Knowledge

There is a connection between the degree of viscosity loss and hydraulic performance. When hydraulic oil experiences significant shear instability leading to high viscosity loss, it can be detrimental to your system. This is because the viscosity of the hydraulic oil may fall outside the specified range for its viscosity grade. Increasing shear reduces the high-temperature properties of the fluid. It means the top temperature operation will decrease by increasing the viscosity loss. For example, imagine the viscosity loss of hydraulic oil A is 1.2% and that for hydraulic oil B is 20%.

If two hydraulic oils test in the Vane Pump at 138 bar (2000 psi) and 52°C for 96 hours the result will be the following data :

The chart above is intended to provide a general understanding of viscosity loss in hydraulic oils; therefore, the data may not be entirely accurate. In practice, viscosity loss persists until all polymer molecules are broken down.