No reagent of BroadSensor’s COD whose maintenance stage is more than 4 weeks, it is only required to keep the window clean. If it is covered by dirt, please clean the window with diluted hydrochloric acid air-laid paper. As for calibration, it is suggested to use the potassium acid phthalate of national standard to perform calibration for one or two points. The calibration stage is generally once for several months.

Compared with the potassium dichromate method’s calibration steps:

1. Installing the sensor on site, reading the sensor’s reading after the value turns stable, and recording it as X1;

2. Taking the water sample in the sensor’s measuring position, using the potassium dichromate method equipment of national standard to measure it, and recording the reading as Y1;

3. Calculating the user calibration value K=Y1/X1

4. Repeating Step 1 to 3 above within 3 days, calculating the average of K value and writing it into the sensor.