Flow testing method for fixed positive and negative pressure conduits

Abstract

The invention discloses a fixed positive and negative pressure conduit flow testing method. According to the invention, through the cooperation of accurate parameter setting and a staged pressure regulation strategy, the pressure control performance is obviously improved. The set target pressure value and the test duration serve as the core basis of adjustment, and the adjustment direction of the pressure system completely meets the test requirement; according to the staged strategy, the initial pressure difference is shortened through the maximum capacity of hardware, then the fluctuation range is compressed through multiple rounds of fine calibration, the single logic limitation of conventional closed-loop control is broken through, and it is ensured that the pressure is stabilized within extremely high precision. The dynamic pre-stabilization mode not only shortens the pressure establishment time, but also provides a stable environmental basis for formal testing, directly improves the accuracy of flow measurement, enables the result to reflect the real performance of the conduit better, adapts to the quick response of different pressure requirements, reduces unnecessary waiting time, and improves the overall testing efficiency.

Description

Technical Field

[0001] This invention belongs to the field of conduit flow testing technology, specifically a fixed positive and negative pressure conduit flow testing method. Background Technology

[0002] Positive and negative pressure conduit flow measurement is a mature industrial metering technology based on the principle of differential pressure in fluid mechanics. Its core mechanism involves installing throttling devices (such as orifice plates or venturi tubes) in the pipeline, causing pressure changes as the fluid flows through. The positive pressure conduit connects to the high-pressure tap upstream of the throttling device, and the negative pressure conduit connects to the low-pressure tap downstream, introducing the pressure signals from both ends into a differential pressure transmitter for detection. Based on the functional relationship between differential pressure and fluid flow rate, combined with temperature and pressure compensation, the system accurately calculates and displays the instantaneous flow rate and cumulative total flow of the medium. This method, with its simple structure, high reliability, and strong applicability, is widely used in complex industrial environments such as petroleum, chemical, metallurgy, and power industries.

[0003] However, existing technologies typically employ a single closed-loop control logic, resulting in insufficient pressure regulation accuracy and significant fluctuations, making it difficult to stabilize within a high-precision range and limiting the accuracy of flow measurement results. Furthermore, the pressure settling time is long, leading to low testing efficiency. The degree of process automation is low, requiring considerable human intervention and easily introducing operational errors. Moreover, most technologies are only compatible with a single pressure mode, failing to flexibly meet the needs of two different testing scenarios: positive and negative pressure. Summary of the Invention

[0004] The purpose of this invention is to provide a method for testing the flow rate of a fixed positive and negative pressure conduit in order to solve the problems mentioned above.

[0005] The technical solution adopted in this invention is as follows: a fixed positive and negative pressure conduit flow testing method, the method comprising the following steps:

[0006] S1: Connect the 220V power supply and start the system. Wait for the system to complete the zero-point calibration of the pressure sensor and the automatic zeroing of the weighing unit to ensure that all basic modules are in a usable state, providing accurate initial conditions for subsequent testing.

[0007] S2: Select the positive or negative pressure test mode on the main touch screen interface. This selection will directly guide the specific operation direction for subsequent sample installation.

[0008] S3: Complete the sample installation according to the mode selected in S2. In positive pressure mode, add no less than 500ml of pure water to the water storage container and connect the tubing to the test interface. In negative pressure mode, empty the water storage container and connect the tubing to the external water source container.

[0009] S4: Set the target pressure value and test duration. The input parameters will serve as the core basis for subsequent adjustments of the pressure control system.

[0010] S5: Initiate the dynamic pressure pre-stabilization process. The system first quickly approaches the target pressure set in S4, and then performs three small-amplitude pressure fine-tunings to ensure that the pressure is stable within the ±0.3kPa accuracy range, laying a stable pressure environment for formal testing.

[0011] S6: Start timing and execute the test. The system records the mass change data within a specified time under stable pressure, and automatically calculates the corresponding flow rate value based on the sample type installed in S3.

[0012] S7: After the test is completed, the data is automatically stored and a report containing traffic results and pressure curves is generated. The data can be exported via the interface for subsequent analysis.

