Underground Gas Detection Device, System and Application

Abstract

To solve the problem that the gas detection sensor in the prior art is easily damaged after the water level rises, the present invention provides an underground gas detection device, system and application, including: a housing, a detection unit and a movable component; wherein, a breathing hole for communicating with the outside is provided on the housing; the detection unit is arranged in the housing and is used for detecting the gas entering the housing from the breathing hole; the movable component is arranged in the housing and is used for sealing the breathing hole when the water level rises and opening the breathing hole when the water level drops. The structure of the present invention is simple. When the underground water level rises, muddy water cannot enter the underground gas detection device, preventing the muddy water from blocking the detection unit, and effectively improving the reliability and service life of the underground gas detection device.

Description

Technical Field

[0001] The present invention belongs to the field of combustible gas detection, and more particularly relates to an underground gas detection device, system and application. Background Art

[0002] Underground pipelines are complex and non-transparent systems that are closely related to people's daily lives. For example, natural gas needed in daily life and wastewater generated in production and life all use underground pipelines. Since underground pipelines are non-transparent, when combustible gas leaks in the underground pipelines, how to accurately and timely locate the leakage point to prevent accidents has become a difficult point in detection.

[0003] In the prior art, there is a combustible gas leakage sensor buried underground. Correspondingly, in order to detect the leakage of pipelines below the ground, the combustible gas leakage sensor must be buried underground, and breathing holes need to be set on the ground to detect the leaked combustible gas.

[0004] In case of rain, the underground water level rises, the breathing holes are flooded, and mud and dirty water will flow into the combustible gas leakage sensor through the breathing holes. Even when the water level recedes, the combustible gas leakage sensor is still blocked, resulting in damage to the combustible gas leakage sensor and loss of detection ability.

[0005] A gas detection device that can prevent damage from mud and water is urgently needed to be developed. Summary of the Invention

[0006] In order to solve the problem that the combustible gas detection sensor in the prior art is easily damaged after the water level rises, the present invention provides an underground gas detection device, system and application, which can be sealed as the underground water level rises to solve the problem that the existing combustible gas detection sensor is easily damaged after the water level rises.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: an underground gas detection device, comprising:

[0008] A housing, on which breathing holes for communicating with the outside are provided;

[0009] A detection unit, arranged in the housing, for detecting the gas entering the housing from the breathing holes;

[0010] An active component, arranged in the housing, for sealing the breathing holes when the water level rises and opening the breathing holes when the water level drops.

[0011] The active component includes:

[0012] A piston member, arranged in the housing, for performing piston movement in the housing to close or open the breathing holes;

[0013] A piston rod, one end of which is connected to the piston member;

[0014] A sealing soft film, connected to the other end of the piston rod;

[0015] The sealing soft film is sealingly arranged at the open end of the housing and is used to move following the change of water level.

[0016] The piston member includes:

[0017] A piston body, which matches with the inner side wall of the housing to form a piston structure;

[0018] An extension body, arranged on the piston body, which matches with the inner side wall of the housing and is used to seal the breathing hole.

[0019] The movable assembly further includes:

[0020] Two guiding partitions, arranged in the housing, are sealingly connected to the piston rod and are used to guide the movement of the piston member.

[0021] The movable assembly further includes:

[0022] A counterweight body, arranged on the piston rod and is used to reset the piston member after the water level drops.

[0023] The housing includes:

[0024] A housing body, on which the breathing hole is arranged;

[0025] An outer side wall, arranged outside the housing body and is used to form an isolation space between the housing body and the outer side wall;

[0026] An air inlet hole for air intake is arranged on the outer side wall.

[0027] A filter screen for filtering sediment is arranged outside the air inlet hole.

[0028] A drain hole for water discharge is arranged at one end of the outer side wall far away from the air inlet hole.

[0029] The housing is cylindrical, frustum-shaped or cuboid-shaped.

