TDLAS-based optical fiber buried gas pipeline leakage monitoring device

Abstract

The utility model discloses a fiber buried gas pipeline leak monitoring device based on TDLAS relates to gas sensing monitoring technical field, specifically includes ground part and underground part, the underground part includes the gas collection plate that is encircled in the periphery of buried gas pipeline in cage cover shape, the bottom of gas collection plate inner chamber is connected with buried gas pipeline through connecting rod, the top of gas collection plate inner chamber is connected with the partition board. The application constructs the physical isolation barrier of fiber probe and soil environment with the air permeable membrane and the air pipe, effectively avoids the dust, moisture and corrosive substance in the soil to adhere or invade the fiber probe, significantly reduces the risk of fiber probe surface pollution, blockage or optical performance degradation, thereby prolongs the continuous reliable working period of fiber probe, reduces the frequent maintenance demand caused by probe pollution, improves the overall operation stability and maintenance economy of system.

Description

Technical Field

[0001] This utility model relates to the field of gas sensing and monitoring technology, specifically to a fiber optic buried gas pipeline leakage monitoring device based on TDLAS. Background Technology

[0002] Natural gas, as a clean and efficient energy source, occupies a core position in urban gas supply. Underground gas pipelines, as the main carriers of urban gas transportation, bear the crucial responsibility of safely delivering gas to households. However, due to factors such as long-term service in complex geological environments (e.g., soil corrosion, groundwater level changes), damage from third-party construction (e.g., unplanned excavation, heavy object crushing), natural aging of materials (e.g., electrochemical corrosion of metal pipelines, embrittlement of plastic pipelines), and joint sealing failure, gas leaks are highly likely to occur. Therefore, real-time and accurate monitoring of underground gas pipeline leaks, timely early warning, and leak location are of great significance for ensuring urban energy security, public safety, and environmental protection.

[0003] In existing technologies, leak monitoring of underground gas pipelines mainly relies on the following methods:

[0004] By monitoring abnormal fluctuations in pressure or flow within the pipeline, it is possible to determine whether a leak exists, but this method cannot pinpoint the specific leak location.

[0005] Detection is based on ultrasonic or pipeline vibration signals generated by leakage, but the soil attenuation effect of buried pipelines will severely weaken the sound wave energy, resulting in short monitoring distance and susceptibility to interference from surrounding environmental noise.

[0006] Electrochemical or semiconductor gas sensors are deployed along the pipeline to locate leaks by detecting abnormal increases in methane concentration in the soil. However, these sensors need to be installed in the open or buried in shallow soil, resulting in high maintenance costs.

[0007] Based on this, this application proposes a fiber optic buried gas pipeline leakage monitoring device based on TDLAS. Utility Model Content

[0008] This invention provides a fiber optic buried gas pipeline leakage monitoring device based on TDLAS, which solves the problems mentioned in the background art, such as inability to locate specific leakage points, high maintenance costs, and susceptibility to interference.

[0009] This utility model provides the following technical solution: a fiber optic buried gas pipeline leakage monitoring device based on TDLAS, comprising an above-ground part and an underground part. The underground part includes a gas-gathering plate arranged in a ring around the buried gas pipeline. The bottom end of the inner cavity of the gas-gathering plate is connected to the buried gas pipeline via a connecting rod. A partition plate is connected to the top end of the inner cavity of the gas-gathering plate, dividing the inner cavity of the gas-gathering plate into a sealed cavity and an open cavity. A venting pipe is provided in the middle of the partition plate, and vent holes are provided on both sides of the venting pipe. The vent holes are located in the open cavity. The top of the cavity is sealed with a breathable membrane through which the vent is supplied with gas. The top of the sealed cavity is equipped with a monitoring component and an isolation component based on TDLAS. The isolation component includes a hollow rotating ring movably fitted around the outer ring of the vent pipe and a driving component for rotating the hollow rotating ring. Hollow isolation plates are provided on both sides of the hollow rotating ring, and the inner cavity of the hollow rotating ring is in communication with the inner cavity of the hollow isolation plate to form a complete exhaust channel. The inner sidewall of the hollow isolation plate is provided with a connection hole adapted to the vent. The hollow rotating ring is movably connected to the partition plate.

