What is the calibration process for a portable dissolved oxygen meter?
A dissolved oxygen analyzer is a device for measuring dissolved oxygen in water. Its working principle is that oxygen is reduced by the working electrode through a diaphragm, generating a diffusion current proportional to the oxygen concentration. By measuring this current, the concentration of dissolved oxygen in water is obtained.
The calibration process of the portable dissolved oxygen analyzer is as follows:
1. Observe whether the thin film at the electrode tip is damaged. If there is any damage, replace the original electrode tip, add electrolyte to the new electrode tip, replace it on the electrode, and wipe the electrode dry.
2. Weigh 5.00g of anhydrous sodium sulfite solid, dissolve it in distilled water, and prepare a 100mL solution, which is a 5% zero calibration solution.
3. Press the start button, turn on the power, dry the electrodes, and carefully absorb the moisture on the film.
4. Place the dissolved oxygen electrode into a 5% sodium sulfite solution, and with the instrument in measurement mode, press the "Mode/Measurement" button to enter the mode selection mode.
5. Press the "▲/mg · L-1/%" key or the "▼/Storage" key to select "ZERO" (bottom left corner of the display screen), and press the "OK/Print" key to enter the zero oxygen calibration function state of the instrument. After the reading stabilizes, press the "OK/Print" button, and the instrument will display "0.00mg/L". After about 5 seconds, the instrument will automatically exit the "ZERO" state.
6. Remove the electrode and dry it, place it on the platform, press the "▲/mg · L-1/%" button or the "▼/Storage" button to select "FULL" (bottom left corner of the display screen), and the instrument will enter the full oxygen calibration function state. Press the "OK/Print" button. After the reading stabilizes, press the "OK/Print" button, and the instrument will display the current dissolved oxygen value. After about 5 seconds, the instrument will automatically exit the "Full" state.
7. Repeat steps 2-6 twice until the calibration is stable.
