An electrolytic reaction device with defoaming function
By introducing a partition and filter plate structure into the electrolysis reactor, combined with foam discharge pipes and exhaust ports, the problem of foam generation in electrocatalytic ash water treatment is solved, the purification efficiency and stability of the device are improved, and the maintenance difficulty is reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHEJIANG SHENGKE ENVIRONMENTAL ENG CO LTD
- Filing Date
- 2025-07-30
- Publication Date
- 2026-06-30
AI Technical Summary
Existing electrocatalytic ash water treatment devices generate a large amount of foam during the treatment process, resulting in low treatment efficiency and substandard treatment effects. Furthermore, foam overflow pollutes the environment or corrodes the equipment, increasing installation difficulty and maintenance costs.
Design an electrolytic reactor with defoaming function. Through the combination of baffles and filter plates, and by utilizing the synergistic effect of defoaming pipes, exhaust ports and filter holes, timely discharge and elimination of bubbles can be achieved, thus protecting the stable operation of the electrolytic reactor.
It improves the purification efficiency of the electrolysis reactor, prevents foam overflow, extends the service life of the device, reduces the difficulty of installation and maintenance, and ensures the stability of the treatment effect.
Smart Images

Figure CN224430322U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of wastewater purification and treatment devices, specifically to an electrolytic reaction device with defoaming function. Background Technology
[0002] As people become more aware of water conservation, greywater reuse is becoming increasingly common. On trains, limited space restricts the amount of clean water that can be carried in each carriage. This water is needed for cleaning and sanitation in washrooms and toilets, as well as for flushing toilets, leading to water shortages. Furthermore, greywater from washrooms and toilets is discharged along with black water from toilet flushing into the onboard sewage treatment system, significantly increasing the system's workload and wasting considerable water resources. If greywater from washbasins and sinks (where it has lower levels of contamination) could be collected and treated separately and used for non-human contact toilet flushing, over 30% of the train's total water consumption could be saved.
[0003] Grey water typically contains various contaminants such as organic matter, ammonia nitrogen, color, bacteria, germs, anionic synthetic detergents, and animal and vegetable oils. Therefore, electrocatalytic grey water treatment devices are generally used to treat it. However, existing electrocatalytic grey water treatment devices have a relatively dispersed structure and many components, making them demanding in terms of installation environment and space. This significantly increases the installation difficulty when applying existing electrocatalytic grey water treatment devices to treat grey water on trains due to limited space. Furthermore, existing electrocatalytic grey water treatment devices generate a lot of foam during the process, due to the presence of many anionic detergents and the fact that the treatment relies on electrocatalysis. This foam hinders the release of gases during the electrocatalytic process, directly affecting the treatment effect and resulting in substandard grey water. In addition, some of the foam overflows directly from the exhaust and outlet ports, while some remains inside the device. Foam overflowing from the exhaust and water outlets can pollute the external environment, while chemicals remaining in the foam inside the device can corrode it and shorten its lifespan. Existing electrocatalytic ash wastewater treatment devices cannot effectively eliminate this foam. This leads to low treatment efficiency and substandard treated ash wastewater when using existing electrocatalytic ash wastewater treatment devices. Utility Model Content
[0004] To address the technical problem that existing greywater treatment devices cannot effectively eliminate bubbles generated during the treatment process, this invention provides an electrolytic reaction device with a defoaming function.
[0005] This utility model is achieved using the following technical solution: an electrolytic reaction device with defoaming function, comprising a housing 1 and a housing 2 fixedly installed on the outside of the housing 1. A partition and a filter plate are installed inside the housing 1. The partition is installed at the lower right of the housing 1 and divides the housing 1 into a left cavity and a right cavity, which are connected at the bottom. An electrolytic reactor for electrolytic catalysis of water is installed in the right cavity. An outlet 1 connected to the housing 2 is also provided on the right side of the right cavity. At least one defoaming pipe is installed on the top of the partition, connecting the left cavity and the right cavity respectively. The filter plate is installed in the left cavity along the horizontal direction of the housing 1 and is located above the partition, with the filter plate inclined to the lower right. The filter plate has multiple filter holes, each of which is staggered with the defoaming pipe in the horizontal direction. An inlet and a bubble outlet are sequentially provided vertically on the left side of the housing 1, located on the upper and lower sides of the filter plate respectively. The foam outlet is connected to the foam discharge pipe through the left cavity. Water entering through the inlet flows into the bottom of the left cavity through the filter holes, and then enters the right cavity through the bottom of the left cavity for electrolysis. The foam generated by electrolysis enters the left cavity through the foam discharge pipe and is discharged along the foam outlet. The electrolyzed water flows into the second tank through the outlet.
