How to calibrate and maintain the dissolved oxygen analyzer electrode:

1、 Calibration method: Generally, standard solution calibration or on-site sampling calibration can be used.

(1) Standard solution calibration method: Standard solution calibration generally uses two-point calibration, namely zero point calibration and range calibration. The zero point calibration solution can be a 2% Na2SO3 solution. The range calibration solution can be selected as a 4M KCl solution (2mg/L) based on the measurement range of the instrument; Humidity sensor probe, stainless steel electric heating tube, PT100 sensor, fluid solenoid valve, cast aluminum heater, heating coil with 50% methanol solution (21.9mg/L).

(2) On site sampling calibration method: In practical use, the Winkler method is often used to calibrate the dissolved oxygen analyzer on site. There are two situations when using this method: when sampling, the instrument reading is M1, the analytical value is A, and when calibrating the instrument, the instrument reading is still M1. In this case, only the instrument reading needs to be adjusted to be equal to A; When sampling, the instrument reading is M1, and the laboratory analysis value is A. When calibrating the instrument, the instrument reading changes to M2. At this time, the instrument reading cannot be adjusted to be equal to A, but should be adjusted to 1MA × M2.

2、 Use and maintenance of dissolved oxygen analyzer electrodes

(1) The electrodes should be cleaned once every 1-2 weeks. If there are contaminants on the membrane, it can cause measurement errors. Be careful when cleaning and be careful not to damage the diaphragm. Rinse the electrode in clean water. If the dirt cannot be washed away, carefully wipe it with a soft cloth or cotton cloth.

(2) The zero point and range of the electrode should be rechecked in February to March.

(3) The regeneration of electrodes takes about one year. When the measurement range cannot be adjusted, it is necessary to regenerate the dissolved oxygen electrode. Electrode regeneration includes replacing the internal electrolyte, replacing the membrane, and cleaning the silver electrode. If there is oxidation phenomenon observed on the silver electrode, it can be polished with fine sandpaper.

(4) If electrode leakage is found during use, the electrolyte must be replaced.

As mentioned above, the use of dissolved oxygen meters is not only about using them correctly, but also about maintenance. Many customers have problems before using them. Most of them are caused by technicians accidentally touching the membrane head when taking out the electrode, which breaks the thin film. This leads to excessive negotiations and turnover repairs between customers and suppliers. Therefore, we hope that users can understand these small knowledge and use them in a formal and careful manner to avoid many unnecessary troubles.