Liquid level checking device

Abstract

The liquid level checking device comprises a water tank, a quantitative water injection unit and a rapid water injection unit, the water tank is communicated with a water inlet pipeline through a main valve, and a liquid level control valve is arranged on the water inlet pipeline; the quantitative water injection unit comprises a quantitative water pumping device, the quantitative water pumping device is communicated with the water tank through a hose, and a one-way valve is arranged at the communication position; the rapid water injection unit comprises a liquid level meter pipeline, one end of the liquid level meter pipeline is communicated with the water inlet pipeline through a water feeding valve, and the other end of the liquid level meter pipeline is communicated with the quantitative water pumping device; according to the liquid level checking device, the liquid level checking accuracy can be improved, meanwhile, in the checking process, the quick drain valve is opened in the checking process, quick adjustment of the liquid level is achieved, the blow-down valve is opened after checking is finished, residual water in a water tank and a pipeline can be quickly drained, and the liquid level checking efficiency can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level debugging (liquid level gauges and liquid level switches used in nuclear power plants), in particular to a liquid level calibration device. Background Art

[0002] Liquid level switches detect when a liquid's level has reached a preset threshold and implement control through switching actions (e.g., starting or stopping a pump, alarming, etc.). Liquid level gauges continuously measure and display the liquid's height or volume. They provide real-time liquid level data and are suitable for monitoring liquid level trends. Both are used for liquid level monitoring and management to ensure that the liquid remains within a safe range. In some applications, liquid level switches and level gauges can be used in conjunction. For example, in chemical process control, a level gauge can provide continuous liquid level monitoring, while a level switch can issue an alarm or control equipment when the liquid level exceeds a certain threshold.

[0003] The calibration of both liquid level switches and level gauges usually requires accuracy verification by providing a liquid of known height (usually a standard liquid). Among them, the calibration of the liquid level switch requires confirming whether the switch switches smoothly (such as from closed to open) when the liquid level reaches the set high liquid level. Similarly, when the liquid level drops and reaches the set low liquid level, check whether the switch switches back to its original state (such as from open to closed). The calibration of the liquid level gauge requires gradually increasing the height of the liquid and recording the liquid level gauge reading (the numerical value of the liquid level) at each known height point. Compare the actual liquid level height with the liquid level gauge reading to check for consistency. The actual height of the liquid level can be measured using a ruler or other measuring tool. Record the relationship between the known liquid level and the level gauge output, calculate the error, and analyze the measurement accuracy of the level gauge.

[0004] Currently, during the calibration of liquid level gauges or level switches, it is impossible to precisely control the liquid level, resulting in low calibration accuracy. Furthermore, using hoses for filling and draining, as well as for connection, creates the risk of water leakage during test switching. After the test, the remaining water in the device cannot be quickly drained, resulting in low test efficiency. Therefore, a liquid level calibration device is needed. Utility Model Content

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a liquid level calibration device to achieve precise control of the liquid level during the calibration process, improve the accuracy of liquid level calibration, and at the same time quickly drain water during and after the calibration process to improve calibration efficiency.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a liquid level calibration device, comprising:

[0007] Water tank, the water tank is connected to the water inlet pipeline through the main valve, and the water inlet pipeline is equipped with a liquid level control valve;

[0008] The quantitative water injection unit includes a quantitative water pump, the quantitative water pump and the water tank are connected through a hose, and a one-way valve is provided at the connection point;

[0009] The fast water injection unit includes a liquid level gauge pipeline, one end of which is connected to the water inlet pipeline through a water supply valve, and the other end is connected to the quantitative water pump;

[0010] Among them, at least three branches are provided on the liquid level meter pipeline, one of which is connected to the water tank through a drain valve.

[0011] As one of the embodiments of the present invention, a first branch, a second branch and a third branch are provided on the liquid level gauge pipeline. The first branch is connected to the local liquid level gauge through a first valve, the second branch is connected to the remote liquid level gauge through a second valve, and the third branch is connected to the upper part of the water tank through a drain valve.