[0006] In a typical technical solution of this utility model, the partition has an inverted L-shaped structure. The partition includes a vertical plate and a horizontal plate. The vertical plate is vertically installed at the bottom of the housing, and the horizontal plate is arranged downward from the right side of the housing and the end of the horizontal plate is connected to the top of the vertical plate.
[0007] As a further improvement of this utility model, the top of the first housing is provided with an exhaust port, which connects to the left cavity. The second housing is provided with an exhaust port, which connects to the interior of the second housing.
[0008] As a further improvement of this utility model, a through hole is provided on the vertical plate, which connects the left cavity and the right cavity. A filter screen is detachably installed at the through hole, and water in the left cavity enters the right cavity through the filter screen.
[0009] As a further improvement of this utility model, a liquid outlet 2 is provided on the side wall of the second box away from the first box, and a filter screen 2 is also installed inside the second box. The filter screen 2 is installed horizontally inside the second box and is located above the liquid outlet 2.
[0010] As a further improvement of this utility model, the bottom of the box body is provided with a drain port, which is located on the left side of the vertical plate and connected to the bottom of the left cavity; the drain port is used to discharge the impurities deposited at the bottom of the left cavity.
[0011] In a typical technical solution of this utility model, a water level detection switch and a temperature sensor are also installed in the right cavity. The water level detection switch is used to detect the water level in the right cavity, and the temperature sensor is used to detect the temperature of the water in the right cavity.
[0012] As a further improvement of this utility model, the second box is set on the side of the first box near the first liquid outlet, and a water outlet pipe is installed at the first liquid outlet. The two ends of the water outlet pipe are respectively connected to the right cavity and the bottom of the second box.
[0013] As a further improvement of this utility model, a groove is formed by extending downward from the left side of the bottom of the box body, and the bottom of the filter screen is inserted into the groove. The groove is used to temporarily store the impurities left behind by the filter screen.
[0014] The technical solution provided by this utility model has the following beneficial effects:
[0015] (1) The electrolytic reaction device with defoaming function provided by this utility model is divided into a left chamber and a right chamber by setting a partition and a filter plate. The partition is used to defoam the air bubbles carried in the water entering the first chamber, so that fewer water bubbles enter the right chamber, thereby improving the electrolytic catalytic effect of the electrolytic reactor in the right chamber and thus improving the water purification efficiency. A foam defoaming channel is provided above the partition, which can timely discharge the air bubbles generated in the right chamber and defoam the air bubbles discharged from the foam defoaming channel under the action of the filter plate. The remaining foam can also be discharged through the foam outlet, thereby achieving timely discharge of air bubbles generated by the electrolytic reaction device to ensure the purification effect of the electrolytic reaction device.
[0016] (2) The electrolytic reaction device with defoaming function provided by this utility model has an exhaust port that is connected to the left cavity, so that the left cavity above the filter plate is directly connected to the atmosphere. This allows the liquid above the filter plate to be subjected to atmospheric pressure, making it easier for bubbles in the liquid above the filter plate to break when they rise to the surface. Therefore, in this embodiment, the exhaust port and the filter hole work together to improve the defoaming effect on the water entering the tank. Attached Figure Description
[0017] Figure 1 A three-dimensional structural diagram of an electrolytic reaction device with defoaming function provided by this utility model.
[0018] Figure 2 This is a schematic diagram of the internal structure of an electrolytic reaction device with defoaming function provided by this utility model.
[0019] Figure 3 A top view of an electrolytic reaction device with defoaming function provided by this utility model.
[0020] Figure 4 This utility model Figure 3 A schematic diagram of the internal structure of the cross section at point AA.
