Physical properties and virial coefficients of sulfur hexafluoride

Abstract

On the basis of new experimental PVT data and of selected literature values, this paper derives a Martin-Hou equation of state which correlates, within i=O.18% standard deviation, data in the experimental ranges of 25-130°, 10-75 bars, and 1.05-13 cc/g. A vapor pressure equation with six constants describes the data within =t0.18% standard deviation between -45 and +45.64", the critical temperature. A density equation with five constants correlates data between -41 and +42" with a per cent standard deviation of =tO.lO'%. The Martin-Hou equation serves to compute virial coefficients and a variance-covariance matrix treatment indicates their probable accuracy.

Measurement and correlation of the ( p, ρ, T) relation of sulphur hexafluoride (SF 6). II. Saturated-liquid and saturated-vapour densities and vapour pressures along the entire coexistence curve

“…The recent measurements of Hurly et al (20) for T 278 K scatter around our values by up to about ±0.1 percent. The vapour pressures of Mears et al (13) deviate sytematically by mostly > +0.1 percent and Jany and Straub's (16) values show large systematic deviations between −1.1 percent and +0.3 percent. The experimental results of other workers (11,12,14) were also considered but not selected for comparison because of wide scatter or greater systematic deviations.…”

“…Due to the unsatisfactory data situation at the time when the equation was developed, this equation shows large deviations by up to +1.8 percent from the new vapour pressure measurements. •, this work; , Kurzeja and Wagner; (2) , Otto and Thomas; (12) , Mears et al; (13) , Watanabe et al; (14) ∇, Jany and Straub; (16) , Biswas and Ten Seldam; (17) , Gilgen et al; (18) ---, values calculated from the equation of state of de Reuck et al (21) plotted for comparison. The grey area corresponds to the experimental uncertainty of the measurements in this work.…”

Measurement and correlation of the (p, ρ, T) relation of sulphur hexafluoride (SF 6). I. The homogeneous gas and liquid region in the temperature range from 225 K to 340 K at pressures up to 12 MPa

“…For T 313 K, the experimental values of Biswas et al (27) deviate systematically from our results by up to +0.2 per cent. In the homogeneous gas region, the measurements of Mollerup (28) scatter within the given uncertainty of ±0.1 ; (22) , Ulybin and Zherdev; (23) , Keramati and Wolgemuth; (25) , Watanabe et al; (26) , Biswas et al; (27) ; (17) , Keramati and Wolgemuth; (25) , Watanabe et al; (26) , Biswas et al; (27) , Mollerup; (28) , Freyhof; (29) , Kamimura et al; (31) , Blanke et al; (32) ---, phase boundary; −·−, values calculated from the equation of state of de Reuck et al (33) plotted for comparison. The grey area corresponds to the experimental uncertainty of the measurements in this work.…”

“…The values of the second virial coefficient B and the third virial coefficient C at each temperature were found by a stepwise reduction of the maximum density of the selected set of measurements until equation (1) from the equation of state of de Reuck et al (33) The first temperature value given above each diagram corresponds to our measurements and the temperature range written in parentheses covers the results of other experimentalists. A summary of the selected sets of measurements (2,17,(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) together with their uncertainties is listed in table 3. In order to avoid overcrowding the diagrams in the case of comprehensive sets of measurements some of the data points have been omitted with no loss of essential information.…”

Second virial coefficients of tetrachloromethane from measurements of the excess molar enthalpy ofyN2+ (1−y)CCl4over the temperature range 333.2 K to 413.2 K

“…--, calculated from the Kihara spherical core potential parameters for CCl4 listed in table 3. The CF 4 measurements, which are those of Lange et al, (17) lie on the same reduced curve as the measurements of SF 6 made by Mears et al (18) Several sets of virial coefficients for these fluids are available, (19) but here we have plotted only those which extend to the lowest reduced temperature. Curve a through the measurements was drawn with a flexicurve.…”