Multi-factor water quality on-line monitoring sampling mechanism

Abstract

This invention discloses a multi-factor online water quality monitoring sampling mechanism, belonging to the field of water environment monitoring technology. The invention includes a mounting frame and an analyzer. The analyzer is fixedly mounted on the mounting frame, and a water pump is fixedly mounted on the front side of the analyzer. A water tank is located on the front side of the analyzer, and a sampling bucket is located within the water tank. The sampling bucket contains a self-cleaning unit and a stratified sampling unit. The advantages are: the self-cleaning unit relies on hydraulically driven rotating shafts to simultaneously clean the filter plate surface and unclog the filter holes, effectively reducing the risk of clogging and significantly extending the manual maintenance cycle; the stratified sampling unit uses negative pressure to drive a valve stem to raise and lower, switching the inlet water layer to obtain representative water samples at different depths. Combined with a float-adaptive water level structure, it adapts to complex hydrological scenarios, exhibits high overall reliability, and can meet the needs of long-term unattended online monitoring outdoors.

Description

Technical Field

[0001] This invention relates to the field of water environment monitoring technology, and in particular to a multi-factor online water quality monitoring and sampling mechanism. Background Technology

[0002] Multi-factor online water quality monitoring is a core technical means for water environment supervision and pollution source control. The sampling front-end device is the core water intake component of the monitoring system. Its anti-clogging performance and operational stability directly determine the reliability of monitoring data and equipment operation and maintenance costs. Most existing conventional online monitoring sampling heads adopt a fixed filter structure, relying on the filter to intercept silt, suspended solids and impurities in the water, and then transport the filtered water sample to the back-end detection instrument.

[0003] For water bodies containing a lot of impurities, these impurities are very easy to adhere to the surface of the filter screen and embed inside the filter pores, clogging the filter screen and affecting subsequent monitoring. Therefore, manual disassembly and cleaning are often required, resulting in high maintenance costs, and monitoring data is prone to problems during the clogging period.

[0004] Meanwhile, existing technologies for stratified sampling often employ electric winch lifting and a structure with multiple sampling heads connected in parallel. These underwater moving parts are numerous, and long-term immersion can easily lead to problems such as corrosion, jamming, and seal failure, resulting in insufficient equipment reliability. Therefore, there is an urgent need to provide a multi-factor online water quality monitoring and sampling mechanism to solve the above problems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-factor online water quality monitoring and sampling mechanism, which solves the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A multi-factor online water quality monitoring sampling mechanism includes a ground, a mounting frame, an analyzer, a water pump, and a fixing plate. The mounting frame is fixedly installed on the ground, the analyzer is fixedly installed on the mounting frame, and the water pump is fixedly installed on the front side of the analyzer. The outlet of the water pump and the inlet of the analyzer are fixedly connected by a water pipe. A water tank is provided on the front side of the water pump, and a fixing plate is provided in the water tank. Two guide rods are fixedly installed below the fixing plate. Multiple sensing blocks are evenly arranged on the guide rods. A float is slidably installed on the guide rods and moves along the direction of the guide rods. A sampling bucket is fixedly installed on the lower side of the float by threads. A filter plate is provided inside the sampling bucket, and multiple filter holes are evenly arranged on the filter plate.

[0007] The sampling bucket is equipped with a self-cleaning unit to clean the filter plate, preventing impurities in the sample from affecting the test results and preventing impurities from clogging the filter plate and affecting the normal operation of the device. The side of the sampling bucket is equipped with a layered sampling unit for sampling and testing water at different water layers.

[0008] The self-cleaning unit includes a bearing. The outer ring of the bearing is fixedly installed in the middle of the sampling bucket. The inner side of the sampling bucket has a cavity with a cylindrical upper end and a conical lower end. The bottom of the sampling bucket has a drain port. The inner ring of the bearing is fixedly installed with a rotating shaft. The rotating shaft passes through the filter plate and is connected to a bearing. The lower end of the rotating shaft has an impeller, which is located below the filter plate.

[0009] Furthermore, a floating plate is floatingly installed above the filter plate, and two sliders are provided on the side of the floating plate. A groove is provided on the inner side of the sampling bucket, and the sliders are slidably installed in the groove.

