Pipeline liquid sampling device

Abstract

The utility model discloses a pipeline liquid sampling device which is installed on a main pipeline, the pipeline liquid sampling device comprises a sampling pipe, a valve, an air cylinder, a connecting pipe, a piston rod and a flow limiting assembly, and the sampling pipe is arranged on the periphery of the main pipeline and communicates with the main pipeline; the valve is arranged on the sampling tube; one end of the inflator is a closed end, and the other end of the inflator is an open end; the connecting area of the connecting pipe and the sampling pipe is located on the side, away from the main pipeline, of the valve; the piston rod penetrates through the opening end of the inflator and has the degree of freedom of moving in the axial direction of the inflator; the flow limiting assembly is arranged at the connecting area and seals the connecting pipe, and the flow limiting assembly responds to the gas pressure in the connecting pipe to open the connecting pipe. When the pipeline liquid sampling device is used, even if the viscosity of liquid in the sampling pipe is large, the liquid can be pushed out of the sampling pipe, residues are few, the sampling accuracy is improved, and use is convenient and fast.

Description

Technical Field

[0001] The present application relates to the technical field of liquid sampling, and in particular to a pipeline liquid sampling device. Background Art

[0002] Currently, when sampling liquid flowing in a pipeline, a sampling tube is usually connected to the main pipeline, and a sampling valve is set on the sampling tube. When sampling is required, the sampling valve is opened and the liquid flows out of the sampling tube. After sampling is completed, the sampling valve is closed.

[0003] However, there is often liquid residue in the sampling tube. The higher the viscosity of the liquid, the greater the residual amount, which leads to inaccurate subsequent sampling and inconvenience in use. Utility Model Content

[0004] The main purpose of this application is to provide a pipeline liquid sampling device, which aims to solve the problem that there is often liquid residue in the sampling tube. The higher the viscosity of the liquid, the greater the residual amount, which leads to inaccurate subsequent sampling and inconvenience in use.

[0005] To achieve the above-mentioned purpose, the present application provides a pipeline liquid sampling device, which is installed on a main pipeline, and the pipeline liquid sampling device includes a sampling tube, a valve, a gas cylinder, a connecting tube, a piston rod and a flow limiting assembly, wherein the sampling tube is arranged on the outer periphery of the main pipeline and is connected to the main pipeline; the valve is arranged on the sampling tube; the gas cylinder is arranged on the outer periphery of the main pipeline, one end of the gas cylinder is a closed end and the other end is an open end; the connecting tube connects the sampling tube and the gas cylinder, and the connection area between the connecting tube and the sampling tube is located on the side of the valve away from the main pipeline; the piston rod is passed through the open end of the gas cylinder and has the freedom to move axially along the gas cylinder; the flow limiting assembly is arranged at the connection area and closes the connecting tube, and the flow limiting assembly responds to the gas pressure in the connecting tube to open the connecting tube.

[0006] Optionally, the sampling tube is provided with a through hole extending along the sampling tube's radial direction, and one end of the connecting tube is inserted into the through hole; the flow limiting assembly includes a first limiting plate and a first spring, the first limiting plate is provided on the inner circumference of the sampling tube and is located at the through hole, the first limiting plate is rotatably connected to the sampling tube and has the freedom to rotate about a first direction, and the first direction is parallel to the axial direction of the sampling tube; the first spring is connected between the first limiting plate and the connecting tube; wherein, the first limiting plate responds to the driving force of the first spring to close the through hole, and the first limiting plate responds to the gas pressure in the connecting tube to open the through hole.

[0007] Optionally, a groove is provided on the inner circumference of the sampling tube, the depth direction of the groove is the same as the radial direction of the sampling tube, the groove has a bottom wall, and the through hole passes through the bottom wall; when the first limiting plate closes the through hole, the first limiting plate is located in the groove and fits with the bottom wall.

[0008] Optionally, the first limiting piece is arc-shaped and has an inner wall surface and an outer wall surface. The axial direction of the first limiting piece is the same as the axial direction of the sampling tube and the diameter of the inner wall surface is the same as the inner diameter of the sampling tube.

