Water flow calibration system suitable for small flow regulation

Abstract

The invention belongs to the technical field of metering instruments, and particularly relates to a water flow calibration system suitable for small flow adjustment. Comprising a flow generating and adjusting device, a constant flow maintaining device and a flow detecting device, the flow generating and adjusting device is used for achieving water flow supply and circulation of a system, keeping the liquid level of an upper water tank water level pool and a lower water tank water level pool constant, achieving stable flowing of water flow in the device and meanwhile controlling the height difference change of the two liquid levels. The micro adjustment of the water flow is realized; the constant-flow maintaining device is used for supplementing water to the upper water tank water storage pond and maintaining the water level in the upper water tank water storage pond to be constant. The flow detection device is used for completing liquid flow calibration work through a standard method and a quality detection method. The problems that an existing traditional water flow calibration device cannot guarantee stable flowing of water flow in the device, and small flow adjustment cannot be conveniently and rapidly conducted are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of metering instruments, and more specifically, it is a water flow calibration system suitable for small flow regulation. Background Art

[0002] Water flow calibration equipment is a type of precision metering device. With the development of social economy and the enhancement of environmental protection awareness, accurately measuring water flow is crucial for multiple industries such as water supply systems, sewage treatment plants, irrigation systems, and industrial cooling cycles. Water flow calibration equipment helps to accurately measure water flow, prevent waste, and thus enable reasonable water resource allocation; in industrial production, they help optimize process control, improve efficiency, reduce resource consumption, and ensure the consistency of product quality. The scientific research field relies on such equipment for basic research and the development of new technical solutions.

[0003] Currently, most existing water flow calibration devices choose to combine the static mass method and the standard method for water flow testing. The static mass method calculates the flow rate by measuring the mass of water collected within a specific time; the standard method realizes high-efficiency water flow calibration by connecting the standard detection pipeline in series with the pipeline to be measured. The standard method uses a standard flow detector and the flowmeter to be tested connected in series for flow detection; and currently in most devices, the calibration device generally uses a water pump for flow supply. The water flow supplied by such a method fluctuates and cannot ensure the stability of the water flow, thus causing noise interference to the standard flow detection equipment and resulting in inaccurate calibration flow rates during specific calibrations. At the same time, such a detection method generally cannot adjust the flow rate in a timely manner and requires manual control of the water valve of the water pump to adjust the flow rate. This method is cumbersome to operate and has low detection and adjustment efficiency.

[0004] Therefore, it is necessary to study a water flow calibration device that combines the static mass method and the standard method. This device shares a water source, a test pipeline, and a control system, can achieve stable calibration of water flow, and at the same time realizes precise adjustment of small flow rates through a simple structure, with the characteristics of convenient operation and high detection efficiency. Summary of the Invention

[0005] Aiming at the deficiencies existing in the prior art, the present invention provides a water flow calibration system suitable for small flow regulation, which is used to solve the problems existing in the existing traditional water flow calibration devices, namely, the inability to ensure the stable flow of water in the device and the inability to conveniently and quickly adjust small flow rates.

[0006] To solve the above technical problems, the present invention is a water flow calibration system suitable for small flow regulation, including a flow generation and regulation device, a constant flow maintenance device, and a flow detection device. The flow generation and regulation device is used to supply and circulate the water flow of the system, keep the liquid levels of the upper water tank water level pool and the lower water tank water level pool constant, realize the stable flow of water in the device, and at the same time control the change of the height difference between the two liquid levels to achieve fine adjustment of the water flow; the constant flow maintenance device is used to supplement water to the upper water tank reservoir and maintain the water level in the upper water tank water level pool constant; the flow detection device is used to complete the liquid flow calibration work by using the standard method and the mass detection method.