[0012] As one embodiment of the present utility model, a first branch, a second branch and a third branch are provided on the liquid level gauge pipeline. The first branch is connected to the liquid level switch through a first valve, the second branch is connected to a vertically arranged observation tube through a second valve, and the third branch is connected to the upper part of the water tank through a drain valve.

[0013] As one embodiment of the present invention, the quantitative water pump is a volumetric quantitative water pump, which includes a pump body and a water pumping cylinder. One end of the water pumping cylinder is connected to the pump body, and the other end passes through the top of the water tank and is provided with a one-way valve.

[0014] As one embodiment of the present invention, the liquid level gauge pipeline includes a horizontal section and a vertical section. The vertical section is arranged parallel to the height direction of the water tank, and the horizontal section is connected to the water pump of the quantitative water pump; the vertical section of the liquid level gauge pipeline is provided with a first branch, a third branch and a second branch from top to bottom.

[0015] As one embodiment of the present invention, an overflow pipe is further provided in the water tank, and the water inlet of the overflow pipe is higher than the height of the liquid level control valve and lower than the height of the connection point between the third branch and the water tank.

[0016] As one embodiment of the present invention, a drain pipe is provided on the water inlet pipeline, and a quick discharge valve is provided on the drain pipe.

[0017] As one embodiment of the present invention, the water inlet pipeline includes an inner water inlet pipe and an outer water inlet pipe respectively arranged inside and outside the water tank. The inner water inlet pipe is arranged parallel to the height direction of the water tank. The lower part of the inner water inlet pipe is connected with the outer water inlet pipe, and a liquid level control valve is provided at its upper end.

[0018] As one embodiment of the present invention, the utility model further comprises a sewage pipe, on which a sewage valve 7 is provided. The sewage pipe is communicated with the bottom of the water tank and the water outlet of the overflow pipe respectively.

[0019] As one embodiment of the present invention, the overflow pipe is an L-shaped elbow, the vertical section of the L-shaped elbow is arranged in the water tank, the horizontal section of the L-shaped elbow extends out of the water tank, and its end is the water outlet of the overflow pipe.

[0020] The utility model has at least the following beneficial technical effects:

[0021] The utility model provides a liquid level calibration device, including a water tank, a quantitative water injection unit and a fast water injection unit. The water tank is connected to a water inlet pipeline through a main valve, and a liquid level control valve is provided on the water inlet pipeline. The quantitative water injection unit includes a quantitative water pump, which is connected to the water tank through a hose, and a one-way valve is provided at the connection point. The above-mentioned quantitative fast water injection unit can quickly fill water and quickly calibrate the normal operation of the equipment. Then, the quantitative water injection unit can provide a liquid level of a known height to the equipment to be calibrated, continuously and quantitatively supply or drain water to the equipment to be calibrated, and continuously observe and record the liquid level meter reading or the action of the liquid level switch (such as from closed to open, from open to closed). Compare the liquid level meter reading with the liquid level of the known height, calculate the error and analyze the measurement accuracy of the liquid level meter, or record the switch response time of the liquid level switch, the reliability of the switching state, and the correspondence between the liquid level and the switch reaction. The above-mentioned continuous quantitative water supply or drainage and recording of the liquid level meter reading or the action of the liquid level switch greatly improves the accuracy of liquid level calibration. At the same time, during the calibration process, the quick discharge valve has been tested to achieve rapid adjustment of the liquid level. After the calibration is completed, the drain valve is opened to quickly discharge the residual water in the water tank and pipeline, thereby improving the efficiency of liquid level calibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. 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 creative work.

[0023] Figure 1 This is a structural diagram of a liquid level calibration device in one embodiment of the present utility model.

[0024] Among them: water tank 1, overflow pipe 2, liquid level control valve 3, quantitative water pump 4, one-way valve 5, hose 6, drain valve 7, first valve 8, second valve 9, water supply valve 10, water inlet pipeline 11, main valve 12, drain valve 13, quick discharge valve 14, liquid level meter pipeline 15. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different perspectives and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features within these embodiments may be combined with one another, unless they conflict.