[0021] The diagram is marked as follows: 1. Box 1; 11. Partition; 111. Horizontal plate; 112. Vertical plate; 113. Filter screen 1; 12. Filter plate; 121. Filter hole; 13. Left cavity; 14. Right cavity; 141. Electrolytic reactor; 15. Water outlet pipe; 16. Foam discharge pipe; 17. Liquid inlet; 18. Foam outlet; 19. Exhaust port 1; 20. Sewage outlet; 21. Groove; 3. Box 2; 31. Exhaust port 2; 32. Liquid outlet 2; 33. Filter screen 2. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.
[0023] This embodiment provides an electrolytic reaction device with defoaming function, such as... Figure 1 and Figure 2As shown, it includes a box 1 and a box 2 3. Box 1 can be a rectangular box with an internal cavity. Box 2 3 can also be a rectangular box, but its volume is smaller than that of box 1, and it is fixedly installed on the outside of box 1. A partition 11 and a filter plate 12 are installed inside the cavity. The partition 11 is installed on the lower right side of box 1 and is used to divide the interior of box 1 into a left cavity 13 and a right cavity 14 that are connected at the bottom. An electrolytic reactor 141 for electrolytically catalyzing the water entering the right cavity 14 is installed inside the right cavity 14. A liquid outlet connected to box 2 3 is also provided on the right side of the right cavity 14. At least one foam discharge pipe 16 is installed on the top of the partition 11, which connects to the left cavity 13 and the right cavity 14 respectively. The left side of the housing 1 has a liquid inlet 17 and a bubble outlet 18 arranged vertically. The liquid inlet 17 and the bubble outlet 18 are respectively located on the upper and lower sides of the filter plate 12. The bubble outlet 18 is connected to the foam discharge pipe 16 through the left cavity 13. In this embodiment, the foam discharged through the foam discharge pipe 16 is blocked by the filter plate 12 and can be discharged along the bubble outlet 18, thereby achieving the purpose of defoaming. The filter plate 12 is installed in the left cavity 13 along the horizontal direction of the housing 1 and is located above the partition plate 11. The filter plate 12 is inclined to the lower right. The filter plate 12 is inclined to the lower right, and the liquid inlet 17 is located on the left side of the housing 1, so that the water entering the housing 1 will flow to the lower right along the filter plate 12 and flow downward when passing through the filter holes 121 on the filter plate 12. This arrangement can achieve the purpose of defoaming the air bubbles in the water entering the housing 1. The filter plate 12 has multiple filter holes 121, each of which is staggered horizontally with the foam discharge pipe 16. This staggered arrangement prevents water flowing from the filter holes 121 from entering the right cavity 14 through the foam discharge pipe 16. When water purification is required, the grey water to be treated can be delivered to the tank 1 through the inlet 17. The water entering the tank 1 flows down the filter plate 12 and through the filter holes 121. The filter plate 12 and the filter holes 121 provide a preliminary defoaming effect on the water entering the tank 1, facilitating subsequent electrolytic catalytic treatment. Water entering the left cavity 13 after passing through the filter hole 121 flows along the partition 11 to the bottom of the left cavity 13, and then enters the right cavity 14 through the bottom of the left cavity 13. The electrolysis reactor 141 in the right cavity 14 electrolyzes the incoming water, effectively removing bacteria, viruses, and other microorganisms from the water, and also degrading organic matter and heavy metals, thus effectively purifying the water. The electrolyzed water enters the tank 2 3 through the outlet on the lower right side of the right cavity 14, and the bubbles generated by electrolysis float to the surface because their density is less than that of water, and enter the left cavity 13 through the foam discharge pipe 16 at the top of the partition 11.In this embodiment, the foam discharge pipe 16 is vertically arranged along the top of the partition 11. This arrangement ensures that water flowing to the partition 11 through the filter hole 121 will not enter the right cavity 14 along the foam discharge pipe 16, thus ensuring the stability of the electrolytic catalysis of the electrolysis reactor 141 in the right cavity 14.
