Diluting and blending device for determining biochemical oxygen demand
The combination of porous silica gel discs and large-bellied glass tubes solves the problem of bubble generation during the biochemical oxygen demand determination process, achieves uniform dilution and mixing of water samples, and ensures the accuracy and stability of the test results.
Patent Information
- Application Number
- CN202422296689.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-20
- Publication Date
- 2025-09-09
- Estimated Expiration
- 2034-09-20
AI Technical Summary
The existing stirring device is prone to generate bubbles during the biochemical oxygen demand determination process, affecting the accuracy of the test results.
A porous silica gel disc and a large-bellied glass tube are combined. By slowly pushing the large-bellied glass tube, the water sample and the dilution water are exchanged in the pores of the porous silica gel disc to achieve dilution and mixing and avoid the generation of bubbles.
The water sample is fully mixed, the accuracy of the test results is guaranteed, the possibility of bubble generation is reduced, and the stability and efficiency of the operation are improved.
Smart Images
Figure CN223320139U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of measuring biochemical oxygen demand in surface water and sewage, and particularly relates to a dilution and mixing device used for measuring biochemical oxygen demand. Background Art
[0002] Biochemical oxygen demand (BOD) is one of the important indicators for evaluating water pollution and the self-purification capacity of water bodies. It can directly reflect the oxygen consumption demand in the self-purification process of water bodies and is also one of the powerful parameters for evaluating the effectiveness of sewage treatment and environmental restoration. The BOD measurement method, namely the five-day biochemical oxygen demand (BOD5), requires that the water sample (or diluted water sample) be incubated in a closed, constant temperature (20°C) for five days. The inherent microbial population in the water sample is used to biochemically degrade biooxidizable pollutants, and the difference in dissolved oxygen content before and after incubation is calculated.
[0003] The determination of biochemical oxygen demand (BOD) usually requires dilution of water samples. During the dilution process, a stirring device is required to mix the water samples to ensure that the sample and dilution water are evenly mixed. General stirring rods or stirrers are prone to generate bubbles during the stirring process, affecting the measurement results. Utility Model Content
[0004] In view of this, the utility model provides a dilution and mixing device for biochemical oxygen demand determination, which can effectively dilute and mix the water sample without causing the water sample to turn over and generate bubbles through a porous silica gel disc.
[0005] The technical solution is as follows: A dilution and mixing device for biochemical oxygen demand determination, comprising a large-bellied glass tube and a graduated cylinder, wherein a porous silicone disc is fixedly connected to the bottom of the large-bellied glass tube, the porous silicone disc is communicated with the large-bellied glass tube, a latex head is provided at the bottom end of the large-bellied glass tube, and the large-bellied glass tube and the porous silicone disc are movably inserted into the graduated cylinder.
[0006] During use of the above technical solution: determine the dilution multiple, directly add the sample and dilution water into the measuring cylinder slowly according to the scale to prevent bubbles from being generated during the transfer process, push the large-bellied glass tube up and down, and the water sample and dilution water are exchanged through the holes of the porous silicone disc. The porous silicone disc can effectively dilute the water sample without causing the water sample to flip over or generate bubbles, and can achieve a sufficient mixing effect, thereby ensuring the accuracy of the test results.
[0007] Preferably, the latex head is tightly sleeved on the bottom end of the large-bellied glass tube.
[0008] Preferably, the diameter of the porous silica gel disc is slightly smaller than the inner diameter of the graduated cylinder.
[0009] Preferably, the graduated cylinder can be detachably mounted on a support frame, an annular mounting frame is fixedly provided on the support frame, and a first limiting mechanism is provided on the annular mounting frame. The first limiting mechanism is operated to fix the graduated cylinder in the annular mounting frame of the support frame.
[0010] Preferably, the first limiting mechanism includes a first sliding cavity and a first arc-shaped through hole provided on the annular mounting frame, the first sliding cavity and the first arc-shaped through hole are communicated, a first piston is sealingly and slidingly installed on the first sliding cavity, a piston rod is provided on the first piston, a first arc-shaped clamping block is fixedly provided on the piston rod, a second sliding cavity is provided on the annular mounting frame, the second sliding cavity is communicated with the first sliding cavity, a second piston is sealingly and slidingly installed in the second sliding cavity, an adjusting screw is rotatably installed on the second piston, and the adjusting screw is threadedly installed on the annular mounting frame, and the operating adjusting screw compresses the gas in the second sliding cavity and the first sliding cavity through the second piston, and pushes the first arc-shaped clamping block to fix the graduated cylinder through the first piston.
