Abnormity detection method in correction process of pressure sensor

Abstract

The invention relates to a method for detecting abnormity in a correction process of a pressure sensor, which is particularly suitable for a high performance liquid chromatography (HPLC) system and an ultra-high performance liquid chromatography (UHPLC) system. According to the method, a first pressure detection limit value Ps1 and a second pressure detection limit value Ps2 are set, readings of a pressure sensor are detected in stages in the automatic calibration process, and a multi-verification mechanism (continuous N times of calibration and standard deviation calculation) is combined to identify abnormal conditions caused by solvent deficiency or bubble interference. Wherein the primary pump moves step by step according to a preset distance L1 and a preset distance L2, and if the reading does not reach a detection limit value, exception processing is carried out, so that error calibration is avoided. When the calibration is valid, the system stores the average value of N results and prompts success; otherwise, prompting failure. According to the method, the calibration precision and the system reliability are remarkably improved, invalid operation and equipment loss are reduced, and the method is suitable for an automatic chromatographic analysis system.

Description

Technical Field

[0001] The present invention relates to the calibration technology of pressure sensors in liquid chromatography systems, and particularly to a method for detecting anomalies during the calibration process of pressure sensors. Background Art

[0002] As an important detection element in the field of industrial automation, pressure sensors are widely used in various fluid pressure monitoring systems. In high-performance liquid chromatography (HPLC) and ultra-high-performance liquid chromatography (UHPLC) systems, the infusion pump unit usually needs to be equipped with one or more pairs of pressure sensors for real-time monitoring of the flow path pressure. These pressure sensors need to have the characteristics of high precision and high stability to ensure the accuracy and reliability of chromatographic analysis results.

[0003] In the prior art, the calibration of pressure sensors mainly adopts regular or irregular calibration procedures to eliminate the inherent pressure difference between sensors. This calibration usually keeps the flow path blocked by manual or automatic high-pressure valves, and uses the method of pressurizing with a plunger pump to obtain the inherent pressure difference data of a pair of pressure sensors in the same flow path. Among them, the automatic calibration technology realizes the full automation of the calibration process through a pre-set calibration program at a fixed time or under a fixed operating state, greatly improving the operating efficiency and reliability of the system.

[0004] However, the existing automatic calibration technology has obvious limitations. First, when there is a lack of solution in the flow path or there are a large number of bubbles in the solution, it will cause deviations or even complete failures in the calibration results. Second, the existing calibration system lacks an effective anomaly detection mechanism and cannot identify and judge the validity of calibration data in real time during the calibration process. These problems may lead to the system performing pressure control based on incorrect calibration data, thereby affecting the accuracy and stability of the entire chromatographic analysis process. In addition, an invalid calibration process not only wastes system resources but also may delay the normal analysis workflow. Summary of the Invention

[0005] In view of this, the present invention provides a method for detecting anomalies during the calibration process of pressure sensors to detect anomalies that cause invalid or incorrect calibration results due to solvent shortage or the presence of a large number of bubbles during the calibration process of pressure sensors.

[0006] To this end, the present invention provides the following technical solutions:

[0007] The present invention discloses a method for detecting anomalies during the calibration process of pressure sensors, including the following steps:

[0008] After the user selects to execute the automatic calibration program or process, the automatic high-pressure valve of the pump unit switches the flow path and automatically performs the solvent perfusion operation;

[0009] Run the primary pump to the maximum liquid suction position, run the accumulation pump to the maximum liquid discharge position, and switch the high-pressure valve flow path to the blocked position;

[0010] Control the primary pump to move a distance L1 towards the liquid discharge position and detect the reading PR of the pressure sensor;

[0011] If PR ≥ the first pressure detection limit value Ps1, perform the inherent differential pressure calibration operation between pressure sensors; otherwise, enter the exception handling;

[0012] Continue to control the primary pump to move a distance L2 towards the liquid discharge position. If PR ≥ the second pressure detection limit value Ps2, determine that the calibration is effective; otherwise, enter the exception handling;

[0013] Repeat the calibration operation N times, calculate the standard deviation. If the standard deviation is less than the preset value, save the average value and prompt that the calibration is successful; otherwise, prompt that the calibration fails.

[0014] Further, the first pressure detection limit value Ps1 is 2 - 5 MPa.