[0026] It should be noted that the illustrations provided in the following embodiments are merely schematic illustrations of the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed at will, and the component layout may also be more complex.

[0027] See Figure 1 To achieve the above-mentioned purpose and other related purposes, the present invention provides a liquid level calibration device, comprising a water tank 1, a quantitative water injection unit and a quick water injection unit, the water tank 1 being connected to a water inlet pipeline 11 through a main valve 12, and a liquid level control valve 3 being provided on the water inlet pipeline 11; the quantitative water injection unit comprising a quantitative water pump 4, which is connected to the water tank 1 through a hose 6, and a one-way valve 5 is provided at the connection point; the quick water injection unit comprising a liquid level gauge pipeline 15, one end of the liquid level gauge pipeline 15 being connected to the water inlet pipeline 11 through a water supply valve 10, and the other end being connected to the quantitative water pump 4; wherein, the liquid level gauge pipeline 15 is provided with at least three branches, one of which is connected to the water tank 1 through a drain valve 13.

[0028] As one embodiment of the present utility model, when in use, a first branch, a second branch and a third branch are provided on the liquid level gauge pipeline 15. The first branch is connected to the local liquid level gauge through the first valve 8, the second branch is connected to the remote liquid level gauge through the second valve 9, and the third branch is connected to the upper part of the water tank 1 through the drain valve 13.

[0029] It should be noted that remote level gauges can transmit measurement data in real time to a remote control room or monitoring system, allowing operators to check the liquid level status at any time. On-site level gauges, on the other hand, provide direct access to the liquid level, facilitating on-site operators to make quick judgments and decisions. Remote and on-site level gauges are typically paired, and their measurement results should be consistent to ensure accuracy. If there is a significant discrepancy between the two readings, it is necessary to investigate possible faults or errors, which may involve sensor failure, improper installation, or other external factors. It is also crucial for individual level gauges to ensure their level accuracy. Therefore, regular calibration of level gauges is necessary.

[0030] First, the aforementioned rapid water injection unit rapidly fills the connected liquid level gauges with water and observes the response time of the liquid level gauges to changes in liquid level. If the liquid level gauge readings quickly reflect changes in liquid level, the equipment is functioning properly. Next, the quantitative water injection unit extracts a fixed amount of water from the water tank 1 (liquid at a known height) and delivers equal amounts to the remote level gauge and the local level gauge through the first valve 8 and the second valve 9. The readings displayed by the remote level gauge and the local level gauge are observed, respectively. The liquid level at the known height is gradually increased, and the level gauge readings at different heights are recorded. Finally, the water is continuously drained through the drain valve 13, and the level gauge readings are observed. By observing horizontally, that is, observing the readings of the remote level gauge and the local level gauge simultaneously, it can be determined whether the liquid level displayed by the remote level gauge and the local level gauge are consistent. If they are inconsistent, it is highly likely that the remote level gauge is malfunctioning. By observing vertically, that is, taking the readings of a single remote level gauge or local level gauge, the level gauge readings at different heights are recorded under continuous water inflow or outflow conditions. It can reflect the precise adjustment of the liquid level, compare the level gauge reading with the liquid level at a known height, and record the error, which can ensure the accuracy and reliability of the level gauge and support effective liquid level monitoring and control when the level gauge is used.

[0031] As one embodiment of the present utility model, a first branch, a second branch and a third branch are provided on the liquid level gauge pipeline. The first branch is connected to the liquid level switch through the first valve 8, the second branch is connected to a vertically arranged observation tube through the second valve 9, and the third branch is connected to the upper part of the water tank through the drain valve.

[0032] Furthermore, since the liquid level switch has no local display, the sight tube can accurately verify the operating height of the liquid level switch.