[0030] The above-mentioned underground gas detection device further includes:

[0031] A plurality of legs, arranged at one end of the housing far away from the detection unit and are used to provide space for the movable assembly.

[0032] A filter screen for filtering sediment is arranged outside a plurality of the legs.

[0033] An underground gas detection system includes:

[0034] At least one underground gas detection device as described above;

[0035] A control center, electrically connected to the underground gas detection devices, for collecting the monitoring data of the underground gas detection devices and judging the leakage condition of the underground pipeline.

[0036] The underground gas detection devices are arranged equidistantly in sequence along the radial direction of the underground pipeline.

[0037] A cavity area for ventilating the underground gas detection devices is arranged between the underground pipeline and the ground.

[0038] An application of the underground gas detection system as described above in the leakage monitoring of natural gas underground pipelines, liquefied petroleum gas underground pipelines, and biogas underground pipelines.

[0039] Beneficial effects: Through the movable component arranged in the housing, the present invention changes according to the change of the water level. When the water level rises, the breathing hole on the housing is sealed by the movable component to protect the detection unit arranged in the housing; at the same time, when the water level drops, the breathing hole is opened by the movable component, so that the detection unit is in an exposed state again and enters the detection state again.

[0040] The structure of the present invention is simple. When the underground water level rises, muddy water cannot enter the underground gas detection device, preventing the muddy water from blocking the detection unit, and effectively improving the reliability and service life of the underground gas detection device. Description of the drawings

[0041] Figure 1 This is an embodiment of the present invention.

[0042] Figure 2 This is Figure 1 the front view of

[0043] Figure 3 This is Figure 1 the structural schematic diagram of the solution shown after the underground water level rises.

[0044] Figure 4 This is another embodiment of the present invention.

[0045] Figure 5 This is Figure 4 the front view of

[0046] Figure 6 This is Figure 4 the structural schematic diagram of the solution shown after the underground water level rises.

[0047] Figure 7 This is yet another embodiment of the present invention.

[0048] Figure 8 is Figure 7 the front view of

[0049] Figure 9 is Figure 7 the structural schematic diagram of the solution shown after the groundwater level rises.

[0050] Figure 10 is Figure 1 the structural schematic diagram of adding an outer wall to the said embodiment.

[0051] Figure 11 is Figure 10 the enlarged view at position E in

[0052] Figure 12 is Figure 4 the structural schematic diagram of adding an outer wall to the said embodiment.

[0053] Figure 13 is Figure 12 the enlarged view at position F in

[0054] Figure 14 is Figure 7 the structural schematic diagram of adding an outer wall to the said embodiment.

[0055] Figure 15 is Figure 14 the enlarged view at position M in

[0056] Figure 16 is the structural schematic diagram of the underground gas detection system described in the present invention.

[0057] Figure 17 is an implementation manner of the underground gas detection system described in the present invention.

[0058] Figure 18 is another implementation manner of the underground gas detection system described in the present invention.

[0059] Among them, 1. housing; 2. detection unit; 3. movable component; 4. leg; 5. underground pipeline; 6. control center; 101. housing body; 102. outer wall; 1A. breathing hole; 301. piston part; 302. piston rod; 303. sealing soft film; 304. guiding partition; 305. counterweight; 102A. air inlet; B. isolation space; C. cavity area; 102B. drain hole; 3011. piston body; 3012. extension body.

[0060] It should be clear that: Figure 17 、 18 At position D in is the underground gas detection device described in the present invention.

[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0062] As Figures 1 - 3 , in order to solve the problem that the combustible gas sensor in the prior art is easily damaged due to the entry of muddy water once the groundwater level rises after being buried underground, the present invention provides an underground gas detection device, including: a housing 1, a detection unit 2, and a movable component 3; wherein, a breathing hole 1A for communicating with the outside is provided on the housing 1. The detection unit 2 is arranged in the housing 1 and is used to detect the gas entering the housing 1 from the breathing hole 1A. Among them, the detection unit 2 is a gas sensor and can generate a signal feedback when detecting gas.