[0007] As a further optimization of the present invention, in a water flow calibration system suitable for small flow regulation of the present invention, the upper water tank is fixed on the first rack, and a vertical upper water tank baffle is fixed inside the upper water tank. The height of the upper water tank baffle is lower than the height of the tank wall of the upper water tank. The left and right sides of the upper water tank baffle are the upper water tank reservoir and the upper water tank water level pool respectively. A first water pump is fixed in the upper water tank reservoir. One end of the soft water pipe of the first water pump is connected to the first water pump, and the other end of the soft water pipe of the first water pump is placed in the upper water tank water level pool;

[0008] The lower water tank is fixed on the second rack, and a vertical lower water tank baffle is fixed inside the lower water tank. The left and right sides of the lower water tank baffle are the lower water tank reservoir and the lower water tank water level pool respectively; an electric ball valve is installed at the water outlet of the lower water tank reservoir. One end of the third liquid supply pipe is connected to the electric ball valve, and the other end of the third liquid supply pipe is placed in the weighing water tank. A second water pump is installed inside the weighing water tank. The second water pump is connected to the single-chip microcomputer and the relay through wires. One end of the soft water pipe of the second water pump is connected to the second water pump, and the other end of the soft water pipe of the second water pump is placed in the water pool;

[0009] One end of the first liquid supply pipe is connected to the water outlet of the upper water tank water level pool, the other end of the first liquid supply pipe is connected to the standard flowmeter, the end of the standard flowmeter is connected to the flowmeter under test, and one end of the second liquid supply pipe is connected to the end of the flowmeter under test, and the other end of the second liquid supply pipe is placed in the lower water tank water level pool.

[0010] As a further optimization of the present invention, in a water flow calibration system suitable for small flow regulation of the present invention, a third water pump is installed in the water pool. One end of the soft water pipe of the third water pump is connected to the third water pump, and the other end of the soft water pipe of the third water pump is connected to the upper water tank reservoir. A double float switch is installed on one side of the upper water tank reservoir. The double float switch is connected to the single-chip microcomputer and the relay through wires. The single-chip microcomputer and the relay are installed on the first rack.

[0011] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention has a plurality of the standard flow meters placed in series at the same height, and the plurality of standard flow meters are integrally installed on a one-dimensional sliding table, and the one-dimensional sliding table can drive the plurality of standard flow meters to move up and down synchronously; an electronic scale is installed below the weighing water tank.

[0012] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention has the first water pump in the upper water tank reservoir always kept in an open state during the working state, ensuring that the water level in the upper water tank water level pool is always the same as the height of the upper water tank baffle. In the working state of the lower water tank water level pool, it is ensured that the water level height in the lower water tank water level pool is the same as the height of the lower water tank baffle, so that the height difference between the upper and lower liquid levels remains unchanged and the water flow is stable.

[0013] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention controls the one-dimensional sliding table to drive the standard flow meter and the flow meter under test to move up and down through a single-chip microcomputer and a relay, and can utilize the hydraulic difference to achieve fine adjustment of the water flow under the condition that the water levels in the upper water tank water level pool and the lower water tank water level pool remain constant and the outlet size remains unchanged.

[0014] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention, after completing a flow calibration, the single-chip microcomputer and the relay can send a control signal to the second water pump to control the second water pump to transfer the water in the weighing water tank to the water pool.

[0015] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention, the minimum flow that the water flow calibration system can adjust is 0.006m 3 / h.

[0016] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention has the position of the upper floating ball in the double floating ball switch lower than the upper water tank baffle, and the position of the lower floating ball in the double floating ball switch higher than the lowest water supply height of the first water pump. When the lower floating ball moves to the lower limit position, the single-chip microcomputer receives this signal and controls the relay to drive the third water pump to supply water to the upper water tank reservoir; when the upper floating ball moves to the upper limit position, the single-chip microcomputer receives the signal and controls the relay to stop the third water pump from supplying water to the upper water tank reservoir.

[0017] As a further optimization of the present invention, a water flow calibration system suitable for small flow regulation of the present invention places the corresponding number of the flow meters under test as required, and a plurality of the flow meters under test are connected end to end with each other for standard method flow calibration;

[0018] The flow calibration by the mass detection method is completed through the cooperation of the electronic scale and the weighing water tank.

[0019] The beneficial effects of a water flow calibration system suitable for small flow regulation according to the present invention are as follows:

[0020] 1. The present invention discloses a water flow calibration system suitable for small flow regulation. By always keeping the water levels in the upper and lower water tanks full, the stable flow of water in the device is ensured. A one-dimensional sliding table is installed below the standard flowmeter and the flowmeter to be tested. While ensuring the stable water flow, the height difference between the two liquid levels is controlled by the up and down movement of the one-dimensional sliding table, thereby realizing the fine adjustment of the water flow. This method effectively ensures the accuracy and stability of water flow calibration and improves the detection efficiency.