[0011] Preferably, a first elastic component is movably installed in the first sliding cavity, one end of the first elastic component is fixedly connected to the first sliding cavity, and the other end of the first elastic component is fixedly connected to the first piston.
[0012] Preferably, the number of the first sliding cavities is three, and the three first sliding cavities are evenly distributed circumferentially on the annular mounting frame. The annular mounting frame is provided with a gas transmission cavity, and the three first sliding cavities are connected through the gas transmission cavity, and the second sliding cavity is connected to the gas transmission cavity.
[0013] During use of the above technical solution: operating the adjusting screw to compress the gas in the second sliding cavity and the first sliding cavity through the second piston, and pushing the first arc-shaped clamping block through the first piston to fix the graduated cylinder, thereby achieving the fixation of graduated cylinders with scales of different capacities and improving the stability of the graduated cylinder.
[0014] Preferably, an L-shaped support rod is slidably mounted on the support frame, and the upper end of the large-bellied glass tube is detachably mounted on the L-shaped support rod. A driving component is detachably mounted on the support frame, and the driving component is transmission-connected to the L-shaped support rod through a reciprocating mechanism. When the driving component is started, the L-shaped support rod is driven to move back and forth along the support frame through the reciprocating mechanism.
[0015] Preferably, the reciprocating mechanism includes a reciprocating groove roller rotatably mounted on a support frame, the output end of the driving component is transmission-connected to the reciprocating groove roller, a sliding groove is provided on the support frame, a sliding block is fixedly provided on the L-shaped support rod, the sliding block is slidingly mounted in the sliding groove, a connecting rod is fixedly provided on the L-shaped support rod, the connecting rod is transmission-connected to the reciprocating groove roller, and the starting driving component drives the L-shaped support rod to move reciprocatingly along the support frame through the cooperation between the reciprocating groove roller and the connecting rod.
[0016] During use of the above technical solution: the driving component is started to drive the L-shaped support rod to move back and forth along the support frame through the cooperation of the reciprocating groove roller and the connecting rod, and the large-bellied glass tube is driven to move up and down reciprocatingly along the graduated cylinder through the L-shaped support rod, thereby improving the stability of the movement of the porous silicone disc, reducing the generation of bubbles, and reducing labor.
[0017] Preferably, an arc-shaped groove is provided on the L-shaped support rod, and two symmetrical third sliding cavities are provided on the L-shaped support rod. Sliding racks are slidably installed in the two third sliding cavities. A double-threaded rod is rotatably installed on the L-shaped support rod. Second screw holes are provided on the two sliding racks. The double-threaded rods are threadedly installed in the two second screw holes. The thread directions of the second screw holes on the two sliding racks are opposite. The double-threaded rods are operated to drive the two sliding racks to move relative to or back to back. Second arc-shaped clamps are fixed on the two sliding racks, and the upper end tube of the big-bellied glass tube is fixed by the two second arc-shaped clamps.
[0018] During use of the above technical solution: the double-threaded rod is operated to drive the two sliding frames to move relative to or back to each other, and the upper end tube of the big-bellied glass tube is fixed by the two second arc-shaped clamping blocks, thereby fixing big-bellied glass tubes of different diameters.
[0019] After adopting the above technical solution, the beneficial effects of the utility model are:
[0020] 1. Determine the dilution multiple, and add the sample and dilution water directly to the graduated cylinder slowly and adhere to the wall according to the scale to prevent bubbles from being generated during the transfer process. Push the large-bellied glass tube up and down, and the water sample and dilution water will be exchanged through the holes of the porous silica gel disc. The porous silica gel disc can effectively dilute the water sample without causing the water sample to turn over or bubbles to be generated, and can achieve a fully mixed effect, thereby ensuring the accuracy of the test results.
[0021] 2. Operate the adjusting screw to compress the gas in the second sliding cavity and the first sliding cavity through the second piston, and push the first arc-shaped clamping block through the first piston to fix the graduated cylinder with scales, thereby achieving the fixation of graduated cylinders with scales of different capacities and improving the stability of the graduated cylinder with scales;
[0022] 3. Start the driving component to drive the L-shaped support rod to move back and forth along the support frame through the cooperation of the reciprocating groove roller and the connecting rod. The L-shaped support rod drives the large-bellied glass tube to move up and down along the graduated cylinder, thereby improving the stability of the movement of the porous silicone disc, reducing the generation of bubbles, and reducing labor.
