JPS60111132A - Leakage inspecting method of tank - Google Patents

Abstract

PURPOSE:To inspect quickly a leakage of an underground tank in a state that a liquid is stored without moving the liquid in the tank by mixing a inert gas for pressure reducing, and exhausting a gas in the tank. CONSTITUTION:When openings of an oiling pipe 3 and a vent pipe 8 are closed by covers 4, 9, and also a measuring port 10 is closed by a plug 12, an underground tank 1 is closed airtightly. Subsequently, when nitrogen gas of a bomb 28 is supplied to an ejector 21 by opening manual valves 25, 28 and 30, a gas such as a gasoline vapor, etc. in the tank 1 is absorbed by the ejector 21 and exhausted through a silencer 27 together with the nitrogen gas, and the inside of the tank 1 is reduced to a prescribed pressure. In this state, when a leakage hole 31, etc. exist in the tank 1, an external air is absorbed and rises in a liquid, a suction sound such as a hollow sound, etc. is generated, this suction sound is detected through a microphone 19, etc., and a leakage of the underground tank can be detected quickly in a state that the liquid is stored without moving the liquid in the tank.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tank leakage testing method for testing whether or not there is a leakage point in a tank.

In general, when it is necessary to regularly inspect a tank for storing liquid for the presence or absence of liquid leakage from the tank, liquid leakage cannot be directly detected visually from the outside. For this reason, various leakage detection methods have been adopted in the past.As a leakage detection method using this conventional technology, all the openings of all the pipes leading into the tank to be inspected are completely closed to make the inside of the tank airtight. The tank is filled with an inert gas such as nitrogen gas to maintain a constant pressure inside the tank, and if there is a leak hole in the tank, the nitrogen gas inside will leak to the outside over time. By detecting the presence or absence of this pressure drop using a pressure gauge or the like, the presence or absence of leakage from the tank is inspected.

However, with the conventional method described above, if all leak tests are carried out with the liquid stored in the tank, the tank will be under pressure, so if there is a leak hole in the tank, the leak will be detected. A large amount of liquid leaks outside from the hole. For this reason, if the liquid to be stored is a dangerous substance such as gasoline or light oil at a gas station, it may mix into the underground water vein, resulting in a very dangerous situation.

Therefore, in the conventional method described above, before performing a leakage test, all the liquid in the tank is drained, temporarily stored outside to empty the tank, and then the tank is filled with nitrogen gas, etc. A pressure drop was detected using a pressure gauge.

However, since the liquid to be extracted is a dangerous substance, a tanker truck is arranged in advance to temporarily store the extracted liquid, all the liquid in the tank is drained and stored in this tanker truck, and the liquid is removed after the inspection is completed. It is necessary to put it back into the tank, which is not only troublesome, but also
This method requires a rental fee for a tanker truck, and has the drawback of requiring a long time for preparation work, liquid draining work, and return work. In addition, it is necessary to fill the tank with a large amount of nitrogen gas, which makes it expensive. On the other hand, since the nitrogen gas after the inspection contains evaporated gas of hazardous substances, The drawback is that a large amount of nitrogen gas cannot be released at once, and must be released gradually.

In order to improve the above-mentioned drawbacks of the conventional method, as shown in Japanese Patent Publication No. 57-46495, the openings of all the pipes leading into the tank to be inspected are closed to make the tank airtight, and the inside of the eye tank is By discharging a portion of the liquid, the pressure inside the tank is maintained at a constant level. If there is a leak in the tank, the pressure inside the tank will increase over time, so use a pressure gauge to check whether this pressure has increased. There is also a known method of inspecting the tank for leakage by detecting leakage.

However, in this conventional method, a portion of the liquid in the tank is discharged using a suction pump or a gasoline measuring machine installed at a gas station, thereby reducing the pressure to a constant pl. The disadvantage was that a container was required for temporary storage. Further, after the inspection is completed, the liquid discharged from the tank must be returned to the tank, which not only complicates the setup for the inspection but also requires a long inspection time.