[0033] As one embodiment of the present invention, the quantitative water pump 4 is a volumetric quantitative water pump, including a pump body and a water pumping cylinder. One end of the water pumping cylinder is connected to the pump body, and the other end passes through the top of the water tank 1 and is provided with a one-way valve 5.

[0034] It should be noted that the quantitative water pump 4 can extract water of a known height from the water tank 1 , and the one-way valve 5 prevents the water from flowing back into the water tank 1 .

[0035] As one embodiment of the present invention, the liquid level gauge pipeline 15 includes a horizontal section and a vertical section. The vertical section is arranged parallel to the height direction of the water tank 1, and the horizontal section is connected to the water pump of the quantitative water pump 4. The vertical section of the liquid level gauge pipeline 15 is provided with a first branch, a third branch, and a second branch from top to bottom.

[0036] As one embodiment of the present invention, an overflow pipe 2 is further provided in the water tank 1 , and the water inlet of the overflow pipe 2 is higher than the height of the liquid level control valve 3 and lower than the height of the connection point between the third branch and the water tank 1 .

[0037] It should be noted that the liquid level control valve 3 controls the set water level height of the water tank 1 to its installation height. At this time, the water inlet is higher than the height of the liquid level control valve 3. When the water level exceeds the height of the liquid level control valve 3, the water is discharged to the outside. At the same time, a drain valve 13 is provided on the third branch, which is a precise control of the liquid level gauge when draining water. The water of the liquid level gauge passes through the first branch and the second branch to the third branch and is discharged to the water tank 1. Therefore, the connection between the third branch and the water tank 1 needs to be higher than the set water level height of the water tank 1.

[0038] As one embodiment of the present invention, a drain pipe is provided on the water inlet pipeline 11 , and a quick discharge valve 14 is provided on the drain pipe.

[0039] As one of the embodiments of the present invention, the water inlet pipeline 11 includes an inner water inlet pipe and an outer water inlet pipe respectively arranged inside and outside the water tank 1. The inner water inlet pipe is arranged parallel to the height direction of the water tank 1. The lower part of the inner water inlet pipe is connected with the outer water inlet pipe, and a liquid level control valve 3 is provided at its upper end.

[0040] One embodiment of the present invention further includes a drain pipe having a drain valve 7 disposed thereon. The drain pipe is connected to the bottom of the water tank 1 and the outlet of the overflow pipe 2. The overflow pipe 2 is an L-shaped elbow, with the vertical section of the L-shaped elbow disposed within the water tank 1 and the horizontal section extending out of the water tank 1, the end of the L-shaped elbow serving as the outlet of the overflow pipe 2.

[0041] In summary, the specific working process of a liquid level calibration device of the present invention includes:

[0042] Before the test, place water tank 1 on site and close all isolation valves on it. Connect water tank 1 to the water inlet pipeline 11 and the water source. Open main valve 12 to fill water tank 1. Actuate liquid level control valve 3 to maintain the set liquid level in tank 1. Close first valve 8 and second valve 9, and open the exhaust valves on the local and remote level gauges.

[0043] The test included the following two situations: In the first situation, the first branch was connected to the local level gauge, and the second branch was connected to the remote level gauge, and the level gauge test was performed. The first valve 8 and the second valve 9 were opened, and the water supply valve 10 was slowly opened. The level gauge quickly filled with water and began to display the liquid level. The water supply valve 10 was closed. The quantitative water pump 4 was used to slowly raise the liquid level of the level gauge to obtain the liquid level display of the local level gauge and the remote level gauge. The drain valve 13 was slowly opened, and the local level gauge and the remote level gauge lowered synchronously. The water was discharged from the water tank 1 through the overflow pipe 2. During the test, the quick discharge valve 14 was opened to achieve rapid adjustment of the liquid level.