[0013] In a preferred embodiment, in step S1, the zero-point calibration of the pressure sensor is first completed. The calibration process lasts for 3 seconds to ensure that the sensor output value is completely matched with the zero-pressure environment. Subsequently, the weighing unit automatically performs a zeroing operation, with a zeroing accuracy of ±0.1g to eliminate initial mass error. After the self-test is completed, the touch screen displays a "System Ready" message. At this time, all basic components such as the pressure pump, water storage container valve, and data acquisition module are in normal working condition without any error messages, providing stable and reliable initial conditions for subsequent steps.

[0014] In a preferred embodiment, in step S2, the positive pressure mode corresponds to the test scenario where the conduit delivers fluid in the forward direction, and the negative pressure mode corresponds to the scenario where the conduit draws fluid in the reverse direction. After the mode is selected, the system automatically switches the hardware configuration: in positive pressure mode, the water inlet control valve of the water storage container is opened; in negative pressure mode, the pre-start program of the vacuum pump is started. This selection directly determines the specific operation method of sample installation in step S3 and serves as a guide for all subsequent test procedures.

[0015] In a preferred embodiment, in step S3, under positive pressure mode, at least 500ml of purified water needs to be added to the water storage container. Then, one end of the conduit is tightly connected to the positive pressure test interface of the system, and the other end is fixed to the outlet of the water storage container, ensuring that there are no leaks at all connections. Under negative pressure mode, the liquid in the water storage container must be completely emptied first. Then, one end of the conduit is connected to the negative pressure test interface of the system, and the other end is connected to the inlet of the external water source container. The interface is checked for sealing to prevent air from entering and affecting the test accuracy. After installation, the system will automatically detect the connection status and proceed to the next step after confirming that there are no errors.

[0016] In a preferred embodiment, in step S4, the target pressure value (P_) is obtained through the system interface. target ) and test duration (T_ test The precise setting of two key parameters will directly guide the S5's phased pressure regulation strategy. The specific operation is as follows:

[0017] First, the user inputs the target pressure value via the parameter setting panel on the touchscreen: in positive pressure mode, the range is 0~50kPa (covering positive pressure delivery scenarios via catheters), and in negative pressure mode, it is -50kPa~0 (matching negative pressure suction requirements). The system verifies the parameter's validity in real time during input—if the value exceeds the pressure sensor's range (±60kPa) or conflicts with the current mode (e.g., a positive value is input in negative pressure mode), a red warning will pop up and the next step will be locked, requiring correction and re-entry. Next, the test duration is set: the selectable range is 10~60 seconds. The duration selection should balance accuracy and efficiency (e.g., select 30 seconds or more for high-precision testing, and 10~15 seconds for rapid screening). The system will automatically recommend the S5's fine-tuning waiting time based on the input duration (e.g., 0.5 seconds for a 30-second test duration, and 0.6 seconds for a 60-second test duration).

[0018] In a preferred embodiment, the initial pressure difference is minimized by utilizing the maximum hardware capability. The system first reads the target pressure value P set in step S4. target Combined with the real-time data P from the pressure sensor after S1 calibration current Calculate the pressure difference ΔP = P target -P current When the absolute value of ΔP is greater than the preset threshold ΔP threshold At pressures of 5 kPa, the system skips the slow adjustment of conventional PID control and directly drives the pressure pump to operate at rated power, quickly reducing the pressure difference. The key to this step is to overcome the adjustment inertia of conventional PID control through an open-loop maximum output strategy, saving time for subsequent fine-tuning. At the same time, the system monitors pressure changes in real time, and once ΔP enters the threshold range, it immediately switches to fine-tuning mode to avoid overshoot and excessive pressure fluctuations.

[0019] In a preferred embodiment, during the first fine-tuning in step S5, the system employs a low proportional coefficient adjustment logic, where the proportional coefficient K... p1 Set the pressure to 1 / 3 of the standard PID setting to initially converge the remaining error after rapid approximation. After adjustment, wait 0.5 seconds for the pressure to stabilize, and then read the new current pressure P. current1 The second fine-tuning further reduced the scaling factor to K. p2 (K) p2 =K p1 / 2), fine-tune for smaller errors, and wait for stabilization again to obtain P. current2 The third fine-tuning introduces an integral term, accumulating minute errors through the integral coefficient Ki to completely eliminate steady-state error and ensure pressure stability within ±0.3 kPa. The parameters for these three fine-tunings are pre-optimized based on the system hardware characteristics, ensuring both adjustment accuracy and shortening stabilization time. Compared to the single adjustment logic of conventional PID controllers, this approach achieves the target accuracy more efficiently.