[0010] The above-ground component includes a laser control unit, an air compressor, and an exhaust fan. The air outlet of the air compressor is connected to the power input of the drive assembly and the fluid inlet of the ventilation duct, and the air inlet of the exhaust fan is connected to the exhaust channel.

[0011] Preferably, the monitoring component includes a laser transmission fiber connected to the laser control unit, a plurality of fiber optic probes connected to the laser transmission fiber, and a photosensitive terminal uniformly arranged above the buried gas pipeline, wherein the fiber optic probes are inserted into the inner cavity of the gas pipeline.

[0012] Preferably, one end of the ventilation pipe is sealed, and the other end of the ventilation pipe is provided with a first electric exhaust valve and an electric intake valve. The air outlet of the air compressor is connected to the ventilation pipe through the electric intake valve.

[0013] Preferably, one end of the exhaust channel is provided with a connecting pipe, which is connected to the air inlet of the exhaust fan.

[0014] Preferably, the partition plate includes a vertical plate connected to the end of the gas-gathering plate, and horizontal plates are provided on both sides of the bottom of the vertical plate. The horizontal plates are movably connected to the hollow rotating ring and the hollow isolation plate.

[0015] Preferably, the drive assembly includes an intake pipe connected to the air compressor outlet and a toothed plate movably connected to the sealing cavity. A guide pipe is movably connected to the middle of the toothed plate. The end of the guide pipe away from the toothed plate is connected to the intake pipe, and the inner cavity of the guide pipe is in communication with the inner cavity of the intake pipe. A spring is provided in the inner cavity of the guide pipe. The toothed plate is connected to the guide pipe through the spring. A semi-toothed ring is provided on the outer side wall of the top of the hollow rotating ring. The toothed plate and the semi-toothed ring are in a meshing state. An electric ball valve is provided at the intake end of the intake pipe, and a second electric exhaust valve is provided on one side of the intake end of the intake pipe.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. This TDLAS-based fiber optic buried gas pipeline leak monitoring device, through the installation of a permeable membrane and ventilation pipes, allows leaked gas to move to the monitoring area of ​​the fiber optic probe via the permeable membrane and ventilation pipes, ensuring a smooth gas transmission path required for gas detection. Furthermore, the permeable membrane and ventilation pipes form a physical isolation barrier between the fiber optic probe and the soil environment, effectively preventing dust, moisture, and corrosive substances in the soil from adhering to or penetrating the fiber optic probe. This significantly reduces the risk of surface contamination, clogging, or optical performance degradation of the fiber optic probe, thereby extending the continuous and reliable working cycle of the fiber optic probe, reducing the need for frequent maintenance due to probe contamination, and improving the overall operational stability and maintenance economy of the system.

[0018] 2. This TDLAS-based fiber optic buried gas pipeline leak monitoring device has a self-cleaning function. It uses compressed air to blow away the soil blocking the permeable membrane from the inside out, ensuring the smooth flow of gas detection, extending the service life of the permeable membrane and maintaining the detection sensitivity of this application. In addition, it uses an isolation component to conduct the dust-laden air generated during the permeable membrane blowing process, avoiding the dust-laden air from affecting the soil density around the buried gas pipeline, maintaining the original loose structure and natural permeability of the soil around the buried gas pipeline, and facilitating the diffusion of leaked gas in the soil. Attached Figure Description

[0019] Figure 1 This is a front view of the fiber optic buried gas pipeline leakage monitoring device based on TDLAS proposed in this utility model.

[0020] Figure 2 This is a three-dimensional schematic diagram of the underground part of the structure of this utility model;

[0021] Figure 3 The structure of this utility model Figure 2 Rear view illustration;

[0022] Figure 4 The structure of this utility model Figure 2Diagram showing the view from below;

[0023] Figure 5 This is a schematic diagram showing the connection between the structural monitoring component and the isolation component of this utility model and the ventilation pipe;

[0024] Figure 6 This is a schematic diagram showing the connection between the hollow rotating ring and the hollow isolation plate in the structure of this utility model;

[0025] Figure 7 This is an exploded schematic diagram of the toothed plate and air intake pipe of this utility model.