[0063] The movable component 3 is arranged in the housing 1 and is used to seal the breathing hole 1A when the water level rises and open the breathing hole 1A when the water level drops; preferably, the movable component 3 can be a piston structure arranged in the housing 1, and the position of the piston in the housing 1 is determined according to the height of the water level, so as to use the piston to seal or open the breathing hole 1A.

[0064] Specifically, the movable component 3 includes: a piston member 301, a piston rod 302, and a sealing soft film 303; wherein, the piston member 301 is arranged in the housing 1 and is used to perform a piston movement in the housing 1 to close or open the breathing hole 1A; one end of the piston rod 302 is connected to the piston member 301; the other end of the piston rod 302 is connected to the sealing soft film 303.

[0065] Preferably, the housing 1 can be a cylindrical shape with one end open; wherein, the detection unit 2 is arranged at the closed end of the cylinder; the detection unit 2 is arranged at the closed end of the cylinder, and the breathing hole 1A is arranged on the side wall of the housing 1 close to the detection unit 2; the sealing soft film 303 is hermetically arranged at the open end of the housing 1 and is used to move following the change of the water level; the sealing soft film 303 is located above the end of the open end of the housing 1, and a space for the sealing soft film 303 to sense the groundwater level is obtained underground through the open end of the housing 1.

[0066] During use, the sealing soft film 303 changes following the change of the groundwater level; when encountering weather such as rain, the groundwater level rises, and the sealing soft film 303 rises following the groundwater level, resulting in the relative position of the sealing soft film 303 in the housing 1 rising, so as to drive the piston member 301 to move upward through the piston rod 302; when the water level reaches a certain level, the piston member 301 blocks the breathing hole 1A, making the housing 1 a sealed body, preventing external muddy water, etc. from entering the housing 1, thereby protecting the safety of the detection unit 2.

[0067] To facilitate the sealing of the breathing hole 1A, the piston member 301 includes: a piston body 3011 and an extension body 3012; wherein, the piston body 3011 matches the inner side wall of the housing 1 to form a piston structure; the extension body 3012 is arranged on the piston body 3011 and matches the inner side wall of the housing 1 for sealing the breathing hole 1A during the upward movement of the piston body 3011.

[0068] When the sealing soft film 303 rises following the groundwater level, it pushes the piston rod 302, causing the piston member 301 to move upward; due to the soft nature of the sealing soft film 303, the piston rod 302 is subjected to a thrust force at a random angle, so it is easy for the piston member 301 to get stuck inside the housing 1.

[0069] To solve the problem that the piston member 301 is prone to getting stuck inside the housing 1, the movable assembly 3 further includes: two guiding partitions 304; wherein, the two guiding partitions 304 are both arranged inside the housing 1 and are hermetically connected to the piston rod 302 through a sealing ring for guiding the movement of the piston member 301.

[0070] Preferably, the two guiding partitions 304 are fixed inside the housing 1 and do not move relative to the housing 1, which can support the housing 1 to prevent the housing 1 from deforming due to external soil pressure; meanwhile, the guiding partitions 304 are provided with holes to allow air to flow inside the housing 1 to prevent the internal air pressure of the housing 1 from affecting the up and down movement of the sealing soft film 303; when the sealing soft film 303 rises to the highest point, through the driving force of the sealing soft film 303, the piston member 301 seals the housing 1, making the housing 1 form a sealed whole, thereby enclosing the detection unit 2 and the movable assembly 3 inside the housing 1 to prevent muddy water intrusion; when the sealing soft film 303 descends, through the pulling force of the sealing soft film 303, the piston member 301 reopens the housing 1, and the detection unit 2 and the movable assembly 3 will be exposed to the air again.

[0071] During use, the guiding partitions 304 can also be set as guiding support components such as guiding rods according to needs.

