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How to automatically calibrate the pH meter

by:Sure     2021-08-15
The maintenance workload of the pH meter used in the production process is very heavy. Faults such as the aging of the pH meter electrode performance need to be judged, the pH meter electrode contamination needs to be cleaned, the pH meter zero drift, range change need to be verified, and so on. Therefore, the on-line self-diagnosis function of the sensor that needs to be judged for the aging of the pH meter electrode performance, and the automatic cleaning device of the pH meter developed for the problem of electrode contamination that needs to be cleaned. The maintenance workload of the pH meter in the production process is large, such as the pH meter electrode. Faults such as performance aging need to be judged, pH meter electrode contamination needs to be cleaned, pH meter zero drift, range change need to be verified, etc. Therefore, the on-line self-diagnosis function of the sensor that needs to be judged for the aging of the pH meter electrode performance, the automatic cleaning device of the pH meter developed for the problem of electrode contamination and cleaning, and the automatic calibration device that needs to be calibrated for the zero drift and range change of the pH meter. There are also some products coming out. This article will focus on the development status of the automatic calibration device for pH meters in recent years.   pH meter will 'aging' over time during use. The characteristics of aging are that the mV per unit pH value becomes smaller, the asymmetric potential becomes larger, and the response speed becomes slower. By cleaning the pH meter electrode, the performance can be restored or partially restored. For example, the number of mV generated by the unit pH value increases, the asymmetric potential decreases, and the response speed becomes faster; through the calibration of the zero point and the span, the electrode can be unrecovered Part of the performance is compensated.   There are two methods to calibrate pH meter: standard buffer solution calibration or actual test solution laboratory analysis and calibration. Because the standard buffer solution calibration method has higher accuracy, it is more practically applied.  The calibration process has one-point calibration, two-point calibration and three-point calibration. One-point calibration only detects the zero point of the pH electrode. It is used when the actual measured value is near the zero point and the slope does not change much. The calibration process is simple and convenient. Two-point calibration is used in the following 5 situations: the electrode has been replaced; the measurement pH value has a wide range; the difference between the measured pH value and the electrode zero pH value is large; the pH measurement accuracy is required to be high; the electrode has a long expected service life . Three-point calibration is used in occasions with a wide range of pH values u200bu200band high requirements for pH measurement accuracy. However, due to the complex calibration process, it is usually less applied. The automatic calibration device of the pH meter has developed rapidly in recent years. Its development is based on the automatic cleaning device of the pH meter and the on-line self-diagnosis function of the sensor. The sensor self-diagnosis function can not only provide the start signal for the automatic cleaning of the intermittent way electrode to be cleaned (the intermittent way electrode can automatically start the cleaning and start in two ways: timing start and start based on the sensor self-diagnosis result), but also for the pH meter. Automatic verification provides basic data. Because the automatic cleaning device, sensor self-diagnosis function and automatic calibration are so closely related, most of the automatic calibration devices introduced by various pH meter manufacturers include automatic cleaning devices and sensor online self-diagnosis functions. Although some manufacturers claim to be automatic calibration devices, according to whether the pH sensor needs to be manually inserted into the standard buffer solution container or the standard buffer solution can be automatically sprayed to the pH sensor, the calibration device is divided into a semi-automatic calibration device and Automatic verification device.
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