[0020] In a preferred embodiment, in step S5, the formula for the output control quantity during the rapid approximation stage is:

[0021] ;

[0022] In the formula:

[0023] Pressure pump output power during rapid approximation phase

[0024] Pressure pump rated maximum output power

[0025] The sign function returns 1 when x > 0 and -1 when x < 0.

[0026] S4 sets the target pressure value

[0027] Real-time pressure sensor readings

[0028] First fine-tuning of the output control formula: ;

[0029] Parameter definition:

[0030] For the first fine-tuning of the pressure pump output power

[0031] This is the first fine-tuning of the proportional gain (preset to 1 / 3 of the standard PID proportional gain).

[0032] To quickly approximate the real-time pressure after the phase ends

[0033] Second fine-tuning of output control formula: ;

[0034] Parameter definition:

[0035] For the second fine-tuning of the pressure pump output power

[0036] For the second fine-tuning of the scaling factor (preset to be 0.05%) (1 / 2)

[0037] Real-time pressure after the first fine-tuning

[0038] The formula for the third fine-tuning of the output control quantity is as follows: ;

[0039] Parameter definition:

[0040] For the third fine-tuning of the pressure pump output power

[0041] Integral adjustment coefficient

[0042] Duration of the third fine-tuning

[0043] Real-time pressure at time t after the second fine-tuning.

[0044] These formulas achieve a combination of "rapid approximation + fine calibration" by dynamically switching adjustment logic and parameters, breaking through the single adjustment limitation of conventional PID, and are the core innovation point to ensure pressure stability and accuracy.

[0045] In a preferred embodiment, in step S6, after the system achieves pressure stabilization in step S5, it automatically starts timing, with the timing duration consistent with the test duration set in step S4. During the test, the weighing unit records mass change data once per second, and the pressure sensor collects pressure values ​​five times per second and feeds them back to the control system in real time, ensuring that the pressure remains stable within an accuracy range of ±0.3 kPa. The system automatically selects the flow rate calculation formula according to the sample mode installed in step S3: in positive pressure mode, the volumetric flow rate is obtained by dividing the mass flowing out per unit time by the liquid density; in negative pressure mode, the volumetric flow rate is obtained by dividing the mass drawn in per unit time by the liquid density. During the test, all data is stored in real time in a temporary buffer.

[0046] In a preferred embodiment, in step S7, after the test is completed, the system automatically stops the pressure supply and closes the relevant valves. Then, all data from this test (including pressure curves, mass change curves, and final flow results) is stored in a local database as a CSV file. Next, a detailed test report is generated, containing core information such as the test date, test time, target pressure value, test duration, average flow rate, and pressure fluctuation range. Users can export the test data and report to an external storage device via the system's USB interface for convenient subsequent data analysis and archiving. After the report is generated, the system returns to the initial interface, awaiting the next test command.

[0047] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0048] 1. In this invention, a significant improvement in pressure control performance is achieved through the combination of precise parameter settings and a phased pressure adjustment strategy. The set target pressure value and test duration serve as the core basis for adjustment, ensuring that the adjustment direction of the pressure system perfectly matches the test requirements. The phased strategy first utilizes the maximum hardware capability to shorten the initial pressure gap, and then compresses the fluctuation range through multiple rounds of fine calibration, breaking through the single logic limitation of conventional closed-loop control and ensuring that the pressure remains stable within an extremely high precision. This dynamic pre-stabilization method not only shortens the pressure settling time but also provides a stable environmental foundation for formal testing, directly improving the accuracy of flow measurement, allowing the results to better reflect the true performance of the conduit, while adapting to rapid responses to different pressure requirements, reducing unnecessary waiting time, and improving overall testing efficiency.

[0049] 2. In this invention, each step, from system startup self-test to mode selection and sample installation, lays a reliable foundation for subsequent core operations. Parameter settings cover the different needs of both positive and negative pressure modes, allowing flexible adjustment of the target pressure range and test duration to handle various catheter testing scenarios. The phased adjustment, along with subsequent real-time data acquisition and automatic report generation, forms a complete closed loop, reducing errors caused by human intervention and improving the reliability of test results. Whether testing catheter performance under positive pressure delivery or negative pressure suction, this method provides a precise, stable, and efficient solution, meeting diverse needs in practical applications. The automated process design also lowers the operational threshold, making it convenient for non-professionals to complete high-precision testing tasks. Attached Figure Description

[0050] Figure 1 This is a schematic diagram illustrating the process principle of the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention 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 merely illustrative and not intended to limit the invention.

