Routine Maintenance of Dissolved Oxygen Meter

Dissolved oxygen refers to the oxygen formed by the dissolution of molecular water in the water body. In general, the dissolved oxygen content in water mainly depends on the balance between the oxygen content in the atmosphere and the oxygen content in water. As a measuring device for dissolved oxygen in water, the dissolved oxygen meter can obtain the concentration of dissolved oxygen in water by measuring the diffusion current proportional to the oxygen concentration generated when oxygen permeates through the diaphragm and is reduced by the working electrode. Calibration method 1. Whether it is a domestic dissolved oxygen meter or an imported dissolved oxygen meter, the general calibration method is air calibration technology. 2. Place the electrode of the dissolved oxygen meter in a water-saturated air environment at a certain temperature, and calibrate with the corresponding saturated dissolved oxygen value at that temperature as the reference standard value after equilibrium. 3. Now, according to the three characteristics of the measurement basis of the dissolved oxygen meter, it is not difficult to explain the calibration process of the dissolved oxygen meter: at a certain temperature (the Henry coefficient remains unchanged), in air-saturated water and water-saturated air, the oxygen content The pressure is the same (feature 2), and since the physical quantity directly measured by the electrode of the dissolved oxygen meter is oxygen partial pressure (feature 1), the dissolved oxygen concentration displayed by conversion is also the same (feature 3). The daily maintenance of the dissolved oxygen meter mainly includes regular cleaning, calibration and regeneration of the electrodes. 1. The electrode should be cleaned once every 1-2 weeks. If there are pollutants on the diaphragm, it will cause measurement errors. Care should be taken when cleaning, taking care not to damage the diaphragm. Rinse the electrode in clean water. If the dirt cannot be washed off, carefully scrub it with a soft cloth or cotton cloth. 2. From February to March, the zero point and span should be re-calibrated. 3. The regeneration of the electrode is carried out about once a year. When the measurement range cannot be adjusted, the dissolved oxygen electrode needs to be regenerated. Electrode regeneration includes replacing the internal electrolyte, replacing the diaphragm, and cleaning the silver electrode. If the silver electrode is observed to be oxidized, it can be polished with fine sandpaper. 4. If the electrode leaks during use, replace the electrolyte. In addition to the above knowledge that needs to be understood, relevant precautions should also be mastered, such as compensation according to the local atmospheric pressure before use; Only when the dissolved oxygen meter is used correctly.