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Search Publications by: Robert F. Berg (Assoc)

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Displaying 26 - 50 of 119

Viscosity-ratio measurements with capillary viscometers

November 27, 2013
Author(s)
Robert F. Berg, Eric F. May, Michael R. Moldover
Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic gas thermometry and for the

Recommended viscosities of 11 dilute gases at 25?degC

December 13, 2012
Author(s)
Robert F. Berg, Michael R. Moldover
Commercially manufactured meters that measure the flow of a process gas are often calibrated with a known flow of a surrogate gas. This requires an accurate model of the flow meter and accurate values of the relevant thermophysical properties for both

Recommended vapor pressure and thermophysical data for ferrocene

August 14, 2012
Author(s)
Michal Fulem, Kvetoslav Ruzicka, Marisa A. Rocha, Luis M.N.B.F. Santos, Robert F. Berg
Recommended vapor pressure data for ferrocene (CAS Registry Number: 102-54-5) in the temperature range from 242 to 447 K were developed by the simultaneous correlation of critically assessed vapor pressures, heat capacities of the crystalline phase and the

Noble gas viscosities at 25 degrees C

August 10, 2012
Author(s)
Robert F. Berg, William C. Burton
Near 25 C, ab initio calculations of the zero-density viscosity of helium gas eta_He have an uncertainty of approximately 0.001 %, which is 1/40th of the uncertainty of the best measurements. The uncertainties of the published calculations for neon [Bich

Calibration of Laminar Flow Meters for Process Gases

June 1, 2012
Author(s)
John D. Wright, Thiago Cobu, Robert F. Berg, Michael R. Moldover
We calibrated three models of commercially-manufactured, laminar flow meters (LFMs) at four pressures (100 kPa, 200 kPa, 300 kPa, and 400 kPa) with five gases (N2, Ar, He, CO2, and SF6) over a 10:1 flow range using NIST’s primary flow standards as

Thermoelectric temperature control device for vapor pressure measurements

August 31, 2011
Author(s)
Robert F. Berg
The static method of measuring equilibrium vapor pressure requires locating the sample at the coldest part of the apparatus to avoid errors due to evaporation and recondensation elsewhere. This paper describes a device that can hold the sample 1 K below

Accurate Measurements of Process Gas Flow with Laminar Flow Meters

October 15, 2010
Author(s)
Thiago Cobu, Robert F. Berg, John D. Wright, Michael R. Moldover
We calibrated three models of commercially-manufactured, laminar flow meters (LFMs) with nitrogen at four pressures (100 kPa, 200 kPa, 300 kPa, and 400 kPa) over a 10:1 flow range using NIST’s primary flow standards and a physical model. Without additional

Capillary flow meter for calibrating spinning rotor gauges

August 6, 2008
Author(s)
Robert F. Berg
This article describes a capillary flow meter whose maximum flow rate of 0.2 micromol/s (~0.2 cm3/min at ambient conditions) covers the range that is useful for calibrating spinning rotor gauges. Knowing the input pressure, output pressure, and temperature

Shear Thinning Near the Critical Point of Xenon

April 17, 2008
Author(s)
Robert F. Berg, Michael R. Moldover, M Yao, G A. Zimmerli
We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span the range of reduced shear rates: 0.001 < γτ < 700, where γτ is the shear rate scaled by the relaxation time τ of

Reference Viscosities of H 2 , CH 4 , Ar and Xe at Low Densities

August 1, 2007
Author(s)
E May, Robert F. Berg, Michael R. Moldover
We determined the zero-density viscosity eta of hydrogen, methane and argon in the temperature range 200 K to 400 K, with standard uncertainties of 0.084 % for hydrogen and argon and 0.096 % for methane. These uncertainties are dominated by the uncertainty

Transport Properties of Argon at Zero Density From Viscosity-Ratio Measurements

April 1, 2006
Author(s)
E May, Michael R. Moldover, Robert F. Berg, John J. Hurly
We determined the zero-density viscosity and thermal conductivity of argon with an uncertainty of only 0.039 % in the temperature range 200 K to 400 K. Our results will improve: (1) the argon-argon interatomic potential, (2) calculated boundary-layer