[0010] Furthermore, the floating plate is floatingly mounted on the rotating shaft, which is provided with a reciprocating spiral groove. A limiting rod is provided at the mounting point of the floating plate and the rotating shaft, and the limiting rod is located in the reciprocating spiral groove. The floating plate moves back and forth along the axial direction of the rotating shaft as the rotating shaft rotates.

[0011] Furthermore, the floating plate is provided with multiple through slots that penetrate the floating plate, and multiple ejector pins are provided on the lower side of the floating plate. The installation position and number of the ejector pins are consistent with the filter holes on the filter plate. Two scrapers are rotatably installed below the filter plate, and the scrapers are fixedly installed on the rotating shaft.

[0012] Furthermore, the stratified sampling unit includes a guide groove, which is disposed inside the sampling barrel, and an installation groove is provided on the side of the guide groove.

[0013] Furthermore, the valve stem is vertically installed in the mounting groove, and a return spring is provided on the top of the plug. Five plugs are evenly arranged on the left side of the valve stem. The plugs are divided into two groups: three plugs on the side closest to the return spring form one group, and the other two form another group. The spacing between each plug is consistent, and the spacing between the upper and lower groups is twice the spacing between the plugs.

[0014] Furthermore, a mounting block is fixedly installed on the top of the valve stem, and a return spring is fixedly installed between the mounting block and the top of the mounting groove. A pressure-sensing plate is provided on the right side of the valve stem, and the pressure-sensing plate is movably installed in the guide groove.

[0015] Furthermore, the plug has a cavity, and a stop block is movably installed in the cavity. The stop block is semi-circular and has a limiting edge at the bottom. A reset spring is provided between the bottom of the stop block and the bottom of the cavity. A through hole is provided on the valve stem between the upper and lower sets of plugs.

[0016] Furthermore, the sampling bucket has three sampling ports on its side, each corresponding to one of the plugs in the upper group, and the opening diameter of the sampling port is smaller than that of the stop block.

[0017] Compared with existing technologies, the advantages of this invention are: 1. The self-cleaning unit works in conjunction with an impeller, scraper, reciprocating spiral groove, floating plate, and ejector pin assembly. Water flow impacts the impeller, driving the shaft to rotate synchronously. The scraper removes impurities attached to the lower surface of the filter plate, while the spiral groove drives the floating plate to reciprocate axially. Simultaneously, the ejector pin inserts and removes fine particles embedded in the filter holes to clear them, achieving self-cleaning. This effectively reduces the risk of filter clogging, significantly extends the manual cleaning and maintenance cycle, and improves sampling stability in high-turbidity water.

[0018] 2: The stratified sampling unit, through the cooperation of pressure-sensitive plates, vertical valve stems, multiple sets of sealing plugs and return springs, relies on the changes in the negative pressure of the water pump to drive the valve stem to rise and fall, automatically switching the on and off states of sampling ports at different heights. The purely mechanical structure realizes stratified sampling of the surface, middle and bottom layers, obtaining representative water samples from different water layers, effectively reducing equipment costs and underwater operation and maintenance difficulties.

[0019] 3: The device is equipped with a float that adapts to the water level along the guide rod, which can automatically adjust the sampling position according to the rise and fall of the water level, always maintaining the standard sampling depth. It is suitable for complex hydrological scenarios and can be directly adapted to existing multi-factor online water quality monitoring systems. It is also suitable for long-term unattended outdoor operation, significantly improving the overall reliability and adaptability to complex working conditions of the equipment.

[0020] In summary, the self-cleaning unit of this invention relies on hydraulically driven rotating shafts to operate synchronously, simultaneously cleaning the filter plate surface and unclogging the filter holes, effectively reducing the risk of clogging and significantly extending the manual maintenance cycle. The stratified sampling unit uses negative pressure to drive the valve stem to raise and lower to switch the inlet water layer, obtaining representative water samples at different depths. Combined with the float adaptive water level structure, it is suitable for complex hydrological scenarios, has strong overall reliability, and can meet the needs of long-term unattended online monitoring outdoors. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a multi-factor online water quality monitoring sampling mechanism proposed in this invention; Figure 2 This is a half-sectional schematic diagram of the present invention; Figure 3 This is a schematic diagram of the sampling bucket installation according to the present invention; Figure 4 This is a schematic diagram of the internal structure of the sampling bucket of the present invention; Figure 5 This is an exploded view of the self-cleaning unit of the present invention; Figure 6 This is a partially enlarged schematic diagram A of the present invention; Figure 7 This is a schematic diagram of the installation of the layered sampling unit of the present invention; Figure 8 This is a half-sectional schematic diagram of the valve stem of the present invention; Figure 9 This is a partially enlarged schematic diagram (B) of the present invention.

