lead tube portion 44B is configured to draw out the lead wire 12 extending from the sensor portion 46 toward the inside of the sensor rod 8 to the outside of the tubular guide 43 via the inside of the movable stem 44.

Here, the spring 45 is located in the cylindrical guide 43 and is disposed between the spring receiving portion 43A and the movable stem 44, and the movable stem 44 is always attached in the direction of arrow B (downward). I am energetic. Then, the spring 45 presses the lower end side of the sensor portion 46 onto the inner surface of the bottom portion of the outer shell 3 (or the punching metal) with a required spring force, and when the leak detector 41 is pulled up in the arrow A direction as described later, The sensor portion 46 is configured to be displaced downward relative to a float 47 described later.

Reference numeral 46 denotes a sensor mounting portion 44 of the movable stem 44.
The movable stem 44 is integrated with A using a means such as press fitting.
A sensor section that constitutes a movable detection means is shown together with the sensor section 46. The sensor section 46 is constructed in substantially the same manner as the sensor section 11 described in the first embodiment, and has a built-in detection element 13 such as a reed switch which serves as a detection section. ing. The lead wire 12 from the sensor portion 46 is led out into the sensor rod 8 via the movable stem 44.

Reference numeral 47 designates a float which is slidably (relatively displaced) on the outer peripheral side of the sensor portion 46, and the float 47 is constructed in substantially the same manner as the float 14 described in the first embodiment. However, the float 47 is directly inserted into the outer peripheral side of the sensor portion 46 and has the ring-shaped magnet 15 built therein. Then, the float 47 floats by the leaked liquid into the detection space 4, and the magnet 15
Is closed and opened (ON, OFF) by approaching and separating the sensor element 13 from the sensing element 13, and at the time of closing, a detection signal for detecting liquid leakage from the sensor section 46 is output via the lead wire 12. Reference numeral 48 denotes a retaining ring which is attached to the lower end side of the sensor portion 46 and which prevents the float 47 from coming off.

Reference numeral 49 denotes a sensor housing which is fixed to the outer peripheral side of the cylindrical guide 43 and constitutes a float holder as a relative displacement compensating means together with the protective cover 50. The sensor housing 49 is made of a resin similar to that of the cylindrical guide 43. The material is formed into a stepped tubular shape, the upper side of which is a cylindrical fitting portion 49A, and the lower side is a large-diameter opening 49.
It is B. A plurality of reinforcing ribs 49C, 49C, ... Are integrally formed on the inner peripheral side of the sensor housing 49 between the fitting portion 49A and the opening 49B.
The respective reinforcing ribs 49C are intended to increase the strength of the sensor housing 49.

The protective cover 50 is made of a resin material similar to that of the sensor housing 49 and has a cylindrical shape with a bottom, and is detachably attached to the opening 49B side of the sensor housing 49. The protective cover 50 surrounds the float 47 from below and protects the sensor portion 46, the float 47, and the like from the outside with the sensor housing 49. Further, each window portion 17A formed of an elongated hole is formed on the peripheral wall side of the protective cover 50, and a bottom hole 50B1 is formed on the bottom portion 50B side which is a contact portion with the float 47, and the bottom hole 50B1 is formed. Further, each window portion 50A is configured to allow liquid (oil liquid F, groundwater or rainwater) or the like accumulated in the detection space 4 to flow inside or outside the protective cover 50.

Here, a male screw portion 50C is formed on the upper end side of the protective cover 50, and the male screw portion 50C is screwed to the opening 49B side of the sensor housing 49,
The protective cover 50 is integrated with the sensor housing 49. Further, the bottom portion 50B of the protective cover 50 is a float 47.
Is supported from below, and the lower end side of the sensor unit 46 is the bottom hole 50B.
The outer shell 3 is allowed to project downward to the inner surface (or the punching metal) side of the outer shell 3 via 1. Then, the leak detector 41 is indicated by the arrow A in the leak detection tube 5.
When pulling up in the direction, the float 47 is lifted together with the sensor rod 8 and the like in the direction of the arrow A by the bottom portion 50B side of the protective cover 50, and the sensor portion 46 causes the spring 45 to move.
As a result, the protective cover 50 is pushed out from the bottom hole 50B1 in the direction of arrow B, whereby the float 47 is displaced relative to the sensor portion 46.

