The calibration of a turbine meter as a secondary flow-rate standard by a one-point relative method using laser Doppler velocimetry

Heat district suppliers demand carefully constructed and calibrated flow sensors of heat meters at temperatures above 100 degrees C for long-term use. The calibration at these temperatures cannot be performed by the common gravimetric standard method due to technical difficulties. A novel one-point relative method using a laser Doppler velocimeter (LDV) was therefore developed which is based on the gravimetric method below 100 degrees C and on the Reynolds law. This method allows a turbine meter to be calibrated as a secondary flow-rate standard with a relative uncertainty less than or equal to 0.2% for temperatures up to 180 degrees C with regard to the flow rate.