[0044] The second situation: the first branch is connected to the liquid level switch, and the second branch is connected to the observation tube, and the liquid level switch test is carried out. Open the first valve 8 and the second valve 9, slowly open the water supply valve 10, the liquid level switch quickly fills with water, the liquid level switch operates, close the water supply valve 10, slowly open the drain valve 13, the liquid level switch recovers, and close the drain valve 13. Use the quantitative water pump 4 to slowly increase the liquid level height of the liquid level switch, the liquid level switch operates, stop pressurizing, open the drain valve 13, and the liquid level switch recovers. During the test, through the auxiliary measuring device (i.e., the vertically arranged observation tube connected to the second branch), it was found that the liquid level exceeded the liquid level switch operation height, the liquid level switch could not operate, the water supply was stopped, and the liquid level switch float was stuck.

[0045] After the test is completed, close the main valve 12 and open the drain valve 7 to quickly drain the remaining water in the water tank 1 and the pipeline.

[0046] It can be seen that (1) when the liquid level calibration device of the present invention is used to calibrate the liquid level meter, it can record the liquid level meter readings at different heights under continuous water inflow or outflow, reflecting the precise adjustment of its liquid level, and compare the liquid level meter readings with the liquid level at a known height, calculate the error and analyze the measurement accuracy of the liquid level meter.

[0047] (2) When the liquid level calibration device is used to calibrate a liquid level quick-close switch, when the liquid level reaches the set high level, confirm whether the switch switches smoothly (e.g., from closed to open). Similarly, when the liquid level drops and reaches the set low level, check whether the switch switches back to its original state (e.g., from open to closed). Record the switch response time, the reliability of the switching state, and the corresponding relationship between the liquid level and the switch response.

[0048] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed in the present invention are intended to be covered by the claims of the present invention.

[0049] In the description herein, many specific details, such as examples of components and / or methods, are provided to provide a complete understanding of the embodiments of the present invention. However, those skilled in the art will recognize that embodiments of the present invention can be practiced without one or more of the specific details or with other devices, systems, components, methods, components, materials, parts, etc. In other cases, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of the embodiments of the present invention.

[0050] Reference throughout this specification to "one embodiment," "an embodiment," or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and not necessarily in all embodiments. Thus, various appearances of the phrases "in one embodiment," "in an embodiment," or "in a specific embodiment" in different places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the invention may be combined with one or more other embodiments in any suitable manner. It should be understood that other variations and modifications of the embodiments of the invention described and illustrated herein are possible in light of the teachings herein and are considered part of the spirit and scope of the invention.

[0051] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separate or more integrated manner, or even removed because they are inoperable in certain circumstances or provided because they may be useful depending on the application.

[0052] In addition, unless otherwise expressly indicated, any marking arrows in the drawings should be regarded as illustrative only and not limiting. Furthermore, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or." Where a term is unclear in providing separation or combination capabilities, the combination of components or steps will also be considered as indicated.

[0053] As used in the description herein and throughout the claims that follow, “a,” “an,” and “the” include plural references unless otherwise indicated. Likewise, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless otherwise indicated.

[0054] The above description of the illustrated embodiments of the present invention (including that described in the Abstract) is not intended to be exhaustive or to limit the present invention to the precise forms disclosed herein. Although specific embodiments of the present invention and examples of the present invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the art will recognize and understand. As noted, these modifications may be made to the present invention in light of the above description of the illustrated embodiments of the present invention, and these modifications will be within the spirit and scope of the present invention.

[0055] The systems and methods have been generally described herein in detail to facilitate understanding of the present invention. In addition, various specific details have been given to provide an overall understanding of the embodiments of the present invention. However, those skilled in the relevant art will recognize that the embodiments of the present invention can be practiced without one or more of the specific details, or can be practiced using other devices, systems, accessories, methods, components, materials, parts, etc. In other cases, well-known structures, materials, and / or operations are not specifically shown or described in detail to avoid confusing various aspects of the embodiments of the present invention.

