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In this paper, the results of an inter-laboratory comparison of two small water flow calibration facilities with extremely low uncertainty between Endress+Hauser Japan Co. Ltd. (E+H-J) and the National Metrology Institute of Japan (NMIJ) is reported. Flowrate range between 30 kg/h and 36,000 kg/h is compared. Expanded uncertainty of mass flowrate is from 0.020% to 0.025% at E+H-J and from 0.021% to 0.023% at NMIJ. In order to achieve low uncertainty, NMIJ carries out a re-evaluation of the uncertainty budget for two weighing tank systems. With advanced control of ambient temperature and calibration, the uncertainty level can be reduced to approximately half of previous levels. Results of the inter-laboratory comparison show excellent agreement for both standards, which is less than 0.018%. En values are also less than 0.52 for all examined flowrate points. These results show a high level of consistency for the facilities at both labs. To know the substantial difference, comparison is performed using corrected fitting curves between the flowrate by the test meters and the reference. As a result, significant difference between two facilities was quite small, and is estimated to be less than 0.001%. Differences in this comparison are one or two orders of magnitude lower than previous comparisons on water flow. [ABSTRACT FROM AUTHOR]

Abstract: The present paper describes a fundamental uncertainty analysis for a flowrate measurement in a pipe using an ultrasonic Doppler velocity profile method and an evaluation of the estimated uncertainty by an actual flow calibration. The uncertainties are estimated for internal factors originating from the measurement equipment; UVP provided by Met-Flow sa. and external factors depending on on-site measurements, such as the inclination angle of the ultrasonic transducer. The relative expanded uncertainty due to internal factors is estimated to be 0.34% with a coverage factor of 2. The relative external uncertainty including external factors is estimated to be from 0.42% to 2.13% depends on the inclination angle of the transducer. The results of the actual flow calibration under the same condition as the uncertainty analysis are within the range of uncertainty considering the internal factors. [Copyright &y& Elsevier]

Abstract: The results of calibration tests of the feedwater flowrate of ultrasonic flowmeters used in a nuclear power plant for variety of upstream conditions obtained using the new high Reynolds number calibration facility at NMIJ are described. In this examination, the measurements are performed for five pattern pipe layouts with one or two elbows. The flow conditioners installed upstream of the flowmeter are the tube bundle type and the Mitsubishi, which are normally used in nuclear power plants. The calibration result for each flowmeter are largely different for each flow conditioner and each upstream pipe layout, except in some special cases. Moreover, the trend of the correction factor with Reynolds number is not uniform for each case. Furthermore, some differences were observed for individual flowmeters. It is recommended that the feedwater flowmeter, especially when used to perform measurement uncertainty recapture, is calibrated based on the actual pipe layout and the Reynolds number corresponding to the actual nuclear power plant conditions. [Copyright &y& Elsevier]

Abstract: A new test facility has been constructed for the National Metrology Institute of Japan (NMIJ) and the National Institute of Advanced Industrial Science and Technology (AIST) for calibration of feedwater flowmeters used in nuclear power stations at Reynolds numbers of up to 18 million. This very large Reynolds number is achieved in a 600 mm pipe at a flowrate of 3.33  m3/s (12,000  m3/h) and a water temperature of 70  ∘C. This calibration facility consists of a circulation loop with four pumps and four reference flowmeter sets, a prover system, a heating and cooling unit, and other components. The expanded uncertainty of this facility is 0.077%. The present paper describes, in detail, the new facility, the calibration method of the reference flowmeter, experiments for flow field, uncertainty estimation, and the results of an example calibration. [Copyright &y& Elsevier]

This study aims to develop a novel methodology, a combined system of optical and ultrasonic measurements, for evaluating spatial propagation characteristics of ultrasonic pulse-echo. The system can record pulse-echo profiles except in the near field where the ultrasound is not well-focused. An in-house-developed stereo-vision system is utilized as a reference to measure the three-dimensional coordinates in spherical particle dispersion in water. Ultrasonic pulse-echo from the particles is identified to the three-dimensional coordinates obtained by the stereo-vision system. Acquiring numerous data of randomly-dispersed particles in water gives higher data density in three-dimensional space than the conventional method using a hydrophone sensor. The method realizes a highly-accurate evaluation of the tilt angle of the pulse emission against the transducer casing axis within O (0. 0 1 ∘). The fact that the pulse-echo waveform in the three-dimensional space, rather than the radiation sound pressure field of the conventional method, can be converted into a database is crucial. • A calibration method for the ultrasound transducer is established. • Ultrasound pulse-echo measurement is combined with a stereo-vision system. • The propagation characteristic of ultrasound pulse-echo is measured with high accuracy. • The calibration result is validated by applying velocity profiling of water flow. [ABSTRACT FROM AUTHOR]

A static weighing system for a liquid microflow calibration rig, whose minimum flow rate is 1 mg/min (equivalent to 1 μL/min for water), was designed and evaluated. The developed weighing system, which can collect over 10 g of water, has two features: (i) an automatic detachable device with a sealing and wiper mechanism in contact with a needle and (ii) a flexible air bag to contain the air from the weighing vessel. Having these two features, the weighing system succeeds in reducing the evaporation effect as well as preventing tension on the weighing scale. However, uncertainty due to the mass difference of adhering liquid on the outside surface of needle before needle insertion and after needle extraction should be considered. Theoretical and experimental analysis were conducted. The mass difference due to the adhering liquid on the needle was estimated to be smaller than 1/3 of the target standard uncertainty of mass measurement set at 0.1 mg, indicating that the detachable procedure was not a dominant uncertainty source for mass measurement. The evaporation rate during collection was experimentally estimated to be less than 0.001 mg/min, which corresponds to less than 0.1% for the lowest flow rate of 1 mg/min. • Weighing system for liquid microflow calibration rig is designed and evaluated. • This study minimizes an evaporation effect for a static weighing method. • Evaporation effect is estimated to be less than 0.1 mg and below 0.1 % at 1 mg/min. • Automatic detachable device is placed between a weighing vessel and a feeding nozzle. • Syringe pumps were calibrated by this weighing system from 1 mg/min to 10,000 mg/min. [ABSTRACT FROM AUTHOR]