Purified water production device with water-saving function

Abstract

The utility model relates to the technical field of purified water production, and discloses a purified water production device with a water-saving function, which comprises a raw water tank and a water delivery pipe, a booster pump is arranged on one side of the raw water tank, and the other side of the water delivery pipe is communicated and connected with a water outlet of the raw water tank. The water conveying pipe is in through connection with a water suction port and a water outlet of the booster pump through pipelines, a first sand filtering device is arranged on one side of the booster pump, a first carbon filtering device is arranged on one side of the first sand filtering device, and a second sand filtering device is arranged on one side of the first carbon filtering device. A second carbon filtering device is arranged on one side of the second sand filtering device, and the water conveying pipe is in through connection with the first sand filtering device, the first carbon filtering device and the second sand filtering device through pipelines. According to the utility model, the first sand filtering device is used as a preliminary filtering stage, and is used for intercepting larger particle impurities and preventing the substances from entering a subsequent filtering system, so that a finer filtering layer is protected, the risk that the finer filtering layer is quickly blocked is reduced, and the first carbon filtering device utilizes the adsorption capacity of activated carbon.

Description

Technical Field

[0001] The utility model relates to the technical field of pure water production, in particular to a pure water production device with a water-saving function. Background Art

[0002] The pure water production device with water-saving function is a new type of water treatment equipment. It is mainly aimed at the production process of preparing pure water or purified water using tap water as source water through reverse osmosis, nanofiltration, ultrafiltration and other methods.

[0003] Traditional pure water production equipment usually requires manual operation, including adjusting water flow, pressure and replacing filter media. This not only increases the workload of operators, but may also lead to equipment failure or water quality problems due to operational errors. In addition, traditional pure water production equipment usually relies on only a single filter layer, which may not be able to effectively remove all types of pollutants, such as colloidal particles, dissolved organic matter, residual chlorine, heavy metal ions, etc.

[0004] Therefore, those skilled in the art provide a pure water production device with a water-saving function to solve the problems raised in the above background technology. Utility Model Content

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a pure water production device with water-saving function. The first sand filter device serves as the preliminary filtration stage. It intercepts larger particulate impurities and prevents these substances from entering the subsequent filtration system, thereby protecting the finer filter layers and reducing the risk of them being quickly blocked. The first carbon filter device uses the adsorption capacity of activated carbon to remove organic matter, chlorine, odor and color in the water, further improving the water quality. The second sand filter device uses ion exchange technology to remove hardness ions in the water, prevent scaling, and protect subsequent equipment. The second carbon filter device further filters tiny particles to ensure that the water is as clean as possible before entering the high-pressure pump and RO membrane. The first-level RO membrane can remove most dissolved solids in the water, including bacteria and viruses, to provide high-purity water. The mixed bed serves as the final fine filtration step. It further improves the purity of the water through ion exchange, ensuring that the water quality meets the most stringent standards. Multiple filtration ensures water The stability and reliability of water quality are suitable for occasions with strict requirements on water quality. Through step-by-step filtration, the pollution and blockage of subsequent equipment are reduced, and the service life of the equipment is extended. The electromagnetic control valve realizes automatic control of water flow, without manual operation, simplifying the operation process. The automation system can accurately adjust the water flow and pressure as needed to ensure the stability and efficiency of the water treatment process, reduce the workload of operators, reduce dependence on manual operation, and save labor costs. The automation system can monitor the equipment operation status in real time. Once an abnormality occurs, measures can be taken immediately, such as closing the solenoid valve to prevent water pollution and equipment damage. Through the automation control system, wastewater can be recycled and reused, the water recycling rate can be improved, and wastewater discharge can be reduced. Through multiple filtration and automation design, the equipment not only provides high-quality water treatment effects, but also improves operating efficiency, reduces operating costs, and realizes water conservation and recycling, with significant environmental and economic benefits.