[0022] In the diagram: 1. Ground, 2. Mounting bracket, 3. Analyzer, 4. Water pump, 5. Fixing plate, 6. Guide rod, 7. Float, 8. Sampling bucket, 9. Sensing block, 10. Sampling port, 11. Pumping pipe, 12. Bearing, 13. Shaft, 14. Impeller, 15. Filter plate, 16. Drain outlet, 17. Floating plate, 18. Sliding block, 19. Slide groove, 20. Reciprocating spiral groove, 21. Scraper, 22. Limiting rod, 23. Through groove, 24. Guide groove, 25. Mounting groove, 26. Valve stem, 27. Plug, 28. Pressure sensing plate, 29. Return spring one, 30. Mounting block, 31. Through hole, 32. Stop block, 33. Return spring two, 34. Pin. Detailed Implementation

[0023] Reference Figures 1-9 A multi-factor online water quality monitoring sampling mechanism includes a ground 1, a mounting frame 2, an analyzer 3, a water pump 4, and a fixing plate 5. The mounting frame 2 is fixedly installed on the ground 1, the analyzer 3 is fixedly installed on the mounting frame 2, the water pump 4 is fixedly installed on the front side of the analyzer 3, and the outlet of the water pump 4 is fixedly connected to the inlet of the analyzer 3 through a water pipe. A water tank is provided on the front side of the water pump 4, and the fixing plate 5 is provided in the water tank. Two guide rods 6 are fixedly installed below the fixing plate 5. Multiple sensing blocks 9 are evenly provided on the guide rods 6. A float 7 is slidably installed on the guide rods 6 and moves along the direction of the guide rods 6. A sampling bucket 8 is fixedly installed on the lower side of the float 7 through threads. A filter plate 15 is provided in the sampling bucket 8, and multiple filter holes are evenly provided on the filter plate 15.

[0024] Analyzer 3 (PLW-304 multi-parameter online analyzer can be used) and water pump 4 (Wailuo PUN-201EH can be used). Analyzer 3 has a built-in multi-parameter detection module, data storage module and wireless transmission module. It can simultaneously detect multiple water quality factors such as pH, turbidity, ammonia nitrogen, and total phosphorus. The detection data is uploaded to the monitoring platform in real time. Water pump 4 is an adjustable speed self-priming pump. The pumping power can be adjusted according to the sampling requirements, and the sampling flow rate control and stratified sampling level switching can be realized simultaneously.

[0025] The sampling bucket 8 is equipped with a self-cleaning unit to clean the filter plate 15, so as to avoid impurities in the sample from affecting the test results and to prevent impurities from clogging the filter plate 15 and affecting the normal operation of the device. The sampling bucket 8 is equipped with a layered sampling unit on the side, which is used to sample and test water at different water layers.

[0026] The float 7 can float up and down along the guide rod 6 as the water level in the tank rises and falls, driving the sampling bucket 8 to rise and fall synchronously, always maintaining the preset sampling depth. The sensor block 9 on the guide rod 6 can work with the sensor element built into the float 7 to provide real-time feedback on the water level and sampling position, ensuring the accuracy of the sampling depth. The top of the sampling bucket 8 is connected to the inlet of the water pump 4 through the water suction pipe 11. When the water pump 4 is running, it creates a negative pressure inside the sampling bucket 8, drawing external water into the bucket through the sampling port 10. After filtration, the water is delivered to the back-end analyzer 3 to complete multi-factor water quality testing.

