JP2002214064A - Method of inspecting gas leakage from already installed gas pipe and gas aspirator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of inspecting gas leakage and a gas aspirator by which gases existing in boreholes can be sucked out without separately preparing any cleaner type suction blower which is only used for sucking out the gases existing in the boreholes and has an explosion-proof constitution. SOLUTION: In the method of inspecting gas leakage, the gas leaking spot of an already installed gas pipe 4 is detected by detecting gas concentrations in a plurality of boreholes 2 when a prescribed period of time has elapsed after the boreholes 2 are drilled above the pipe 4 and the gases existing in the boreholes 2 are sucked out. The sucking out of the gases is performed by respectively connecting ejectors 6 to the boreholes 2 and discharging the gases existing in the boreholes 2 to the outside by supplying compressed air to the ejectors 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a gas leaking point in an existing gas pipe buried underground, and more particularly, to a method and an apparatus therefor. The present invention relates to a method and an apparatus for inspecting a gas leaking point in an existing gas pipe by digging a borehole above a pipe, sealing the borehole, and sucking gas inside the borehole.

[0002]

2. Description of the Related Art When gas leaks from an existing gas pipe buried underground, the gas pipe must be repaired. However, digging all existing gas pipes to check for leaks would require a large-scale construction, and it would be practically difficult to dig all existing gas pipes. Therefore, a gas leak location is inspected without digging all the gas pipes, and only the gas pipes near the gas leak location are dug to repair the leak location.

Here, as a method of inspecting a gas leaking point in an existing gas pipe without digging a gas pipe buried underground, a conventional method of inspecting a gas pipe having an inner diameter of about 30 mm above the existing gas pipe has been proposed. There is known a method in which ten boring holes are excavated, the concentration of gas present inside the boring holes is detected, and a leakage point is specified based on the concentration value of the gas.

[0004] However, the above-described method has a problem that it is difficult to identify a leak point when the gas concentration inside the plurality of boreholes is saturated. Therefore, as a method for solving the above-described problem, the boring hole is closed and the gas inside the boring hole is sucked before detecting the gas concentration inside the boring hole, and after a predetermined time has elapsed, the boring hole is removed. There is known a method of measuring the gas concentration inside the device.

That is, as shown in FIG. 5, 5 to 10 (six in FIG. 5) boreholes 101 having an inner diameter of about 30 mm are excavated along the existing gas pipe.
At this time, the depth of the boring hole 101 to be excavated is set to about 10
00 mm. That is, the gas pipe 4 is about 120
This is because it is buried in a place of 0 mm. Further, in order to improve the accuracy of the inspection, the drilling is performed so that the inner diameters of all the boring holes 101 are equal.
mm. Next, the hollow suction rod 103 connected to the explosion-proof suction blower 106 via the suction pipe 104 is inserted into the inside of the boring hole 101, and the boring hole 10 is inserted.
The first opening 102 is sealed with a rubber packing or the like. still,
The explosion-proof suction blower 106 is a vacuum cleaner type device that rotates an impeller by a motor. Then, the gas existing inside the bore hole 103 is sucked by the explosion-proof suction blower 106 connected to the suction rod 103, whereby the gas existing inside the bore hole 103 is removed together with the gas existing inside the bore hole 103. Removes gas remaining in the surrounding ground.

After a predetermined time has elapsed, the suction rod 1
A gas concentration sensor 105 connected to the boring hole 103 through the suction pipe 104 detects a gas concentration inside the boring hole 103, and the boring hole 1 having the highest gas concentration is detected.
It is determined that gas is leaking near 03. Then, the location is dug back with an air drill or the like to repair the gas leaking portion of the gas pipe.

According to such a method, the boring hole 1
Since the gas remaining in the bore hole 103 is sucked together with the gas existing in the borehole 103 a predetermined time before the gas concentration inside the gas sensor 03 is detected, the gas existing in the ground is removed. Therefore, when inspecting a gas leak location, if the initial state is immediately after gas is sucked into the bore hole 103, the initial state is that the bore hole 10
3 and there is no gas in the ground. Therefore, after a lapse of a predetermined time from the initial state, the gas concentration in the bore hole 103 is measured, and the gas concentration near the bore hole 103 having the highest gas concentration at this time is measured. Since the gas leakage point is detected by determining that the gas is leaking, the gas leakage point can be detected even if the gas inside the bore hole 103 is saturated before the gas is sucked.

