Notes on the Application of the International Practical Temperature Scale of 1968

Abstract

An attempt is made to clarify many of the unfamiliar calculations associated with this new scale.

Equation of State for Supercooled Water at Pressures up to 400 MPa

“…84 Temperatures on the IPTS-48 scale were first converted to IPTS-68 and then to ITS-90. The conversion from IPTS-48 to IPTS-68 was performed according to the equations given by Bedford and Kirby; 85 these conversion equations were found to agree with those of Douglas. 86 In the Temperature (K)…”

Density, thermal expansivity, and compressibility of liquid water from 0.deg. to 150.deg.. Correlations and tables for atmospheric pressure and saturation reviewed and expressed on 1968 temperature scale

“…and z (7), giving the change owing to the redefinition of the zinc point on the IPTS-68, is given by 4.9035 X 10~5 7(7/1 00 -1 ) Z(f) " 1 -2.94855 X 10"4 7 (6) For the range of temperatures considered here, both w and z are small enough that their arguments may be either 768 or f48 without loss of precision. For temperatures below 0°C, Equation 4 is no longer exact, but it is close enough for all the data considered here.…”

Liquid phase PVTx properties of carbon tetrachloride-octamethylcyclotetrasiloxane binary mixtures

“…The change in volume of the sample in the bellows relative to the volume at some reference pressure, usually atmospheric pressure, as pressure is applied to the system Is a function of the following: the vacuum corrected weight of the sample in the bellows, Wvc; the density of the sample at the reference pressure, p(P0,7); the temperature and pressure corrected cross-sectional area of the bellows, A(P,T)\ and the change in length of the bellows with pressure, ALB(P,T). Appropriate temperature and pressure corrections were applied to ALb(P,T) and A(P,T) to obtain the true compression of the sample as represented by eq 1. k(P,T) = [v(P0,T)~v(P,T)]/v(Pa,T) = ALb(P,T) • A(P, T) • p(Pq, T)/Wvc (1) The quantity [v(P0,T) -v(P,T)]/v(P0,T) = k(P,T) is the compression of the sample where v(P,T) is the specific volume at pressure P and temperature T and v(P0,7) is the specific volume at reference pressure P0 and temperature T. The relative volume is defined by eq 2. v(P,T)/v(Po,T) = 1 -k(P,T)…”

“…With the exception of the density at atmosphere pressure, all terms on the right hand side of eq 1 were obtained during the course of this study. The atmospheric pressure density was determined by Herring (20) to ±1 X 10~5 g cm-3 using a hydrostatic weighing technique.…”