Laser optical flow measurement
The actual measurement uncertainty of the calibration depends on the on-site flow conditions. Hence the position of the ball valve in regards to the flow situation is critical and must be chosen well. For the characterization of the flow conditions, we developed a key coefficient modell resulting in five velocity profile classes. The following table shows the achievable measurement uncertainties for each one of these profile classes. These numbers are based on the measured value with a coverage factor of k = 2 for resulting 95 % confidence interval.
Until 2021 more than 200 flow sensors of district-heating and drink water supply were calibrated on-site. One third of the calibrated flow sensors showed a significant or rather high measurement error. These numbers confirm the benefits of the on-site calibration method for flow sensors.