[0052] Example:

[0053] Reference Figure 1 The method for testing the flow rate of a fixed positive and negative pressure conduit includes the following steps:

[0054] S1: Connect the 220V power supply and start the system. Wait for the system to complete the zero-point calibration of the pressure sensor and the automatic zeroing of the weighing unit to ensure that all basic modules are in a usable state, providing accurate initial conditions for subsequent testing.

[0055] S2: Select the positive or negative pressure test mode on the main touch screen interface. This selection will directly guide the specific operation direction for subsequent sample installation.

[0056] S3: Complete the sample installation according to the mode selected in S2. In positive pressure mode, add no less than 500ml of pure water to the water storage container and connect the tubing to the test interface. In negative pressure mode, empty the water storage container and connect the tubing to the external water source container.

[0057] S4: Set the target pressure value and test duration. The input parameters will serve as the core basis for subsequent adjustments of the pressure control system.

[0058] S5: Initiate the dynamic pressure pre-stabilization process. The system first quickly approaches the target pressure set in S4, and then performs three small-amplitude pressure fine-tunings to ensure that the pressure is stable within the ±0.3kPa accuracy range, laying a stable pressure environment for formal testing.

[0059] S6: Start timing and execute the test. The system records the mass change data within a specified time under stable pressure, and automatically calculates the corresponding flow rate value based on the sample type installed in S3.

[0060] S7: After the test is completed, the data is automatically stored and a report containing traffic results and pressure curves is generated. The data can be exported via the interface for subsequent analysis.

[0061] In step S1, the zero-point calibration of the pressure sensor is first completed. The calibration process lasts for 3 seconds to ensure that the sensor output value is completely matched with the zero-pressure environment. Then, the weighing unit automatically performs a zeroing operation, and the zeroing accuracy must reach ±0.1g to eliminate the initial mass error. After the self-test is completed, the touch screen displays the "System Ready" prompt. At this time, all basic components such as the pressure pump, water storage container valve, and data acquisition module are in normal working condition without any error messages, providing stable and reliable initial conditions for subsequent steps.

[0062] In step S2, the positive pressure mode corresponds to the test scenario where the conduit delivers fluid in the forward direction, while the negative pressure mode corresponds to the scenario where the conduit draws fluid in the reverse direction. After the mode is selected, the system will automatically switch the hardware configuration: in positive pressure mode, the water inlet control valve of the water storage container will be opened; in negative pressure mode, the pre-start program of the vacuum pump will be started. This selection will directly determine the specific operation method for sample installation in step S3 and will serve as a guide for all subsequent test procedures.

[0063] In step S3, under positive pressure mode, add at least 500ml of purified water to the water storage container, then tightly connect one end of the conduit to the positive pressure test interface of the system, and fix the other end to the outlet of the water storage container, ensuring no leaks at any connection. Under negative pressure mode, first completely empty the liquid in the water storage container, then connect one end of the conduit to the negative pressure test interface of the system, and the other end to the inlet of the external water source container, checking the interface for sealing to prevent air from entering and affecting the test accuracy. After installation, the system will automatically detect the connection status and proceed to the next step after confirming that everything is correct.

[0064] In step S4, the target pressure value (P_) is obtained through the system interface. target ) and test duration (T_ test The precise setting of two key parameters will directly guide the S5's phased pressure regulation strategy. The specific operation is as follows:

[0065] First, the user inputs the target pressure value via the parameter setting panel on the touchscreen: in positive pressure mode, the range is 0~50kPa (covering positive pressure delivery scenarios via catheters), and in negative pressure mode, it is -50kPa~0 (matching negative pressure suction requirements). The system verifies the parameter's validity in real time during input—if the value exceeds the pressure sensor's range (±60kPa) or conflicts with the current mode (e.g., a positive value is input in negative pressure mode), a red warning will pop up and the next step will be locked, requiring correction and re-entry. Next, the test duration is set: the selectable range is 10~60 seconds. The duration selection should balance accuracy and efficiency (e.g., select 30 seconds or more for high-precision testing, and 10~15 seconds for rapid screening). The system will automatically recommend the S5's fine-tuning waiting time based on the input duration (e.g., 0.5 seconds for a 30-second test duration, and 0.6 seconds for a 60-second test duration).