[0009] Optionally, the flow limiting assembly further includes a rotating shaft, which is rotatably connected in the groove and has an axial direction that is the same as that of the sampling tube. The rotating shaft has the freedom to rotate around its own axis, and the first limiting plate is sleeved on the outer periphery of the rotating shaft.

[0010] Optionally, a projection of the rotating shaft on the bottom wall along the radial direction of the sampling tube is located outside the through hole.

[0011] Optionally, the outer periphery of the inner wall surface of the first limiting piece is in contact with the notch of the groove; the first limiting piece further has a side wall surface, and a gap is formed between the side wall surface and the groove.

[0012] Optionally, the current limiting assembly further includes a sealing ring, which is fixed to the inner periphery of the groove and located at the gap; wherein, when the first limiting piece closes the through hole, the first limiting piece squeezes the sealing ring.

[0013] Optionally, the gas cylinder is provided with an air inlet extending along its own radial direction; the pipeline liquid sampling device also includes a second limiting plate, a support block and a second spring, the second limiting plate is arranged on the inner circumference of the gas cylinder and located at the air inlet, the second limiting plate is rotatably connected to the gas cylinder and has the freedom to rotate about a second direction, and the second direction is parallel to the axial direction of the gas cylinder; the support block is located in the gas cylinder and is arranged at the closed end of the gas cylinder; the second spring is connected between the second limiting plate and the support block; wherein, the second limiting plate responds to the driving force of the second spring to close the air inlet, and the second limiting plate responds to the gas pressure in the gas cylinder to open the air inlet.

[0014] Optionally, the connecting tube and the air inlet hole are located at the closed end of the gas cylinder; the pipeline liquid sampling device also includes a limiting ring, the axial direction of the limiting ring is the same as the axial direction of the gas cylinder and divides the interior of the gas cylinder into a first space and a second space; wherein, the connecting tube and the air inlet hole are both located in the first space, and the piston rod is located in the second space.

[0015] A pipeline liquid sampling device proposed in an embodiment of the present application opens a valve when sampling is required to allow part of the liquid in the main pipeline to flow into the sampling tube. Then, the valve is closed and the piston rod is pushed to allow the gas in the gas cylinder to gather at the connecting tube. The gas pressure at the connecting tube gradually increases and enters the sampling tube through the flow limiting component. The gas pushes the liquid in the sampling tube to be discharged from the end of the sampling tube away from the main pipeline, and the discharged liquid is collected. In this way, even if the viscosity of the liquid in the sampling tube is relatively high, it will be pushed out of the sampling tube, leaving less residue, thereby improving the accuracy of sampling and facilitating use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the overall structure of a pipeline liquid sampling device provided in an embodiment of the present application;

[0017] Figure 2 for Figure 1 A schematic cross-sectional view of the gas cylinder in the embodiment;

[0018] Figure 3 for Figure 1 A schematic cross-sectional view of the sampling tube in the embodiment;

[0019] Figure 4 for Figure 3 A schematic diagram of the structural disassembly of the embodiment;

[0020] Figure 5 for Figure 4 A magnified view of the structure at center A.

[0021] In the figure: 1. main pipeline; 2. sampling tube; 21. through hole; 22. groove; 3. valve; 4. air cylinder; 41. air inlet; 5. connecting pipe; 61. first limit plate; 62. first spring; 63. rotating shaft; 7. piston rod; 71. second limit plate; 72. support block; 73. second spring; 74. limit ring.