[0008]

However, the method of sucking the gas existing inside the bore hole 103 by the above-mentioned method is used only for sucking the gas existing inside the bore hole 103. An explosion-proof vacuum cleaner type suction blower 106 must be separately prepared. Therefore, there are the following problems. That is, first, as described above, the explosion-proof suction blower 106 is a vacuum cleaner type device in which the impeller is rotated by the motor. Therefore, the explosion-proof suction blower 106 must have an explosion-proof structure in order to prevent ignition of the sucked gas.
This results in a large-scale device. Second,
Since a single explosion-proof suction blower 106 suctions gas from a large number of boreholes, the negative pressure is small. Further, since the negative pressure is easily received by the length of the suction hose 104, the suction force varies depending on the location of the borehole 103 to be sucked. Thereby, even if the suction of some of the plurality of boring holes 103 is completed, but the suction of the other boring holes 103 is not completed, the suction of the other boring holes 103 is completed. Suction must be continued until. Therefore, it takes a very long time to suck the gas existing inside all the boring holes 103 to be inspected. Therefore, it takes time to complete the gas leak inspection. And to prevent this,
Although it is conceivable to reduce the number of the boring holes 103 for performing suction, if this method is adopted, the number of times of performing the gas leakage inspection increases, so that it takes time to perform all the inspections.

The present invention has been made to solve the above problems. That is, the subject is
The gas present inside the borehole can be sucked without separately preparing an explosion-proof vacuum cleaner type suction blower used only for sucking the gas in the borehole. An object of the present invention is to provide a gas leakage inspection method and a gas suction device which are easy to move and have a short suction time for gas present in a borehole.

[0010]

In order to solve the above-mentioned problems, a gas leakage inspection method for an existing gas pipe according to the present invention comprises the steps of: excavating a plurality of boreholes above an existing gas pipe, sealing the borehole; After performing suction of gas existing in
After a lapse of a predetermined time, in the gas leak inspection method for an existing gas pipe that detects a gas leak location by detecting a gas concentration inside a borehole, the gas suction is performed by using a different ejector for each borehole. It is characterized in that compressed air is supplied to the ejector and the gas present in the borehole is discharged to the outside.

In the gas leakage inspection method for an existing gas pipe according to the present invention, the ejector has a hollow cylindrical shape and a gas suction port is formed at one end thereof. A compressed air supply port is formed on the side surface, and a discharge port is formed at the other end. A seal member is attached to the outer periphery of the ejector, and the one end is inserted into the bore hole so that the outer periphery of the ejector is It is characterized in that the space between the hole and the boring hole is sealed.

Further, the gas suction device according to the present invention is a gas suction device for sucking gas existing inside a plurality of boreholes excavated above an existing gas pipe when detecting a gas leak location. And an ejector connected to the boring for sucking a gas inside the boring hole, wherein the ejector discharges a gas existing inside the boring hole to the outside by supplying compressed air. Characterized in that:

Further, the gas suction device of the present invention is the above-described gas suction device, wherein the ejector has a hollow cylindrical shape, a gas suction port is formed at one end thereof, and a compressed air supply port is formed at a side surface thereof. Is formed at the other end, and the discharge port is formed at the other end. The gas suction port is inserted into the inside of the boring hole, and between the outer periphery of the ejector and the boring hole by a seal member attached to the outer periphery of the ejector. Are sealed.

According to the gas leakage inspection method for an existing gas pipe having the above characteristics, when inspecting a gas leak location in the existing gas pipe buried underground, a boring hole is provided above the existing gas pipe. Is excavated and hermetically sealed, and gas existing inside the borehole is sucked. Thereafter, the boring hole is left in a sealed state for a predetermined time, and after the predetermined time has elapsed, the gas concentration inside the boring hole is detected, and based on the gas concentration, the gas leak location in the existing gas pipe is detected. are doing.