[0072] For the underground gas detection device as described above, when the groundwater level rises, the housing 1 can be made into a sealed body by the sealing soft film 303 following the groundwater level rise; in an ideal state, after the groundwater level drops, the sealing soft film 303 follows the groundwater level drop, and the piston body 3011 can be reset; however, in actual use, due to interference factors such as the friction of the piston structure and the presence of muddy water at the open end of the housing 1, it is difficult for the piston body 3011 to be reset.

[0073] To solve the problem of difficult reset of the piston body 3011, the movable assembly 3 further includes: a counterweight 305; the counterweight 305 is arranged on the piston rod 302 for discharging muddy water after the water level drops to reset the piston member 301.

[0074] Preferably, the counterweight 305 is arranged in the enclosed space formed by the two guiding partitions 304 to avoid being affected by external sundries such as muddy water.

[0075] Preferably, the counterweight 305 is connected to the piston rod 302 by means of adhesives or other technical means. Since the counterweight 305 is arranged in the enclosed space formed by the two guiding partitions 304, the counterweight 305 will not have problems such as corrosion, and brass counterweights can be selected. However, due to the long-term existence in the underground environment, water vapor is inevitably present. Therefore, an anti-rust paint can be brushed on the outer surface of the counterweight 305 or a hydrophobic coating can be provided.

[0076] The preparation method of the hydrophobic coating is as follows:

[0077] S1. First, clean the surface of the counterweight 305 substrate, and then treat the surface of the counterweight 305 substrate with an anti-rust liquid;

[0078] S2. Immerse the counterweight 305 substrate treated in S1 in a polyvinyl alcohol-polyacrylic acid aqueous solution, and air-dry the immersed counterweight 305 substrate in a dust-free environment for standby; the polyvinyl alcohol-polyacrylic acid aqueous solution is composed of the following components in mass percentages: 0.5-2% of polyvinyl alcohol, 4.5-5% of polyacrylic acid, 0.25%-0.35% of glyoxal, 1-2% of hydrophobic modified nano-silica with an average particle size of 30 nm, and the balance is water;

[0079] S3. Perform a silanization reaction on the counterweight 305 substrate treated in S2 and a silanization reagent in a vacuum. After the reaction ends, rinse the surface of the substrate and dry it to obtain the hydrophobic coating.

[0080] Through the above setting of the hydrophobic coating, the counterweight 305 can have good hydrophobicity, ensuring its service life and use reliability.

[0081] During actual use, since the housing 1 itself is buried underground and there are several olfactory holes on the ground. Therefore, when the underground gas detection device of the present invention is buried underground and encounters heavy rain, on the one hand, the problem of rising groundwater level needs to be solved, and on the other hand, the intrusion of surface seepage water also needs to be considered; although a filter screen can be provided on the breathing hole 1A, in order to enable the breathing hole 1A to ventilate and detect the leakage of the underground pipeline, the filter screen cannot be too fine to prevent poor ventilation. If muddy water enters the housing 1 through the breathing hole 1A, the muddy water will accumulate on the top of the piston member 301, and during the upward movement of the piston member 301, the muddy water will be pushed onto the detection unit 2, which may cause damage to the detection unit 2. Therefore, the protection of the breathing hole 1A against the intrusion of muddy water is also very important.

[0082] To prevent surface seepage water from entering the interior of the housing 1 through the breathing hole 1A; as Figures 10 - 11 The housing 1 includes: a housing body 101 and an outer side wall 102; wherein, a breathing hole 1A is provided on the housing body 101; the outer side wall 102 is arranged outside the housing body 101 to form an isolation space B between the housing body 101 and the outer side wall 102; an air inlet hole 102A for air intake is provided on the outer side wall 102.

[0083] During use, in case of heavy rain, the surface seepage water will enter the isolation space B through the air inlet hole 102A, rather than entering the housing 1 through the breathing hole 1A, ensuring the working environment of the detection unit 2.

