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Feasibility of an Accurate Dynamic Standard for Water Flow

Published

Author(s)

Iosif I. Shinder, Michael R. Moldover

Abstract

We used NIST's primary water flow standard to study the feasibility of accurately determining mass flow rates mdot of water "dynamically," that is from the time derivative of the weight W of the collection tank: mdot,dynamic = (dW/dt)/g. When data for a constant flow in the range 10 kg/s < mdot < 60 kg/s was averaged over 40 seconds, the average dynamic flow rate <mdot,dynamic>, agreed with the static standard within the noise, (<mdot,dynamic>/mdot,static – 1) = 0.00015{plus or minus}0.00033. (The uncertainty is the standard deviation of one measurement). These results are consistent with arguments that dW/dt is only weakly sensitive to jet entering the collection tank and to the turbulence inside the tank. We conclude that further study of a dynamic flow standard for larger flows is justified. A dynamic standard can use a conventional diverter that is much simpler than the uni-directional diverter with collector/bypass unit that was designed and built for NIST's primary, static standard.
Citation
Flow Measurement and Instrumentation
Volume
21

Keywords

flow measurement, primary standard, dynamic gravitational method, flow metrology
Created June 1, 2010, Updated February 19, 2017