Here, a gas suction device used for sucking a gas connects an ejector to the boring hole, and supplies compressed air to the ejector to remove gas present inside the boring hole. To be discharged. At that time, in the gas suction device, compressed air must be supplied to the ejector. As a device for supplying the compressed air, the compressed air is supplied to an air drill or the like used when digging a road or constructing a gas pipe. A construction air compressor that supplies air can be used.
Such an air compressor is always present during gas leak inspection. That is, when a gas leak location is found, immediately after that, the ground is excavated and the gas pipe is repaired. Therefore, it is not necessary to separately prepare a suction blower used only for sucking the gas existing in the borehole. Furthermore, the ejector can be made large enough to be inserted inside the borehole,
Easy to move.

Further, according to the present invention, since the ejector is individually connected to each of the boring holes, a boring hole serving as a gas supply source can be connected to each of the boring holes. Therefore, each of the boring holes can be individually suctioned, whereby the force for sucking the gas inside the boring hole can be increased. Therefore, the time until the gas suction is completed can be shortened.

Further, generally, the air pressure of the compressed air is hardly affected by the length of the air supply path connecting the compressor and each ejector. For this reason, when an ejector is attached to the end of the air supply path, even if the length of the air supply path is slightly different for each ejector, compressed air with a uniform air pressure can be supplied to each ejector. Further, the negative pressure generated from the ejector is determined by the air pressure supplied to the ejector. Here, since the air pressure supplied to each ejector is made uniform, the negative pressure generated from each ejector is also uniform. For this reason,
Even if the length of the air supply path is slightly different, the suction force for sucking the gas inside the borehole is uniform for each ejector, and this causes variations in the time until the suction of the gas inside the borehole is completed. Almost no. That is, even if the gas suction time of the boring hole 2 at which the gas suction ends first becomes somewhat longer, the gas suction time at the boring hole 2 at which the gas suction ends at the latest becomes shorter. The time required to finish sucking the gas inside the borehole 2 is considerably short. Therefore, it is possible to shorten the gas suction time inside all of the plurality of boring holes 2.

Furthermore, when an ejector is attached to the end of the air supply passage, compressed air having a uniform air pressure can be supplied to each ejector even if the length of the air supply passage is slightly different for each ejector. Therefore, a seal member is attached to the outer periphery of the ejector, and when performing a gas leakage inspection, by inserting the gas suction port into the inside of the boring hole to seal between the outer periphery of the ejector and the boring hole. An ejector can be set near each boring hole. Therefore, the force for sucking the gas inside the borehole can be further increased. Therefore, the time until the gas suction ends can be further reduced.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a gas leak inspection method for an existing gas pipe according to the present invention will be described in detail with reference to the drawings.

First, as shown in FIG. 2, 5 to 10 boring holes 2 are excavated from the ground 3 in which the existing gas pipes 4 are buried into the ground. At this time, the depth of the boring hole 2 to be excavated is about 1000 mm. This is because the gas pipe 4 is buried at a location approximately 1200 mm from the ground. Further, in order to increase the accuracy of the inspection, excavation is performed so that the inner diameters of all the boring holes 2 are equal, and in the present embodiment, the inner diameter is set to about 30 mm.

Then, the suction device 1 is connected to the borehole 2, and the gas existing in the ground is removed by sucking the gas existing inside the borehole 2.
Here, the configuration of the suction device 1 will be described.

That is, as shown in FIG.
The ejector 6 is attached to the opening of the boring hole 2 to suck the gas in the boring hole 2. Here, the ejectors 6 are separately provided in the respective boring holes 2. The ejector 6 has a hollow cylindrical shape. As shown in FIG. 3, the ejector 6 has a suction port (not shown) at a lower end and a discharge port 6 at an upper end.
A is formed. Further, a compressed air supply port 6C into which compressed air is supplied is formed in the side surface.
A rubber seal member 6 </ b> C for sealing between the inner surface of the boring hole 2 and the outer periphery of the ejector 6 is attached to the side surface. Then, the suction port formed at the lower end of the ejector 6 is inserted into the inside of the boring hole 2, and the gap between the inner surface of the boring hole 2 and the outer periphery of the ejector 6 is sealed with a sealing member 6 </ b> C, thereby sealing the boring hole 2. You. Further, a sensor (not shown) for detecting the concentration of gas present in the borehole 2 is attached near the lower end of the ejector 6.