[0006] To achieve the above objectives, the present invention provides the following technical solutions:

[0007] A pure water production device with a water-saving function includes a raw water tank and a water delivery pipe, wherein a booster pump is provided on one side of the raw water tank, and the other side of the water delivery pipe is connected to the water outlet of the raw water tank, and the water delivery pipe is connected to the water suction port and the water outlet of the booster pump through pipelines, respectively, a first sand filter device is provided on one side of the booster pump, a first carbon filter device is provided on one side of the first sand filter device, a second sand filter device is provided on one side of the first carbon filter device, and a second carbon filter device is provided on one side of the second sand filter device, the water delivery pipe is connected to the first sand filter device, the first carbon filter device, and the second sand filter device through pipelines, respectively, a high-pressure pump is provided on one side of the second carbon filter device, a water suction pipe is provided on the other side of the outer wall of the high-pressure pump, and a drain pipe is provided on one side of the outer wall of the high-pressure pump;

[0008] The water pipes are both connected with the suction pipe and the discharge pipe, and the ports of the water pipes at the upper and lower ends inside the first sand filter device and the second sand filter device are both connected with the first filter, and the inner bottom surfaces of the first sand filter device and the second sand filter device are both provided with a second gravel support layer, the upper end of the second gravel support layer is provided with a coarse sand layer, the upper end of the coarse sand layer is provided with a fine sand layer, and the upper end of the fine sand layer is provided with a first gravel support layer, the upper end of the first carbon filter device and the second carbon filter device are both connected with the second filter, and the inner bottom surfaces of the first carbon filter device and the second carbon filter device are both provided with a second anthracite support layer, the upper end of the second anthracite support layer is provided with an activated carbon adsorption layer, and the upper end of the activated carbon adsorption layer is provided with a first anthracite support layer.

[0009] Through the above technical solution, the raw water tank is used to store untreated source water, and the booster pump is connected to the raw water tank to increase the water pressure to ensure that the water can pass through the subsequent filtration system smoothly. The water outlet of the raw water tank and the water suction port and water outlet of the booster pump are connected through a water pipe to form a water flow channel. The first sand filter device is used to remove suspended matter and larger particle impurities in the water. The first carbon filter device uses activated carbon to adsorb organic matter, chlorine, odor and color in the water. The second sand filter device uses ion exchange technology to remove hardness ions in the water. The second carbon filter device further filters tiny particles to prepare for the subsequent high-pressure pump and RO membrane. Through the above technical solution, the high-pressure pump is used to increase the water pressure so that water can pass through the RO membrane. The high-pressure pump is connected through the suction pipe and the drain pipe to form the front and rear water flow channels of the RO membrane.

[0010] Furthermore, the front end of the high-pressure pump is provided with an installation box, and multiple primary RO membranes are provided inside. Both sides of the outer wall are fixedly connected to the inner wall of the installation box. The water pipes pass through one side of the installation box to the outside of the installation box and are connected to the inner wall of the primary RO membrane.

[0011] Through the above technical solution, a plurality of primary RO membranes are installed in the installation box, an intermediate water tank is installed on the other side, and an intermediate pump is installed on the other side through the pipeline to connect the water inlet and outlet of the intermediate water tank and to the water suction port and discharge port of the intermediate pump;

[0012] Through the above technical solution, the intermediate water tank is connected to the intermediate pump, which is usually used to provide power for subsequent water treatment equipment such as the mixed bed, ensuring that water can pass through these equipment smoothly.

[0013] Furthermore, a mixed bed is provided on the other side of the intermediate pump, and a plurality of support legs are fixedly connected to the lower surface for supporting the mixed bed. A pure water tank is provided on the other side for supporting the mixed bed, and the pure water tank is connected to the interior of the mixed bed and the pure water tank. The upper ends of the raw water tank and the pure water tank are snap-fitted with a box cover, and the middle of the upper surface is fixedly connected with a handle for storing the purified water after final treatment. The setting of the handle allows the operator to easily open and close the box cover, which is critical for regular inspection and maintenance of the interior of the water tank.

[0014] Furthermore, a raw water inlet pipe is provided on the other side of the outer wall of the lower end of the raw water tank and is connected to the interior of the raw water tank. A first electromagnetic control valve is provided on the upper end of the raw water inlet pipe and the first electromagnetic control valve is used to control the inflow of raw water.

[0015] Furthermore, a pure water outlet pipe is provided on the other side of the lower end of the outer wall of the pure water tank and is connected to the interior of the pure water tank. A second electromagnetic control valve is provided on the upper end of the pure water outlet pipe and a second electromagnetic control valve is provided for controlling the outflow of pure water.

