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Title: Uncertainty Analysis Of Large Water Flow Calibration Facility
Author: Y. Terao, m. Takamoto
Source: 1999 International Symposium on Fluid Flow Measurement
Year Published: 1999
Abstract: The NRLM large water flow calibration facility, which sets the primary standard of water flow rate in Japan, is one of the largest calibration facilities for water flow meters in the world. This facility covers a flow rate range of 0.014 to 0.83 m3/s (50 to 3000 m3/h). The test lines range from 100 to 1100 mm in diameter (D) with a minimum upstream straight pipe length of 100D. The flow rate is measured using the weighing and timing method. The uncertainty of this facility has been estimated in accordance with the ISO Guide to the expression of uncertainty in measurement. The expanded uncertainty of the flow rate (k 2) was estimated to be 0.034%. The major error sources and their contribution to the standard uncertainty of the flow rate were the measurements of (a) the mass of the water in the weighing tank (0.0130%), (b) the duration for which water flow was diverted to the weighing tank (0.0085%), (c) the buoyancy for the correction of the mass of water in the tank (0.0070%) and (d) the density of the water (0.0025%). The results of an international comparison with the primary standard in Sweden are also described.