[0022] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0025] In this utility model, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0026] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0027] refer to Figures 1 to 5 , it should be understood that Figure 4 The connections between the components should be like Figure 3 As compact as in the example, this is just an example. Figure 4Some of the components in the middle are displayed separately for easy understanding. An embodiment of the present application provides a pipeline liquid sampling device, which is installed on the main pipeline 1. The pipeline liquid sampling device may include a sampling tube 2, a valve 3, an air cylinder 4, a connecting tube 5, a piston rod 7 and a flow limiting assembly, wherein the sampling tube 2 is arranged on the outer periphery of the main pipeline 1 and is connected to the main pipeline 1; the valve 3 is arranged on the sampling tube 2; the air cylinder 4 is arranged on the outer periphery of the main pipeline 1, one end of the air cylinder 4 is a closed end and the other end is an open end; the connecting tube 5 connects the sampling tube 2 and the air cylinder 4, and the connection area between the connecting tube 5 and the sampling tube 2 is located on the side of the valve 3 away from the main pipeline 1; the piston rod 7 is passed through the open end of the air cylinder 4 and has the freedom of movement along the axial direction of the air cylinder 4; the flow limiting assembly is arranged at the connection area and closes the connecting tube 5, and the flow limiting assembly responds to the gas pressure in the connecting tube 5 to open the connecting tube 5.

[0028] The embodiment of the present application proposes a pipeline liquid sampling device. When sampling is required, the valve 3 is opened to allow part of the liquid in the main pipeline 1 to flow into the sampling tube 2. Then the valve 3 is closed and the piston rod 7 is pushed to make the gas in the gas cylinder 4 gather at the connecting tube 5. The gas pressure at the connecting tube 5 gradually increases and enters the sampling tube 2 through the flow limiting component. The gas pushes the liquid in the sampling tube 2 to be discharged from the end of the sampling tube 2 away from the main pipeline 1, and the discharged liquid can be collected. In this way, even if the viscosity of the liquid in the sampling tube 2 is relatively high, it will be pushed out of the sampling tube 2, leaving less residue, thereby improving the accuracy of sampling and making it convenient to use.

[0029] Specifically, the valve 3 can be a solenoid valve, which makes it easier to control the opening and closing of the valve 3 ; it should be understood that the closer the connection area between the connecting tube 5 and the sampling tube 2 is to the valve 3 , the better the effect of the gas pushing the liquid in the sampling tube 2 out.

[0030] It should be noted that when the flow limiting component is not driven by the gas in the connecting tube 5 , it always closes the connection area between the connecting tube 5 and the sampling tube 2 so that the liquid in the sampling tube 2 does not enter the connecting tube 5 .

[0031] refer to Figure 3 and Figure 4 In an exemplary embodiment, the sampling tube 2 is provided with a through hole 21 extending along its own radial direction, and one end of the connecting tube 5 is inserted into the through hole 21; the current limiting assembly may include a first limiting piece 61 and a first spring 62, the first limiting piece 61 is provided on the inner circumference of the sampling tube 2 and is located at the through hole 21, the first limiting piece 61 is rotatably connected to the sampling tube 2 and has the freedom to rotate about a first direction, and the first direction is parallel to the axial direction of the sampling tube 2; the first spring 62 is connected between the first limiting piece 61 and the connecting tube 5; wherein, the first limiting piece 61 responds to the driving force of the first spring 62 to close the through hole 21, and the first limiting piece 61 responds to the gas pressure in the connecting tube 5 to open the through hole 21.

[0032] Specifically, such as Figure 4 As shown, the first direction is the X direction, and the first spring 62 is always in a stretched state, so that the first limiting piece 61 is always subjected to the tension of the first spring 62, so that the first limiting piece 61 closes the through hole 21, thereby blocking the connection between the connecting tube 5 and the sampling tube 2; when the gas pressure in the connecting tube 5 is relatively large, the gas pushes the first limiting piece 61 to rotate around the first direction X, so that the first limiting piece 61 is separated from the through hole 21, and the connecting tube 5 is connected to the sampling tube 2, so that the gas can enter the sampling tube 2 to push the liquid in the sampling tube 2 to be discharged.

[0033] refer to Figure 3 and Figure 4 In an exemplary embodiment, a groove 22 is provided on the inner circumference of the sampling tube 2. The depth direction of the groove 22 is the same as the radial direction of the sampling tube 2. The groove 22 has a bottom wall, and the through hole 21 passes through the bottom wall. When the first limiting piece 61 closes the through hole 21, the first limiting piece 61 is located in the groove 22 and fits against the bottom wall.