[0084] Preferably, in order to prevent sediment from entering, a filter screen for filtering sediment is provided outside the air inlet hole 102A; the filter screen provided outside the air inlet hole 102A can be set to 300 - 500 meshes, preferably 400 meshes, and the material can be selected as stainless steel.

[0085] In addition, in order to drain the water stored in the isolation space B, a drain hole 102B for water discharge is provided at one end of the outer side wall 102 away from the air inlet hole 102A; during use, the drain hole 102B is in contact with the outside soil, and the water in the isolation space B is drained by utilizing the water absorption of the soil.

[0086] The drain hole 102B can be set in a flared shape, with the diameter near the outside soil being larger than the diameter near the isolation space B; through the above-mentioned flared shape, the water in the isolation space B contacts the outside soil through the large diameter, and the water is sucked away from the isolation space B by utilizing the water absorption of the soil, achieving the water absorption effect.

[0087] The number of the drain holes 102B is not limited and can be set as required. Preferably, a drain hole 102B array is provided at one end of the outer side wall 102 away from the air inlet hole 102A, each drain hole 102B is in a flared shape, and the large diameter of the flared shape is in contact with the outside soil, facilitating drainage.

[0088] As Figures 4 - 9 To ensure the reliability of use, the underground gas detection device described in the present invention can have different shapes, and the housing 1 can also be frustum-shaped or cuboid-shaped; at this time, the extension body 3012 in the housing 1 matches the inner side wall of the frustum-shaped or cuboid-shaped housing 1 to complete the sealing of the breathing hole 1A when the water level rises, completing the sealing of the housing 1; the structures of other parts are the same as those of the cylindrical housing 1.

[0089] When the housing 1 is frustum-shaped, the piston body 3011 is circular corresponding to the inner side of the housing 1; the extension body 3012 is shaped corresponding to the inner side wall of the frustum; at this time, if the breathing hole 1A is arranged in a ring shape on the slope of the frustum, the extension body 3012 also needs to be ring-shaped to achieve the effect of closing the breathing hole 1A.

[0090] When the housing 1 is cuboid-shaped, the piston body 3011 is square or rectangular corresponding to the inner side of the housing 1; the extension body 3012 is plate-shaped corresponding to the inner side wall of the cuboid; at this time, if breathing holes 1A are arranged on all four sides of the cuboid, the extension body 3012 needs to be arranged on all four inner sides of the housing 1 simultaneously to achieve the effect of closing the breathing holes 1A; if breathing holes 1A are arranged only on the opposite side surfaces of the cuboid, the extension body 3012 needs to be arranged at the corresponding positions to achieve the effect of closing the breathing holes 1A; under the action of the square or rectangular extension body 3012, when the extension body 3012 rises to the highest point, it can close the breathing holes 1A on both sides to prevent the detection unit 2 from being waterlogged.

[0091] It should be clear that: when introducing the outer side wall 102 to construct the isolation space B, to ensure the diversity of the shape of the underground gas detection device, such as Figures 12 - 15 , the outer side wall 102 can be set in the same shape as the housing body 101 to form the shapes of different housings 1; but an isolation space B must be formed for waterproofing.

[0092] In use, it is found that the sealing soft film 303 described in the present invention is arranged at the open end of the cylindrical, frustum-shaped or cuboid-shaped housing 1. Due to the influence of sediment carried in the water, during the rising process of the water level, the rising and falling change speeds of the sealing soft film 303 are slow, which is not conducive to the use of the detection unit 2. To improve the sensitivity of the sealing soft film 303, the underground gas detection device described in the present invention further includes a plurality of legs 4; among them, the legs 4 are all arranged at one end of the housing 1 far from the detection unit 2 to provide space for the open end of the housing 1 to intake water; preferably, in order to prevent sediment from entering below the sealing soft film 303 and affecting the rising and falling of the sealing soft film 303, a filter screen for filtering sediment is arranged on the outer sides of the plurality of legs 4; so that during the rising or falling process of the underground water level, the sediment is filtered, and only water can enter below the housing 1, enabling the sealing soft film 303 to quickly respond to the change of the underground water level, thereby improving the sensitivity of the underground gas detection device of the present invention.

