JP5404326B2 - Underground tank leak detection device - Google Patents

Description

  The present invention relates to an apparatus for detecting liquid leakage in a liquid storage tank installed underground. The liquid leakage referred to here means both leakage of liquid in the tank (hereinafter referred to as “storage liquid”) to the outside of the tank and leakage of groundwater outside the tank into the tank.

  Gas tanks and other underground tanks for liquid storage installed in the basement are difficult to detect even if the shell (wall) has holes or cracks and leaks. Therefore, when the shell of the underground tank is formed in a double structure, that is, with two layers of the inner shell and the outer shell, a gap is provided between the inner shell and the outer shell, and the stored liquid or groundwater enters the gap. In addition, a liquid leakage detection device for detecting this is provided.

  FIG. 3 is a schematic cross-sectional view of a tank 1 provided with such a liquid leak detection device. The shell of the underground tank 1 has a double structure of an inner shell 31 and an outer shell 33 with a gap 34 interposed therebetween. Let The inner shell 31 is made of, for example, steel, and the outer shell 33 is made of FRP (fiber reinforced resin). The tank 1 is provided with a cylindrical body 2 having a lower end reaching the tank bottom and an upper end opened to the ground. The peripheral edge of the lower end of the cylindrical body 2 is fixed to the inner shell 31 in a liquid-sealed state by welding or the like, and is blocked from the space 32 for storing the stored liquid. A small hole 35 communicating with the gap 34 is provided in the inner shell 31 at the bottom of the cylindrical body 2, and the inside of the cylindrical body 2 communicates with the gap 34 via the small hole 35.

  A detection device 37 is installed at the bottom of the cylindrical body 2. The detection device 37 includes a float and a switch that detects the rising operation of the float. The lead wire 7 drawn out from the switch is connected to a monitoring device 36 installed on the ground through the cylindrical body 2. In general, a reed switch is used as a switch, and a magnet for turning on and off the reed switch is attached to the float. A lid 41 is provided at the opening at the upper end of the cylindrical body 2.

  When the liquid leakage occurs in the tank, the detecting device 37 having the above structure detects the liquid leakage by the float rising due to the leaked liquid and the reed switch detecting this rise. That is, when a hole or crack occurs in the inner shell 31 and the stored liquid leaks into the gap 34, the leaked liquid moves to the bottom side of the tank through the gap 34 and flows into the cylinder 2 from the small hole 35. To do. The inflowing liquid floats up the float, and the rise of the float operates the reed switch. The operation of the reed switch is detected by the monitoring device on the ground, and the occurrence of liquid leakage is notified by an alarm or the like.

  Further, when a hole or a crack occurs in the outer shell 33 and the groundwater leaks into the gap 34, the leaked groundwater flows into the cylindrical body 2 from the small hole 35 through the gap 34. The inflowing groundwater floats and operates the reed switch, and the operation of the reed switch is detected by the monitoring device on the ground, and the occurrence of liquid leakage is notified by an alarm or the like. When the stored liquid and groundwater leak at the same time, the liquid leak is detected by the same action. Further, when the stored liquid leaks into the cylindrical body 2, the leaked liquid raises the float and the liquid leakage is detected.

  It is an abnormal situation that a liquid leak occurs in the tank 1, and no liquid leak usually occurs. Therefore, since the detection device 37 does not operate, even if the detection device 37 fails, it cannot be recognized. Therefore, the float is periodically raised to check whether the detection device 37 operates normally. This inspection is performed by drawing the wire 24 having the lower end connected to the float through the cylinder 2 to the ground. In other words, the float is raised by pulling up the wire 24, and it is checked whether or not the raising operation is detected and an alarm is issued.

  During this inspection, if the float cannot be pulled up even if the wire is tangled and pulled up, or if the float tilts and does not rise in the correct posture when the wire is pulled up, an increase in the float is detected. In other words, it is determined that the detection device has failed even though the detection device has not actually failed.

  In order to avoid such a situation, how to connect the wire and the float is an important problem. Patent Document 1 below shows a structure in which a lever that swings around a fulcrum when a wire is pulled up is provided under the float and the float is raised by a wire pulling operation. Patent Document 2 discloses a liquid leak detection device having a structure in which the pulling force of the wire is made to coincide with the detection position located at the center of the float by connecting the both ends of the float with the lower end of the wire being bifurcated. ing.

JP-A-8-159850 Japanese Patent Laid-Open No. 10-293057

  The detection device 37 is strongly required not to cause malfunction or failure. In order to avoid malfunctions and failures, it is desirable to simplify the structure by reducing the number of parts. This is also desirable for providing the device at a low cost.