[0023] 4. Operate the double-threaded rod to drive the two sliding frames to move relative to or back to each other, and fix the upper end of the big-bellied glass tube through the two second arc-shaped clamping blocks to achieve fixation of big-bellied glass tubes with different diameters. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0025] Figure 1 It is a three-dimensional diagram of the utility model;
[0026] Figure 2 It is an exploded view of the utility model;
[0027] Figure 3 This is a perspective view of the second embodiment of the present utility model;
[0028] Figure 4 It is a partial three-dimensional diagram of the second embodiment of the present utility model;
[0029] Figure 5 This is an exploded view of the second embodiment of the present utility model;
[0030] Figure 6 For this utility model Figure 5 A partial enlarged view of point A in the middle;
[0031] Figure 7 For this utility model Figure 5 A partial enlarged view of point B in the middle;
[0032] Figure 8 This is a partial exploded view of the second embodiment of the present utility model;
[0033] Figure 9 It is a partial three-dimensional diagram of the second embodiment of the present utility model;
[0034] Figure 10 It is a partial cross-sectional view of the second embodiment of the present utility model;
[0035] Figure 11 This is a partial cross-sectional view of the L-shaped support rod of the utility model;
[0036] Figure 12 It is a partial three-dimensional diagram of the second embodiment of the present utility model;
[0037] Figure 13 It is a partial three-dimensional diagram of the dust cover of the utility model;
[0038] In the figure, 1. large-bellied glass tube; 2. latex head; 3. porous silicone disc; 4. graduated cylinder; 5. support frame; 6. annular mounting frame; 7. first arc-shaped through hole; 8. first sliding cavity; 9. gas delivery cavity; 10. second sliding cavity; 11. first screw hole; 12. second piston; 13. adjusting screw; 14. first piston; 15. piston rod; 16. first arc-shaped clamping block; 17. first elastic component; 18. first mounting frame; 19. first mounting hole; 20. sliding groove; 21. first rotating shaft; 22. driving component; 23. reciprocating groove roller; 24. L-shaped support rod; 25. sliding block; 26. connecting rod; 27. arc-shaped groove; 28. third sliding cavity; 29. second mounting hole; 30. double-threaded rod; 31. sliding frame; 32. second screw hole; 33. second arc-shaped clamping block; 34. dust cover; DETAILED DESCRIPTION
[0039] 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.
[0040] Example 1
[0041] like Figures 1 to 2 As shown, a dilution and mixing device for biochemical oxygen demand determination includes a large-bellied glass tube 1 and a graduated cylinder 4. A porous silicone disc 3 is fixedly connected to the bottom of the large-bellied glass tube 1, and the porous silicone disc is connected to the large-bellied glass tube 1. A latex head 2 is provided at the bottom end of the large-bellied glass tube 1. The large-bellied glass tube 1 and the porous silicone disc 3 are movably inserted into the graduated cylinder 4.
[0042] The latex head 2 is tightly sleeved on the bottom end of the big-bellied glass tube 1.
[0043] The diameter of the porous silica gel disc 3 is slightly smaller than the inner diameter of the graduated cylinder 4 .
[0044] The upper end of the large glass tube 1 is provided with a circular dust cover 34, the aperture of which is just buckled on the measuring cylinder 4. When not in use, the large glass tube 1 is placed in the measuring cylinder 4 and the dust cover 34 is just buckled to prevent the large glass tube 1 and all parts inside the measuring cylinder 4 from being contaminated.
[0045] The working steps of this utility model are as follows:
[0046] Step 1: Determine the dilution multiple and add the sample and dilution water to the graduated cylinder slowly according to the calculated volume, without transferring (bubbles are easily generated during the transfer process).
[0047] Step 2: Insert the main body of the big-bellied glass tube 1 (with a porous silicone disc 3 and a latex head 2). By pushing the big-bellied glass tube 1 up and down, the water sample and the dilution water are exchanged through the holes of the porous silicone disc 3. The up and down movement of the porous silicone disc 3 can promote the dispersion and mixing of the water sample between different layers. This dispersion and mixing helps to evenly dilute the water sample without causing strong tumbling, turning up the water sample, and generating bubbles. It can also achieve a fully mixed effect, thereby ensuring the accuracy of the test results.
[0048] In actual operation: 1. Control speed: The up and down moving speed of the porous silica gel disc 3 can be controlled. A slower speed helps to reduce the tumbling of the water sample and the generation of bubbles.