Thus, in this embodiment having the above-described structure, it is possible to obtain substantially the same effects as the first embodiment. However, in this embodiment, in particular, the lower end of the sensor rod 8 has a cylindrical shape. A movable stem 44 is provided so as to be relatively displaceable up and down via a guide 43 and a spring 45. A sensor portion 46 is fixedly provided on the lower end side of the movable stem 44, and on the outer peripheral side of the cylindrical guide 43. Sensor housing 4
The upper portion (fitting portion 49A) side of 9 is fixed, and the lower portion (opening portion 49B) side of the sensor housing 49 supports the float 47 from the bottom portion on the bottom portion 50B side and the sensor portion via the bottom hole 50B1. Since the protective cover 50 is provided to allow 46 to project downward, the following operational effects can be obtained.

That is, when the operation of the leak detector 41 is checked, if the upper end side of the sensor rod 8 is pulled up in the direction of arrow A (upward) at the inspection port 24 side shown in FIG. 47 is the bottom 50 of the protective cover 50
The sensor unit 46 is lifted by the B side together with the sensor rod 8 and the like in the arrow A direction, and the sensor portion 46 is pushed out by the spring 45 from the bottom hole 50B1 of the protective cover 50 in the arrow B direction. The magnet 15 can be relatively displaced with respect to the detection element 13, and the reed switch of the detection element 13 is closed (ON) to output a detection signal from the sensor section 46 to detect the liquid leakage. Can be output via.

After that, when the sensor rod 8 is gradually moved in the direction of arrow B in the leak detection tube 5, the float 47 moves in the direction of arrow B together with the sensor rod 8 and the bottom portion 50B of the protective cover 50. The sensor unit 46
Since the lower end side thereof contacts the inner surface of the bottom portion of the outer shell 3 (or the punching metal) and is pushed in the direction of arrow A against the spring 45 together with the movable stem 44, the sensor portion 46 is moved to the float 47 by this. Relative displacement to
The magnet 15 can be separated from the sensing element 13, and the reed switch of the sensing element 13 is opened again (OF
F) can be easily returned to the state, and the sensor portion 46 is indicated by the arrow B, with respect to the float 47 on the protective cover 50.
By performing relative displacement in the A direction, it is possible to easily check the closing / opening (ON / OFF) operation of the leak detector 41.

Next, FIG. 9 shows a third embodiment of the present invention. The feature of this embodiment is that the relative displacement for compensating for the relative displacement between the float and the detecting portion when the operation of the leak detector is checked. The compensating means is constituted by a spring, one end side of which is attached to the lower end side of the sensor holder in a hooked state, and the other end side of which is in contact with the bottom inner surface (or punching metal) of the outer shell. Also in this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 61 denotes a leak detector according to the present embodiment which is provided by being inserted into the leak detector tube 5. The leak detector 61 is the same as the leak detector 7 described in the first embodiment. Similarly, although it has a long sensor rod 8 and a tubular stem 63 is fixed to the lower end side of the sensor rod 8 via a stepped tubular spring receiver 62, the leak detector 61 An upper end 67A of a spring 67, which will be described later, is attached to the spring receiver 62 in a state in which it does not come off. Here, the spring receiver 62 constitutes a sensor holding body together with the stem 63 and the sensor rod 8, and an annular hooking portion 62A to which the upper end side 67A of the spring 67 is hooked is formed on the lower outer peripheral side of the spring receiver 62. ing.

Reference numeral 64 designates a sensor portion integrated on the lower end side of the stem 63 by means of press fitting or the like.
Is substantially the same as the sensor unit 11 described in the first embodiment, and is a detection element 1 such as a reed switch that serves as a detection unit.
Built-in 3. The lead wire 12 from the sensor portion 64 is led out into the sensor rod 8 via the stem 63.

A float 65 is slidably (relatively displaceably) attached to the outer peripheral side of the sensor portion 64, and the float 65 is constructed in substantially the same manner as the float 14 described in the first embodiment. However, the float 65 is formed in a stepped tubular shape, and the ring-shaped magnet 15 is built in the upper end side thereof. Then, when the liquid leaks into the detection space 4, the float 65 operates so that the liquid floats up from the inner surface of the bottom portion of the outer shell 3 (or the punching metal). 66 is attached to the lower end side of the sensor unit 64,
A retaining ring for preventing the float 65 from being pulled out is shown.