[0034] Specifically, when the first limiting piece 61 closes the through hole 21, the first limiting piece 61 is located in the groove 22 and fits against the bottom wall. At this time, if the valve 3 is opened, the liquid entering the sampling tube 2 will not be blocked by the first limiting piece 61, and the liquid flows more smoothly.

[0035] Furthermore, the first limiting piece 61 is arc-shaped and has an inner wall surface and an outer wall surface. The axial direction of the first limiting piece 61 is the same as the axial direction of the sampling tube 2 and the diameter of the inner wall surface is the same as the inner diameter of the sampling tube 2. In this way, the inner wall surface of the first limiting piece 61 can be understood as a part of the inner circumference of the sampling tube 2. When the liquid flows, it is less affected by the first limiting piece 61, the liquid flows more smoothly, the impact force of the liquid on the first limiting piece 61 is reduced, and the service life is longer.

[0036] refer to Figure 4 In an exemplary embodiment, the flow limiting assembly may further include a rotating shaft 63, which is rotatably connected to the groove 22 and has an axial direction that is the same as that of the sampling tube 2. The rotating shaft 63 has the freedom to rotate around its own axial direction, and the first limiting plate 61 is sleeved on the outer periphery of the rotating shaft 63.

[0037] Specifically, the first limiting piece 61 is fixed to the rotating shaft 63 . When the gas pushes the first limiting piece 61 to rotate, the first limiting piece 61 and the rotating shaft 63 rotate synchronously around the axial direction of the rotating shaft 63 .

[0038] Furthermore, the projection of the rotating shaft 63 on the bottom wall along the radial direction of the sampling tube 2 is located outside the through hole 21. In this way, when the axial direction of the rotating shaft 63 does not intersect with the extension direction of the first spring 62, it is ensured that the first limiting piece 61 can fit into the bottom wall and close the through hole 21 under the tension of the first spring 62; at the same time, the first limiting piece 61 can rotate around the axial direction of the rotating shaft 63 under the gas pressure in the connecting tube 5.

[0039] Furthermore, the rotating shaft 63 should be close to the edge of the groove 22, so that the first limiting piece 61 will not be affected by the groove 22 when rotating, ensuring that the first limiting piece 61 can rotate normally.

[0040] In an exemplary embodiment, the outer periphery of the inner wall surface of the first limiting piece 61 is in contact with the notch of the groove 22 ; the first limiting piece 61 further has a side wall surface, and a gap is formed between the side wall surface and the groove 22 .

[0041] Specifically, the outer periphery of the inner wall surface of the first limiting piece 61 fits with the notch of the groove 22, so that the liquid in the sampling tube 2 is difficult to enter the connecting tube 5 through the gap between the first limiting piece 61 and the groove 22; at the same time, there is a gap between the side wall surface of the first limiting piece 61 and the groove 22, so that when the first limiting piece 61 rotates axially around the rotating shaft 63, the side wall surface of the first limiting piece 61 will not be blocked by the groove 22, ensuring that the first limiting piece 61 can rotate normally.

[0042] In an exemplary embodiment, the current limiting assembly may further include a sealing ring fixed to the inner periphery of the groove 22 and located at the gap; wherein, when the first limiting piece 61 closes the through hole 21 , the first limiting piece 61 squeezes the sealing ring.

[0043] Specifically, when the first limiting piece 61 closes the through hole 21 , the first limiting piece 61 squeezes the sealing ring, further improving the sealing effect between the first limiting piece 61 and the groove 22 , and preventing the liquid in the sampling tube 2 from entering the connecting tube 5 .