[0021] 2. The present invention discloses a water flow calibration system suitable for small flow regulation. Through the cooperation of a double float switch, a single-chip microcomputer and a water pump, the automatic replenishment of the water volume in the storage pool is realized. At any flow rate, the water volume in the upper water tank storage pool can be replenished in time and the full water level of the upper water tank water level pool can be ensured, effectively ensuring sufficient water supply and the stability of the liquid level. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below with reference to the drawings and specific implementation methods.

[0023] Figure 1 It is a schematic diagram of the flow generation and regulation device of the present invention;

[0024] Figure 2 It is a schematic diagram of the overall structure of the present invention.

[0025] In the figure: Flow generation and regulation device A; Upper water tank 1; Upper water tank water level pool 2; First water pump soft water pipe 3; Upper water tank storage pool 4; First water pump 5; Upper water tank baffle 6; First rack 7; First liquid supply pipe 8; Lower water tank baffle 9; Second liquid supply pipe 10; Lower water tank water level pool 11; Lower water tank storage pool 12; Lower water tank 13; Second rack 14; Weighing water tank 15; Electric ball valve 16; Third liquid supply pipe 17; Second water pump 18; Second water pump soft water pipe 19;

[0026] Constant flow maintenance device B; Third water pump 20; Water pool 21; Third water pump soft water pipe 22; Single-chip microcomputer and relay 23; Double float switch 24;

[0027] Flow detection device C; Standard flowmeter 25; Flowmeter to be tested 26; One-dimensional sliding table 27; Electronic scale 28. SPECIFIC EMBODIMENTS

[0028] As Figure 1-2 shown, the present invention provides a water flow calibration system suitable for small flow regulation, including a flow generation and regulation device A, a constant flow maintenance device B and a flow detection device C;

[0029] The flow rate generation and regulation device A includes an upper water tank 1, an upper water tank water level pool 2, a first water pump flexible water pipe 3, an upper water tank storage pool 4, a first water pump 5, an upper water tank baffle 6, a first mounting rack 7, a first liquid supply pipe 8, a lower water tank baffle 9, a second liquid supply pipe 10, a lower water tank water level pool 11, a lower water tank storage pool 12, a lower water tank 13, a second mounting rack 14, a weighing water tank 15, an electric ball valve 16, a third liquid supply pipe 17, a second water pump 18, and a second water pump flexible water pipe 19;

[0030] The constant flow rate maintaining device B includes a third water pump 20, a water pool 21, a third water pump flexible water pipe 22, a single-chip microcomputer and relay 23, and a double float switch 24;

[0031] The flow rate detection device C includes a standard flowmeter 25, a flowmeter to be tested 26, a one-dimensional sliding table 27, and an electronic scale 28.

[0032] The flow rate generation and regulation device A is used to realize the water flow supply and circulation of the system, keep the liquid levels of the upper water tank water level pool 2 and the lower water tank water level pool 11 constant, realize the stable flow of water in the device, and at the same time control the change of the height difference between the two liquid levels to realize the micro-regulation of the water flow rate; the constant flow rate maintaining device B is used to supplement water to the upper water tank storage pool 4 and maintain the constant water level in the upper water tank water level pool 2; the flow rate detection device C is used to complete the liquid flow rate calibration work by using the standard method and the mass detection method.

[0033] The upper water tank 1 is fixed on the first mounting rack 7. A vertical upper water tank baffle 6 is fixed inside the upper water tank 1. The height of the upper water tank baffle 6 is lower than the height of the tank wall of the upper water tank 1. The left and right sides of the upper water tank baffle 6 are respectively the upper water tank storage pool 4 and the upper water tank water level pool 2. A first water pump 5 is fixed in the upper water tank storage pool 4. One end of the first water pump flexible water pipe 3 is connected to the first water pump 5, and the other end of the first water pump flexible water pipe 3 is placed in the upper water tank water level pool 2;

[0034] The lower water tank 13 is fixed on the second mounting rack 14. A vertical lower water tank baffle 9 is fixed inside the lower water tank 13. The left and right sides of the lower water tank baffle 9 are respectively the lower water tank storage pool 12 and the lower water tank water level pool 11; An electric ball valve 16 is installed at the water outlet of the lower water tank storage pool 12. One end of the third liquid supply pipe 17 is connected to the electric ball valve 16, and the other end of the third liquid supply pipe 17 is placed in the weighing water tank 15. A second water pump 18 is installed inside the weighing water tank 15. The second water pump 18 is connected to the single-chip microcomputer and relay 23 through an electric wire. One end of the second water pump flexible water pipe 19 is connected to the second water pump 18, and the other end of the second water pump flexible water pipe 19 is placed in the water pool 21;

