Faults in waste water flow measurements are very common - quality assurance needed

The majority of waste water flow measurements are installed in open channels. The only way to assure the quality of these measurements is by on-site calibration. 

Indmeas carries out yearly on-site calibrations at municipal water purification plants as well as in most large paper and pulp plants in Finland and Sweden.  

"Quality assurance of these measurements is indeed important. According to our calibration history over 200 out of totally 600 waste water flow measurements have shown an error of + - 10%, when calibrated for the first time", tells measurement engineer Risto Saraste.

"By a regular calibration program systematic measurement erros are eliminated and the stability of the quality can be monitored in the long-term", Saraste continues.