  The present invention relates to a liquid leakage detection device that detects a liquid leakage by detecting a rising operation of a float due to the buoyancy of a leaked liquid, and operates by raising the float by pulling up a wire connected to the float during operation inspection. In the underground tank liquid leak detection device, which is inspected, the pulling force of the wire is transmitted to the float in a well-balanced manner, so that no malfunction occurs at the time of inspection, and the structure is simple and the number of parts is small. It is an object to obtain a detection device that can prevent the occurrence of a failure.

  The underground tank liquid leakage detection apparatus according to the present invention is an apparatus for detecting liquid leakage in an underground tank 1 for liquid storage having double-structured shells 31 and 33, and a storage liquid storage section 32 in the tank 1. A cylinder 2 whose inside is communicated with the gap 34 between the inner shell 31 and the outer shell 33 of the tank 1, a vertical linear guide 5 disposed at the bottom of the cylinder, and the linear guide 5. A liquid leak detection device for an underground tank, comprising a float 11 guided in the ascending / descending direction by 5, a switch 6 for detecting an upward movement of the float, and a string or wire 24 for pulling up the float 11 for operation confirmation. It is.

  The underground tank liquid leak detection device according to the present invention is guided by a second linear guide 22 provided in parallel to the linear guide 5 on the side of the float 11 and movably along the second linear guide. A sliding moving body or a rolling moving body 19, which is attached to a bracket 15 fixed to the float 11, and the string or wire 24 is positioned between the float 11 and the moving body 19. The bracket 15 is connected to one place.

  The liquid leakage detection device 37 having a preferred structure according to the present invention includes a frame 3 placed on the bottom surface of the cylindrical body 2. A guide 5 that guides the lifting and lowering of the float 11 is erected substantially at the center of the frame 3, the second linear guide 22 is a rail or a long hole provided in the side wall 3 a of the frame 3, and the moving body 19 is The slider or roller 19 is moved by being guided by the rail or the long hole 22.

  The bracket 15 is preferably formed of a plate material fixed to the upper surface or the lower surface of the float 11, one side portion of the plate material is bent 90 degrees upward or downward, and the movable body 19 is attached to the refracting portion 16. A structure in which the string or wire 24 is connected to the upper end portion of the refracting portion 16 is preferable in that the entire apparatus can be simplified.

  In the underground tank liquid leakage detection device of the present invention configured as described above, the float 11 is floated by the liquid leaking into the cylindrical body 2 and the floating operation is detected by the switch 6. Detect leaks. When checking the operation, open the lid 41 at the upper end of the cylinder 2 reaching the ground and pull up the string or wire 24 to raise the float 11 and check whether the rise is detected. .

  The detection device of the present invention can be simplified in structure, can be provided at low cost with few failures. Further, the lower end of one string or wire 24 is connected to only one place, so that the float 11 can be reliably pulled up with good balance and without causing trouble due to the inclination of the float 11. Then, the second linear guide 22 is a long hole provided in the side wall 3a of the frame body, and the moving body 19 is a slider or roller 19 with a groove that is guided by the straight edges on both sides of the long hole 22, thereby simplifying the operation. With the simple structure, there is an effect that the lifting operation of the float 11 due to the buoyancy of the leaked liquid and the lifting operation of the float 11 when the string or wire 24 is pulled up are performed smoothly.

The side view which shows one Example of the liquid leak detection apparatus of this invention Front view of the device of FIG. Schematic diagram showing the relationship between the underground tank and the leak detector

  Hereinafter, an embodiment of a liquid leakage detection apparatus of the present invention will be described with reference to the drawings. The illustrated liquid leak detection apparatus includes a frame body 3 located at the bottom of a cylindrical body 2 provided inside an underground tank 1. A guide pipe 5 made of a magnetic material such as synthetic resin is erected at the center of the frame 3, and a reed switch 6 is fixed in the guide pipe 5. The lead wire 7 of the reed switch 6 passes through the guide pipe 5 and is drawn out from the frame 3 into the cylinder 2 and passes through the cylinder 2 and is drawn out from the upper end to the ground.

  The float 11 is provided with a guide hole penetrating vertically at the center thereof, and the guide pipe 5 is inserted into the guide hole so that the float 11 can freely move up and down between the lower stopper 12 and the upper stopper 13. Yes. A magnet is embedded in the peripheral wall portion of the guide hole of the float 11, and the magnet operates the reed switch 6 when the float 11 moves up. When the float 11 is in contact with the lower stopper 12, the magnet is separated from the reed switch 6, and the reed switch 6 does not operate. The lower stopper 12 and the upper stopper 13 are fixed to the frame body 3 and the guide pipe 5.