[0016] The utility model has the following beneficial effects:

[0017] 1. The utility model proposes a pure water production device with water-saving function. The coarse sand layer and fine sand layer in the first sand filter device and the second sand filter device serve as the filtration stage, which intercepts larger particulate impurities and prevents these substances from entering the subsequent filtration system, thereby protecting the finer filtration layers and reducing the risk of them being quickly blocked. The first carbon filter device and the second carbon filter device use the adsorption capacity of activated carbon to remove organic matter, chlorine, odor and color in the water, further improving the water quality. The second sand filter device uses ion exchange technology to remove hardness ions in the water, prevent scaling, protect subsequent equipment, and ensure that the water is as clean as possible before entering the high-pressure pump and RO membrane. The first-level RO membrane can remove most dissolved solids in the water, including bacteria and viruses, to provide high-purity water. The mixed bed serves as the final fine filtration step, which further improves the purity of the water through ion exchange, ensuring that the water quality meets the most stringent standards. Multiple filtration ensures the stability and reliability of the water quality, and is suitable for occasions with strict requirements on water quality. Through step-by-step filtration, the pollution and clogging of subsequent equipment are reduced, and the service life of the equipment is extended.

[0018] 2. The pure water production device with water-saving function proposed by the utility model realizes automatic control of water flow by electromagnetic control valve, without manual operation, which simplifies the operation process. The automation system can accurately adjust the water flow and pressure as needed to ensure the stability and efficiency of the water treatment process, reduce the workload of operators, reduce dependence on manual operation, and save labor costs. The automation system can monitor the operating status of the equipment in real time. Once an abnormality occurs, measures can be taken immediately, such as closing the electromagnetic valve to prevent water pollution and equipment damage. Through the automation control system, wastewater can be recycled and reused, the recycling rate of water can be improved, and wastewater discharge can be reduced. The equipment not only provides high-quality water treatment effects through multiple filtration and automation design, but also improves operating efficiency, reduces operating costs, and realizes water conservation and recycling, with significant environmental and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an axonometric diagram of the pure water production device with water-saving function proposed in the utility model;

[0020] Figure 2 This is a top view of the pure water production device with water-saving function proposed by the utility model;

[0021] Figure 3 This is an axonometric diagram of the partial structure of the pure water production device with water-saving function proposed in the utility model;

[0022] Figure 4 This is a partial structural axonometric drawing of the pure water production device with water-saving function proposed in the utility model;

[0023] Figure 5 This is an exploded view of the partial structure of the pure water production device with water-saving function proposed by the utility model;

[0024] Figure 6 This is a partial structural axonometric diagram of the pure water production device with water-saving function proposed in the utility model;

[0025] Figure 7 This is a structural diagram of the first sand filter device and the second sand filter device of the pure water production device with water-saving function proposed by the utility model;

[0026] Figure 8 This is a structural diagram of the interior of the first carbon filter device and the second carbon filter device of the pure water production device with water-saving function proposed by the utility model.

[0027] Legend:

[0028] 1. Raw water tank; 2. Booster pump; 3. First sand filter device; 4. First carbon filter device; 5. Second sand filter device; 6. Second carbon filter device; 7. High-pressure pump; 8. Suction pipe; 9. Drain pipe; 10. Installation box; 11. Primary RO membrane; 12. Intermediate water tank; 13. Intermediate pump; 14. Mixed bed; 15. Support legs; 16. Pure water tank; 17. Tank cover; 18. Handle; 19. Raw water inlet pipe; 20. First solenoid control valve; 21. Pure water outlet pipe; 22. Second solenoid control valve; 23. Water pipe; 24. First filter; 25. First gravel support layer; 26. Fine sand layer; 27. Coarse sand layer; 28. Second gravel support layer; 29. ​​Second filter; 30. First anthracite support layer; 31. Activated carbon adsorption layer; 32. Second anthracite support layer. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the specific embodiments of the present invention to clearly and completely describe the technical solutions in the specific embodiments of the present invention. Obviously, the specific embodiments described are only part of the specific embodiments of the present invention, not all of the specific embodiments. Based on the specific embodiments of the present invention, all other specific embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Reference Figure 1-8 , a specific embodiment provided by the present utility model: a pure water production device with a water-saving function, comprising a raw water tank 1 and a water delivery pipe 23, a booster pump 2 is provided on one side of the raw water tank 1, the other side of the water delivery pipe 23 is connected to the water outlet of the raw water tank 1, the water delivery pipe 23 is connected to the water suction port and the water outlet of the booster pump 2 through pipelines, a first sand filter device 3 is provided on one side of the booster pump 2, a first carbon filter device 4 is provided on one side of the first sand filter device 3, a second sand filter device 5 is provided on one side of the first carbon filter device 4, a second carbon filter device 6 is provided on one side of the second sand filter device 5, a high-pressure pump 7 is provided on one side of the second carbon filter device 6, a water suction pipe 8 is provided on the other side of the outer wall of the high-pressure pump 7, and a drain pipe 9 is provided on one side of the outer wall of the high-pressure pump 7;

