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Search Publications by: Aaron Johnson (Fed)

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Displaying 26 - 50 of 60

Thermal Effects on Critical Flow Venturis

April 14, 2015
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover, Woong Kang, Liang Zhang
Critical flow venturis (CFVs) are widely used as working and transfer standards for gas flow measurement because of their long-term calibration stability (5 (e.g., a 2 mm throat diameter flowing air at 1 MPa), CFVs exhibit sensitivity to the environmental

NIST's Fully Dynamic Gravimetric Liquid Flowmeter Standard.

April 13, 2015
Author(s)
Jodie G. Pope, Aaron N. Johnson, Bernard J. Filla, Joey T. Boyd, Vern E. Bean, Christopher J. Crowley
We describe a new dynamic, gravimetric, liquid flow standard (LFS) that determines flow by measuring the rate of change of the liquid mass accumulating in a collection tank. The LFS is a fully- automated,15 kg/s system that uses a proportional–integral

Liquid Piston Prover Uncertainty Analysis Spreadsheet

March 25, 2014
Author(s)
John D. Wright, Aaron N. Johnson, Jodie G. Pope
This publication is a spreadsheet that calculates the mass and volume flow uncertainty for a piston prover liquid flow standard based on user inputs of component uncertainties. The calculations use the basis equation and uncertainty analysis presented in

Liquid Flow Meter Calibrations with the 0.1 L/s and 2.5 L/s Piston Provers

January 15, 2014
Author(s)
Jodie G. Pope, John D. Wright, Aaron N. Johnson, Christopher J. Crowley
This document provides a description of the 2.5 L/s and 0.1 L/s liquid flow calibration standards operated by the National Institute of Standards and Technology (NIST) Fluid Metrology Group to provide flow meter calibrations for customers. The 0.1 L/s and

Greenhouse Gas Emissions and Dispersion #2. Comparison of FDS Predictions with Gas Velocity Measurements in the Exhaust Duct of a Stationary Source

April 25, 2013
Author(s)
Kuldeep Prasad, Kevin Li, Elizabeth F. Moore, Rodney Bryant, Aaron Johnson, James Whetstone
The burning of fossil fuels remains a major source of greenhouse gases responsible for global warming and climate change. In order to reduce greenhouse gas emissions, it is imperative to develop a capability to accurately measure these emissions from point

Improved Nozzle Manifold for Gas Flow Calibrations

June 20, 2012
Author(s)
Aaron N. Johnson, Chunhui Li, John D. Wright, Gina M. Kline, Christopher J. Crowley
We developed a new nozzle manifold that reduced the uncertainty of flow calibrations from 0.09 % to as low as 0.074 % for flows of air up to 0.84 kg/s (43 000 L/min at reference conditions of 101.325 kPa and 293.15 K). The nozzle manifold also reduces the

Extended Lee model for the turbine meter & calibrations with surrogate fluids

May 1, 2012
Author(s)
Jodie G. Pope, John D. Wright, Aaron N. Johnson, Michael R. Moldover
We developed a physical model termed the “extended Lee model” for calibrating turbine meters to account for 1) fluid drag on the rotor, 2) bearing static drag and 3) bearing viscous drag. We tested the extended Lee model using a dual rotor, 2.5 cm diameter

Bilateral Comparison between NIST and PTB for Flows of High Pressure Natural Gas

April 6, 2012
Author(s)
Aaron N. Johnson, B Mickan, H. Toebben, Tom Kegel
In 2009 NIST developed a U.S. national flow standard to provide traceability for flow meters used for custody transfer of pipeline quality natural gas. NIST disseminates the SI unit of flow by calibrating a customer flow meter against a parallel array of

Comparison of Gas Velocity Measurements and CFD Predictions in the Exhaust Duct of a Stationary Source

July 13, 2011
Author(s)
Rodney A. Bryant, Olatunde B. Sanni, Elizabeth F. Moore, Robert P. Borthwick, Marco G. Fernandez, Iosif I. Shinder, Jiann C. Yang, Aaron N. Johnson
Two series of independent flow measurements were conducted for cross validation of flow velocity in the exhaust duct of the NIST Large Fire Laboratory. In the first series, two pressure measurement probe types, an S probe and a 3-D probe, were used to

Bilateral Comparison Confirms NIMs and NISTs Gas Flow Capabilities

October 15, 2010
Author(s)
Aaron N. Johnson, CHUNHUI LI
The bilateral comparison between NIM and NIST for gas flow was conducted from June 2008 to October 2009. Two critical flow venturis (CFVs) with nominal throat diameters of 10 mm and 20 mm, respectively, were selected as transfer standards. The CFVs were

Gas Flowmeter Calibrations With the 26 m 3 PVTt Standard

November 25, 2009
Author(s)
Aaron N. Johnson, John D. Wright
This document describes NIST s 26 m3 pressure, volume, temperature, and time (PVTt) primary flow standard. This standard is used to calibrate gas flow meters over a range extending from 200 standard L/min to 77,000 standard L/min where the reference

NIST Calibration Services for Liquid Volume

November 24, 2009
Author(s)
Vern E. Bean, Pedro I. Espina, John D. Wright, J F. Houser, Sherry D. Sheckels, Aaron N. Johnson
NIST provides calibration services for metal volume provers for liquid volumes from 4 L to 7600 L using gravimetric and volumetric methods. This document describes the procedures and methods of calculation used in the calibration service. The covered

Gas Flowmeter Calibrations With the Working Gas Flow Standard

November 23, 2009
Author(s)
John D. Wright, Jean-Phillipe Kayl, Aaron N. Johnson, Gina M. Kline
The Working Gas Flow Standard (WGFS) uses critical venturis, critical nozzles, or laminar flowmeters as working standards to calibrate customer flowmeters. The working standards are periodically calibrated with primary standards: the 34 L, 677 L, or 26 m3

The Calculation of Natural Gas Viscosity

August 14, 2009
Author(s)
Aaron N. Johnson, William Johansen
The calculation of natural gas viscosity has been implemented many different ways including the use of constants. Different methods of calculating natural gas viscosity may produce values with differences as large as 50%. Increasing natural gas prices

Natural Gas Flow Calibration Service

August 1, 2008
Author(s)
Aaron Johnson
This document describes NIST's high pressure natural gas flow calibration service (NGFCS). Flow calibrations are conducted offsite at the Colorado Experimental Engineering Station Incorporated (CEESI) in Garner, Iowa. A parallel array of nine turbine meter

Comparisons by PTB, NIST, and LNE-LADG in Air and Natural Gas With Critical Venturi Nozzles Agree Within 0.05 %

May 16, 2006
Author(s)
B Mickan, Roland H. Kraemer, D Dopheide, Hans-Jurgen Hotze, Heino-Michael Hinze, Aaron Johnson, John D. Wright, J-P Vallet
The PTB, NIST, and LNE-LADG conducted a comparison of gas flow measurement standards in air and natural gas in the pressure range from 0.9 to 42 bar. The artifacts used in the intercomparisons were four critical venturis with ISO standard toroidal shape

Relaxation Effects in Small Critical Nozzles

January 1, 2006
Author(s)
Aaron N. Johnson, C L. Merkle, Michael R. Moldover, John D. Wright
We computed the flow of four gases (He, N 2, CO 2, and SF 6) through a critical nozzle by augmenting traditional computational fluid dynamics (CFD) with a rate equation that accounts for τ relax, a species-dependent relaxation time that characterizes the
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