[0093] "A plurality of" in this article means: 3, 4, 5...

[0094] It should be noted in particular that: Since there are many limitations in the space for the sealed soft film 303 to sense the groundwater level by striving for sealing through the open end of the cylindrical, frustum-shaped or cuboid-shaped housing 1, such as: the length of the housing 1 needs to be made as long as possible. This brings the problem of excessive volume. Therefore, by setting at least 3 legs 4 and setting a filter screen on the legs 4, the filter screen can be set at 300-500 meshes, preferably 400 meshes, and the material can be selected as stainless steel; through the setting of this filter screen, the length of the housing 1 can be reduced, and the sealed soft film 303 can be set at the end of the open end of the housing 1; by using the space constructed by the filter screen on the legs 4, the sealed soft film 303 can sense the change of the groundwater level, which can improve the sensitivity and reliability of the underground gas detection device described in the present invention.

[0095] It should be clear that: The detection unit 2 described in the present invention can be any combustible gas sensor.

[0096] It should be clear that: The outer edge of the sealed soft film 303 described in the present invention can be pasted to the inner side wall of the housing 1, and the middle part is used to sense the height of the water level, and its material can be corrosion-resistant materials such as flexible PE and rubber.

[0097] The present invention Figure 5 The extension body 3012 in it can select soft materials such as elastic rubber, elastic TPU, and elastic silica gel according to needs; structures such as the housing 1, the guiding partition 304, the piston body 3011, and the piston rod 302 can all be hard materials, such as hard plastic ABS.

[0098] Polyethylene film is abbreviated as PE film, which is colorless, odorless, non-toxic, and odorless, and is semi-transparent. It has high mechanical strength and excellent dielectric properties, and has moisture resistance for humid environments. It can withstand low temperatures down to -70°C and still maintain flexibility and chemical stability in low-temperature environments. It is insoluble in most solvents at room temperature and does not react with moisture, oils, compounds, etc. Compared with films of other materials, at the same thickness, the PE film has lower transparency but better flexibility, and the biggest advantage is environmental protection and non-toxicity.

[0099] PE film can generally be divided into low-density polyethylene (LDPE) with a density of about 0.92 g / cm 2 ; The low-density polyethylene film has good transparency and heat sealability and can prevent water and moisture; but it has low tensile strength, large tensile elongation, and is easy to wrinkle; medium-density polyethylene (MDPE) has a density of about 0.93-0.94 g / cm 2 ; Its performance is between high-density and low-density polyethylene. High-density polyethylene (HDPE) has a density of 0.94-0.965 g / cm 2 ; The high-density PE film has better heat resistance and mechanical strength than the low-density PE film, with a small tensile elongation, and the film thickness is generally above 0.03 mm, but the transparency is poor.

[0100] Generally speaking, as the density increases, the mechanical properties and barrier properties will correspondingly improve, and the heat resistance is also good. The sealing soft film 303 described in the present invention can be selected as high-density polyethylene (HDPE) with a density of 0.965 g / cm 2 , having good heat resistance and mechanical strength, and at the same time having the advantage of a small tensile elongation rate.

[0101] Such as Figure 16 , an underground gas detection system, comprising: at least one underground gas detection device as described above and a control center 6; the control center 6 and the underground gas detection device are both electrically connected, and the connection can be wired or wireless, for collecting the monitoring data of the underground gas detection device and judging the leakage situation of the underground pipeline 5; preferably, the control center 6 can be a computer, a laptop, a mobile phone and other portable intelligent devices, equipped with corresponding software therein, and can display the detection signal and alarm information of the underground gas detection device on the screen of the control center 6.