[0044] refer to Figure 1 and Figure 2 In an exemplary embodiment, the gas cylinder 4 is provided with an air inlet hole 41 extending in its radial direction; the pipeline liquid sampling device may further include a second limiting piece 71, a support block 72 and a second spring 73, the second limiting piece 71 is provided on the inner periphery of the gas cylinder 4 and is located at the air inlet hole 41, the second limiting piece 71 is rotatably connected to the gas cylinder 4 and has the freedom to rotate about a second direction, and the second direction is parallel to the axial direction of the gas cylinder 4; the support block 72 is located in the gas cylinder 4 and is provided at the closed end of the gas cylinder 4; the second spring 73 is connected to the second limiting piece 71 and the support block 72. between the support blocks 72; wherein, the second limiting plate 71 responds to the driving force of the second spring 73 to close the air inlet hole 41, and the second limiting plate 71 responds to the gas pressure in the gas cylinder 4 to open the air inlet hole 41; the connecting pipe 5 and the air inlet hole 41 are located at the closed end of the gas cylinder 4; the pipeline liquid sampling device may further include a limiting ring 74, the axial direction of the limiting ring 74 is the same as the axial direction of the gas cylinder 4 and divides the interior of the gas cylinder 4 into a first space and a second space; wherein, the connecting pipe 5 and the air inlet hole 41 are both located in the first space, and the piston rod 7 is located in the second space.

[0045] Specifically, such as Figure 2 As shown, the second direction is the Y direction, and the second spring 73 is always in a compressed state. The second spring 73 will push the second limiting piece 71 to always fit the inner circumference of the air cylinder 4, thereby closing the air inlet 41. When the piston rod 7 is pushed into the air cylinder 4, the air inlet 41 is closed, the gas pressure in the first space increases and pushes the first limiting piece 61 to rotate, and the gas enters the sampling tube 2. When the liquid is discharged from the sampling tube 2, the gas pressure in the connecting tube 5 is relatively small, and the first spring 62 pulls the first limiting piece 61 to close the through hole 21; when the piston rod 7 is pulled, a negative pressure is formed in the first space, and the second limiting piece 71 is subjected to the external gas pressure of the air cylinder 4, so that the second limiting piece 71 rotates about the second direction Y to open the air inlet 41. In this way, the piston rod 7 can be pulled smoothly, which is convenient for subsequent recycling. When the piston rod 7 is pulled, the second spring 73 pushes the second limiting piece 71 to rotate to close the air inlet 41.

[0046] It should be understood that the second limiting plate 71 can also be rotatably connected to the air cylinder 4 through a rotating shaft, the axial direction of the rotating shaft is the same as the axial direction of the air cylinder 4, and the projection of the rotating shaft on the inner circumference of the air cylinder 4 along the radial direction of the air cylinder 4 is located outside the air inlet hole 41, and the axial direction of the rotating shaft does not intersect with the extension direction of the second spring 73.

[0047] Among them, the limit ring 74 ensures that the gas can flow back and forth in the first space and the second space. At the same time, the limit ring 74 can limit the movement distance of the piston rod 7 to prevent the piston rod 7 from squeezing the support block 72 and causing damage to the piston on the piston rod 7. When the limit ring 74 and the piston on the piston rod 7 are squeezed, the piston is evenly stressed and is not easily damaged.

[0048] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A pipeline liquid sampling device, characterized in that: Installed on the main pipeline (1), the pipeline liquid sampling device comprises: A sampling tube (2) is arranged on the outer periphery of the main pipeline (1) and is in communication with the main pipeline (1); A valve (3) is provided on the sampling tube (2); An air cylinder (4) is arranged on the outer periphery of the main pipeline (1), and one end of the air cylinder (4) is a closed end and the other end is an open end; a connecting pipe (5) connecting the sampling pipe (2) and the gas cylinder (4), wherein the connection area between the connecting pipe (5) and the sampling pipe (2) is located on a side of the valve (3) facing away from the main pipe (1); A piston rod (7) is provided at the open end of the gas cylinder (4) and has the freedom to move along the axial direction of the gas cylinder (4); A flow limiting component is provided at the connection area and closes the connection pipe (5), and the flow limiting component responds to the gas pressure in the connection pipe (5) to open the connection pipe (5).