[0015] Further, the second pressure detection limit value Ps2 is 90% - 95% of the upper limit of the pump unit pressure.

[0016] Further, the distance L1 is calculated and determined according to Ps1, the compressibility of the solution, and a margin of 5% - 10%.

[0017] Further, the distance L2 is calculated and determined according to Ps2, the compressibility of the solution, and a margin of 5% - 10%.

[0018] Further, the exception handling includes terminating the calibration and prompting the user to check the flow path status.

[0019] Further, the method is applicable to high-performance liquid chromatography or ultra-high-performance liquid chromatography systems.

[0020] Advantages and positive effects of the present invention: Through staged pressure detection (setting the first pressure detection limit value Ps1 and the second pressure detection limit value Ps2) and a multiple verification mechanism (continuously calibrating N times and calculating the standard deviation), the present invention can effectively identify and eliminate abnormal situations caused by solvent shortage or bubble interference, thereby significantly improving the accuracy and reliability of the calibration results; by dynamically adjusting the pumping distance (L1, L2) and automatically terminating the invalid calibration process, it can avoid the system running in an abnormal state, reduce equipment wear and extend the service life; at the same time, the fully automated calibration process and intelligent exception prompt function significantly reduce the need for manual intervention, improve the operation efficiency, are applicable to various HPLC / UHPLC systems, and ultimately ensure the accuracy of chromatographic analysis data and the stability of system operation. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a flowchart of a method for detecting anomalies during the calibration process of a pressure sensor in an embodiment of the present invention. Specific embodiments

[0023] In order to enable those skilled in the art of this technology to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0024] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0025] In an HPLC / UHPLC system, in a liquid chromatograph, the primary pump (P1) and the accumulation pump (P2) are connected in parallel with a double plunger structure, and their coordinated movement is achieved through a synchronous control mechanism: during liquid suction, P1 retracts and P2 advances to form a negative pressure to suck in the solvent; during blockage measurement, P2 maintains the maximum liquid discharge position, and P1 moves forward to apply pressure. The two share an infusion path, and the fluid enters the blocked port of the high-pressure valve V1 after passing through P1, the one-way valve SV1, P2, and SV2 in sequence from the solvent bottle. In the calibration mode, V1 switches to a completely blocked state to form a closed loop. A pair of pressure sensors (PS1, PS2) are respectively installed upstream of V1 (between P2 and V1) and downstream (10 - 20 mm downstream of the blocked end of V1) to monitor the pressure difference in real time: when P1 moves to apply pressure, PS1 detects the pump-end pressure, and PS2 verifies the pressure in the downstream closed loop. The pressure difference between the two needs to meet the preset threshold (e.g., PS1 ≥ 3 MPa, PS2 ≥ 90% of the pump upper limit). If the pressure difference is abnormal (continuous low pressure or fluctuation), an alarm will be triggered to accurately identify solvent shortage, bubble interference, or sensor failure.

[0026] During the automatic calibration process of the pressure sensor in the liquid chromatograph, the calibration result may be invalid or incorrect due to the lack of solution in the flow path or the presence of a large number of bubbles in the solution. It is necessary to judge the validity of the calibration result during or after the automatic calibration process. When the calibration result is invalid, the user should be reminded to pay attention and pause the subsequent operations.

[0027] As Figure 1 shown, in the embodiment of the present invention, a method for detecting abnormalities during the calibration of a pressure sensor is provided. This detection method judges the validity of the calibration result through the first pressure detection limit (lower pressure, such as 2 - 5 Mpa) and the second pressure detection limit (higher pressure, usually 90% - 95% of the pressure upper limit of the pump unit). The specific implementation steps are as follows:

[0028] S1. After the user selects to execute the automatic calibration program or process, the pump unit automatically switches the flow path of the high-pressure valve and automatically performs a solvent perfusion operation for about 2 minutes.

[0029] S2. After the perfusion operation is completed, the primary pump automatically runs to the maximum liquid suction position and stops, and the accumulation pump runs to the maximum liquid discharge position and stops. Thereafter, the high-pressure valve flow path is switched to the blocked position.

[0030] S3. The accumulation pump remains stationary, and the primary pump is controlled to slowly move a certain distance L1 towards the liquid discharge position, and the reading PR of the pressure sensor is detected and output.

[0031] Among them, L1 is calculated based on the set first pressure detection limit and the compressibility (compression ratio) of the common solution, with a margin of about 5% - 10% added.

