Because of different measuring principles, the final readings are different. For example, two kinds of equipment respectively use the potassium dichromate method and permanganate method of China’s national standard method to measure the same water sample, the results will have three to five times difference. BroadSensor’s COD calibration method refers to COD equipment of the potassium dichromate method, the consistency and accuracy of BroadSensor’s measuring liquid is the same as the national standard method equipment’s, even better than the national standard method equipment’s on the occasion of zero drift and being less than 30mg/L.

Through site comparison and site calibration, when water composition does not change fiercely, BroadSensor’s COD and the national standard method equipment can reach good consistency and close accuracy.