[0026] In the diagram: 1. Laser control unit; 2. Air compressor; 3. Electric ball valve; 4. Second electric exhaust valve; 5. Exhaust fan; 6. Air-gathering plate; 7. Laser transmission fiber optic cable; 8. Air inlet pipe; 9. Vertical plate; 10. Ventilation pipe; 11. Semi-toothed ring; 12. Groove; 13. Ventilation hole; 14. Connecting rod; 15. Hollow isolation plate; 16. Horizontal plate; 17. Hollow rotating ring; 18. Connecting hole; 19. Guide tube; 20. Spring; 21. Toothed plate; 22. Photosensitive terminal; 23. Breathable membrane; 24. Fiber optic probe; 25. First electric exhaust valve; 26. Electric air inlet valve; 27. Connecting pipe. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] This utility model provides embodiments: Please refer to Figures 1-7 The fiber optic underground gas pipeline leakage monitoring device based on TDLAS includes an above-ground part and an underground part. The above-ground part includes core components such as a laser control unit 1, an air compressor 2, an exhaust fan 5, and a controller. All the devices work together to achieve accurate detection and location of leaks in underground gas pipelines.

[0029] The underground portion includes a gas-gathering plate 6 that is arranged in a ring around the buried gas pipeline, such as... Figures 1 to 4 As shown, the bottom of the gas-gathering plate 6 is located below the buried gas pipeline, which limits the gas leaking from the bottom of the buried gas pipeline and restricts the horizontal diffusion of the gas, so that the gas can be gathered into the inner cavity of the gas-gathering plate 6. The upper end of the gas-gathering plate 6 is shaped like a V-shape. Through the directional flow guiding effect of the inclined surfaces on both sides, it can effectively gather the gas leaking from the buried gas pipeline, so that the diffused gas gathers in the central area at the top of the gas-gathering plate 6, thereby improving the concentration and efficiency of subsequent gas detection.

[0030] The bottom end of the inner cavity of the gas-gathering plate 6 is connected to the underground gas pipeline via a connecting rod 14. The gas-gathering plate 6 in this application adopts a modular splicing structure design, and the connection method of the components constituting the gas-gathering plate 6 can be set according to the requirements, without any restrictions. Through the setting of the gas-gathering plate 6, the structure supports quick assembly and disassembly, which facilitates the subsequent maintenance of underground detection components by staff and provides convenient operating space for the maintenance of underground gas pipelines. At the same time, the material of the gas-gathering plate 6 can be determined according to the actual application scenario requirements.

[0031] A partition plate is connected to the top of the inner cavity of the gas-gathering plate 6. The partition plate includes a vertical plate 9 connected to the end of the gas-gathering plate 6, and horizontal plates 16 are provided on both sides of the bottom of the vertical plate 9. The partition plate divides the inner cavity of the gas-gathering plate 6 into a sealed cavity and an open cavity, with the buried gas pipeline located in the open cavity. A venting pipe 10 is provided in the middle of the partition plate, and venting holes 13 are provided on both sides of the venting pipe 10. The venting holes 13 are located at the top of the open cavity, and are sealed by a breathable membrane 23 through which gas passes. The breathable membrane 23 protects the venting holes 13, preventing soil from entering the venting pipe 10 through the venting holes 13. In use, gas leaking from the buried gas pipeline can pass through the soil and enter the venting pipe 10 through the breathable membrane 23. The material of the breathable membrane 23 can be set according to requirements and is not limited here.

[0032] A TDLAS-based monitoring component is installed at the top of the sealed cavity. This component includes a laser transmission fiber 7 connected to the laser control unit 1, several fiber optic probes 24 connected to the laser transmission fiber 7, and photosensitive terminals 22 uniformly arranged above the buried gas pipeline. The fiber optic probes 24 are inserted into the inner cavity of the ventilation pipe 10, forming a detection channel that directly contacts the gas being measured. In this application, the fiber optic probes 24 collect the laser absorption spectrum signal of the gas inside the ventilation pipe 10 in real time and transmit the light signal to different photosensitive terminals 22 via the laser transmission fiber 7. The controller in this application determines the location of the leak point by analyzing the propagation time difference of the leak signal between different photosensitive terminals and the gradient change in the concentration of the leaking gas, thus achieving accurate detection and location of leaks in the buried gas pipeline.