[0035] One end of the first liquid supply pipe 8 is connected to the water outlet of the upper water tank water level pool 2, the other end of the first liquid supply pipe 8 is connected to the standard flowmeter 25, the end of the standard flowmeter 25 is connected to the flowmeter under test 26, one end of the second liquid supply pipe 10 is connected to the end of the flowmeter under test 26, and the other end of the second liquid supply pipe 10 is placed in the lower water tank water level pool 11.

[0036] A third water pump 20 is installed in the water pool 21. One end of the third water pump soft water pipe 22 is connected to the third water pump 20, and the other end of the third water pump soft water pipe 22 is connected to the upper water tank storage pool 4. A double float switch 24 is installed on one side of the upper water tank storage pool 4. The double float switch 24 is connected to the single-chip microcomputer and relay 23 through an electric wire. The single-chip microcomputer and relay 23 are installed on the first frame 7.

[0037] Multiple standard flowmeters 25 are placed in series at the same height. The multiple standard flowmeters 25 are integrally installed on a one-dimensional sliding table 27. The one-dimensional sliding table 27 can drive the multiple standard flowmeters 25 to move up and down synchronously. An electronic scale 28 is installed below the weighing water tank 15. The standard flowmeter 25 and the flowmeter under test 26 are placed at the same height to ensure that the water flow velocity through the standard flowmeter 25 and the flowmeter under test 26 is the same, and further ensure that the flow through the standard flowmeter 25 and the flowmeter under test 26 is the same within the same time.

[0038] The one-dimensional sliding table 27 includes three parts: a motor, a lead screw, and a sliding table. The single-chip microcomputer sends a pulse signal to the driver. The driver drives the motor to control the rotation of the lead screw. A sliding table is installed on the lead screw. The standard flowmeter 25 and the flowmeter under test 26 are fixed on the sliding table. The rotation of the lead screw drives the sliding table to move up and down.

[0039] Standard method flow calibration means: using the standard flowmeter 25 and the flowmeter under test 26 in series for water flow calibration. The standard flowmeter 25 is a flowmeter that can work normally after debugging, while the flowmeter under test 26 refers to a flowmeter that has not been debugged and it is not known whether it can work normally.

[0040] The first water pump 5 in the upper water tank storage pool 4 is always kept open during the working state to ensure that the water level of the upper water tank water level pool 2 is always the same as the height of the upper water tank baffle 6. During the working state of the lower water tank water level pool 11, it is ensured that the water level height of the lower water tank water level pool 11 is the same as the height of the lower water tank baffle 9, so that the height difference between the upper and lower liquid levels remains unchanged and the water flow is stable.

[0041] By controlling the one-dimensional sliding table 27 to drive the standard flowmeter 25 and the flowmeter under test 26 to move up and down through the single-chip microcomputer and relay 23, it is possible to utilize the hydraulic pressure difference to achieve a fine adjustment of the water flow under the condition that the water levels of the upper water tank water level pool 2 and the lower water tank water level pool 11 remain constant and the outlet size remains unchanged.

[0042] After completing a flow rate calibration, the single-chip microcomputer and the relay 23 can send a control signal to the second water pump 18 to control the second water pump 18 to transfer the water in the weighing water tank 15 to the water pool. The water flow in the flow rate detection device C is detected once within a period of time or at a certain flow rate. Before each re-detection, the water in the weighing water tank 15 needs to be transported to the water pool 21 through the third water pump 20 for the next detection.

[0043] The minimum flow rate that the water flow calibration system can adjust is 0.006m 3 / h.

[0044] In the double float switch 24, the position of the upper float ball is lower than the upper water tank baffle 6, and the position of the lower float ball in the double float switch 24 is higher than the lowest water supply height of the first water pump 5. When the lower float ball moves to the lower limit position, the single-chip microcomputer receives this signal and controls the relay to drive the third water pump 20 to supply water to the upper water tank storage pool 4; when the upper float ball moves to the upper limit position, the single-chip microcomputer receives the signal and controls the relay to stop the third water pump 20 from supplying water to the upper water tank storage pool 4.