[0049] 2. Pore exchange: The pores on the porous silica gel disc 3 allow the water sample to be exchanged vertically through the pores. This exchange method helps to evenly mix the water sample instead of achieving it through violent stirring.
[0050] 3. Reduce air contact: The design of the porous silica gel disc 3 reduces the contact area between the water sample and the air, thereby reducing the chance of air being drawn into the water sample, which helps to reduce the generation of bubbles.
[0051] 4. Mild dynamic action: The dynamic action generated by the up and down movement of the porous silica gel disc 3 is relatively mild and will not cause violent turbulence of the water sample.
[0052] 5. Maintaining surface tension: The surface tension of water helps to maintain the stability of the water sample. The up and down movement of the porous silicone disc 3 will not destroy this surface tension, thereby reducing the formation of bubbles.
[0053] 6. Laminar flow effect: The up and down movement of the porous silica gel disc 3 may produce a laminar flow effect. This flow pattern helps to smoothly mix the water sample and reduces the generation of turbulence and bubbles.
[0054] In this way, the porous silica gel disc 3 can effectively dilute and mix the water sample without causing the water sample to flip over or generate bubbles.
[0055] Example 2
[0056] Based on the first embodiment, Figures 1-12As shown, the graduated cylinder 4 can be detachably mounted on the support frame 5, on which an annular mounting frame 6 is fixedly provided, and on which a first limiting mechanism is provided. The first limiting mechanism is operated to fix the graduated cylinder 4 in the annular mounting frame 6 of the support frame 5.
[0057] The first limiting mechanism includes a first sliding cavity 8 and a first arc-shaped through hole 7 provided on the annular mounting frame 6. The first sliding cavity 8 is connected to the first arc-shaped through hole 7. A first piston 14 is sealingly and slidingly installed on the first sliding cavity 8. A piston rod 15 is provided on the first piston 14. A first arc-shaped clamping block 16 is fixedly provided on the piston rod 15. A second sliding cavity 10 is provided on the annular mounting frame 6. The second sliding cavity 10 is connected to the first sliding cavity 8. A second piston 12 is sealingly and slidingly installed in the second sliding cavity 10. An adjusting screw 13 is rotatably installed on the second piston 12. The adjusting screw 13 is threadedly installed on the annular mounting frame 6. When the adjusting screw 13 is operated, the gas in the second sliding cavity 10 and the first sliding cavity 8 is compressed by the second piston 12, and the first arc-shaped clamping block 16 is pushed by the first piston 14 to fix the graduated measuring cylinder 4.
[0058] Specifically: the piston rod 15 is slidably installed in the first arc-shaped through hole 7;
[0059] A first elastic component 17 is movably installed in the first sliding cavity 8 . One end of the first elastic component 17 is fixedly connected to the first sliding cavity 8 , and the other end of the first elastic component 17 is fixedly connected to the first piston 14 .
[0060] Specifically, the first elastic component 17 is a return spring, a first screw hole 11 is defined on the annular mounting frame 6 , and the adjusting screw 13 is threadedly mounted in the first screw hole 11 .
[0061] There are three first sliding cavities 8 , which are evenly distributed circumferentially on the annular mounting frame 6 . A gas transmission cavity 9 is provided on the annular mounting frame 6 . The three first sliding cavities 8 are connected through the gas transmission cavity 9 , and the second sliding cavity 10 is connected to the gas transmission cavity 9 .
[0062] In actual operation: place the graduated measuring cylinder 4 in the annular mounting bracket 6, operate the adjusting screw 13 to rotate along the first screw hole 11, and drive the second piston 12 to move downward along the second sliding cavity 10 through the adjusting screw 13, and compress the gas in the second sliding cavity 10 and the first sliding cavity 8 through the second piston 12, so that the air pressure is increased, and push the first arc-shaped clamping block 16 through the first piston 14 and the piston rod 15 to fix the graduated measuring cylinder 4, so as to fix the graduated measuring cylinders 4 with different capacities, and compress the first elastic component 17 at the same time. When disassembly is required, operate the adjusting screw 13 to drive the second piston 12 to move upward, so that the gas pressure in the first sliding cavity 8 and the second sliding cavity 10 is reduced, and the first arc-shaped clamping block 16 is driven to reset through the first elastic component 17.