[0024] In this design, during the electrolytic catalysis process, a certain amount of water needs to be added to tank 1. This is to prevent the electrolytic reactor 141 from burning out due to insufficient water in tank 1. Therefore, in this embodiment, after the bubbles generated by the electrolytic reactor 141 are discharged through the foam discharge channel and enter the left cavity 13, since the left cavity 13 contains a certain amount of water, as the electrolytic reactor 141 continues to generate bubbles, under the combined action of the baffle 11 and the filter plate 12, the bubbles generated by the foam discharge channel will be discharged horizontally through the bubble outlet 18, thereby achieving the purpose of defoaming the bubbles generated in the electrolytic reactor.
[0025] The top of the housing 1 is provided with an exhaust port 19, which connects to the left cavity 13. In this embodiment, by setting the exhaust port 19 and connecting it to the left cavity 13, the portion of the left cavity 13 above the filter plate 12 is directly connected to the atmosphere. This allows the liquid above the filter plate 12 to be subjected to atmospheric pressure, making it easier for bubbles in the liquid above the filter plate 12 to rise to the surface and break. Therefore, in this embodiment, the exhaust port 19 and the filter hole 121 work together to improve the defoaming effect on the water entering the housing 1.
[0026] Partition 11 has an inverted L-shaped structure. Please refer to... Figures 2 to 4The partition 11 includes a vertical plate 112 and a horizontal plate 111. The vertical plate 112 is vertically installed at the bottom of the housing 1. One end of the horizontal plate 111 is fixedly installed on the right side of the housing 1, and the other end of the horizontal plate 111 is inclined downward to the left and fixedly connected to the upper end of the vertical plate 112. By setting the horizontal plate 111 to be inclined downward from right to left, the water flowing down from the filter hole 121 can quickly flow along the horizontal plate 111 to the bottom of the left cavity 13. In addition, in this embodiment, the bubbles generated in the right cavity 14 will be discharged through the bubble venting pipe. Some of the bubbles entering the left cavity 13 will break. The impurities wrapped in these broken bubbles will fall onto the horizontal plate 111 under the action of gravity. The impurities falling onto the horizontal plate 111 will be washed by the water flowing down from the filter hole 121 and flow along the horizontal plate 111 to the bottom of the left cavity 13, thus accumulating at the bottom of the left cavity 13. A through hole is provided on the vertical plate 112, connecting the left cavity 13 and the right cavity 14. A filter screen 113 is detachably installed at the through hole, allowing water in the left cavity 13 to enter the right cavity 14 through the filter screen 113. By providing the filter screen 113, impurities in the water entering the right cavity 14 through the left cavity 13 can be intercepted, preventing impurities from entering the right cavity 14 and thus preventing impurities from depositing on the electrolysis reactor 141, thereby achieving the purpose of protecting the electrolysis reactor 141.
[0027] Filter holes 121 are located on the filter plate 12 near the horizontal plate 111. This design maximizes the length of water flow on the filter plate 12, thereby increasing the defoaming time of the water in the cavity above the filter plate 12. Simultaneously, the water flowing down from the filter holes 121 also falls onto the horizontal plate 111 and flows along it to the bottom of the left cavity 13. This extends the water flow time in the left cavity 13, allowing sufficient time for impurities to separate from the water. Multiple defoaming pipes 16 are installed horizontally at intervals on the horizontal plate 111. Each filter hole 121 is horizontally staggered from each defoaming pipe 16.
[0028] The right cavity 14 is also equipped with a water level detection switch and a temperature sensor. The water level detection switch is used to detect the water level in the right cavity 14, and the temperature sensor is used to detect the temperature of the water in the right cavity 14. In this embodiment, the outer surface of the housing 1 is also equipped with a display screen, which is electrically connected to the water level detection switch and the temperature sensor respectively. The display screen is used to display the water level data detected by the water level detection switch and the temperature data detected by the temperature sensor. In actual application, the operator can control the operation of the electrolysis reaction device according to the water level and temperature in the right cavity 14 displayed on the display screen. The specific operation is as follows: When the electrolysis reaction device is performing electrolysis of catalytic water, the inlet 17 is opened first to deliver the water to be purified into the left cavity 13. The water entering will flow to the right along the filter plate 12 and flow downward through the filter holes 121 on the filter plate 12. The downward flowing water will flow along the partition 11 to the bottom of the left cavity 13. The water at the bottom of the left cavity 13 will enter the right cavity 14 through the filter screen 113. When the water level detection switch detects that the water level in the right chamber 14 has reached the electrolytic catalytic level of the electrolysis reactor 141, the operator can start the electrolysis reactor 141, allowing it to perform electrolytic catalytic activity on the water in the right chamber 14. Conversely, if the operator observes that the water level detection switch indicates the water level in the right chamber 14 is below the minimum water level set for the electrolytic catalytic reaction of the electrolysis reactor 141, the operator will shut down the electrolysis reactor 141 until the water level in the right chamber 14 rises to the electrolytic catalytic level, at which point the reactor will be restarted. This setting effectively protects the electrolysis reactor 141, preventing damage caused by it continuing electrolytic catalytic activity when the water level in the right chamber 14 is too low.
