Reference
Viscosity-Pressure Coefficients (α) for Lubricants
Measured pressure-viscosity coefficients (α) for real lubricants, preserved from werktuigbouw.nl.
These are the α values the Barus & Roelands viscosity-pressure calculator needs as an input — the original site never published the underlying Barus/Roelands equations client-side, only one worked reference case, so this table is the closest the source gives to real, usable α data for other lubricants.
Roelands (1966) — α at three temperatures
| Lubricant | α at 38 °C | α at 99 °C | α at 149 °C |
|---|---|---|---|
| Advanced ester | 15.2 | 13.8 | 13.4 |
| Formulated advanced ester | 18.4 | 14.8 | 12.2 |
| Polyalkyl aromatic | 20.3 | 17.4 | 14.5 |
| Synthetic paraffinic oil | 28.4 | 26.9 | 25.5 |
| Synthetic paraffinic oil + antiwear | 28.4 | 26.9 | 25.5 |
| C-ether | 14.5 | 9.1 | 7.4 |
| Super-refined naphtenic mineral oil | 30.8 | 18.1 | 13.4 |
| Synthetic hydrocarbon (traction fluid) | 31.5 | 13.6 | 15 |
| Fluorinated polyether | 44.6 | 43.8 | 43.5 |
Roelands, D.J.A. (1966), “Correctional aspects of the viscosity-temperature-pressure relationship of lubricating oils”, Druk. V.R.B., Groningen, Netherlands.
Evans (1983) — viscosity and α at 40 °C and 100 °C
| Lubricant | η at 40 °C [mPa·s] | α at 40 °C [1/GPa] | η at 100 °C [mPa·s] | α at 100 °C [1/GPa] |
|---|---|---|---|---|
| Sebacate | 10.7 | 14.2 | 2.8 | 11.6 |
| Santotrac 50 | 28.4 | 28.7 | 4.6 | 16.5 |
| Santovac-5 5P4E | 266 | 35 | 15 | 14.9 |
| HVI-650 | 450 | 27.5 | 27 | 17.5 |
Evans, C.R. (1983), “Measurement and mapping of the rheological properties of elastohydrodynamic lubricants”, Ph.D. thesis, University of Cambridge.
Source: werktuigbouw.nl’s piezo.htm reference page, preserved verbatim.