The present invention improves the drawbacks of each of the conventional methods described above, and makes it possible to perform a leakage test while the liquid is stored in the tank without moving the liquid at all.

In order to achieve the above object, the leakage inspection method according to the present invention is characterized in that when the inside of a tank is brought into a reduced pressure state, an evacuation means such as an ejector pump that operates with an inert gas pumps the gas inside the tank. The reason for this is that it is configured so that it is mixed with the water and discharged outside the tank.

With this configuration, the pressure inside the tank can be brought to a reduced pressure state without tampering with the liquid in the tank at all. In addition, by using an inert gas for exhaust, gases such as gasoline vapor mixed with air in the tank can be removed.
It is discharged into the atmosphere together with the inert gas, ensuring safety. Furthermore, when returning the inside of the tank to atmospheric pressure after the inspection, it is only necessary to pump inert gas, and there is no need to worry about unexpected accidents caused by static electricity, etc. that occur when returning the discharged liquid as in the conventional technology. do not have.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a case in which the present invention is applied to an underground tank of a gasoline filling station will be described together with embodiments shown in the drawings.

FIG. 1 shows a configuration diagram of the present invention. In the figure, 1 is an underground tank buried underground of a gas station. A predetermined amount of liquid 2 is stored in the underground tank 1, and a liquid phase part A and a gas It is defined by phase part B. Reference numeral 3 denotes a suction pipe for sucking up the liquid 2 from a lubrication pipe that replenishes liquid from a tank truck or the like to the underground tank 1. ,
At the time of leakage inspection, the pressure inside the tank 1 becomes negative, so it is automatically closed. 8 is a ventilation pipe that communicates the gas phase part B in the underground tank 1 with the atmosphere, and during leakage inspection, the ventilation pipe 8 is connected to the lid 9.
It is sealed airtight.

In addition, the said weighing machine 6 is a motor 6A as well-known.

A pump 6B provided next to the check valve 7 and operated by the motor 6A, an outflow side 60 that measures the amount of oil supplied, and a nozzle 6 provided on the outflow side of the flowmeter 60 via a hose 6D.
Consists of E, etc.

Reference numeral 10 denotes a measuring port for measuring the liquid level in the underground tank 1. A liquid level sensor 11 is inserted into the measuring port 10 into the underground tank 1, and the measuring port 10 is airtightly covered with a stopper 12. The liquid level sensor 11 is connected via a signal line 15 to a liquid level measuring device 14 installed in a gas station office 13, etc., and the liquid level in the underground tank 1η is measured by the liquid level measuring device 14. It is designed to be displayed.

Note that the above configuration is substantially the same as the configuration of a gasoline filling station according to the prior art.

16 is a ventilation pipe, and one end of the ventilation pipe 16 is connected to the stopper 1.
2 into the gas phase gas of the underground tank 1, and the other end is installed in the office 13, and a pressure gauge 17 (hereinafter referred to as a manometer) is installed in the office 13 to monitor changes in the pressure inside the underground tank 1 in a depressurized state. , pressure gauge 17).

Next, 18 is a signal line, and one end of the signal line 18 is suspended in the gas phase part B of the underground tank 1 through the stopper 12, and a microphone 19 for collecting sound is connected to the tip of the signal line 18. , and the other end of the signal line 18 is connected to a measuring device or recording device 20 (hereinafter referred to as
A measuring device 20) is connected thereto.

Furthermore, 21 is an ejector as a pressure reducing means for reducing the pressure inside the underground tank 1, and the inlet 2 of the ejector 21 is
1A is nitrogen gas via piping 22? A regulator 24 and a manual valve 25 are connected to the piping 23.
is provided.