[0027] The self-cleaning unit includes a bearing 12. The outer ring of the bearing 12 is fixedly installed in the middle of the sampling barrel 8. The inner side of the sampling barrel 8 is provided with a cavity that is cylindrical at the top and conical at the bottom. The bottom of the sampling barrel 8 is provided with a drain port 16. The inner ring of the bearing 12 is fixedly installed with a rotating shaft 13. The rotating shaft 13 passes through the filter plate 15 and is connected with a bearing. The lower end of the rotating shaft 13 is provided with an impeller 14, which is located below the filter plate 15.

[0028] A floating plate 17 is floatingly installed above the filter plate 15. Two sliders 18 are provided on the side of the floating plate 17. A groove 19 is provided on the inner side of the sampling barrel 8. The sliders 18 are slidably installed in the groove 19.

[0029] The floating plate 17 is floatingly mounted on the rotating shaft 13. The rotating shaft 13 is provided with a reciprocating spiral groove 20. A limiting rod 22 is provided at the mounting point of the floating plate 17 and the rotating shaft 13. The limiting rod 22 is located in the reciprocating spiral groove 20. The floating plate 17 moves back and forth along the axial direction of the rotating shaft 13 as the rotating shaft 13 rotates.

[0030] The floating plate 17 is provided with multiple through slots 23 that pass through the floating plate 17. Multiple ejector pins 34 are provided on the lower side of the floating plate 17. The installation position and number of ejector pins 34 are consistent with the filter holes on the filter plate 15. Two scrapers 21 are rotatably installed below the filter plate 15. The scrapers 21 are fixedly installed on the rotating shaft 13.

[0031] During operation, as the floating plate 17 descends, the ejector pin 34 is simultaneously inserted into the filter holes of the filter plate 15, pushing out fine sand and suspended particles embedded in the holes. When the floating plate 17 rises, the ejector pin 34 is completely withdrawn from the filter holes, allowing water to flow smoothly through them. At the same time, the rotating shaft 13 drives the scraper 21 to rotate continuously on the lower surface of the filter plate 15, scraping away flocculent impurities and large particles of dirt attached to the bottom surface of the filter plate. The scraped-off impurities slide down the conical cavity wall at the bottom of the sampling bucket 8 and are finally discharged out of the bucket through the bottom drain port 16. This achieves synchronous self-cleaning of the filter plate surface and filter holes, effectively reducing the risk of clogging and extending the manual maintenance cycle.

[0032] The stratified sampling unit includes a guide groove 24, which is located inside the sampling barrel 8, and an installation groove 25 is provided on the side of the guide groove 24.

[0033] The valve stem 26 is vertically installed in the mounting groove 25. The top of the plug 27 is provided with a return spring 29. Five plugs 27 are evenly arranged on the left side of the valve stem 26. The plugs 27 are divided into two groups. The three plugs 27 on the side closer to the return spring 29 form one group, and the other two form another group. The spacing between each plug 27 is consistent, and the spacing between the upper and lower groups is twice the spacing between the plugs 27.

[0034] A mounting block 30 is fixedly installed on the top of the valve stem 26. A return spring 29 is fixedly installed between the mounting block 30 and the top of the mounting groove 25. A pressure sensing plate 28 is provided on the right side of the valve stem 26. The pressure sensing plate 28 is movably installed in the guide groove 24.

[0035] The plug 27 has a cavity, and a stop block 32 is movably installed in the cavity. The stop block 32 is semi-circular and has a limiting edge at the bottom. A reset spring 33 is provided between the bottom of the stop block 32 and the bottom of the cavity. A through hole 31 is provided on the valve stem 26 between the upper and lower plugs 27.

[0036] The sampling bucket 8 has three sampling ports 10 on its side. Each sampling port 10 corresponds to a plug 27 in the upper group, and the opening diameter of the sampling port 10 is smaller than that of the stop block 32.

[0037] The pressure sensor 28 is located on the negative pressure chamber side inside the sampling barrel 8. When the pumping power of the water pump 4 changes, the magnitude of the negative pressure inside the sampling barrel changes synchronously. When the negative pressure increases, the pressure sensor 28 is offset to one side of the barrel by the air pressure difference, which drives the valve stem 26 to slide upward along the mounting groove 25 against the elastic force of the return spring 29. When the negative pressure decreases, the return spring 29 pushes the mounting block 30 downward, which drives the valve stem 26 to fall back to its original position. The valve stem's lifting and lowering position can be controlled by adjusting the water pump power.

