As long as the selection, setting, and proper maintenance, can generally meet the measurement requirements of the process. Disadvantages of the use of the dissolved oxygen analyzer are as follows: incorrect use and maintenance; abnormal temperature compensation due to internal leakage of the electrode; and reduced input impedance of the electrode.

1. Daily maintenance The daily maintenance of the instrument mainly includes the periodic cleaning, calibration, and regeneration of the electrodes.

(1) The electrode should be cleaned every 1 to 2 weeks. If there is any contamination on the diaphragm, it will cause measurement error. 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 out, use a soft cloth or cotton cloth to scrub it carefully.

(2) The zero and span should be recalibrated from February to March.

(3) The regeneration of the electrodes takes place approximately once every year. When the measurement range is not adjusted, the dissolved oxygen electrode needs to be regenerated. Electrode regeneration includes changing 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 an electrode leak is found during use, the electrolyte must be replaced.

2. The calibration method of the instrument calibration instrument can be calibrated by standard liquid or field sampling.

(1) Standard solution calibration method: The standard solution calibration generally adopts two-point calibration, namely zero calibration and span calibration. The zero calibration solution can use 2% Na2SO3 solution. The range calibration solution can be selected according to the instrument measurement range 4M KCl solution (2mg/L); 50% methanol solution (21.9mg/L).

(2) On-site sampling calibration method (Winkler method): In actual use, the Winkler method is used to perform on-site calibration of the dissolved oxygen analyzer. There are two situations when using this method: when sampling, the meter reading is M1, the assay analysis value is A, and when the meter is calibrated, the meter reading is still M1, then only the meter reading should be adjusted to be A; the meter reading is M1, the assay analysis value is A. When the meter is calibrated, the meter reading is changed to M2. At this time, the adjustment meter reading cannot be equal to A, and the meter reading should be adjusted to 1 MA×M2.

3. Problems to be noticed in use The following problems should be paid attention to during use: Since the signal impedance of the dissolved oxygen electrode is high (about 20 MΩ), the maximum distance between the dissolved oxygen electrode and the converter is 50 m; the dissolved oxygen electrode should also be used when not in use. State, can be connected to the dissolved oxygen converter. Electrodes with long or renewed regeneration (replacement of electrolytes or membranes) should be placed in an oxygen-free environment for 1–2 h before use; due to temperature changes affecting the diffusion of the electrode membrane and the oxygen solubility, the calibration time must be For a long time (about 10 minutes), the temperature compensation resistance is balanced; the oxygen partial pressure is related to the altitude of the area; the instrument must be compensated according to the local atmospheric pressure before use; when the salt content of the solution is high, the instrument calibration time should be Use a solution with a similar salt content; for the flow measurement method, the minimum flow rate through the electrode is required to be 0.3 m/s.