Current paper represents the results of viscosity and density measurements of vacuum oils for diffusion vacuum pumps. Vacuum oil samples are represented by the following brands: VM-1S, LEYBONOL LVO 500 and Alcarin-D24. All the measurements have been carried out at atmospheric pressure: viscosity has been measured by the capillary method in the temperature range from 293 K to 373 K, and density has been measured by the pycnometer and hydrostatic weighing methods in the temperature range from 293 K to 473 K.

The density and viscosity of liquid 1-hexene and 1-heptene have been simultaneously measured over the temperature range from (298 to 473) K and pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The combined expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of k = 2 is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid 1-hexene and 1-heptene. Theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher (VTF) type equations with pressure-dependent coefficients were used to represent the temperature and pressure dependences of the measured viscosities for liquid 1-hexene and 1-heptene. Also the friction theory (FT) viscosity model together with derived Tait-type equation of state (EOS) was used to accurately represent measured viscosity data. The measured values of the density and viscosity of 1-hexene and 1-heptene in the liquid phase were compared in detail with reported data and with the values calculated from correlations.

The density and viscosity of \(n\)-heptane have been simultaneously measured over the temperature range from 298 K to 470 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques, respectively. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95 % confidence level with a coverage factor of \(k= 2\) is estimated to be 0.15 % to 0.30 %, 0.05 %, 0.02 K, and 1.5 % to 2.0 % (depending on temperature and pressure ranges), respectively. The measured densities were used to develop a Tait-type equation of state for liquid \(n\)-heptane. Theoretically based Arrhenius–Andrade and Vogel–Tamman–Fulcher type equations with pressure-dependent coefficients were used to describe the temperature and pressure dependences of the measured viscosities for liquid \(n\)-heptane. The measured values of the density and viscosity were compared in detail with reported data and with the values calculated from a reference EOS and correlation models for the viscosity.

Density and viscosity of monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG) and their binary, (50%MEG + 50%DEG), (50%MEG + 50%TEG), (50%DEG + 50%TEG), and ternary (33.33%MEG + 33.33%DEG + 33.34%TEG) mixtures have been simultaneously measured over the temperature range from 293 K to 465 K and at pressures up to 245 MPa using the hydrostatic weighing and falling-body techniques. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.15-0.30%, 0.05%, 0.02 K, and 1.5-2.0% (depending on temperature and pressure ranges), respectively. Tait-type equation of state (EOS) for pure MEG, DEG, and TEG has been developed using the measured (p, rho, T) data. Theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equation with pressure dependent coefficients was used to describe the temperature dependence of measured viscosities for pure polyethylene glycols. (C) 2011 Elsevier B.V. All rights reserved.

A new apparatus to measure simultaneously the density and viscosity of liquids has been designed and constructed based on the hydrostatic weighing and falling-body principles. The density and viscosity of monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG) and their binary, (50%MEG + 50%DEG), (50%MEG + 50%TEG), (50%DEG + 50%TEG), and ternary (33.33%MEG + 33.33%-DEG + 33.34%TEG) mixtures have been measured over the temperature range from 293 K to 473 K and at atmospheric pressure. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.15% to 0.30%, 0.05%, 0.06 K, and 1.5% to 2.0% (depending on temperature and pressure ranges), respectively. The theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equations were used to describe the temperature dependence of measured viscosities for pure polyethylene glycols and their mixtures. (C) 2011 Elsevier Ltd. All rights reserved.

Evaluation of characteristic points in the neighborhood of the critical point and far from it on binodal and critical isobar of water in liquid state is put forward. Coefficients for binodal and critical isobar equations and characteristic points are presented.