[0063] An L-shaped support rod 24 is slidably mounted on the support frame 5, and the upper end of the large-bellied glass tube 1 is detachably mounted on the L-shaped support rod 24. A driving component 22 is detachably mounted on the support frame 5, and the driving component 22 is transmission-connected to the L-shaped support rod 24 through a reciprocating mechanism. When the driving component 22 is started, the L-shaped support rod 24 is driven to move back and forth along the support frame 5 through the reciprocating mechanism.
[0064] The reciprocating mechanism includes a reciprocating groove roller 23 rotatably mounted on the support frame 5, the output end of the driving component 22 is transmission-connected to the reciprocating groove roller 23, a sliding groove 20 is provided on the support frame 5, a sliding block 25 is fixedly provided on the L-shaped support rod 24, the sliding block 25 is slidingly installed in the sliding groove 20, a connecting rod 26 is fixedly provided on the L-shaped support rod 24, the connecting rod 26 is transmission-connected to the reciprocating groove roller 23, and the driving component 22 is started to drive the L-shaped support rod 24 to move back and forth along the support frame 5 through the cooperation between the reciprocating groove roller 23 and the connecting rod 26.
[0065] Specifically: two parallel first mounting frames 18 are provided on the support frame 5, and a first mounting hole 19 is opened on the first mounting frame 18. A coaxial first rotating shaft 21 is fixedly provided on the reciprocating groove roller 23, and the first rotating shaft 21 is rotatably installed in the first mounting hole 19. The driving component 22 is a forward and reverse low-speed motor, which is installed on the support frame 5 by bolts and nuts. The output end of the forward and reverse low-speed motor is fixedly connected to the first rotating shaft 21. The cross section of the sliding groove 20 is in a "concave" shape, and the cross section of the sliding block 25 is in a "convex" shape corresponding to the sliding groove 20.
[0066] In actual operation: starting the driving component 22 drives the L-shaped support rod 24 to move back and forth along the support frame 5 through the cooperation of the reciprocating groove roller 23 and the connecting rod 26, and drives the large-bellied glass tube 1 to move up and down reciprocatingly along the graduated cylinder 4 through the L-shaped support rod 24, thereby improving the stability of the movement of the porous silicone disc 3, reducing the generation of bubbles, and reducing the workload.
[0067] An arcuate groove 27 is formed on the L-shaped support rod 24. Two symmetrical third sliding cavities 28 are formed on the L-shaped support rod 24. Sliding frames 31 are slidably installed in the two third sliding cavities 28. A double-threaded rod 30 is rotatably installed on the L-shaped support rod 24. Second screw holes 32 are formed on the two sliding frames 31. The double-threaded rod 30 is threadedly installed in the two second screw holes 32. The second screw holes 32 on the two sliding frames 31 have opposite thread directions. Operating the double-threaded rod 30 drives the two sliding frames 31 to move relative to or opposite to each other. Second arc-shaped clamping blocks 33 are fixed on the two sliding frames 31. The upper end of the large-bellied glass tube 1 is fixed by the two second arc-shaped clamping blocks 33.
[0068] Specifically: a second mounting hole 29 is opened on the L-shaped support rod 24, a second rotating shaft is provided on the double-threaded rod 30, and the second rotating shaft is rotatably installed in the second mounting hole 29, and the external threads at both ends of the double-threaded rod 30 have opposite thread directions.
[0069] In actual operation, the double-threaded rod 30 is operated to drive the two sliding frames 31 to move relative to or back to each other, and the upper end of the large-bellied glass tube 1 is fixed by the two second arc-shaped clamping blocks 33, so as to fix the large-bellied glass tubes 1 with different diameters.
[0070] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements shall fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.
Claims
1. A dilution and mixing device for biochemical oxygen demand determination, comprising a large-bellied glass tube (1) and a graduated cylinder (4), characterized in that: The bottom of the large-bellied glass tube (1) is fixedly connected to a porous silica gel disc (3), the porous silica gel disc is connected to the large-bellied glass tube (1), a latex head (2) is provided at the bottom end of the large-bellied glass tube (1), and the large-bellied glass tube (1) and the porous silica gel disc (3) are movably inserted into a graduated cylinder (4).
2. A dilution and mixing device for biochemical oxygen demand determination according to claim 1, characterized in that: The latex head (2) is tightly sleeved on the bottom end of the large-bellied glass tube (1).
3. A dilution and mixing device for biochemical oxygen demand determination according to claim 2, characterized in that: The diameter of the porous silica gel disc (3) is slightly smaller than the inner diameter of the graduated cylinder (4).
