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Publication Citation: Feasibility of an Accurate Dynamic Standard for Water Flow

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Author(s): Iosif I. Shinder; Michael R. Moldover;
Title: Feasibility of an Accurate Dynamic Standard for Water Flow
Published: June 01, 2010
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
Pages: pp. 128 - 133
Keywords: flow measurement, primary standard, dynamic gravitational method, flow metrology
Research Areas: Measurement Standards, Flow, Flow, Standards, Chemical Engineering & Processing, Calibrations (Mechanical), Manufacturing, Chemistry, Metrology