[0033] One end of the ventilation duct 10 is sealed, and the other end is equipped with a first electric exhaust valve 25 and an electric intake valve 26. The air outlet of the air compressor 2 is connected to the ventilation duct 10 via the electric intake valve 26. In use, when the first electric exhaust valve 25 is open, leaked gas entering the ventilation duct 10 can be discharged through the first electric exhaust valve 25. When cleaning of the permeable membrane 23 is required, the first electric exhaust valve 25 is closed, and the electric intake valve 26 is open. 2. Compressed air can be blown into the ventilation pipe 10 through the electric air intake valve 26. The compressed air in the ventilation pipe 10 is discharged through the breathable membrane 23, forming a directional airflow field from the inside to the outside. This airflow can effectively peel off and blow away the clogging soil particles attached to the pores of the breathable membrane 23, achieving efficient self-cleaning of the breathable membrane 23. By regularly performing this blowing and maintenance procedure, the probability of clogging of the breathable membrane 23 can be significantly reduced, maintaining the long-term stability of its gas permeability performance, thereby extending the service life of the breathable membrane 23 and maintaining the detection sensitivity of this application.

[0034] To prevent the purging airflow from affecting the soil density around the buried gas pipeline, this application includes an isolation component. The isolation component comprises a hollow rotating ring 17 movably fitted around the outer ring of the vent pipe 10 and a drive assembly for rotating the hollow rotating ring 17. Hollow isolation plates 15 are provided on both sides of the hollow rotating ring 17, and the inner cavity of the hollow rotating ring 17 is in communication with the inner cavity of the hollow isolation plate 15, forming a complete exhaust channel. The inner wall of the hollow isolation plate 15 is provided with a connecting hole 18 adapted to the vent hole 13. A connecting pipe 27 is provided at one end of the exhaust channel, connecting to the air inlet of the exhaust fan 5. When the connecting hole 18 is aligned with the vent hole 13, the airflow passing through the breathable membrane 23 can enter the isolation component composed of the hollow rotating ring 17 and the hollow isolation plate 15 through the connecting hole 18. When the exhaust fan 5 is working, it can extract the dust-laden air from the isolation component, reducing the probability of blockage. The isolation component is in a movable connection with the horizontal plate 16.

[0035] The drive assembly includes an intake pipe 8 connected to the air outlet of the air compressor 2 and a toothed plate 21 movably connected to the sealing cavity. An electric ball valve 3 is provided at the intake end of the intake pipe 8, and a second electric exhaust valve 4 is provided on one side of the intake end of the intake pipe 8. When the electric ball valve 3 is in the open state, the air compressor 2 can blow compressed air into the inner cavity of the intake pipe 8. When the second electric exhaust valve 4 is in the open state, the compressed air in the intake pipe 8 can be discharged through the second electric exhaust valve 4.

[0036] Both sides of the top of the air-gathering plate 6 are provided with grooves 12 that fit the toothed plate 21. The toothed plate 21 is movably connected to the inner cavity of the grooves 12. A guide tube 19 is movably connected to the middle of the toothed plate 21. The end of the guide tube 19 away from the toothed plate 21 is connected to the air intake pipe 8, and the inner cavity of the guide tube 19 is in communication with the inner cavity of the air intake pipe 8. A spring 20 is provided in the inner cavity of the guide tube 19. The toothed plate 21 is connected to the guide tube 19 through the spring 20. Through the arrangement of the guide tube 19 and the spring 20, the compressed air in the air intake pipe 8 passes through... The air can enter the inner cavity of the toothed plate 21 through the guide tube 19. Under the directional thrust generated by the compressed air, the toothed plate 21 can move horizontally. When the air compressor 2 stops working and the electric ball valve 3 is in the closed state, the position of the toothed plate 21 can remain unchanged. When the second electric exhaust valve 4 is in the open state, the compressed air in the intake pipe 8 is discharged through the second electric exhaust valve 4, releasing the restriction of the compressed air on the toothed plate 21. Under the action of the spring 20, the toothed plate 21 can be reset, realizing the reciprocating motion of the toothed plate 21.

