What is the calibration procedure for a portable dissolved oxygen meter?
The dissolved oxygen meter is a device for measuring dissolved oxygen in water. The working principle is that oxygen is reduced by the working electrode through the diaphragm to generate a diffusion current proportional to the oxygen concentration. By measuring this current, the concentration of dissolved oxygen in the water can be obtained.
The calibration operation process of the portable dissolved oxygen meter is as follows:
1. Observe whether the film at the electrode cap is damaged. If it is damaged, replace the original electrode cap, add electrolyte to the new electrode cap, replace it on the electrode, and dry the electrode.
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. Put the dissolved oxygen electrode into 5% sodium sulfite solution. When the instrument is in the measurement state, press the "Mode/Measurement" key, and the instrument will enter the mode selection state.
5. Press the "▲/mg．L-1/%" key or the "▼/Storage" key to select "ZERO" (the lower left corner of the display), press the "OK/Print" key, and the instrument enters the zero oxygen calibration function state. After the reading is stable, press the "OK/Print" key, the instrument will display "0.00mg/L", and the instrument will automatically exit the "ZERO" state after about 5 seconds.
6. Take out the electrode and dry it, put it on the platform, press "▲/mg．L-1/%" key or "▼/storage" key to select "FULL" (the lower left corner of the display), the instrument enters full Oxygen calibration function status, press the "OK/Print" key. After the reading is stable, press the "OK/Print" button, the instrument will display the current dissolved oxygen value, and the instrument will automatically exit the "FULL" state after about 5 seconds.
7. Repeat steps 2-6 twice until the calibration is stable.