A compressed air supply hose 7 (see FIG. 1) is connected to the compressed air supply port 6B. The compressed air supply hose 7 is connected to a joint 8, and the joint 8 is connected to a compressed air supply hose. 9 is connected to a compressor 10. Further, a regulator 11 for adjusting the air pressure inside the compressed air supply hose 7 is provided near the compressed air supply port 6B of the compressed air supply hose 7. The compressor 10 used here may be a general one such as one for supplying air to an air drill or the like used in gas piping work or the like.

Then, the gas existing in the boring hole 2 and its surroundings is suctioned by the suction device 1 having the above configuration. That is, the air pressure of the compressed air is applied to the compressed air supply port 6B of the ejector 6 from the compressor 10 via the joint 8 and the compressed air supply hose 7, and the ejector 6
Then, the air pressure is converted into a negative pressure, and the gas present in the borehole 2 and its surroundings is sucked from the suction port formed at the lower end of the ejector 6, and the gas is discharged from the discharge port 6A together with the compressed air. At this time, suction is performed until all the gas inside and around the boring hole 2 is exhausted, and the suction time of the gas existing in the boring hole 2 and its surroundings is measured during a period of 15 to 30 minutes. It is determined appropriately according to the surrounding environment in.

Then, immediately after the end of the suction of the gas, the concentration of the gas present in each of the boreholes 2 is measured. In this measurement, the state where the ejector 6 is set in the boring hole 2 is maintained, and the measurement is performed by a sensor (not shown) attached near the lower end of the ejector 6 in a state where the boring hole 2 is sealed. This is for accurately measuring the gas concentration immediately after the gas is sucked. Thereafter, the state in which the borehole 2 is sealed is maintained for about several minutes, and the concentration of the gas present inside each borehole 2 is measured again to determine the diffusion state of the gas inside the borehole 2. Find out. Then, it is determined that the gas is leaking in the vicinity of the boring hole 2 where the gas concentration is highest. Thus, it is possible to detect a gas leak point of the gas pipe buried underground.

Next, the operation of the gas leakage inspection method for an existing gas pipe having the above characteristics will be described. According to the gas leakage inspection method for an existing gas pipe having the above characteristics, when inspecting a gas leak location in the existing gas pipe 4 buried underground, a boring hole is provided above the existing gas pipe 4. 2 is excavated and hermetically sealed, and the gas existing inside the borehole 2 is sucked. Thereafter, the state where the borehole 2 is hermetically sealed is maintained. The gas concentration is detected, and the location of the gas leak in the existing gas pipe 4 is detected based on the gas concentration.

Here, when the gas is sucked, in the suction device 1 used in this embodiment, the ejector 6 is connected to the boring hole 2, and compressed air is supplied to the ejector 6 so that the inside of the boring hole 6 is removed. The gas that is present in is discharged outside. At this time, in the present embodiment, the compressor 10 is used as a device for supplying compressed air. However, as the compressor 10, for example, an air drill used for excavating a road or constructing a gas pipe is used. A compressor that supplies air can be used. Such a compressor is always present when performing a gas leak inspection. That is, it is common practice to prepare a tool for repairing the gas pipe 4 in advance when performing a gas leak inspection, and to repair the gas pipe 4 immediately after a gas leak location is found. Therefore,
In the suction device 1 used in the present embodiment, there is no need to separately prepare a suction blower just for sucking the gas existing inside the borehole 2 unlike the conventional gas leakage inspection device. Furthermore, since the ejector 6 can be made large enough to be inserted into the inside of the boring hole 2,
The movement of the ejector 6 can be easily performed.

According to the present embodiment, the ejectors 6 are individually connected to the respective boring holes 2. Thereby, the ejector 6 which is a gas supply source can be connected to each of the boring holes 2. Therefore, each of the boring holes 2 can be individually suctioned, whereby the force for sucking the gas inside the boring holes 2 can be increased.