2. The pipeline liquid sampling device according to claim 1, characterized in that: The sampling tube (2) is provided with a through hole (21) extending in its radial direction, and one end of the connecting tube (5) is inserted into the through hole (21); the flow limiting assembly comprises: a first limiting piece (61) arranged on the inner periphery of the sampling tube (2) and located at the through hole (21); the first limiting piece (61) is rotatably connected to the sampling tube (2) and has a degree of freedom of rotation about a first direction, the first direction being parallel to the axial direction of the sampling tube (2); a first spring (62) connected between the first limiting piece (61) and the connecting pipe (5); The first limiting piece (61) responds to the driving force of the first spring (62) to close the through hole (21), and the first limiting piece (61) responds to the gas pressure in the connecting pipe (5) to open the through hole (21).

3. The pipeline liquid sampling device according to claim 2, characterized in that: The inner circumference of the sampling tube (2) is provided with a groove (22), the depth direction of the groove (22) is the same as the radial direction of the sampling tube (2), the groove (22) has a bottom wall, and the through hole (21) passes through the bottom wall; When the first limiting piece (61) closes the through hole (21), the first limiting piece (61) is located in the groove (22) and fits against the bottom wall.

4. The pipeline liquid sampling device according to claim 3, characterized in that: The first limiting piece (61) is arc-shaped and has an inner wall surface and an outer wall surface. The axial direction of the first limiting piece (61) is the same as the axial direction of the sampling tube (2), and the diameter of the inner wall surface is the same as the inner diameter of the sampling tube (2).

5. The pipeline liquid sampling device according to claim 3, characterized in that: The current limiting component also includes: The rotating shaft (63) is rotatably connected in the groove (22) and has an axial direction that is the same as the axial direction of the sampling tube (2). The rotating shaft (63) has the freedom to rotate around its own axial direction. The first limiting piece (61) is sleeved on the outer periphery of the rotating shaft (63).

6. The pipeline liquid sampling device according to claim 5, characterized in that: The projection of the rotating shaft (63) on the bottom wall along the radial direction of the sampling tube (2) is located outside the through hole (21).

7. The pipeline liquid sampling device according to claim 4, characterized in that: The outer periphery of the inner wall surface of the first limiting piece (61) is in contact with the notch of the groove (22); The first limiting piece (61) further has a side wall surface, and a gap is formed between the side wall surface and the groove (22).

8. The pipeline liquid sampling device according to claim 7, characterized in that: The current limiting component also includes: a sealing ring fixed to the inner periphery of the groove (22) and located at the gap; Wherein, when the first limiting piece (61) closes the through hole (21), the first limiting piece (61) squeezes the sealing ring.

9. The pipeline liquid sampling device according to claim 1, characterized in that: The gas cylinder (4) is provided with an air inlet hole (41) extending in its radial direction; the pipeline liquid sampling device further comprises: a second limiting piece (71) disposed on the inner periphery of the air cylinder (4) and located at the air inlet hole (41); the second limiting piece (71) is rotatably connected to the air cylinder (4) and has a degree of freedom of rotation about a second direction, the second direction being parallel to the axial direction of the air cylinder (4); a support block (72) located in the gas cylinder (4) and disposed at the closed end of the gas cylinder (4); a second spring (73) connected between the second limiting piece (71) and the supporting block (72); The second limiting plate (71) responds to the driving force of the second spring (73) to close the air inlet (41), and the second limiting plate (71) responds to the gas pressure in the gas cylinder (4) to open the air inlet (41).

10. The pipeline liquid sampling device according to claim 9, characterized in that: The connecting pipe (5) and the air inlet (41) are located at the closed end of the air cylinder (4); the pipeline liquid sampling device also includes: A limiting ring (74) has an axial direction that is the same as that of the gas cylinder (4) and divides the interior of the gas cylinder (4) into a first space and a second space; Wherein, the connecting pipe (5) and the air inlet (41) are both located in the first space, and the piston rod (7) is located in the second space.

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