[0045] The upper water tank water level pool 2 and the lower water tank water level pool 11 are used to keep the height difference between the upper and lower liquid levels constant. Among them, after the lower water tank water level pool 11 is filled with water, the electric ball valve 16 is opened for operation. The upper water tank water level pool 2 needs to always maintain a full water level and the water level in the upper water tank storage pool 4 cannot be higher than the upper water tank baffle 6 to prevent the water level height of the upper water tank 1 from changing and affecting the water flow calibration. The double float switch 24 is used to realize water level control. When the water level is at the lower limit, the single-chip microcomputer drives the third water pump 20 to supply water to the upper water tank storage pool 4. When the upper float ball moves to the upper limit, the third water pump 20 is stopped from supplying water to the upper water tank storage pool 4.

[0046] The double float switch 24 is a mechanical device for liquid level control. The double float switch contains two independent float balls, which are respectively used to detect the high liquid level and the low liquid level. When the liquid level rises, the float ball will float with the liquid level; on the contrary, when the liquid level drops, the float ball will sink. For high liquid level control, when the liquid level rises to the preset height, the upper float ball will trigger the corresponding switch action to close the water pump and stop the water supply. When the liquid level drops to the preset height, the lower float ball will trigger the corresponding switch action to open the water pump for water supply.

[0047] The corresponding number of the to-be-tested flowmeters 26 is placed according to requirements, and multiple to-be-tested flowmeters 26 are connected end to end with each other for standard method flow calibration;

[0048] Through the cooperation of the electronic scale 28 and the weighing water tank 15, the flow calibration by the mass detection method is completed.

[0049] The purpose of the static mass detection method is the same as that of the standard method, that is, to determine whether the calibrated flow rate of the flowmeter 26 to be tested precisely meets the requirements within a certain period of time or during a single calibration. The specific implementation method is as follows: during a single flow calibration, the electric ball valve 16 is in the open state, and the water flowing through the standard flowmeter 25 and the flowmeter 26 to be tested flows into the weighing tank 15. When a single flow calibration is completed, the electric ball valve 16 is closed. At this time, in addition to being able to view the water flow indication in the standard flowmeter 25, the user can also view the indication in the electronic scale 28, that is, the mass of the water in this water flow calibration. By dividing the mass by the density, the volume of the water in this water flow calibration can be obtained. Dividing this volume by the time used for this flow calibration can obtain the flow rate of this flow calibration. This method can achieve small flow detection and can also be used as a way to verify the standard detection method. Subsequently, the water flow detected last time in the weighing tank 15 is pumped away by the third water pump 20, and then the next flow detection can be carried out.

Claims

1. A water flow calibration system suitable for small flow regulation, comprising a flow generation and regulation device (A), a constant flow maintenance device (B) and a flow detection device (C), characterized in that: The flow generation and regulation device (A) is used to realize the water flow supply and circulation of the system, maintain the liquid level of the upper water tank water level pool (2) and the lower water tank water level pool (11) constant, realize the stable flow of water in the device, and control the change of the height difference between the two liquid levels at the same time to realize the slight regulation of the water flow; the constant flow maintenance device (B) is used to replenish the water volume of the upper water tank water storage pool (4) and maintain the water level in the upper water tank water level pool (2) constant; the flow detection device (C) is used to complete the liquid flow calibration work by using the standard method and the quality detection method.