Further, in general, the air pressure of the compressed air is less affected by the length of the compressed air supply hose 7 than the negative pressure. Therefore, the air pressure of the compressed air supplied by the compressor 10 is evenly transmitted to the end of the compressed air supply hose 7 even if the length of the compressed air supply hose 7 is slightly different for each ejector. Further, in the present embodiment, the regulator 1 provided near the connection between the compressed air supply hose 7 and the ejector 6 is provided.
1 makes the air pressure uniform. The negative pressure generated in the ejector 6 is determined by the air pressure supplied to the ejector 6. Here, since the air pressure supplied to each ejector 6 is uniform, the negative pressure generated from each ejector 6 is also uniform. Therefore, even if the length of the compressed air supply hose 7 is slightly different, the suction force for sucking the gas inside the boring hole 2 is uniform in each ejector 6, and therefore, the gas suction inside the boring hole 2 is sucked. There is almost no variation in the time until the process is completed. That is, even if the gas suction time of the boring hole 2 at which the gas suction ends first becomes somewhat longer, the gas suction time at the boring hole 2 at which the gas suction ends at the latest becomes shorter. The time required to complete the suction of the gas inside 2 is considerably shortened, whereby the suction time of the gas inside all the boring holes 2 can be shortened. Therefore, the suction of the gas inside the borehole 2 can be completed quickly for all of the plurality of boreholes 2, so that the measurement of the gas concentration inside the borehole 2 can be started quickly, and thereby, The time required for the gas leak inspection can be reduced.

When the ejector 6 is attached to the end of the compressed air supply hose 7, the compressed air supply hose 7
Is slightly different for each ejector 6,
Since uniform and strong compressed air can be supplied to each ejector 6, a seal member 6C is attached to the outer periphery of the ejector 6, and when performing a gas leak inspection, the gas suction port is connected to the boring hole. 2, the ejector 6 can be set near each of the boring holes 2 by sealing between the outer periphery of the ejector 6 and the boring hole 2. Therefore, the force for sucking the gas inside the borehole 2 can be further increased. Thereby, the suction time of the gas inside the borehole 2 can be shortened. Therefore, it is possible to reduce the time for the gas leakage inspection.

That is, according to the gas leakage inspection method of the present embodiment, the force for sucking the gas inside the borehole 2 can be increased, and the gas suction of the borehole 2 at which the gas suction is completed at the earliest. Since the difference between the time and the gas suction time at the boring hole 2 where the gas suction ends at the latest is reduced, the gas suction time inside the boring hole 2 can be shortened. Therefore, boring hole 2
The measurement of the gas concentration in the inside can be started promptly, whereby the time for the gas leak inspection can be shortened.

Further, in the present embodiment, the air pressure of the compressed air is applied from the compressor 10 to the compressed air supply port 6B of the ejector 6, and the ejector 6 converts the air pressure into a negative pressure to convert the air pressure into the bore hole 2. The gas is sucked, and when a large air pressure is applied to the ejector 6, the negative pressure applied to the inside of the boring hole 2 can be increased. When a small air pressure is applied to the ejector 6, the negative pressure applied to the inside of the boring hole 2 can be increased. Can be reduced. This allows
By changing the air pressure applied from the compressor 10 to the ejector 6 by the regulator 11, the negative pressure when sucking the gas inside the borehole 2 can be adjusted. Therefore, the suction force when sucking the gas inside the borehole 2 can be easily adjusted according to the geological condition of the place where the existing gas pipe 4 is buried.

Further, in this embodiment, a rubber seal member 6B is attached to the outer periphery of the ejector 6, and a gas suction port (not shown) attached to the lower end of the ejector 6 is connected to the boring hole. Since the ejector 6 and the boring hole 2 are connected by being inserted into the hole 2, the outer periphery of the ejector 2 and the boring hole 2 are sealed by the sealing member 6B as shown in FIG. Therefore, when the ejector 2 is connected to the boring hole 6, the opening of the boring hole 6 can be easily and reliably sealed.

As described in detail above, the gas leakage inspection method for an existing gas pipe according to the present embodiment excavates and seals a plurality of boreholes 2 above the existing gas pipe 4, and seals the inside of the borehole 2. A method of detecting a gas leakage location by detecting the gas concentration inside the borehole 2 after a predetermined time has elapsed after performing suction of the existing gas. Each of the ejectors 6 is connected to each other, and compressed air is supplied to the ejectors 6 to discharge the gas existing inside the boring hole 2 to the outside. It is not necessary to separately prepare a suction blower used only for sucking the existing gas. This makes it possible to use the suction device 1 that is easy to carry and move and that has a short time for sucking the gas. It is possible.