The outlet 21B of the ejector 21 is connected to a silencer 27 via a pipe 26, and a manual valve 28 is provided in the middle of the pipe 26. Further, the suction port 21C of the ejector 21 is connected to one end of the piping '29, and the suction port 21C of the ejector 21 is connected to one end of the piping '29.
The other end of 9 opens into the gas phase part B of the underground tank 1 via a plug 12, and a manual valve 30 is provided in the middle.

In addition, in the figure, 31 indicates a leak hole formed in the gas phase part B of the underground tank 1, and 32 indicates a bubble rising in the liquid 2.

In order to perform a leakage test using the device configured as described above, first, as shown in the figure, the openings of the lubricating pipe 3 and the ventilation pipe 8 are each airtightly covered with the lids 4 and 9, and the measuring port 1 is closed.
0 is hermetically sealed with a stopper 12. As a result, since the suction 'u5 is also closed by the check valve 7, the inside of the underground tank 1 is airtightly closed. At this time, the microphone 19 is suspended from the mounting frame 12 to the gas phase part B of the underground tank 1 via the stopper 12, and the ventilation tube 16 is opened from the mounting frame 12 to the gas phase part B.

Next, in order to reduce the pressure inside the underground tank 1, a manual valve 25,
All valves 28' and 30 are opened, and nitrogen gas in the nitrogen gas pump 23 is supplied to the ejector 21. At this time, since the inside of the underground tank 1 is completely closed, the gas consisting of air and gasoline vapor in the gas phase part B of the underground tank 1 is sucked into the sijector 21 through the suction port 21C through the pipes 29, and It is released into the atmosphere from the silencer 27 through the piping 26 together with the removed gas. and,
The pressure inside the underground tank 1 is reduced while monitoring the reduced pressure state on the pressure side 17, and when the inside of the nuclear underground tank is reduced to a predetermined pressure, the manual valve 25.30'f: closes and stops suction. At this time, a large amount of gasoline vapor is mixed into the air inside the underground tank 1, but this gasoline vapor is released into the atmosphere together with nitrogen gas, which is an inert gas, creating a dangerous environment such as an explosion. I never make it.

However, when there is a leak hole 31 in the liquid phase part A of the underground tank 1, outside air is sucked in from the leak hole 31 because the inside of the underground tank 1 is in a reduced pressure state, and this sucked outside air becomes bubbles 32. and rises in the liquid 2. Except for this,
Air bubbles 321dr rise while emitting intake sounds such as "bubbling" and "bubbling", so this can be detected using microphone 1.
By collecting the sound at 9 and measuring it with the measuring device ft20 via the signal line 18, the presence or absence of the leak hole 31 can be determined, and leakage of the underground tank 1 can be inspected.

During this inspection work, immediately after the ejector 21 has reduced the pressure inside the underground tank 1, the reduced pressure is at its highest, so if a speaker is used in the measuring device 20, a loud intake sound with a rapid generation cycle will be heard immediately after the ejector 21 stops. I can hear it. Additionally, if a measuring device 20--a sound level meter is used--the predetermined noise can be measured and recorded. Furthermore, is there a cassette tail coder in the measuring device 20? When used, the momentary intake sound can be recorded and used later for necessary analysis.

On the other hand, if there is a leak hole in the gas phase part B of the underground tank 1, or if the plug 12 or the like is incomplete and air enters from the outside, a "shushu" sound may be heard from the leak hole or the incomplete part. Since the air cools inside the underground tank 1 while emitting a continuous intake sound, it can be clearly distinguished from the intake sound when there is a leak hole 31 in the liquid phase part A as shown in Fig. 1. , the presence or absence of air AUJ part B in the underground tank 1 can be immediately detected and determined.

Furthermore, the presence or absence of a leak hole in a location outside the underground tank 1 where intake sound is difficult to detect and distinguish using the microphone 19, such as a leak hole in a location away from the underground tank 1 in the middle of the ventilation pipe 8, is also checked. Monitoring the pressure in tank 1 At pressure 1t17, it can be confirmed that the pressure in tank 1 increases due to air entering through the leak hole.

