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Search Publications by: John D. Wright (Assoc)

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Displaying 51 - 67 of 67

Gas Flowmeter Calibrations with the 34 L and 677 L PVTt Standards

June 23, 2004
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover, Gina M. Kline
This document provides a description of the 34 L and 677 L pressure, volume, temperature, and time (PVTt) primary gas flow standards operated by the National Institute of Standards and Technology (NIST) Fluid Flow Group. These facilities are used to

Volumetric Gas Flow Standard with Uncertainty of 0.02% to 0.05%

November 1, 2003
Author(s)
John D. Wright, Michael R. Moldover, Aaron N. Johnson, A Mizuno
A new pressure, volume, temperature, and time (PVTt) primary gas flow standard for calibrating flowmeters has an expanded uncertainty (k = 2) of between 0.02% and 0.05%. The standard diverts a steady flow into a collection tank of known volume during a

What Is the Best Transfer Standard for Gas Flow?

March 1, 2003
Author(s)
John D. Wright
National metrology institutes around the world have embarked on an effort to compare their primary gas flow standards under the supervision of the Comit International des Poids et Mesures and its Working Group on Fluid Flow. As the pilot laboratory for the

Design and Uncertainty Analysis for a PVTt Gas Flow Standard

February 1, 2003
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover
A new pressure, volume, temperature, and time (PVTt) primary gas flow standard has been constructed at the National Institute of Standards and Technology with an expanded uncertainty of between 0.02 % and 0.05 % (k = 2). The standard covers a flow range of

The Effect of Vibrational Relaxation of the Discharge Coefficient of Critical Flow Venturis

December 1, 2000
Author(s)
Aaron N. Johnson, John D. Wright, Shin-ichi Nakao, C L. Merkle, Michael R. Moldover
This paper identifies a new mechanism that can affect the discharge coefficient of critical nozzle flows. Specifically, vibrational relaxation effects are demonstrated to significantly influence the discharge coefficient of selected gases in critical

Uncertainty in Primary Gas Flow Standards Due to Flow Work Phenomena

June 1, 2000
Author(s)
John D. Wright, Aaron N. Johnson
Static gravimetric and static volumetric gas flow standards are both affected by uncertainty components related to the measurement of the change of mass of gas within the inventory volume. In the process of diverting gas into the collection vessel, rapid

Flow Calibration Services at NIST

April 1, 2000
Author(s)
John D. Wright, Pedro I. Espina
The Fluid Flow Group of the National Institute of Standards and Technology in Gaithersburg, Maryland offers calibration services for flow meters used in gas, water, and liquid hydrocarbon. Gas flow meters are calibrated using PVTt systems, piston provers

Laboratory Primary Standards

April 1, 2000
Author(s)
John D. Wright
Commonly used primary calibration techniques for the measurement of liquid and gas flows are described. The techniques described include: static gravimetric and dynamic gravimetric methods for both gases and liquids, liquid piston displacement provers

Numerical Characterization Of The Discharge Coefficient In Critical Nozzles

July 1, 1998
Author(s)
Aaron N. Johnson, Pedro I. Espina, John D. Wright, G E. Mattingly, C L. Merkle
The discharge coefficient in critical nozzles flowing N 2, Ar, CO 2, and H 2 in the Reynolds Number range (2,000 to 22,000) is studied computationally to assess the capability of Computational Fluid Dynamics (CFD) in assisting experimental calibration. A

The Performance of Transit Time Flowmeters in Heated Gas Mixtures

June 1, 1998
Author(s)
John D. Wright
An ultrasonic transit time flowmeter was tested over Reynolds numbers from 1000 to 100,000 in a calibration facility that generates gas flows with controlled temperature and composition. The gas mixtures were composed of air, nitrogen, carbon dioxide