[0029] The temperature sensor is used to detect the temperature inside the right cavity 14. When the operator observes that the temperature sensor detects that the water temperature inside the right cavity 14 exceeds the maximum temperature of the electrolysis catalysis of the electrolysis reactor 141, the operator will shut down the electrolysis reactor 141 until the temperature inside the right cavity 14 drops to the temperature range of the electrolysis catalysis of the electrolysis reactor 141, and then restart the electrolysis reactor 141 to perform electrolysis operation, thereby achieving the purpose of protecting the electrolysis reactor 141.
[0030] Box 2 (3) is located on the side of Box 1 (1) near the liquid outlet. A water outlet pipe 15 is installed at the liquid outlet, with its two ends connected to the right cavity 14 and the bottom of Box 2 (3), respectively. Water after electrolytic catalysis enters Box 2 (3) through the water outlet pipe 15, where it is temporarily stored. Box 2 (3) also has a liquid outlet 2 (32), which can be connected to other equipment to transport the temporarily stored electrolytic water to other necessary equipment. A vent 2 (31) is located on the top of Box 2 (3), connecting it to the atmosphere and the interior of Box 2 (3). This vent 2 (31) ensures that Box 2 (3) is open to the atmosphere, allowing the liquid inside to be subjected to atmospheric pressure. This causes any small amount of air bubbles entering Box 2 (3) to easily break up when they rise to the surface. In this embodiment, a filter screen 2 33 is also installed inside the housing 2 3. The filter screen 2 33 is installed horizontally inside the housing 2 3 and located above the liquid outlet 2 32. By setting the filter screen 2 33, air bubbles entering the housing 2 3 can be squeezed and broken by the filter screen 2 33 when they rise to the surface. The synergistic effect of the exhaust port 2 31 and the filter screen 2 33 can effectively defoam the air bubbles entering the housing 2 3.
[0031] The water outlet pipe 15 can be an L-shaped structure. The L-shaped structure makes it easy to connect the second chamber 3 and the first chamber 1 into a U-shaped structure, so that the water electrolyzed in the right cavity 14 can directly enter the second chamber 3 through the water outlet pipe 15.
[0032] A groove 21 extends downwards from the left side of the bottom of box 1. Please refer to [reference needed]. Figure 4 The bottom of filter screen 113 is inserted into groove 21. By setting groove 21 and inserting the bottom of filter screen 113 into groove 21, impurities deposited at the bottom of left cavity 13 and impurities trapped by filter screen 113 will fall into groove 21 under the action of gravity, thereby achieving unified collection of impurities at the bottom of left cavity 13 and impurities trapped by filter screen 113 through groove 21. A drain port 20 is also opened at the bottom of box 1 at the location of groove 21, and drain port 20 is connected to groove 21. After electrolytic catalysis is completed or when sludge cleaning is required, the impurities collected in groove 21 can be discharged by opening drain port 20, thereby achieving the purpose of cleaning box 1.
[0033] It is understood that the electrolytic reaction device with defoaming function provided by this utility model can be applied not only to sewage treatment but also to other electrolytic reactions that produce foam, so as to remove the foam generated by the electrolytic reactions in these situations.