In addition, when underground water veins enter through the leak hole 31 of the underground tank 1, in addition to the above-mentioned sound detection and pressure detection, the liquid level sensor 11 inserted into the underground tank 1 is used.
It goes without saying that the presence or absence of the leak hole 31 can be detected by changes in the measured liquid level.

Next, after the leakage inspection inside the underground tank 1 is completed, it is necessary to restore the inside of the underground tank 1 to the atmospheric pressure state. For this purpose, by closing the manual valve 28 and opening the manual valve 25.30, the nitrogen gas in the nitrogen gas bottle 23 is released from the pipe 2.
2.29i into underground tank 1. Then, the restoration state inside the underground tank 1 is monitored with the pressure gauge 17, and when the pressure reaches atmospheric pressure, the manual valve 25 is closed, and the manual valve 28 is closed.
When the valve 30 is opened, the restoring operation is completed. Therefore, since it is only necessary to replenish nitrogen gas during restoration, the operation is simple, and when returning the liquid, compared to the conventional method of returning the liquid that has been drained and stored in a container. There is no risk of a 4-shot accident due to static electricity generated during the operation.

In this embodiment, the microphone 19 is provided separately from the liquid level sensor 11, but if a coaxial cylindrical capacitance type liquid level sensor 1r is provided as the liquid level sensor, for example, as shown in FIG. As shown in the figure, the inner cylinder 1 of this liquid level sensor lr
A microphone 19 is fixedly installed inside the inner cylinder 1'a.
A hole 11'c is provided in the outer cylinder x1'b to easily collect intake sound, and a microphone 19 is connected to the liquid level sensor 11.
The connector 11'd is integrally constructed.
It may also be configured to connect to the measuring device 20 via the signal line 18.

Further, in the above embodiment, the microphone 19 was described as being installed in the gas phase part B in the underground tank 1, but the microphone 19 was provided in the liquid phase part A.
Or when it comes into contact with the outside wall of the underground tank 1,
Since the gas phase part B in the underground tank 1 is a resonance chamber,
Intake sound can be clearly detected.

Furthermore, piping 29f from the ejector 21: metering port 10
Plug 12'ff: Although described as being inserted through the
It may be inserted into the oil supply pipe 3, and the microphone 19,
The ventilation pipe 16 may also be inserted into the oil supply pipe 3 in the same manner.

Since the tank leakage inspection method according to the present invention has been described in detail above, it is possible to obtain a reduced pressure state without discharging the oil in the underground tank, and it is also possible to easily restore the pressure after calibration. It is possible to carry out the same procedure, and furthermore, it is possible to ensure complete safety and other effects.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a tank leakage inspection method according to the present invention, and FIG. 2 is a sectional view showing an example of the mounting form of a microphone and a liquid level sensor. 1... Underground tank, 2... Liquid, 3... Oil supply pipe,
4゜0611 store completion 10. West 1Pze# 11;,,
, Yuki+Shi) Sugisen 710.4h mountain 4t, 8...Vent pipe, 10...Measuring port, 11...Liquid level sensor, 14...
・Liquid level measuring device, 16... Ventilation pizo, 17... Pressure gauge, 19... Microphone, 20... Recording device,
21... Ejector, 22, '2 fi, 29
...Piping, 23...Nitrogen gas cylinder, 24...Regulator, 25°28.30...Manual valve, 27...
・Yairensa, 31...Leak hole.

Claims (1)

[Claims] The inside of the tank in which the oil liquid is stored is airtightly closed, the gas inside the tank is discharged to the outside of the tank, the inside of the tank is reduced in pressure, and if there is a leakage hole in the tank, the outside is closed in the reduced pressure state. In a tank leakage inspection method in which the presence or absence of leakage is inspected by the generation of intake noise due to the air sucked into the tank from the tank or by the increase in the tank internal pressure, the gas in the tank is removed to create a depressurized state. A tank leakage inspection method characterized by mixing the mixture with water and discharging it outside the tank.