Development of a gravimetric system using a conical rotating double-wing diverter for low liquid flow rates. (August 2017)

• Record Type: Journal Article
• Authors: Cheong, Kar-Hooi; Doihara, Ryouji; Shimada, Takashi; Terao, Yoshiya
• Is Part Of: Flow measurement and instrumentation. Volume 56(2017)
• Page Start: 1
• Page End: 13
• Publication Date: 2017-08
• Subjects: Gravimetric system -- Conical rotating double-wing diverter -- Low flow rates -- Calibration -- Diverter timing error -- Evaporation rate; Fluid dynamic measurements -- Periodicals; Flow meters -- Periodicals; Fluides, Dynamique des -- Mesure -- Périodiques; Débitmètres -- Périodiques; 681.2805
• DOI: 10.1016/j.flowmeasinst.2017.05.006
• Languages: English
• ISSNs: 0955-5986

Abstract

Abstract: An improved gravimetric system for low flow rates was developed at National Metrology Institute of Japan (NMIJ) to perform calibration method of flying-start-and-stop. The present paper describes the main features of the gravimetric system comprising three main components – a compact and umbrella-like conical rotating double-wing diverter, a weighing tank with a chimney-like inlet structure, and a liquid discharge mechanism using a suction nozzle – with explanation of the design considerations behind each feature. Performance tests show that, under the most unfavorable conditions, diverter timing error relative to liquid collection time is below 0.003% whereas evaporation rate of weighing tank relative to amount of liquid collection is below 0.005%. Dependency of diverter timing error on flow rates due to liquid collection loss was also revealed, and this shortcoming was improved by either one of the two following countermeasures: adjustment of nozzle sizes or modification of wing shape. These two measures are both effective in achieving a consistent timing error with varying flow rates. The overall performance results confirm the gravimetric system's capability in performing low flow calibration. Highlights: An improved gravimetric system for low flow rates was developed. The system comprises a diverter, a weighing tank and a liquid discharge mechanism. Diverter timing error relative to liquid collection time is below 0.003%. Evaporation rate relative to amount of liquid collection is below 0.005%. Nozzle size adjustment or wing shape modification improves diverter's performance.