Use of portable dissolved oxygen meters

1, calibration: 4.1 Observe whether the film at the electrode is damaged, if it is damaged, replace the original electrode, add electrolyte to the new electrode, replace it on the electrode, and wipe the electrode dry. 4.2 Weigh 5.00g anhydrous sodium sulfite solid, dissolve it with distilled water, and prepare 100mL solution, that is, 5% zero calibration solution. 4.3 Press the "ON/OFF" button, turn on the power supply, wipe the electrode dry, and carefully blot the water on the film. 4.4 Put the dissolved oxygen electrode into 5% sodium sulfite solution. When the instrument is in the measuring state (the words CONC are displayed in the lower left corner), press the "Mode/measurement" button, and the instrument will enter the mode selection state. 4.5 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 will enter the zero-oxygen calibration function. After the reading is stable, press the "OK/Print" key, the instrument displays "0.00mg/L", and the instrument automatically exits the "ZERO" state after about 5 seconds. 4.6 Remove the electrode and wipe it dry, put it on the platform, press the "▲/mg·L-1/%" key or "▼/ storage" key to select "FULL" (lower left corner of the display), the instrument enters the full oxygen calibration function state, press the "OK/print" key. After the reading is stable, press the "OK/Print" key, the instrument displays the current dissolved oxygen value, and the instrument automatically exits the "FULL" state after about 5 seconds. 4.7 Repeat steps 4.2 to 4.6 twice until the calibration is stable. 4.8 If after repeated calibration, the instrument does not return to zero or the full dissolved oxygen value is less than 7mg/L, replace the new electrode and repeat steps 4.2 to 4.6. 2, measurement: 5.1 Press "ON/OFF", turn on the power, directly into the measurement state (CONC displayed in the lower left corner). Place the electrode into the solution to be measured and record after the reading is stable. 6, precautions: 6.1 When measuring or flushing the electrode, be careful not to damage the film at the electrode. 6.2 The electrode is placed in the solution to be tested or in the pool at a depth of about 10cm or below.