[0031] The water pipes 23 are both connected to the water suction pipe 8 and the drainage pipe 9. The upper and lower ends of the water pipes 23 in the first sand filter device 3 and the second sand filter device 5 are both connected to the first filter 24. The bottom surfaces of the first sand filter device 3 and the second sand filter device 5 are both provided with a second gravel support layer 28. The upper end of the second gravel support layer 28 is provided with a coarse sand layer 27. The upper end of the coarse sand layer 27 is provided with a fine sand layer 26. The upper end of the fine sand layer 26 is provided with a first gravel support layer 25. The upper and lower ends of the water pipes 23 in the first carbon filter device 4 and the second carbon filter device 6 are both connected to the second filter 29.

[0032] The inner bottom surfaces of the first carbon filter device 4 and the second carbon filter device 6 are both provided with a second anthracite support layer 32, an activated carbon adsorption layer 31 is provided on the upper end of the second anthracite support layer 32, and a first anthracite support layer 30 is provided on the upper end of the activated carbon adsorption layer 31. The raw water tank 1 is used to store untreated source water, and is connected to the raw water tank 1 through a booster pump 2 to increase the water pressure to ensure that the water can pass through the subsequent filtration system smoothly. The water outlet of the raw water tank 1 and the water intake and outlet of the booster pump 2 are connected through a water pipe 23 to form a water flow channel. A first sand filter device 3 is provided on one side of the booster pump 2, a first carbon filter device 4 is provided on one side of the first sand filter device 3, a second sand filter device 5 is provided on one side of the first carbon filter device 4, and a second carbon filter device 6 is provided on one side of the second sand filter device 5;

[0033] The water delivery pipe 23 is connected to the first sand filter device 3, the first carbon filter device 4, and the second sand filter device 5 through pipelines. The first sand filter device 3 removes suspended matter and larger particle impurities in the water. The first carbon filter device 4 uses activated carbon to adsorb organic matter, chlorine, odor and color in the water. The second sand filter device 5 removes hardness ions such as calcium and magnesium in the water through ion exchange technology. The second carbon filter device 6 further filters tiny particles to prepare for the subsequent high-pressure pump 7 and RO membrane. A high-pressure pump 7 is provided on one side of the second carbon filter device 6, a water suction pipe 8 is provided on the other side of the outer wall of the high-pressure pump 7, and a drain pipe 9 is provided on one side of the outer wall of the high-pressure pump 7;

[0034] The water pipes 23 are all connected with the water suction pipe 8 and the drainage pipe 9, and are used to increase the water pressure through the high-pressure pump 7 so that water can pass through the RO membrane. The high-pressure pump 7 is connected through the water suction pipe 8 and the drainage pipe 9 to form the front and rear water flow channels of the RO membrane. The front end of the high-pressure pump 7 is provided with an installation box 10, and a plurality of primary RO membranes 11 are provided inside the installation box 10. Both sides of the outer wall of the primary RO membrane 11 are fixedly connected to the inner wall of the installation box 10. The water pipes 23 all pass through one side of the installation box 10 to the outside of the installation box 10 and are connected with the inner wall of the primary RO membrane 11. The plurality of primary RO membranes 11 are provided in the installation box 10 for deep filtration of dissolved solids in the water. An intermediate water tank 12 is provided on the other side of the installation box 10, and an intermediate pump 13 is provided on the other side of the intermediate water tank 12.