[0066] In step S5, the initial pressure difference is shortened by utilizing the maximum hardware capability. The system first reads the target pressure value P set in S4. target Combined with the real-time data P from the pressure sensor after S1 calibration current Calculate the pressure difference ΔP = P target -P current When the absolute value of ΔP is greater than the preset threshold ΔP threshold At pressures of 5 kPa, the system skips the slow adjustment of conventional PID control and directly drives the pressure pump to operate at rated power, quickly reducing the pressure difference. The key to this step is to overcome the adjustment inertia of conventional PID control through an open-loop maximum output strategy, saving time for subsequent fine-tuning. At the same time, the system monitors pressure changes in real time, and once ΔP enters the threshold range, it immediately switches to fine-tuning mode to avoid overshoot and excessive pressure fluctuations.

[0067] In step S5, during the first fine-tuning, the system uses a low proportional coefficient adjustment logic, where the proportional coefficient K... p1 Set the pressure to 1 / 3 of the standard PID setting to initially converge the remaining error after rapid approximation. After adjustment, wait 0.5 seconds for the pressure to stabilize, and then read the new current pressure P. current1 The second fine-tuning further reduced the scaling factor to K. p2 (K) p2 =K p1 / 2), fine-tune for smaller errors, and wait for stabilization again to obtain P. current2The third fine-tuning introduces an integral term, accumulating minute errors through the integral coefficient Ki to completely eliminate steady-state error and ensure pressure stability within ±0.3 kPa. The parameters for these three fine-tunings are pre-optimized based on the system hardware characteristics, ensuring both adjustment accuracy and shortening stabilization time. Compared to the single adjustment logic of conventional PID controllers, this approach achieves the target accuracy more efficiently.

[0068] In step S5, the formula for the output control quantity during the rapid approximation stage is as follows:

[0069] ;

[0070] In the formula:

[0071] The pressure pump output power during the rapid approach phase;

[0072] The pressure pump's rated maximum output power;

[0073] The sign function returns 1 when x > 0 and -1 when x < 0.

[0074] The target pressure value set by S4;

[0075] Real-time pressure sensor readings;

[0076] First fine-tuning of the output control formula: ;

[0077] Parameter definition:

[0078] The output power of the pressure pump during the first fine-tuning;

[0079] This is the first fine-tuning of the proportional coefficient (preset to 1 / 3 of the regular PID proportional coefficient).

[0080] To quickly approximate the real-time pressure after the phase ends;

[0081] Second fine-tuning of output control formula: ;

[0082] Parameter definition:

[0083] The pressure pump output power is adjusted for the second fine-tuning.

[0084] For the second fine-tuning of the scaling factor (preset to be 0.05%) (1 / 2 of)

[0085] Real-time pressure after the first fine-tuning

[0086] The formula for the third fine-tuning of the output control quantity is as follows: ;

[0087] Parameter definition:

[0088] For the third fine-tuning of the pressure pump output power

[0089] Integral adjustment coefficient

[0090] Duration of the third fine-tuning

[0091] Real-time pressure at time t after the second fine-tuning.

[0092] These formulas achieve a combination of "rapid approximation + fine calibration" by dynamically switching adjustment logic and parameters, breaking through the single adjustment limitation of conventional PID, and are the core innovation point to ensure pressure stability and accuracy.

[0093] In step S6, after the system achieves pressure stabilization in step S5, it automatically starts timing, with the timing duration matching the test duration set in step S4. During the test, the weighing unit records mass change data once per second, and the pressure sensor collects pressure values ​​five times per second and feeds them back to the control system in real time, ensuring the pressure remains stable within an accuracy range of ±0.3 kPa. The system automatically selects the flow rate calculation formula based on the sample mode set in step S3: in positive pressure mode, the volumetric flow rate is obtained by dividing the mass flowing out per unit time by the liquid density; in negative pressure mode, the volumetric flow rate is obtained by dividing the mass drawn in per unit time by the liquid density. During the test, all data is stored in real-time in a temporary buffer.