Further, according to the present embodiment, the air pressure of the compressed air is applied from the compressor 10 to the compressed air supply port 6 B of the ejector 6, and the ejector 6 converts the air pressure into a negative pressure, and Since the internal gas is sucked, the boring hole 2 can be easily and appropriately changed according to the geological condition of the place where the existing gas pipe 4 is buried by changing the air pressure applied from the compressor 10 to the ejector 6.
The suction force at the time of sucking the gas inside the can be adjusted.

In the gas leakage inspection method for an existing gas pipe according to the present embodiment, the ejector 6 has a hollow cylindrical shape and has a gas suction port at one end. A compressed air supply port 6B is formed on the side surface, and a discharge port 6A is formed on the other end. A rubber seal member 6C is attached to the outer periphery of the ejector 6, and the one end is connected to the boring hole 2B. The seal between the outer periphery of the ejector 6 and the boring hole 2 is characterized by being inserted into the inside of the hole, so that the suction force for sucking the gas existing in each of the boring holes 2 can be further enhanced. Thus, the time for sucking the gas can be further shortened.

Furthermore, the suction device 1 of the present embodiment sucks the gas present inside the plurality of boreholes 2 excavated above the existing gas pipe 4 when detecting a gas leak location. A gas suction device 1 having an ejector 6 connected to the boring hole 2 for sucking gas inside the boring hole 2, wherein the ejector 6 is configured to supply compressed air to the inside of the boring hole 2. It is characterized in that the gas present in the hole is discharged to the outside, so that there is no need to separately prepare a suction blower used only for sucking the gas present in the borehole 2, Thereby, it is easy to carry or move, and the time for sucking gas can be shortened.

Further, in the suction device 1 of the present embodiment, the ejector 6 has a hollow cylindrical shape, a gas suction port is formed at one end thereof, and a compressed air supply port 6B is formed at a side surface thereof. A discharge port 6A is formed at an end, and the gas suction port is inserted into the boring hole 6, and the outer periphery of the ejector 6 and the boring hole 2 are connected by a sealing member 6C attached to the outer periphery of the ejector 6. By being characterized by the space being sealed,
Since the ejector 6, which is a gas suction source, can be set near each of the boreholes 2, the suction force for sucking the gas existing in each of the boreholes 2 can be further increased. Can be further shortened.

In the suction device of the present embodiment, when the ejector 6 is set in the boring hole 2, the outer periphery of the ejector 6 is connected to the boring hole 2 by a rubber sealing member 6 C on the outer periphery of the ejector 6. Since the gap is sealed, the opening of the boring hole can be easily and reliably sealed when the ejector 6 is connected to the boring hole 2.

The present embodiment is merely an example and does not limit the present invention. Therefore, naturally, the present invention can be variously modified and improved without departing from the gist thereof. For example, the sensor for measuring the concentration of the gas existing inside the borehole 2 does not necessarily need to be provided near the lower end of the ejector, and may be provided anywhere where the concentration of the gas can be measured. Further, in the present embodiment, six boring holes 2 are excavated, but any number of boring holes 2 may be excavated as long as they are 5 to 10 locations.

[0041]

According to the present invention, a plurality of boreholes are drilled above an existing gas pipe to seal the borehole, the gas existing inside the borehole is sucked, and after a predetermined time elapses, the borehole is bored. In the gas leak inspection method for an existing gas pipe, which detects a gas leak location by detecting a gas concentration inside the gas pipe, the suction of the gas is performed by connecting a separate ejector to each of the boring holes and connecting the compressed air to the ejector. Is supplied to discharge the gas present inside the borehole to the outside, so separately prepare a suction blower used only for sucking the gas present inside the borehole. There is no need to use this, so that a device that is easy to carry or move can be used as a device for sucking gas. Further, the time for sucking the gas can be shortened.