[0038] Under normal conditions, the second return spring 33 pushes the stop block 32 outward, causing the stop block 32 to extend out of the surface of the plug 27. The sampling port 10 at the corresponding position is sealed and blocked by the stop block 32. When the valve stem 26 rises to the corresponding position, the plug 27 at the corresponding layer moves away from the sampling port 10. The external water body pushes the stop block 32 inward under water pressure, compresses the second return spring 33, and flows into the sampling tank 8 through the sampling port 10 and the through hole 31. The sampling ports at non-target layers remain blocked, ensuring that only water samples at the specified depth are collected. The limiting edge at the bottom of the stop block 32 can prevent it from coming out of the cavity. When under reverse pressure, the stop block 32 fits tightly against the inner wall of the sampling port, and the sealing performance is stable.

[0039] Example 1: Continuous Online Monitoring of Surface Water This embodiment corresponds to the routine water quality monitoring scenario of conventional rivers and landscape water bodies. After the overall assembly of the device is completed, the float 7 drives the sampling bucket 8 to float on the water surface. By default, water is introduced through the upper sampling port to continuously collect surface water samples. During operation, the water pump 4 operates at a constant low power, and a stable negative pressure is maintained inside the sampling bucket 8. The surface water flows into the bucket through the uppermost sampling port 10, pushes open the corresponding baffle 32, and passes through the through groove 23 of the floating plate 17 and the filter holes of the filter plate 15 in sequence, before impacting the impeller 14 downwards and driving the rotating shaft 13 to rotate.

[0040] The rotating shaft 13 synchronously drives the scraper 21 to scrape away impurities on the lower surface of the filter plate. At the same time, the reciprocating spiral groove 20 drives the floating plate 17 and the ejector pin 34 to move up and down repeatedly to continuously clear the filter holes and ensure stable sampling flow. The filtered water sample is transported to the analyzer 3 through the pumping pipe 11 to complete multi-factor water quality detection and data upload. When the water level rises or falls, the float 7 rises and falls synchronously along the guide rod 6 to always maintain the surface sampling depth, which is suitable for monitoring natural water bodies with fluctuating water levels.

[0041] Example 2: Alternating sampling of multiple water layers This embodiment is for scenarios that require stratified sampling, such as water quality vertical distribution surveys and pollution source tracing investigations. By adjusting the water pump power, the sampling depth is switched to obtain surface, middle and bottom water samples in sequence.

[0042] When sampling surface water, the water pump operates at low power, the return spring 29 is in a naturally extended state, the valve stem 26 is in the lowest position, and the top set of plugs 27 corresponds one-to-one with the three sampling ports 10. Only the surface sampling port is open, while the middle and bottom sampling ports remain blocked. When it is necessary to collect middle layer water samples, the water pump power is increased to increase the negative pressure inside the tank. The pressure sensor 28 drives the valve stem 26 to rise one level, and the plug 27 in the middle position opens the middle layer sampling port, while the other layers are blocked. When it is necessary to collect bottom layer water samples, the water pump power is further increased to the maximum level, the valve stem 26 rises to the highest position, and the bottom set of plugs opens the bottom layer sampling port, completing the deep water sample collection. After each layer of water sample collection is completed, the water pump power drops back, and the valve stem automatically resets. This can be used to cycle through multiple layers of water for alternating sampling, obtaining representative water quality data at different depths.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A multi-factor online water quality monitoring and sampling mechanism, comprising a ground (1), a mounting frame (2), an analyzer (3), a water pump (4), and a fixing plate (5), wherein the mounting frame (2) is fixedly installed on the ground (1), characterized in that, The analyzer (3) is fixedly installed on the mounting frame (2), the water pump (4) is fixedly installed on the front side of the analyzer (3), the outlet of the water pump (4) is fixedly connected to the inlet of the analyzer (3) through a water pipe, a water tank is provided on the front side of the water pump (4), a fixing plate (5) is provided in the water tank, two guide rods (6) are fixedly installed below the fixing plate (5), a plurality of sensing blocks (9) are evenly provided on the guide rods (6), a float (7) is slidably installed on the guide rods (6), the float (7) moves along the direction of the guide rods (6), a sampling bucket (8) is fixedly installed on the lower side of the float (7) through a thread, a filter plate (15) is provided in the sampling bucket (8), a plurality of filter holes are evenly provided on the filter plate (15); The sampling bucket (8) is equipped with a self-cleaning unit for cleaning the filter plate (15) to prevent impurities in the sample from affecting the test results and to prevent impurities from clogging the filter plate (15) and affecting the normal operation of the device. The sampling bucket (8) is equipped with a layered sampling unit on its side for sampling and testing water bodies of different water layers. The self-cleaning unit includes a bearing (12), the outer ring of which is fixedly installed in the middle of the sampling bucket (8). The inner side of the sampling bucket (8) is provided with a cavity that is cylindrical at the top and conical at the bottom. The bottom of the sampling bucket (8) is provided with a drain port (16). The inner ring of the bearing (12) is fixedly installed with a rotating shaft (13). The rotating shaft (13) passes through the filter plate (15) and is connected with a bearing. The lower end of the rotating shaft (13) is provided with an impeller (14), which is located below the filter plate (15).