[0094] In step S7, after the test is completed, the system automatically stops the pressure supply and closes the relevant valves. Then, all data from this test (including pressure curves, mass change curves, and final flow results) is stored in the local database as a CSV file. Next, a detailed test report is generated, containing core information such as the test date, test time, target pressure value, test duration, average flow rate, and pressure fluctuation range. Users can export the test data and report to an external storage device via the system's USB interface for convenient subsequent data analysis and archiving. After the report is generated, the system returns to the initial interface, awaiting the next test command.

[0095] From the above, we can conclude that:

[0096] In this invention, a significant improvement in pressure control performance is achieved through the combination of precise parameter settings and a phased pressure regulation strategy. The set target pressure value and test duration serve as the core basis for adjustment, ensuring that the pressure system's adjustment direction perfectly aligns with test requirements. The phased strategy first utilizes the maximum hardware capability to shorten the initial pressure gap, then compresses the fluctuation range through multiple rounds of fine calibration, breaking through the single logic limitation of conventional closed-loop control and ensuring pressure stability within extremely high precision. This dynamic pre-stabilization method not only shortens pressure settling time but also provides a stable environmental foundation for formal testing, directly improving the accuracy of flow measurement and allowing the results to better reflect the true performance of the conduit. Simultaneously, it adapts to rapid responses to different pressure requirements, reducing unnecessary waiting time and improving overall testing efficiency.

[0097] In this invention, each step, from system startup self-test to mode selection and sample installation, lays a reliable foundation for subsequent core operations. Parameter settings cover the different needs of both positive and negative pressure modes, allowing flexible adjustment of the target pressure range and test duration to handle various catheter testing scenarios. The phased adjustment, along with subsequent real-time data acquisition and automatic report generation, forms a complete closed loop, reducing errors caused by human intervention and improving the reliability of test results. Whether testing catheter performance under positive pressure delivery or negative pressure suction, this method provides a precise, stable, and efficient solution, meeting diverse needs in practical applications. The automated process design also lowers the operational threshold, making it convenient for non-professionals to complete high-precision testing tasks.

[0098] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the term "comprising" or any other variations thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0099] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the flow rate of a fixed positive and negative pressure conduit, characterized in that: The method includes the following steps: S1: Connect the 220V power supply and start the system. Wait for the system to complete the zero-point calibration of the pressure sensor and the automatic zeroing of the weighing unit to ensure that all basic modules are in a usable state and to provide accurate initial conditions for subsequent testing. S2: Select the positive or negative pressure test mode on the main touch screen interface. This selection will directly guide the specific operation direction of subsequent sample installation. S3: Complete the sample installation according to the mode selected in S2. In positive pressure mode, add no less than 500ml of pure water to the water storage container and connect the tubing to the test interface. In negative pressure mode, empty the water storage container and connect the tubing to the external water source container. S4: Set the target pressure value and test duration. The input parameters will serve as the core basis for subsequent adjustments of the pressure control system. S5: Initiate the dynamic pressure pre-stabilization process. The system first quickly approaches the target pressure set in S4, and then performs three small-amplitude pressure fine-tuning to ensure that the pressure is stable within the accuracy range of ±0.3kPa, laying a stable pressure environment for formal testing. S6: Start timing and execute the test. The system records the mass change data within a specified time under stable pressure and automatically calculates the corresponding flow rate value based on the sample type installed in S3. S7: After the test is completed, the data is automatically stored and a report containing traffic results and stress curves is generated. The data can be exported through the interface for subsequent analysis.

2. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S1, the zero-point calibration of the pressure sensor is first completed. The calibration process lasts for 3 seconds to ensure that the sensor output value is completely matched with the zero-pressure environment. Then, the weighing unit automatically performs a zeroing operation, and the zeroing accuracy needs to reach ±0.1g to eliminate the initial mass error.

3. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S2, the positive pressure mode corresponds to the test scenario of the conduit conveying fluid in the forward direction, and the negative pressure mode corresponds to the scenario of the conduit drawing fluid in the reverse direction. After the mode is selected, the system will automatically switch the hardware configuration: in the positive pressure mode, the water inlet control valve of the water storage container is opened, and in the negative pressure mode, the pre-start program of the vacuum pump is started.

4. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S3, under positive pressure mode, at least 500ml of purified water needs to be added to the water storage container. Then, one end of the conduit is tightly connected to the positive pressure test interface of the system, and the other end is fixed at the outlet of the water storage container to ensure that there is no leakage at all connections. Under negative pressure mode, the liquid in the water storage container needs to be completely emptied first. Then, one end of the conduit is connected to the negative pressure test interface of the system, and the other end is connected to the inlet of the external water source container. Check the sealing of the interface to prevent air from entering and affecting the test accuracy. After installation, the system will automatically check the connection status and proceed to the next step after confirming that everything is correct.

5. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S4, the two key parameters, target pressure value and test duration, are precisely set through the system interface. These parameters will directly guide the phased pressure adjustment strategy in S5. The specific operation is as follows: First, the user inputs the target pressure value through the parameter setting panel on the touch screen: the range can be set from 0 to 50 kPa in positive pressure mode and from -50 kPa to 0 in negative pressure mode; the system will check the rationality of the parameters in real time when inputting them - if the value exceeds the range of the pressure sensor or conflicts with the current mode, the interface will pop up a red prompt and lock the next operation, and the value needs to be corrected and re-entered; then the test duration is set.

6. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S5, the initial pressure difference is shortened by utilizing the maximum hardware capability; the system first reads the target pressure value P set in S4. target Combined with the real-time data P from the pressure sensor after S1 calibration current Calculate the pressure difference ΔP = P target -P current When the absolute value of ΔP is greater than the preset threshold ΔP threshold At this time, the system skips the slow adjustment of conventional PID and directly drives the pressure pump to operate at rated power, quickly narrowing the pressure difference; the key to this step is to break through the adjustment inertia of conventional PID through the open-loop maximum output strategy, saving time for subsequent fine adjustment. Meanwhile, the system will monitor pressure changes in real time. Once ΔP enters the threshold range, it will immediately switch to fine-tuning mode to avoid overshooting that causes excessive pressure fluctuations.

7. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S5, during the first fine-tuning, the system uses a low proportional coefficient adjustment logic, where the proportional coefficient K... p1 Set the pressure to 1 / 3 of the standard PID setting to initially converge the remaining error after rapid approximation. After adjustment, wait 0.5 seconds for the pressure to stabilize, and then read the new current pressure P. current1 The second fine-tuning further reduced the scaling factor to K. p2 To fine-tune the process to minimize errors, wait for it to stabilize again to obtain P. current2 The third fine-tuning introduces an integral step, which accumulates minute errors through the integral coefficient Ki, completely eliminating static error and ensuring that the pressure remains stable within the range of ±0.3 kPa.

8. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S5, the formula for the output control quantity during the rapid approximation stage is as follows: ； In the formula: The pressure pump output power during the rapid approach phase; The pressure pump's rated maximum output power; The sign function returns 1 when x > 0 and -1 when x < 0. The target pressure value set by S4; Real-time pressure sensor readings; First fine-tuning of the output control formula: ; Parameter definition: The output power of the pressure pump during the first fine-tuning; This is the first fine-tuning of the scaling factor; To quickly approximate the real-time pressure after the phase ends; Second fine-tuning of output control formula: ; Parameter definition: The pressure pump output power is adjusted for the second fine-tuning. This is the second fine-tuning of the scaling factor; Real-time pressure after the first fine-tuning; The formula for the third fine-tuning of the output control quantity is as follows: ; Parameter definition: The pressure pump output power is adjusted for the third time. This is the integral adjustment coefficient; The duration of the third fine-tuning; This represents the real-time pressure at time t after the second fine-tuning.

9. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S6, after the system achieves pressure stabilization in step S5, it automatically starts timing, with the timing duration matching the test duration set in step S4. During the test, the weighing unit records mass change data once per second, and the pressure sensor collects pressure values ​​five times per second and feeds them back to the control system in real time, ensuring that the pressure remains stable within an accuracy range of ±0.3 kPa. The system automatically selects the flow rate calculation formula based on the sample mode installed in step S3: in positive pressure mode, the volumetric flow rate is obtained by dividing the mass flowing out per unit time by the liquid density; in negative pressure mode, the volumetric flow rate is obtained by dividing the mass drawn in per unit time by the liquid density. During the test, all data is stored in real time in a temporary buffer.

10. The method for testing the flow rate of a fixed positive and negative pressure conduit as described in claim 1, characterized in that: In step S7, after the test is completed, the system automatically stops the pressure supply and closes the relevant valves; then all the data of this test is stored in the local database in CSV file format; then a detailed test report is generated, which includes the test date, test time, target pressure value, test duration, average flow rate value, and pressure fluctuation range.

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