Further, according to the present invention, in the gas leakage inspection method for an existing gas pipe, the ejector has a hollow cylindrical shape, a gas suction port is formed at one end, and a compressed air supply port is formed at a side surface thereof. A discharge member is formed at the other end, and a seal member is attached to the outer periphery of the ejector, and the one end is inserted into the inside of the boring hole to seal between the outer periphery of the ejector and the boring hole. Since the ejector, which is a gas suction source, can be set in the vicinity of each boring hole by the feature, it is possible to further increase the suction force for sucking the gas existing in each boring hole. Thus, the time for sucking the gas can be further shortened.

Further, the present invention is a gas suction device for sucking a gas existing inside a plurality of boreholes excavated above an existing gas pipe when detecting a gas leak location, An ejector connected to the boring hole for sucking a gas inside the boring hole, wherein the ejector discharges a gas existing inside the boring hole to the outside by supplying compressed air; With this feature, it is possible to provide a suction device which is easy to carry or move and has a short time until gas suction is completed, thereby shortening the time for gas leakage inspection.

Further, the present invention is the above-described gas suction device, wherein the ejector is a hollow cylindrical shape, a gas suction port is formed at one end, and a compressed air supply port is formed at a side surface thereof. A discharge port is formed at the other end, the gas suction port is inserted into the inside of the boring hole, and a gap between the outer periphery of the ejector and the boring hole is sealed by a seal member attached to the outer periphery of the ejector. Since the ejector, which is a gas suction source, can be set in the vicinity of each boring hole, the suction force for sucking the gas present in each boring hole is further increased, By
It is possible to provide a gas suction device in which the time until the gas suction ends is even shorter.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which a suction device is set in a boring hole.

FIG. 2 is a diagram showing a state in which a boring hole is excavated above an existing gas pipe.

FIG. 3 is a perspective view of the ejector of the embodiment.

FIG. 4 is a view showing a state in which an ejector is inserted into an opening of a boring hole.

FIG. 5 is a diagram showing a conventional gas leakage inspection method and apparatus for an existing gas pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Suction apparatus 2 Boring hole 4 Existing gas pipe 6 Ejector 6A Discharge port 6B Compressed air supply hole 10 Compressor

Continued on the front page (72) Inventor Takashi Imagawa 19-18 Sakuradacho, Atsuta-ku, Nagoya City, Aichi Prefecture Inside Kunigasa Co., Ltd. (72) Inventor Hidetoshi Matsuura 19-18, Sakuradacho, Atsuta-ku, Nagoya City, Aichi Prefecture East F-term in Kokusa Gas Co., Ltd. (reference) 2G052 AA01 AC12 AD02 AD22 AD42 BA14 CA14 CA29 CA30 2G067 AA14 BB04 BB12 DD17

Claims (4)

[Claims] 1. After excavating a plurality of boreholes above an existing gas pipe and sealing the borehole, sucking gas present inside the borehole, and after elapse of a predetermined time, the gas inside the borehole is removed. In the gas leakage inspection method for an existing gas pipe that detects a gas leakage location by detecting a concentration, the gas suction is performed by connecting a separate ejector to each of the boring holes and supplying compressed air to the ejector. A gas leakage inspection method for an existing gas pipe, which comprises discharging gas existing inside a borehole to the outside. 2. The gas leak inspection method for an existing gas pipe according to claim 1, wherein the ejector has a hollow cylindrical shape, a gas suction port is formed at one end thereof, and a compressed air supply port is formed on a side surface thereof. A discharge port is formed at the other end, and a seal member is attached to the outer periphery of the ejector, and the one end is inserted into the bore hole to seal between the outer periphery of the ejector and the bore hole. A gas leakage inspection method for an existing gas pipe, characterized in that: 3. A gas suction device for sucking gas existing inside a plurality of boreholes excavated above an existing gas pipe when detecting a gas leak location, wherein the gas suction apparatus is connected to the borehole. The ejector has an ejector that sucks a gas inside the boring hole, wherein the ejector discharges gas existing inside the boring hole to the outside by supplying compressed air. Gas suction device. 4. The gas suction device according to claim 3, wherein the ejector has a hollow cylindrical shape, a gas suction port is formed at one end thereof, and a compressed air supply port is formed at a side surface thereof. A discharge port is formed at the other end, and the gas suction port is inserted inside the boring hole,
A gas suction device, wherein a gap between an outer periphery of the ejector and the boring hole is sealed by a seal member attached to an outer periphery of the ejector.