Further, reference numeral 67 denotes a spring as a relative displacement compensating means which is attached to the spring receiver 62 at the lower end side of the sensor rod 8 via a hooking portion 62A, and the spring 67 extends from the upper end side 67A to the lower end side 67B. The lower end side 67B is in contact with the bottom inner surface (or the punching metal) of the outer shell 3 and supports the entire leak detector 61 so as to be vertically movable from below. ing.

During normal time when there is no liquid leakage, the magnet 15 is kept in contact with the float 65 on the inner surface of the bottom of the outer shell 3 (or the punching metal).
From the sensing element 13 of the sensor unit 64 to the required size (for example, 1
The spring 67 elastically supports the sensor rod 8 and the spring receiver 62 from below so that they are separated by about 0 mm).

On the other hand, when the operation of the leak detector 61 is checked, from the upper end side of the leak detecting tube 5 with the lower surface side of the float 65 abutting on the inner surface of the bottom portion of the outer shell 3 (or the punching metal). By pushing the sensor rod 8 in the direction of arrow B (downward) against the spring 67, the sensor portion 64 moves in the direction of arrow B (downward) relative to the float 65 via the spring receiver 62 and the stem 63. It will be displaced.

As a result, the sensor portion 64 is pushed in the directions of arrows B and A with respect to the float 65 remaining on the inner surface of the bottom portion of the outer shell 3 (or the punching metal).
The detection element 13 approaches and separates from the magnet 15 in the float 65 to close the reed switch of the detection element 13,
Leakage detector 6 that can be opened (ON, OFF)
You can easily check the closing / opening (ON / OFF) operation of 1.

Thus, the present embodiment having such a configuration can obtain substantially the same effects as the first embodiment, but especially in this embodiment, the operation of the leak detector 61 is checked. For example, the sensor unit 64 and the float 65
The means for compensating the relative displacement with respect to can be constituted by the spring 67, and the structure of the leak detector 61 can be simplified.

In each of the above embodiments, the leak detector 7
It is described that the detection element 13 as a detection portion including a reed switch is provided in the sensor portion 11 (46, 64) of (41, 61), and the ring-shaped magnet 15 is provided on the float 14 (47, 65) side. However, the present invention is not limited to this, and for example, an operating transformer type, eddy current type, ultrasonic type, or optical type detecting element having an explosion-proof structure is provided on the sensor unit 11 (46, 64) side, and the float 14 ( 47,6
The configuration of 5) may be configured to detect the approach and separation.

In each of the above embodiments, the case where the leak detection device for the underground tank is applied to the oil storage tank 1 of the gas station has been described as an example. However, the present invention is not limited to this, and various oil liquids, for example, may be used. It can also be applied to an underground tank with a double-shell structure that stores liquids, etc.

[0095]

As described above in detail, according to the first aspect of the present invention, the signal from the leak detector is gas-liquid tightly drawn to the outside on the lid body for keeping the inside of the leak detecting tube in a sealed state. Since the joint box for wires is integrally formed, the joint box and lid can be used as a single component (integrated structure) to easily close the upper end side of the leak detection tube, and the number of components and mounting The number of (connection) points can be reduced and workability at the time of installation can be greatly improved. In addition, the seal structure etc. can be simplified, the possibility of airtight leakage is reduced, and reliability and durability as a leak detection device are reduced. It is possible to surely improve the sex.

Further, as in the invention described in claim 2, a flange portion fixed in an abutting state to the upper end side of the leak detection tube is integrally formed with the lid body, and the joint box is provided on the flange portion. And the cylindrical inspection opening are arranged side by side, so that the joint box and the cylindrical inspection opening are provided on the flange portion of the lid so that the joint box and the cylindrical inspection opening reinforce each other. Can be integrally formed with high strength, and the strength of a connection box (joint box) or the like can be significantly increased as compared with the prior art.