2. The multi-factor online water quality monitoring and sampling mechanism according to claim 1, characterized in that, A floating plate (17) is floatingly installed above the filter plate (15). Two sliders (18) are provided on the side of the floating plate (17). A groove (19) is provided on the inner side of the sampling bucket (8). The sliders (18) are slidably installed in the groove (19).

3. The multi-factor online water quality monitoring and sampling mechanism according to claim 2, characterized in that, The floating plate (17) is floatingly mounted on the rotating shaft (13). The rotating shaft (13) is provided with a reciprocating spiral groove (20). A limiting rod (22) is provided at the mounting point of the floating plate (17) and the rotating shaft (13). The limiting rod (22) is located in the reciprocating spiral groove (20). The floating plate (17) moves back and forth along the axial direction of the rotating shaft (13) as the rotating shaft (13) rotates.

4. The multi-factor online water quality monitoring and sampling mechanism according to claim 3, characterized in that, The floating plate (17) is provided with multiple through slots (23) that pass through the floating plate (17). Multiple ejector pins (34) are provided on the lower side of the floating plate (17). The installation position and number of the ejector pins (34) are consistent with the filter holes on the filter plate (15). Two scrapers (21) are rotatably installed below the filter plate (15). The scrapers (21) are fixedly installed on the rotating shaft (13).

5. The multi-factor online water quality monitoring and sampling mechanism according to claim 1, characterized in that, The stratified sampling unit includes a guide groove (24), which is located inside the sampling bucket (8), and the side of the guide groove (24) is provided with an installation groove (25).

6. The multi-factor online water quality monitoring and sampling mechanism according to claim 5, characterized in that, The valve stem (26) is vertically installed in the mounting groove (25). The top of the plug (27) is provided with a return spring (29). Five plugs (27) are evenly arranged on the left side of the valve stem (26). The plugs (27) are divided into two groups. The three plugs (27) on the side closer to the return spring (29) form one group, and the other two form another group. The spacing between each plug (27) is consistent, and the spacing between the two groups is twice the spacing between the plugs (27).

7. The multi-factor online water quality monitoring and sampling mechanism according to claim 6, characterized in that, A mounting block (30) is fixedly installed on the top of the valve stem (26), and a reset spring (29) is fixedly installed between the mounting block (30) and the top of the mounting groove (25). A pressure-sensing plate (28) is provided on the right side of the valve stem (26), and the pressure-sensing plate (28) is movably installed in the guide groove (24).

8. The multi-factor online water quality monitoring and sampling mechanism according to claim 7, characterized in that, The plug (27) has a cavity, and a stop block (32) is movably installed in the cavity. The stop block (32) is semi-circular and has a limiting edge at the bottom. A reset spring (33) is provided between the bottom of the stop block (32) and the bottom of the cavity. A through hole (31) is provided on the valve stem (26) between the upper and lower plugs (27).

9. The multi-factor online water quality monitoring and sampling mechanism according to claim 1, characterized in that, The sampling bucket (8) has three sampling ports (10) on its side. Each sampling port (10) corresponds to a stopper (27) in the upper group, and the opening diameter of the sampling port (10) is smaller than that of the stopper (32).

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