Investigations of uncertainties from hot water flowmeters using laser Doppler velocimetry

Electromagnetic flowmeters will be used as working standards for determining volumetric flowrates for hot water. Flowmeters for hot water can be calibrated by the well-known mass-time method only up to 100°C. But the district heat suppliers are greatly interested in flowrate measurements at higher temperatures in order to exactly calculate the delivered heat energy. The described one-point relative method using LDV is a time-saving procedure and allows the determination of the metrological performance of flowmeters as a function of flowrate and temperature above 100°C. The relative uncertainties in the determination of the flowrates are about 0.2%.