This video show the operation of the online COD analyzer. Click the [single-step] button to enter the interface. This interface allows users to individually execute specific steps in the maintenance process. When the analyzer anomaly occurs, single-step can help you check each critical step one by one and quickly located the fault point. On the left is the multi-position valve control area. Ten buttons correspond to the ten valve ports of the exhaust valve. The upper right side is the other function area. Four buttons correspond to the digestion fan, which provides heat dissipation. The water pump draws water samples. The cabinet fan provides heat dissipation. The alarm output provides an alarm if the measured value exceeds the specified value. The lower right side is the peristaltic pump area. The forward and reverse rotation of the peristaltic pump correspond to the extraction and discharge of liquid, respectively. To change reagents, first click [Reverse] in the Roller pump menu then click the corresponding reagent button to open the valve. After draining the reagent from the original line, click [stop] to stop the peristaltic pump and click the reagent button to close the value. Then insert the line into the new reagent bottle. click the corresponding reagent button again to open the value and click [forward] in the Roller pump menu to refill the reagent. Finally, click [stop] to stop the peristaltic pump and click the reagent button to close the value.