Accurate thermophysical properties of hydrocarbons are critical for chemical engineering applications, including fuel research and solvent/process modeling. This study presents simultaneous density and viscosity measurements of n-dodecane (a common diesel surrogate) and n-hexane (a representative light hydrocarbon) using a Density & Viscosity Meter (DVM) based on a balanced torsional resonator.

Measurements were conducted from 283 to 473 K and 0.1 to 200 MPa. In balanced torsional resonators, resonant frequency shifts with density while damping correlates with viscosity, enabling concurrent property extraction. After careful calibration, pure-fluid tests yielded high-quality datasets across temperature–pressure conditions. The results provide valuable reference data to improve models for energy systems and compressed-liquid behavior.

• Understand the operating principle of balanced torsional resonators for simultaneous density and viscosity measurement.
• Review the experimental setup, calibration steps, and uncertainty considerations for high-T/high-P measurements.
• Examine property trends of n-dodecane and n-hexane across 283–473 K and 0.1–200 MPa.
• See how combined density–viscosity datasets improve fuel surrogates, phase behavior studies, and process simulations.
• Discuss implications for thermophysical property modeling in energy and chemical engineering applications.