[0102] For comprehensive detection, such as Figure 17 , an implementation mode of the underground gas detection system: the underground gas detection devices can be arranged equidistantly in sequence along the radial direction of the underground pipeline 5; and, a cavity area C for ventilating the underground gas detection devices is arranged between the underground pipeline 5 and the ground, which can make the underground gas detection devices communicate with the space above the ground and the space of the underground pipeline 5 at the same time, facilitating the simultaneous monitoring of the ground gas and the leaked gas of the underground pipeline.

[0103] Also for comprehensive detection, such as Figure 18 , another implementation mode of the underground gas detection system: the ground surface is a compact ground surface, and surface water is difficult to enter the cavity area C. The main water entering the cavity area C is groundwater. The underground gas detection devices can be arranged equidistantly in sequence along the radial direction of the underground pipeline 5. The cavity area C is distributed in a network shape underground and communicates with the space constructed by the legs 4 of the underground gas detection devices and the breathing holes 1A to monitor the leaked gas of the underground pipeline.

[0104] It should be clear that: the gas described in this article can be one or several of natural gas, liquefied petroleum gas, and biogas.

[0105] The underground gas detection system described in the present invention can be applied to the leakage detection of natural gas underground pipelines, liquefied petroleum gas underground pipelines, and biogas underground pipelines.

[0106] The above is only the specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily change or replace, and all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An underground gas detection device, characterized in that, Comprising: A housing, on which a breathing hole for communicating with the outside world is provided; A detection unit, arranged inside the housing, for detecting the gas entering the housing from the breathing hole; An active component, arranged inside the housing, for closing the breathing hole when the water level rises and opening the breathing hole when the water level drops; The active component includes: A piston member, arranged inside the housing, for performing a piston motion inside the housing to close or open the breathing hole; A piston rod, one end of which is connected to the piston member; A sealing soft film, connected to the other end of the piston rod; The sealing soft film is sealingly arranged at the open end of the housing and is used to move following the change of the water level; The active component further includes: Two guiding partitions, arranged inside the housing, sealingly connected to the piston rod, for guiding the motion of the piston member; The active component further includes: A counterweight, arranged on the piston rod, for resetting the piston member after the water level drops; The housing includes: A housing body, on which the breathing hole is provided; An outer side wall, arranged outside the housing body, for forming an isolation space between the housing body and the outer side wall; An air inlet hole for air intake is provided on the outer side wall.

2. The underground gas detection device according to claim 1, characterized in that, The piston member includes: A piston body, matching with the inner side wall of the housing to form a piston structure; An extension body, arranged on the piston body, matching with the inner side wall of the housing, for closing the breathing hole.

3. The underground gas detection device according to claim 1, characterized in that: A filter screen for filtering sediment is arranged outside the air inlet hole.

4. The underground gas detection device according to claim 1, characterized in that: A drain hole for water discharge is provided at one end of the outer side wall away from the air inlet hole.

5. The underground gas detection device according to claim 1, characterized in that, The housing is in a cylindrical shape, frustum shape or cuboid shape.

6. The underground gas detection device according to claim 1, characterized in that, It further includes: A plurality of legs, arranged at one end of the housing away from the detection unit, for providing space for the active component.

7. The underground gas detection device according to claim 6, characterized in that: Filter screens for filtering sediment are arranged outside the plurality of legs.

8. An underground gas detection system, characterized in that, Comprising: At least one underground gas detection device as described in any one of claims 1 to 7; A control center, electrically connected to all the underground gas detection devices, for collecting the monitoring data of the underground gas detection devices and judging the leakage situation of the underground pipeline.

9. An underground gas detection system according to claim 8, characterized in that: All the underground gas detection devices are arranged at equal intervals in sequence along the radial direction of the underground pipeline.

10. An underground gas detection system according to claim 8, characterized in that: A hollow area for ventilating the underground gas detection devices is provided between the underground pipeline and the ground.

11. Application of an underground gas detection system as claimed in claim 8 in leakage monitoring of natural gas underground pipelines, liquefied petroleum gas underground pipelines, and biogas underground pipelines.

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