Empirical models for the density and the viscosity of squalane (C30H62; 2,6,10,15,19,23-hexamethyltetracosane) have been developed based on an exhaustive review of the data available in the literature and new experimental density and viscosity measurements carried out as a part of this work. The literature review showed there was a substantial lack of density and viscosity data at high temperature (373 to 473) K and high pressure conditions (pressures up to 200 MPa). These gaps were addressed with new experimental measurements carried out at temperatures of (338 to 473) K and at pressures of (1 to 202.1) MPa. The new data were utilized in the model development to improve the density and viscosity calculation of squalane at all conditions including high temperatures and high pressures.The model presented in this work reproduces the best squalane density and viscosity data available based on a new combined outlier and regression algorithm. The combination of the empirical models and the regression approach resulted in models which could reproduce the experimental density data with average absolute percent deviation of 0.04%, bias of 0.000%, standard deviation of 0.05%, and maximum absolute percent deviation of 0.14% and reproduce the experimental viscosity data with average absolute percent deviation of 1.4%, bias of 0.02%, standard deviation of 1.8% and maximum absolute percent deviation of 4.9% over a wide range of temperatures and pressures. Based on the data set used in the model regression (without outliers), the density model is limited to the pressure and temperature ranges of (0.1 to 202.1) MPa and (273 to 525) K, while the viscosity model is limited to the pressure and temperature ranges of (0.1 to 467.0) MPa and (273 to 473) K. These models can be used to calibrate laboratory densitometers and viscometers at relevant hightemperature, high-pressure conditions.

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The authors would like to thank Professor Bair for his insightful comments on ultrahigh-pressure viscosities. The viscosity model used by Schmidt et al. was a Tait-like2,3 model that has been shown to correlate accurately the viscosity of many fluids in the original investigation’s pressure range (0.1–275.8 MPa (40000 psi)) of interest. The upper pressure is indicative of the high pressures found in the petroleum industry4. However, after discussions with Professor Bair, it became clear a reference model that can accurately model the viscosity of squalane at ultrahigh-pressures is of interest to those working in the area of tribology.