[0056] Thus, although the present invention has been described herein with reference to specific embodiments thereof, freedom of modification, various changes and substitutions are within the foregoing disclosure, and it should be understood that in some cases, some features of the present invention will be employed without the corresponding use of other features without departing from the scope and spirit of the proposed invention. Thus, many modifications may be made to adapt particular circumstances or materials to the true scope and spirit of the present invention. The present invention is not intended to be limited to the specific terminology used in the claims below and / or to the specific embodiments disclosed as the best mode contemplated for carrying out the invention, but the present invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Therefore, the scope of the present invention will be determined solely by the appended claims.

Claims

1. A liquid level calibration device, characterized in that: include: A water tank (1), the water tank (1) is connected to a water inlet pipeline (11) via a main valve (12), and the water inlet pipeline (11) is provided with a liquid level control valve (3); A quantitative water injection unit, comprising a quantitative water pump (4), wherein the quantitative water pump (4) and the water tank (1) are connected via a hose (6), and a one-way valve (5) is provided at the connection point; A fast water injection unit, comprising a liquid level gauge pipeline (15), one end of which is connected to the water inlet pipeline (11) via a water supply valve (10), and the other end of which is connected to the quantitative water pump (4); The liquid level meter pipeline (15) is provided with at least three branches, one of which is connected to the water tank (1) via a drain valve (13).

2. The liquid level calibration device according to claim 1, characterized in that: The liquid level meter pipeline (15) is provided with a first branch, a second branch and a third branch. The first branch is connected to the local liquid level meter via a first valve (8), the second branch is connected to the remote liquid level meter via a second valve (9), and the third branch is connected to the upper part of the water tank (1) via the drain valve (13).

3. The liquid level calibration device according to claim 1, characterized in that: The liquid level gauge pipeline (15) is provided with a first branch, a second branch and a third branch. The first branch is connected to the liquid level switch via a first valve (8), the second branch is connected to a vertically arranged observation tube via a second valve (9), and the third branch is connected to the upper part of the water tank (1) via the drain valve (13).

4. The liquid level calibration device according to claim 2 or 3, characterized in that: The quantitative water pump (4) is a volumetric quantitative water pump, comprising a pump body and a water pumping cylinder. One end of the water pumping cylinder is connected to the pump body, and the other end passes through the top of the water tank (1) and is provided with the one-way valve (5).

5. The liquid level calibration device according to claim 4, characterized in that: The liquid level gauge pipeline (15) comprises a horizontal section and a vertical section, wherein the vertical section is arranged parallel to the height direction of the water tank (1), and the horizontal section is connected to the water pump cylinder of the quantitative water pump (4); the vertical section is provided with the first branch, the third branch and the second branch in sequence from top to bottom.

6. The liquid level calibration device according to claim 5, characterized in that: An overflow pipe (2) is also provided in the water tank (1), and the water inlet of the overflow pipe (2) is higher than the height of the liquid level control valve (3) and lower than the height of the connection point between the third branch and the water tank (1).

7. The liquid level calibration device according to claim 6, characterized in that: The water inlet pipeline (11) is provided with a drain pipe, and the drain pipe is provided with a quick discharge valve (14).

8. The liquid level calibration device according to claim 7, characterized in that: The water inlet pipeline (11) comprises an inner water inlet pipe and an outer water inlet pipe respectively arranged inside and outside the water tank (1); the inner water inlet pipe is arranged parallel to the height direction of the water tank (1); the lower portion of the inner water inlet pipe is connected to the outer water inlet pipe, and the upper end thereof is provided with the liquid level control valve (3).

9. The liquid level calibration device according to claim 8, characterized in that: It also includes a sewage pipe, on which a sewage valve (7) is provided. The sewage pipe is respectively connected to the bottom of the water tank (1) and the water outlet of the overflow pipe (2).

10. The liquid level calibration device according to claim 9, characterized in that: The overflow pipe (2) is an L-shaped elbow, the vertical section of the L-shaped elbow is arranged in the water tank (1), the horizontal section of the L-shaped elbow extends out of the water tank (1), and the end thereof is the water outlet of the overflow pipe (2).

Images