[0034] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An electrolytic reaction device with defoaming function, characterized in that, It includes a box body one (1) and a box body two (3) fixedly installed on the outside of the box body; a partition (11) and a filter plate (12) are installed inside the box body one (1). The partition (11) is installed at the lower right of the box body one (1) and is used to divide the box body one (1) into a left cavity (13) and a right cavity (14) connected at the bottom; an electrolysis reactor (141) for electrolytic catalysis of water is installed inside the right cavity (14), and a liquid outlet one connected to the box body two (3) is also provided on the right side of the right cavity (14); at least one foam discharge pipe (16) connected to the left cavity (13) and the right cavity (14) is installed on the top of the partition (11); The filter plate (12) is installed in the left cavity (13) along the horizontal direction of the first chamber (1) and is located above the partition plate (11). The filter plate (12) is inclined to the lower right. The filter plate (12) is provided with multiple filter holes (121), and each filter hole (121) and the bubble discharge pipe are staggered in the horizontal direction. The left side of the first chamber (1) is provided with an inlet (17) and a bubble outlet (18) in the vertical direction. The inlet (17) and the bubble outlet (18) are respectively located in the filter. The upper and lower sides of the plate (12); the bubble outlet (18) is connected to the foam discharge pipe (16) through the left cavity (13), the water entering through the liquid inlet (17) flows into the bottom of the left cavity (13) through the filter hole (121), and enters the right cavity (14) through the bottom of the left cavity (13) for electrolysis; the foam generated by electrolysis enters the left cavity (13) through the foam discharge pipe (16) and is discharged along the bubble outlet (18), and the water after electrolysis flows into the second box (3) through the liquid outlet.
2. The electrolytic reaction device with defoaming function as described in claim 1, characterized in that, The partition (11) has an inverted L-shaped structure; the partition (11) includes a vertical plate (112) and a horizontal plate (111). The vertical plate (112) is vertically installed at the bottom of the box body (1), and the horizontal plate (111) is set downward from the right side of the box body (1) and the end of the horizontal plate (111) is connected to the top of the vertical plate (112).
3. The electrolytic reaction device with defoaming function as described in claim 1, characterized in that, The top of the first box (1) is provided with an exhaust port (19), which is connected to the left cavity (13); the second box (3) is provided with an exhaust port (31), which is connected to the interior of the second box (3).
4. The electrolytic reaction device with defoaming function as described in claim 2, characterized in that, The vertical plate (112) is provided with a through hole, which connects the left cavity (13) and the right cavity (14). A filter screen (113) is detachably installed at the through hole, and water in the left cavity (13) enters the right cavity (14) through the filter screen (113).
5. The electrolytic reaction device with defoaming function as described in claim 1, characterized in that, The second box (3) has a liquid outlet (32) on one side wall away from the first box (1). The second box (3) is also equipped with a filter screen (33), which is installed horizontally inside the second box (3) and located above the liquid outlet (32).
6. The electrolytic reaction device with defoaming function as described in claim 2, characterized in that, The bottom of the box (1) is provided with a drain port (20), which is located on the left side of the vertical plate (112) and connected to the bottom of the left cavity (13); the drain port (20) is used to discharge the impurities deposited at the bottom of the left cavity (13).
7. The electrolytic reaction device with defoaming function as described in claim 2, characterized in that, The filter holes (121) are disposed on the filter plate (12) on one side near the horizontal plate (111), the foam discharge pipes (16) are installed on the horizontal plate (111), and each filter hole (121) is staggered from each foam discharge pipe (16) in the horizontal direction.
8. The electrolytic reaction device with defoaming function as described in claim 1, characterized in that, The right cavity (14) is also equipped with a water level detection switch and a temperature sensor. The water level detection switch is used to detect the water level in the right cavity (14), and the temperature sensor is used to detect the temperature of the water in the right cavity (14).
9. The electrolytic reaction device with defoaming function as described in claim 1, characterized in that, The second box (3) is located on the side of the first box (1) near the first liquid outlet. A water outlet pipe (15) is installed at one of the liquid outlets. The two ends of the water outlet pipe (15) are respectively connected to the bottom of the right cavity (14) and the second box (3).
10. The electrolytic reaction device with defoaming function as described in claim 4, characterized in that, A groove (21) is formed by extending downward from the left side of the bottom of the box body (1). The bottom of the filter screen (113) is inserted into the groove (21). The groove (21) is used to temporarily store the impurities trapped by the filter screen (113).