2. A water flow calibration system suitable for small flow regulation according to claim 1, characterized in that: The upper water tank (1) is fixed on the first stand (7), a vertical upper water tank baffle (6) is fixed inside the upper water tank (1), the height of the upper water tank baffle (6) is lower than the height of the box wall of the upper water tank (1), the left and right sides of the upper water tank baffle (6) are respectively the upper water tank water storage tank (4) and the upper water tank water level tank (2), a first water pump (5) is fixed inside the upper water tank water storage tank (4), one end of the first water pump soft water pipe (3) is connected to the first water pump (5), and the other end of the first water pump soft water pipe (3) is placed in the upper water tank water level tank (2); The lower water tank (13) is fixed on the second stand (14), a vertical lower water tank baffle (9) is fixed in the lower water tank (13), and the left and right sides of the lower water tank baffle (9) are respectively the lower water tank water storage tank (12) and the lower water tank water level tank (11); an electric ball valve (16) is installed at the water outlet of the lower water tank water storage tank (12), one end of the third liquid supply pipe (17) is connected to the electric ball valve (16), and the other end of the third liquid supply pipe (17) is placed in the weighing water tank (15), and a second water pump (18) is installed inside the weighing water tank (15), and the second water pump (18) is connected to the single chip microcomputer and the relay (23) through electric wires, and one end of the second water pump soft water pipe (19) is connected to the second water pump (18), and the other end of the second water pump soft water pipe (19) is placed in the water tank (21); One end of the first liquid supply pipe (8) is connected to the water outlet of the upper water tank water level pool (2), the other end of the first liquid supply pipe (8) is connected to the standard flow meter (25), the end of the standard flow meter (25) is connected to the flow meter to be tested (26), one end of the second liquid supply pipe (10) is connected to the end of the flow meter to be tested (26), and the other end of the second liquid supply pipe (10) is placed in the lower water tank water level pool (11).

3. A water flow calibration system suitable for small flow regulation according to claim 2, characterized in that: A third water pump (20) is installed in the water pool (21); one end of the third water pump soft water pipe (22) is connected to the third water pump (20); the other end of the third water pump soft water pipe (22) is connected to the upper water tank (4); a double float switch (24) is installed on one side of the upper water tank (4); the double float switch (24) is connected to a single-chip microcomputer and a relay (23) through electric wires; the single-chip microcomputer and the relay (23) are installed on the first stand (7).

4. A water flow calibration system suitable for small flow regulation according to claim 2, characterized in that: A plurality of the standard flow meters (25) are placed in series at the same height, and the plurality of standard flow meters (25) are integrally mounted on a one-dimensional slide (27), and the one-dimensional slide (27) can drive the plurality of standard flow meters (25) to move up and down synchronously; an electronic scale (28) is mounted below the weighing water tank (15).

5. A water flow calibration system suitable for small flow regulation according to claim 2, characterized in that: The first water pump (5) in the upper water tank reservoir (4) is kept in an open state when in operation, ensuring that the water level of the upper water tank water level pool (2) is always at the same height as the upper water tank baffle (6); the lower water tank water level pool (11) is kept in an operating state, ensuring that the water level of the lower water tank water level pool (11) is at the same height as the lower water tank baffle (9), so that the height difference between the upper and lower liquid levels remains unchanged and the water flow rate is stable.

6. A water flow calibration system suitable for small flow regulation according to claim 3, characterized in that: By controlling a one-dimensional slide table (27) through a single chip computer and a relay (23), the standard flow meter (25) and the flow meter to be tested (26) are driven to move up and down, and the water level of the upper water tank water level pool (2) and the lower water tank water level pool (11) is kept constant and the size of the water outlet is unchanged, the hydraulic pressure difference can be used to achieve a slight adjustment of the water flow rate.

7. A water flow calibration system suitable for small flow regulation according to claim 6, characterized in that: After completing a flow calibration, the single chip microcomputer and the relay (23) can control the second water pump (18) to transfer the water in the weighing water tank (15) to the water pool by sending a control signal to the second water pump (18).

8. A water flow calibration system suitable for small flow regulation according to claim 7, characterized in that: The minimum flow rate that the water flow calibration system can adjust is 0.006m 3 / h.

9. A water flow calibration system suitable for small flow regulation according to claim 3, characterized in that: The position of the upper float in the double float switch (24) is lower than the upper water tank baffle (6), and the position of the lower float in the double float switch (24) is higher than the lowest water supply height of the first water pump (5). When the lower float moves to the lower limit position, the single chip microcomputer receives the signal and controls the relay to drive the third water pump (20) to supply water to the upper water tank reservoir (4); when the upper float moves to the upper limit position, the single chip microcomputer receives the signal and controls the relay to stop the third water pump (20) from supplying water to the upper water tank reservoir (4).

10. A water flow calibration system suitable for small flow regulation according to claim 6, characterized in that: The flowmeters (26) to be tested are placed in corresponding quantities according to the requirements, and a plurality of flowmeters (26) to be tested are connected end to end to each other for flow calibration using the standard method; The flow calibration of the mass detection method is completed by cooperating with the electronic scale (28) and the weighing water tank (15).

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