[0035] The water supply pipe 23 is connected to the water inlet and water outlet of the intermediate water tank 12 through a pipeline and is connected to the water suction port and discharge port of the intermediate pump 13. It is connected to the intermediate water tank 12 through the intermediate pump 13 to provide the necessary pressure for the subsequent water treatment stage. The intermediate pump 13 is usually used to provide power for subsequent water treatment equipment such as the mixed bed 14 to ensure that water can pass through these equipment smoothly. A mixed bed 14 is provided on the other side of the intermediate pump 13. A plurality of support legs 15 are fixedly connected to the lower surface of the mixed bed 14. The plurality of support legs 15 are used to support the mixed bed 14. A pure water tank 16 is provided on the other side of the mixed bed 14. The water supply pipe 23 is connected to the interior of the mixed bed 14 and the pure water tank 16. The upper ends of the raw water tank 1, the intermediate water tank 12 and the pure water tank 16 are all snap-fitted with a box cover 17. The middle part of the upper surface of the box cover 17 is fixedly connected with a handle 18. The pure water tank 16 is used to store the purified water after final treatment.

[0036] The setting of the handle 18 allows the operator to easily open and close the box cover 17, which is very critical for regular inspection and maintenance of the interior of the water tank. A raw water inlet pipe 19 is provided on the other side of the outer wall of the lower end of the raw water tank 1. The raw water inlet pipe 19 is connected to the interior of the raw water tank 1. A first electromagnetic control valve 20 is provided at the upper end of the raw water inlet pipe 19. The raw water inlet pipe 19 and the first electromagnetic control valve 20 are used to control the inflow of raw water. A pure water outlet pipe 21 is provided on the other side of the lower end of the outer wall of the pure water tank 16. The pure water outlet pipe 21 is connected to the interior of the pure water tank 16. A second electromagnetic control valve 22 is provided at the upper end of the pure water outlet pipe 21. The pure water outlet pipe 21 and the second electromagnetic control valve 22 are used to control the outflow of pure water.

[0037] Working principle: Raw water flows out from the raw water tank 1 and is pressurized by the booster pump 2. The water pressure is enhanced, which is beneficial to the subsequent filtration and treatment process. The first sand filter device 3 serves as the preliminary filtration stage. It intercepts larger particulate impurities and prevents these substances from entering the subsequent filtration system, thereby protecting the finer filter layers and reducing the risk of them being quickly blocked. The first carbon filter device 4 uses the adsorption capacity of activated carbon to remove organic matter, chlorine, odor and color in the water, further improving the water quality. The second sand filter device 5 uses ion exchange technology to remove hardness ions such as calcium and magnesium in the water to prevent scaling and protect subsequent equipment. The second carbon filter device 6 further filters tiny particles to ensure that the water is as clean as possible before entering the high-pressure pump 7 and RO membrane. The first-level RO membrane 11 can remove most dissolved solids in the water, including bacteria and viruses, providing high purity. Water, the mixed bed 14 is the final fine filtration step, which further improves the purity of water through ion exchange and ensures that the water quality meets the most stringent standards. Multiple filtration ensures the stability and reliability of water quality and is suitable for occasions with strict requirements on water quality. Through step-by-step filtration, the pollution and blockage of subsequent equipment such as RO membranes are reduced, and the service life of the equipment is extended. The first electromagnetic control valve 20 and the second electromagnetic control valve 22 realize automatic control of water flow without manual operation. The automation system can accurately adjust the water flow and pressure as needed to ensure a stable and efficient water treatment process. The system can monitor the operating status of the equipment in real time. Once an abnormality occurs, measures can be taken immediately, such as closing the solenoid valve, to prevent water pollution and equipment damage. Through the automated control system, wastewater can be recycled and reused, the recycling rate of water can be improved, and wastewater discharge can be reduced.