4. A dilution and mixing device for biochemical oxygen demand determination according to any one of claims 1 to 3, characterized in that: The graduated cylinder (4) is detachably mounted on a support frame (5); an annular mounting frame (6) is fixedly provided on the support frame (5); a first limiting mechanism is provided on the annular mounting frame (6); and the graduated cylinder (4) is fixed in the annular mounting frame (6) of the support frame (5) by operating the first limiting mechanism.
5. A dilution and mixing device for biochemical oxygen demand determination according to claim 4, characterized in that: The first limiting mechanism comprises a first sliding cavity (8) and a first arc-shaped through hole (7) provided on the annular mounting frame (6); the first sliding cavity (8) and the first arc-shaped through hole (7) are communicated; a first piston (14) is sealingly and slidingly installed on the first sliding cavity (8); a piston rod (15) is provided on the first piston (14); a first arc-shaped clamping block (16) is fixedly provided on the piston rod (15); a second sliding cavity (10) is provided on the annular mounting frame (6); the second sliding cavity ( 10) is communicated with the first sliding cavity (8), a second piston (12) is sealed and slidably installed in the second sliding cavity (10), an adjusting screw (13) is rotatably installed on the second piston (12), and the adjusting screw (13) is threadedly installed on the annular mounting frame (6). When the adjusting screw (13) is operated, the gas in the second sliding cavity (10) and the first sliding cavity (8) is compressed through the second piston (12), and the first arc-shaped clamping block (16) is pushed through the first piston (14) to fix the graduated cylinder (4).
6. A dilution and mixing device for biochemical oxygen demand determination according to claim 5, characterized in that: A first elastic component (17) is movably installed in the first sliding cavity (8), one end of the first elastic component (17) is fixedly connected to the first sliding cavity (8), and the other end of the first elastic component (17) is fixedly connected to the first piston (14).
7. A dilution and mixing device for biochemical oxygen demand determination according to claim 6, characterized in that: The number of the first sliding cavities (8) is three, and the three first sliding cavities (8) are evenly distributed circumferentially on the annular mounting frame (6). The annular mounting frame (6) is provided with a gas transmission cavity (9), and the three first sliding cavities (8) are connected through the gas transmission cavity (9), and the second sliding cavity (10) is connected to the gas transmission cavity (9).
8. A dilution and mixing device for biochemical oxygen demand determination according to any one of claims 5 to 7, characterized in that: An L-shaped support rod (24) is slidably mounted on the support frame (5), and the upper end of the large-bellied glass tube (1) is detachably mounted on the L-shaped support rod (24). A driving component (22) is detachably mounted on the support frame (5), and the driving component (22) is transmission-connected to the L-shaped support rod (24) through a reciprocating mechanism. When the driving component (22) is started, the L-shaped support rod (24) is driven to move back and forth along the support frame (5) through the reciprocating mechanism.
9. A dilution and mixing device for biochemical oxygen demand determination according to claim 8, characterized in that: The reciprocating mechanism comprises a reciprocating groove roller (23) rotatably mounted on a support frame (5); the output end of the driving component (22) is transmission-connected to the reciprocating groove roller (23); a sliding groove (20) is provided on the support frame (5); a sliding block (25) is fixedly provided on the L-shaped support rod (24); the sliding block (25) is slidably mounted in the sliding groove (20); a connecting rod (26) is fixedly provided on the L-shaped support rod (24); the connecting rod (26) is transmission-connected to the reciprocating groove roller (23); when the driving component (22) is started, the L-shaped support rod (24) is driven to reciprocate along the support frame (5) through the cooperation between the reciprocating groove roller (23) and the connecting rod (26).
10. A dilution and mixing device for biochemical oxygen demand determination according to claim 9, characterized in that: The L-shaped support rod (24) is provided with an arc groove (27), and the L-shaped support rod (24) is provided with two symmetrical third sliding cavities (28). A sliding frame (31) is slidably installed in the two third sliding cavities (28). A double-threaded rod (30) is rotatably installed on the L-shaped support rod (24). The two sliding frames (31) are provided with second screw holes (32). The double-threaded rod (30) is threadedly installed in the two second screw holes (32). The second screw holes (32) on the two sliding frames (31) have opposite thread directions. The double-threaded rod (30) is operated to drive the two sliding frames (31) to move relative to or back to each other. The two sliding frames (31) are fixedly provided with a second arc clamping block (33). The upper end tube of the large-bellied glass tube (1) is fixed by the two second arc clamping blocks (33).