On the Melting Curve of Sulfur Hexafluoride

Harvey, Allan H.

doi:10.1063/1.5005537

Cited by 2 publications

(7 citation statements)

References 14 publications

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“…(2) and Eq. (3) are both correct and applicable to our cells within the melting range (0.3 ≤ F ≤ 0.8), then according to GW [7] and Harvey [20], the relative standard uncertainties in l and dp/dT are 0.01 % and 1.6 %, respectively. The relative uncertainty from the calculated value of dT/dz would then be only about 1.6 %, or u(dT/dz) = 0.00186 mK/cm.…”

Section: Pressure Head Correctionsmentioning

confidence: 80%

“…This density is equivalent to a molar volume of 64.0 cm 3 •mol −1 . Harvey [20] made a similar data extrapolation of the solid molar volume, based on a more extensive set of data, that yielded an equivalent value of 64.10(25) cm 3 •mol −1 . We adopt this value for the purposes of calculations for static pressure head corrections discussed in Sec.…”

Section: Solid Phasementioning

confidence: 99%

“…A revised melting-line equation was derived by Harvey [20] for use between the TP pressure of 0.231 MPa and approximately 48 MPa (253 K). The slope of the melting line dpm/dT, as evaluated at the TP, is a property of interest for immersion-type fixed-point cells, since the inverse slope governs the size of the static pressure head correction [11].…”

Section: The Melting Linementioning

confidence: 99%

“…where the solid-phase molar volume vs = 0.438×10 −3 m 3 /kg is based on the extrapolated value from Harvey [20].…”

Section: The Melting Linementioning

confidence: 99%

“…We estimated the magnitude of these errors by analyzing our immersion profile data using the dT/dz value as calculated from GW [7] density and the Harvey [20] melting line (see Sec. 4.2).…”

Section: Immersion Errorsmentioning

confidence: 99%

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Realizations of the Triple Point of Sulfur Hexafluoride in Transportable and Refillable Cells

Tew

Quelhas

2018

J. RES. NATL. INST. STAN.

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The Minamata Convention on Mercury has created a near-term need to develop alternative fixed points to replace the mercury triple point (Hg TP) for calibration of standard platinum resistance thermometers (SPRTs) on the International Temperature Scale of 1990 (ITS-90). The sulfur hexafluoride (SF6) TP is a good candidate to provide adequate “drop-in compatible” replacements for the lowest costs. We report our first results of SF6 TP realizations performed at the National Institute of Standards and Technology (NIST) using a new series of transportable and refillable triple-point cells. The melting curves are presented at various melted fractions F and compared to evaluate the reproducibility and overall uncertainty for the realizations. We obtained a TP temperature of 223.55587(33) K at F = 50 % and 223.55607(35) K at F = 100 % as a weighted average of realizations using two adiabatic-type cells and two immersion-type cells. (Unless otherwise stated, uncertainties are standard uncertainties corresponding to a 68 % confidence level.) Temperatures were derived using a combination of five different SPRTs as calibrated at NIST on the ITS-90. The data were evaluated over a region of the melting plateau for melted fraction F between 30 % ≤ F ≤ 80 % with a 0.2 mK wide melting range. The results from the immersion-type cells were used to derive an experimental value for the SF6 TP static head correction of −11.6(1.7) mK/m. This value implies an initial slope of the pressure-temperature (p-T) equilibrium melting line of 1.55 MPa/K, whichis in agreement with the value predicted via the Clapeyron equation. The uncertainties of these initial SF6 TP realizations are limitedby uncertainty in the realization of the ITS-90 (0.25 mK) and, to a lesser extent, static pressure head effects and chemical impurities.

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Section: Pressure Head Correctionsmentioning

confidence: 80%

Section: Solid Phasementioning

confidence: 99%

Section: The Melting Linementioning

confidence: 99%

“…where the solid-phase molar volume vs = 0.438×10 −3 m 3 /kg is based on the extrapolated value from Harvey [20].…”

Section: The Melting Linementioning

confidence: 99%

“…We estimated the magnitude of these errors by analyzing our immersion profile data using the dT/dz value as calculated from GW [7] density and the Harvey [20] melting line (see Sec. 4.2).…”

Section: Immersion Errorsmentioning

confidence: 99%

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Realizations of the Triple Point of Sulfur Hexafluoride in Transportable and Refillable Cells

Tew

Quelhas

2018

J. RES. NATL. INST. STAN.

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The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids

Huber

Lemmon

Bell

et al. 2022

Ind. Eng. Chem. Res.

128

100

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The NIST REFPROP software program is a powerful tool for calculating thermophysical properties of industrially important fluids, and this manuscript describes the models implemented in, and features of, this software. REFPROP implements the most accurate models available for selected pure fluids and their mixtures that are valid over the entire fluid range including gas, liquid, and supercritical states, with the goal of uncertainties approaching the level of the underlying experimental data. The equations of state for thermodynamic properties are primarily of the Helmholtz energy form; a variety of models are implemented for the transport properties. We document the models for the 147 fluids included in the current version. A graphical user interface generates tables and provides extensive plotting capabilities. Properties can also be accessed through third-party apps or user-written code via the core property subroutines compiled into a shared library. REFPROP disseminates international standards in both the natural gas and refrigeration industries, as well as standards for water/steam.

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On the Melting Curve of Sulfur Hexafluoride

Cited by 2 publications

References 14 publications

Realizations of the Triple Point of Sulfur Hexafluoride in Transportable and Refillable Cells

Realizations of the Triple Point of Sulfur Hexafluoride in Transportable and Refillable Cells

The NIST REFPROP Database for Highly Accurate Properties of Industrially Important Fluids

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