[0038] Finally, it should be noted that the above is only a preferred specific implementation method of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned specific implementation methods, those skilled in the art can still modify the technical solutions described in the aforementioned specific implementation methods or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A pure water production device with a water-saving function, comprising a raw water tank (1) and a water delivery pipe (23), characterized in that: A booster pump (2) is provided on one side of the raw water tank (1), and the other side of the water delivery pipe (23) is connected to the water outlet of the raw water tank (1). The water delivery pipe (23) is connected to the water intake and water outlet of the booster pump (2) through pipelines. A first sand filter device (3) is provided on one side of the booster pump (2), a first carbon filter device (4) is provided on one side of the first sand filter device (3), a second sand filter device (5) is provided on one side of the first carbon filter device (4), and a second carbon filter device (6) is provided on one side of the second sand filter device (5). The water delivery pipe (23) is connected to the first sand filter device (3), the first carbon filter device (4), and the second sand filter device (5) through pipelines. A high-pressure pump (7) is provided on one side of the second carbon filter device (6), a water suction pipe (8) is provided on the other side of the outer wall of the high-pressure pump (7), and a drain pipe (9) is provided on one side of the outer wall of the high-pressure pump (7). The water pipes (23) are connected to the water suction pipe (8) and the drainage pipe (9); the ports of the water pipes (23) at the upper and lower ends of the first sand filter device (3) and the second sand filter device (5) are connected to the first filter (24); the bottom surfaces of the first sand filter device (3) and the second sand filter device (5) are provided with a second gravel support layer (28); the upper end of the second gravel support layer (28) is provided with a coarse sand layer (27); the upper end of the coarse sand layer (27) is provided with a fine sand layer (26); the fine sand layer ( 26) is provided with a first gravel support layer (25), the ports of the upper and lower water pipes (23) inside the first carbon filter device (4) and the second carbon filter device (6) are both connected to the second filter (29), the inner bottom surfaces of the first carbon filter device (4) and the second carbon filter device (6) are both provided with a second anthracite support layer (32), the upper end of the second anthracite support layer (32) is provided with an activated carbon adsorption layer (31), and the upper end of the activated carbon adsorption layer (31) is provided with a first anthracite support layer (30).

2. The pure water production device with water-saving function according to claim 1, characterized in that: A mounting box (10) is provided at the front end of the high-pressure pump (7), and a plurality of primary RO membranes (11) are provided inside the mounting box (10). Both sides of the outer wall of the primary RO membrane (11) are fixedly connected to the inner wall of the mounting box (10), and the water pipes (23) pass through one side of the mounting box (10) to the outside of the mounting box (10) and are connected to the inner wall of the primary RO membrane (11).

3. The pure water production device with water-saving function according to claim 2, characterized in that: An intermediate water tank (12) is provided on the other side of the installation box (10), and an intermediate pump (13) is provided on the other side of the intermediate water tank (12). The water delivery pipe (23) is connected to the water inlet and outlet of the intermediate water tank (12) through a pipeline and is also connected to the water suction port and discharge port of the intermediate pump (13).

4. The pure water production device with water-saving function according to claim 3 is characterized in that: A mixed bed (14) is provided on the other side of the intermediate pump (13), and a plurality of supporting legs (15) are fixedly connected to the lower surface of the mixed bed (14).

5. The pure water production device with water-saving function according to claim 4 is characterized in that: A pure water tank (16) is provided on the other side of the mixed bed (14), and the water delivery pipe (23) is connected to the interior of the mixed bed (14) and the pure water tank (16). The upper ends of the raw water tank (1), the intermediate water tank (12) and the pure water tank (16) are all snap-fitted with a box cover (17), and the middle part of the upper surface of the box cover (17) is fixedly connected with a handle (18).

6. The pure water production device with water-saving function according to claim 1, characterized in that: A raw water inlet pipe (19) is provided on the other side of the outer wall of the lower end of the raw water tank (1), and the raw water inlet pipe (19) is connected to the interior of the raw water tank (1). A first electromagnetic control valve (20) is provided at the upper end of the raw water inlet pipe (19).

7. The pure water production device with water-saving function according to claim 5, characterized in that: A pure water outlet pipe (21) is provided on the other side of the lower end of the outer wall of the pure water tank (16), and the pure water outlet pipe (21) is connected to the interior of the pure water tank (16). A second electromagnetic control valve (22) is provided at the upper end of the pure water outlet pipe (21).

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