[0037] A sealing sleeve structure is provided between the guide tube 19 and the toothed plate 21. The sealing sleeve structure is used to ensure the airtightness between the guide tube 19 and the toothed plate 21 and to prevent compressed air leakage. The material and structure of the sealing sleeve can be set according to the requirements and are not limited here.

[0038] A semi-toothed ring 11 is provided on the outer wall of the top of the hollow rotating ring 17, and the toothed plate 21 is engaged with the semi-toothed ring 11. When the toothed plate 21 moves, it can drive the hollow rotating ring 17 to rotate through the engaged semi-toothed ring 11. The hollow rotating ring 17 drives the hollow isolation plate 15 connected to it to rotate. The hollow isolation plate 15 can separate from the vent hole 13 or align the connecting hole 18 with the vent hole 13. When the connecting hole 18 is aligned with the vent hole 13, the hollow isolation plate 15 can squeeze away the soil adhering to the outer surface of the breathable membrane 23, thus achieving pre-cleaning of the breathable membrane 23.

[0039] All electrical components involved in this application are existing technologies. Those skilled in the art can select appropriate models of electrical components according to their needs. No restrictions or elaborations are made here. Those skilled in the art understand their connection methods. With the help of those skilled in the art, all electrical components in this application and their compatible power supplies are connected by wires. According to the actual situation, appropriate controllers are selected to meet control requirements. For specific connections and control sequences, please refer to the description below. The electrical connections between each electrical component are completed in the order of their operation. The detailed connection methods are well-known technologies in the art. The following mainly introduces the working principle and process, and will not describe the electrical control.

[0040] In summary, when this TDLAS-based fiber optic underground gas pipeline leak monitoring device is used, if a leak occurs in the underground gas pipeline, the leaking gas gradually gathers towards the central area at the top of the gas-gathering plate 6 under the interception and guidance effect of the gas-gathering plate 6, and finally enters the ventilation pipe 10 through the permeable membrane 23. The fiber optic probe 24 in the ventilation pipe 10 collects the laser absorption spectrum signal of the gas in the ventilation pipe 10 in real time, and transmits the light signal to different photosensitive terminals 22 through the laser transmission fiber 7. The controller of this application determines the location of the leak point by analyzing the propagation time difference of the leak signal between different photosensitive terminals and the gradient change of the leaking gas concentration, thereby achieving accurate detection and location of underground gas pipeline leaks.

[0041] When the breathable membrane 23 needs cleaning, the air compressor 2 blows compressed air into the intake pipe 8. The compressed air in the intake pipe 8 enters the inner cavity of the toothed plate 21 through the guide pipe 19. Under the directional thrust generated by the compressed air, the toothed plate 21 can move horizontally. When the toothed plate 21 moves, it drives the hollow rotating ring 17 to rotate through the semi-toothed ring 11. The hollow rotating ring 17 drives the hollow isolation plate 15 to rotate until the connecting hole 18 is aligned with the breathable membrane 23. At this time, the air compressor 2 stops working, and the electric ball valve 3 is closed, so that the position of the toothed plate 21 remains unchanged. The air compressor 2 then blows compressed air into the cavity of the toothed plate 21. Compressed air is injected into the ventilation duct 10 and discharged through the breathable membrane 23, forming a directional airflow field from the inside out. This airflow can effectively peel off and blow away the clogging soil particles attached to the pores of the breathable membrane 23, achieving efficient self-cleaning of the breathable membrane 23. The dust-laden airflow generated in this process enters the inner cavity of the isolation component through the connecting hole 18. The controller of this application controls the exhaust fan 5 to work and draw away the dust-laden airflow in the isolation component. Through continuous airflow suction, the deposition rate of dust particles in the inner cavity of the isolation component can be effectively reduced, reducing the probability of the isolation component being blocked.

[0042] All standard parts used in this utility model can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each structure adopt conventional technical means such as bolt connection in the existing technology. The machinery, parts and equipment adopt conventional models in the existing technology. The materials and specifications of each component can be selected according to the requirements and are not limited here. The contents not described in detail in this specification belong to the prior art known to those skilled in the art. Although the embodiments of this utility model have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of this utility model. The scope of this utility model is defined by the appended claims and their equivalents.