[0032] S4. When the reading PR >= the first pressure detection limit value Ps1, perform the calibration operation in subsequent S5; otherwise, enter the exception handling process.

[0033] S5. Perform the calibration operation for the inherent pressure difference between pressure sensors.

[0034] This calibration usually keeps the flow path blocked through a manual or automatic high-pressure valve, and uses the method of pressurizing with a plunger pump to obtain the inherent pressure difference data of a pair of pressure sensors in the same flow path.

[0035] S6. Continue to control the primary pump to slowly move a certain distance L2 towards the liquid ejection position. During the movement, if the reading of the pressure sensor reaches the pressure upper limit set by the pump unit, stop the movement of the primary pump and detect the reading output of the pressure sensor.

[0036] Among them, L2 is calculated based on the set second pressure detection limit value and the compressibility (compression ratio) of the common solution, and adding a margin of about 5% - 10%.

[0037] S7. When the reading PR >= the second pressure detection limit value Ps2, it is determined that this calibration operation is effective; otherwise, enter the exception handling process.

[0038] Among them, the exception handling process includes terminating the calibration and prompting the user to check the flow path status, and also includes: recording the number of errors, and returning to step S1 to start again after the flow path status is normal.

[0039] To improve the reliability of automatic calibration, the above calibration steps are continuously performed N times (usually 2 - 3 times). When the standard deviation of the continuous N valid calibration results is less than the preset value (1 - 2 bar), the calibration result is valid, and the average value of these N calibration results is saved in the non-volatile semiconductor memory for backup, and the user is prompted that this calibration is successful. Otherwise, the user is prompted that this calibration fails.

[0040] In the above embodiments, through staged pressure detection (setting the first pressure detection limit value Ps1 and the second pressure detection limit value Ps2) and a multiple verification mechanism (continuously calibrating N times and calculating the standard deviation), abnormal situations caused by solvent shortage or bubble interference can be effectively identified and excluded, thereby significantly improving the accuracy and reliability of the calibration results; by dynamically adjusting the pumping distance (L1, L2) and automatically terminating the invalid calibration process, the system can be prevented from running in an abnormal state, reducing equipment wear and extending the service life; at the same time, the fully automated calibration process and the intelligent abnormal prompt function significantly reduce the need for manual intervention, improve the operation efficiency, are applicable to various HPLC / UHPLC systems, and ultimately ensure the accuracy of chromatographic analysis data and the stability of system operation.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An abnormal detection method during the calibration process of a pressure sensor, characterized in that, The steps include the following: After the user selects to execute the automatic calibration program or process, the pump unit automatically switches the flow path of the high-pressure valve and automatically performs the solvent perfusion operation; Run the primary pump to the maximum liquid suction position, run the accumulator pump to the maximum liquid discharge position, and switch the high-pressure valve flow path to the blocked position; Control the primary pump to move a distance L1 towards the liquid discharge position and detect the reading PR of the pressure sensor; If PR ≥ the first pressure detection limit value Ps1, perform the calibration operation for the inherent pressure difference between the pressure sensors; otherwise, enter the exception handling; Continue to control the primary pump to move a distance L2 towards the liquid discharge position. If PR ≥ the second pressure detection limit value Ps2, determine that the calibration is effective; otherwise, enter the exception handling; Repeat the calibration operation N times, calculate the standard deviation. If the standard deviation is less than the preset value, save the average value and prompt that the calibration is successful; otherwise, prompt that the calibration fails.

2. The method according to claim 1, characterized in that, The first pressure detection limit value Ps1 is 2 - 5 MPa.

3. The method according to claim 1, characterized in that, The second pressure detection limit value Ps2 is 90% - 95% of the upper pressure limit of the pump unit.

4. The method according to claim 1, characterized in that The distance L1 is calculated and determined according to Ps1, the compressibility of the solution, and a margin of 5% - 10%.

5. The method according to claim 1, characterized in that, The distance L2 is calculated and determined according to Ps2, the compressibility of the solution, and a margin of 5% - 10%.

6. The method according to claim 1, characterized in that, The exception handling includes terminating the calibration and prompting the user to check the flow path status.

7. The method according to claim 1, wherein The method is applicable to high performance liquid chromatography or ultra-high performance liquid chromatography systems.

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