Energy consumption is a key factor to focus on in a hydraulic system to help reduce costs and improve productivity. Energy losses in hydraulic systems come in two categories, mechanical losses and volumetric losses.
Mechanical efficiency losses come from energy consumed to push fluid through the pump. Mechanical efficiency decreases with increased viscosity because it takes more energy to push a thicker fluid through the pump. Volumetric efficiency losses come from internal leakage or slippage in the pump. Volumetric efficiency decreases with decreased viscosity because a thinner fluid will leak easier within the pump. Below is a visual of the change in efficiency as the viscosity changes.
Since the change in viscosity has opposite effects on these two categories of energy losses, overall efficiency is a balance between mechanical and volumetric losses. Optimal efficiency is obtained when the viscosity is consistent over a range of operating temperatures. This is achieved with a hydraulic fluid with a shear stable high viscosity index or VI. The viscosity index indicates the effect of the temperature change on the viscosity of the oil. A high viscosity index means that the viscosity doesn’t change as much over a wide range of temperatures.
It can make a big difference on the bottom line - A high performance hydraulic oil like Mobil DTE 10 ExcelTM Series can provide up to 6% increase in hydraulic pump efficiency*. Proper hydraulic oil selection helps to reduce efficiency losses, increase energy savings, and increase productivity.
Read more about hydraulic fluid efficiency here.
*Energy efficiency relates solely to the fluid performance when compared with ExxonMobil's standard hydraulic fluids. The technology used allows up to 6 percent increase in hydraulic pump efficiency compared with Mobil DTETM 20 Series when tested in standard hydraulic applications. The energy efficiency claim for this product is based on test results on the use of the fluid conducted in accordance with applicable industry standards and protocols. Efficiency improvements will vary based on operating conditions and applications.