Claims

1. A fiber optic buried gas pipeline leakage monitoring device based on TDLAS, comprising above-ground and underground components, characterized in that: The underground portion includes a gas-gathering plate (6) encircling the underground gas pipeline in a ring shape. The bottom end of the inner cavity of the gas-gathering plate (6) is connected to the underground gas pipeline via a connecting rod (14). A partition plate is connected to the top end of the inner cavity of the gas-gathering plate (6), which divides the inner cavity of the gas-gathering plate (6) into a sealed cavity and an open cavity. A ventilation pipe (10) is provided in the middle of the partition plate. Ventilation holes (13) are provided on both sides of the ventilation pipe (10). The ventilation holes (13) are located at the top of the open cavity, and the ventilation holes (13) are sealed by a breathable membrane (23) through which gas passes. The top of the sealed cavity is provided with a monitoring component and an isolation component based on TDLAS; the isolation component includes a hollow rotating ring (17) movably sleeved on the outer ring of the ventilation pipe (10) and a driving component for driving the hollow rotating ring (17) to rotate. Hollow isolation plates (15) are provided on both sides of the hollow rotating ring (17), and the inner cavity of the hollow rotating ring (17) is in communication with the inner cavity of the hollow isolation plate (15) to form a complete exhaust channel. The inner side wall of the hollow isolation plate (15) is provided with a connection hole (18) adapted to the ventilation hole (13). The hollow rotating ring (17) is movably connected to the partition plate. The above-ground part includes a laser control unit (1), an air compressor (2) and an exhaust fan (5). The air outlet of the air compressor (2) is connected to the power input end of the drive assembly and the fluid inlet end of the ventilation pipe (10). The air inlet of the exhaust fan (5) is connected to the exhaust channel.

2. The fiber optic buried gas pipeline leakage monitoring device based on TDLAS according to claim 1, characterized in that: The monitoring component includes a laser transmission fiber (7) connected to the laser control unit (1), a plurality of fiber optic probes (24) connected to the laser transmission fiber (7), and a photosensitive terminal (22) uniformly arranged above the buried gas pipeline. The fiber optic probes (24) are inserted into the inner cavity of the gas pipeline (10).

3. The fiber optic buried gas pipeline leakage monitoring device based on TDLAS according to claim 1, characterized in that: One end of the ventilation pipe (10) is sealed, and the other end of the ventilation pipe (10) is provided with a first electric exhaust valve (25) and an electric intake valve (26). The air outlet of the air compressor (2) is connected to the ventilation pipe (10) through the electric intake valve (26).

4. The fiber optic buried gas pipeline leakage monitoring device based on TDLAS according to claim 1, characterized in that: One end of the exhaust channel is provided with a connecting pipe (27), which is connected to the air inlet of the exhaust fan (5).

5. The fiber optic buried gas pipeline leakage monitoring device based on TDLAS according to claim 1, characterized in that: The partition plate includes a vertical plate (9) connected to the end of the gas-gathering plate (6). Horizontal plates (16) are provided on both sides of the bottom of the vertical plate (9). The horizontal plates (16) are movably connected to the hollow rotating ring (17) and the hollow isolation plate (15).

6. The fiber optic buried gas pipeline leakage monitoring device based on TDLAS according to claim 1, characterized in that: The drive assembly includes an air inlet pipe (8) connected to the air outlet of the air compressor (2) and a toothed plate (21) movably connected to the sealing cavity. A guide pipe (19) is movably connected to the middle of the toothed plate (21). The end of the guide pipe (19) away from the toothed plate (21) is connected to the air inlet pipe (8), and the inner cavity of the guide pipe (19) is in communication with the inner cavity of the air inlet pipe (8). A spring (20) is provided in the inner cavity of the guide pipe (19). The toothed plate (21) is connected to the guide pipe (19) through the spring (20). A half-toothed ring (11) is provided on the outer side wall of the top of the hollow rotating ring (17). The toothed plate (21) and the half-toothed ring (11) are in a meshing state. An electric ball valve (3) is provided at the air inlet end of the air inlet pipe (8), and a second electric exhaust valve (4) is provided on one side of the air inlet end of the air inlet pipe (8).

Images