Further, as in the invention described in claim 3,
By providing a lock mechanism for positioning the sensor holder and a cap that seals the inspection port on the inspection port of the lid, the inspection port can be reliably sealed with the cap and the cap is removed from the inspection port. Then, while confirming the upper end side of the sensor holder from the inspection port, the operation of moving the sensor holder up and down can be appropriately performed, and the operation check of the leak detector can be easily performed. Further, by operating the lock mechanism, upward and downward movements of the sensor holding body can be regulated at arbitrary positions, and the sensor holding body is appropriately fixed (positioned) to the lid body at the upper end side of the leak detection tube. )can do. Then, even when the worker or the like moves away from the position of the inspection port, the detection unit of the leak detector (sensor unit) can be held in the closed (ON) state, and the reliability of leak detection can be improved.

Further, according to the invention as set forth in claim 4, by providing a scale portion extending from the upper end side to the lower end side of the sensor holder on the outer peripheral surface of the sensor holder, the sensor holder is provided. The amount of movement when moving up and down can be accurately measured via the scale portion, and thus the amount of leakage of the liquid that has leaked (entered) into the detection space can be easily measured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a leak detection device for an oil storage tank according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the leak detector, and is an arrow in FIG.
It is a II-II direction sectional drawing.

FIG. 3 is a partially cutaway front view showing a leak detection tube, a lid, a leak detector and the like in FIG. 1 in an enlarged manner.

FIG. 4 is a plan view of a lid body, a cap and the like shown in FIG.

5 is a right side view of a lid body, a cap and the like shown in FIG.

6 is an enlarged cross-sectional view of the sensor holder, the upper end side of the inspection port, the cap, and the like in the direction of arrows VI-VI in FIG.

7 is an enlarged front view showing the set screw in FIG.

FIG. 8 is an enlarged vertical sectional view showing a main part of a leakage detection device according to a second embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view showing an enlarged main part of a leak detection device according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Oil Storage Tank (Underground Tank) 2 Inner Shell (Tank Body) 3 Outer Shell 4 Detection Space 5 Leakage Detection Tube 6 Flange 7,41,61 Leakage Detector 8 Sensor Rod (Sensor Holder) 9,62 Spring Bearing 10 Guide Stem 11, 46, 64 Sensor part 12 Lead wire (signal line) 13 Detection element (detection part) 14, 47, 65 Float 15 Magnet 16, 49 Sensor housing 17 Protective cover 18, 45, 67 Spring 19 Lid body 19A Flange part 20 , 29 packing 23 joint box 24 inspection port 26 scale 27 set screw (lock mechanism) 28 cap 32 pressure inspection plug 33 pressure inspection hole 42 cylindrical flange 43 cylindrical guide 44 movable stem (movable detection means) 50 protective cover (float) Holder) 63 stem

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takehiko Sudo 3-9-1 Meguro, Meguro-ku, Tokyo Tokiko Yuki Co., Ltd. (72) Inventor Tsukasa Uno 3-9-1 Meguro, Meguro-ku, Tokyo Tokiko Yuki Co., Ltd.

Claims (4)

[Claims] 1. An underground tank having a double-shell structure composed of an inner shell and an outer shell, which defines a detection space between the inner shell and the outer shell, and a lower end side of which communicates with the inside of the detection space. A leak detection pipe provided in the underground tank, the upper end side of which protrudes outside the underground tank, and the liquid leakage into the detection space, which is inserted from the upper end side of the leak detection pipe toward the detection space. A float type leak detector having a float provided on the lower end side of the sensor holding body for detecting the above, and a lid body provided on the upper end side of the leak detection tube and holding the inside of the leak detection tube in a sealed state. A leak detecting device for an underground tank, wherein a joint box for a signal line that draws out a signal from the leak detector to the outside in a gas-liquid tight manner is integrally formed on the lid. 2. A flange portion fixed to the upper end side of the leak detection tube in an abutting state, and a tubular shape which is located on the flange portion and into which the upper end side of the sensor holding body is inserted. The leak detection device for an underground tank according to claim 1, wherein an inspection port is integrally formed, and the joint box and the inspection port are arranged in parallel on the flange portion. 3. A lock mechanism for restricting upward and downward movements of the sensor holder to position the sensor holder at the inspection opening of the lid, and a detachable mount on the upper end side of the inspection opening. The leak detection device for an underground tank according to claim 2, further comprising: a cap that seals the inspection port. 4. A scale portion is provided on an outer peripheral surface of the sensor holder, the scale portion extending from an upper end side to a lower end side of the sensor holder and for measuring a vertical movement amount of the sensor holder. Item 4. A leak detection device for an underground tank according to item 1, 2 or 3.