  A bracket 15 made of a plate material is fixed to the bottom of the float 11, and the bracket 15 includes a refracting portion 16 that is refracted upward at a position on one side of the float 11. A circular slider 19 provided with a flange 19a on one side and a water drop washer 17 are overlapped and fixed with a screw 18 on the outside of the refracting portion, that is, on the side opposite to the float.

  A groove 21 is formed between the flange 19 a of the slider 19 and the washer 17. The slider 19 is guided by the long hole 22 in a state where the groove 21 is fitted in the edge of the vertical hole 22 formed in the side wall 3 a of the frame 3. A wire 24 for pulling up the float 11 is connected to the upper end of the washer 17.

  The wire 24 extends upward through a guide hole 27 provided in the intermediate plate 23 supporting the upper stopper 13 and the top plate 26 of the frame body, and the upper end thereof is a hook (not shown) provided inside the upper end of the cylindrical body 2. Is not).

  The peripheral edge of the lower end of the cylindrical body 2 is welded to the inner shell 31 of the tank in a liquid-sealed state, and is completely cut off from the space 32 for storing the stored liquid. A small hole 35 communicating with the gap 34 between the inner shell 31 and the outer shell 33 of the tank is provided in the inner shell 31 at the bottom of the cylindrical body 2. The small holes 35 communicate with each other. The upper end of the cylindrical body 2 is located on the ground, and a lid is attached to the upper end.

  In the above structure, when a leak or leakage occurs due to holes or cracks in the inner shell 31 or the outer shell 33 of the tank, the leaked stored liquid or groundwater passes through the gap 34 and the small hole 35 and the bottom of the cylinder 2. When a certain amount of liquid flows in, the float 11 is lifted. When the float 11 moves up to a height close to the upper stopper 13, the reed switch 6 is operated, an operation signal is sent to the monitoring device 36 (see FIG. 3), and a liquid leak alarm is issued.

  When checking the operation of the detection device, the lid attached to the upper end of the cylinder 2 is opened, and the upper end of the wire 24 is pulled up. This lifting force is transmitted to the washer 17 to raise the slider 19 along the long hole 22 and raise the float 11 via the bracket 15. The force against the pulling force of the wire 24 is the own weight of the float 11, the bracket 15, the washer 17 and the slider 19, and the frictional resistance between the float 11 and the guide pipe 5 and between the long hole 22 and the slider 19. In the structure of the present invention, since the pulling force of the wire 24 acts at a position approximately in the middle of these resistance forces, the float 11 can be balanced and the guide pipe 5 and the slider can be balanced just by connecting one point of the lower end of the wire 24. 19 can be guided and lifted in a correct posture without tilting.

1 underground tank 2 cylinder 3 small hole 5 guide pipe 6 reed switch
11 Float
15 Bracket
16 Refraction part
19 Slider
21 groove
22 Slotted hole
24 wires
31 Inner shell
32 spaces
34 Gap

Claims (3)

This is a liquid leak detection device for a liquid storage underground tank (1) having a double-structured shell (31, 33), which is isolated from the liquid reservoir (32) in the tank (1). Cylinder (2) communicated with the gap (34) between the inner shell (31) and outer shell (33) of the tank (1), and a vertical straight guide ( 5), a float (11) guided by the linear guide (5), a switch (6) for detecting the rising motion of the float, and a string or wire (24) for pulling up the float (11). In the underground tank liquid leak detection device,
A second linear guide (22) provided in parallel to the linear guide (5) on the side of the float (11), and a movable body (19) guided by the second linear guide; The moving body is attached to a bracket (15) fixed to the float (11), and the string or wire (24) is positioned between the float (11) and the moving body (19) at the bracket (15). ) Liquid leak detection device for underground tanks connected to one place.   A frame (3) and the bracket (15) made of a plate material fixed to the upper surface or the lower surface of the float (11) are provided, and the second linear guide (22) is provided on the frame (3). The liquid leak detection device according to claim 1, wherein the movable body (19) is attached to a surface on the side opposite to the float of the vertical refracting portion (16) provided on one side of the bracket (15). .   The second linear guide is a long hole (22), and the movable body (19) is a slider or roller (19) having a groove (21) guided by the edge of the long hole. Liquid leak detection device.

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