Use and Maintenance of Online Dissolved Oxygen Meter

The probe of the online dissolved oxygen meter has a linear response. After the calibration of the zero point and the highest range point, the data of the instrument used to measure the dissolved oxygen in water is acceptable. If the test results of the water sample are abnormal, iodometric titration can be used. Compare and judge whether there is a problem with the measurement results of the dissolved oxygen meter. If the relative deviation between the results of the iodometric method and the electrochemical probe method is within ±5%, the measurement data of the probe method are considered to be within the error range. If the relative deviation from the iodometric method exceeds the range of ±5% or the response of the electrochemical probe is not linear, it is necessary to check the performance status of the dissolved oxygen instrument, such as whether it needs to be recalibrated, replace the electrode gas permeable membrane, fill the internal electrode with liquid or grind the maintenance electrode, etc. . Use and maintenance of online dissolved oxygen meter:

1. After the instrument needs to be powered on, it needs to wait for the electrode to be polarized for 0.5h before starting the measurement or calibration;

2. Under normal circumstances, zero calibration can be performed once a month, and the instrument must be calibrated with water-saturated air every time it is used; in addition, the linearity of the probe response is checked every 2 months;

3. The probe should be cleaned with pure water after use. The breathable membrane should not be damaged during cleaning. After use, the probe should be stored in the protective cover, and the sponge in the protective cover should be kept wet. When not in use, every 1~2 weeks Clean and maintain the electrode probe once;

4. It is recommended to replace the internal filling liquid of the electrode every 2 months. After each replacement of the internal filling liquid, the instrument needs to be re-calibrated. When replacing the internal filling liquid, first rinse the electrode and the inside of the electrode sleeve with the filling liquid. Fill the electrode sleeve with filling liquid, then screw the electrode on the sleeve vertically and slowly to ensure that there are no air bubbles inside the electrode.

5. Regenerate the dissolved oxygen electrode every year, including replacing the internal electrolyte, replacing the breathable membrane, and cleaning the silver electrode; if the surface of the silver electrode is oxidized, it needs to be polished with fine sandpaper;

6. During the measurement of the online dissolved oxygen meter, the probe is repeatedly stirred in the water body for measurement. The relative speed of the water flow is greater than 0.3m/s or the magnetic stirrer rotates the water sample at 500rpm. If the speed is too high or too low, the data will be distorted. , to prevent air bubbles from staying on the diaphragm and affecting the results during measurement.