Comparability of measurements is essential for the effective functioning of the single Market. To achieve this requires an internationally structured and harmonized metrological system. Specially in the field of flow measurements there is an urgent need to demonstrate the equivalence of measurements throughout the EU. The purpose of this project is to compare the characteristics of the LABEIN facilities for the calibration of flowmeters with those of NEL and DTI, which had participated in previous intercomparisons sponsored by BCR.
The objectives of the project have been achieved in two steps. First, the LABEIN flow measurement facility has been characterized by making velocity profiles, by determining the operational range with respect to pressure pulsation/fluctuations and by determining the accuracy of the diverter system. The two different transfer packages have been used to compare the calibration of the LABEIN facilities with those of NEL and DTI over a large range of flow. The packages consisted in a magmeter and a turbine meter for the comparison between LABEIN and DTI, and two orifice plates with a bundle straightener for the comparison between LABEIN and NEL.
Excellent agreement was observed between the DTI and LABEIN at all flow ranges except at very low ones, possibly caused by cavitation effects. Good agreement between LABEIN and NEL was found using the orifice plate package for high flow rates when the plate was placed downstream. However, at low flow rates, the plates being in upstream position, some differences in the results were observed.