Hydraulic system hardware design and component selection must consider the performance capabilities of the hydraulic fluid.  Selecting a hydraulic fluid with the proper viscometric profile is critical in order to obtain optimum system response and guarantee long-term performance.  A fluid with high viscosity at low temperature will resist flow and may cause pump cavitation.  The use of a fluid with insufficient viscosity at peak operating temperature will result in poor volumetric efficiency and, in some cases, overheating and pump seizure. 

In a highly competitive environment, it is essential to maximize the efficiency of the hydraulic pump in order to minimize component size and costs, reduce energy consumption requirements and emissions, and improve reliability.  To achieve these goals, it is necessary to minimize internal pump leakage at high operating temperatures, and reduce mechanical energy losses at low start-up temperatures.

Cost effective hydraulic systems are designed with the smallest possible pump and fluid reservoir in order to reduce size and weight.  The fluid in these systems must function under ever increasing temperature and pressure demands. 

Maximum Efficiency Hydraulic Fluid, or MEHF, is a higher level of fluid formulation technology that provides significant improvements in hydraulic pump efficiency over a wide range of operating conditions.   

MEHF products are formulated to minimize mechanical energy losses at low temperature, and also reduce internal pump leakage under high pressure/high temperature operating conditions.   The resulting improvement in pump efficiency over the entire temperature operating range provides many productivity benefits to the equipment designer, including:

• Increased hydraulic power and reproducible equipment performance over a wider temperature range.  Improvements of 5 to 20% have been documented
• Energy savings per unit work of 5% or more, with a corresponding reduction in energy costs and exhaust emissions
• Reduced need for auxiliary cooling
• Reduced risk of overheating and consequent equipment shutdown or damage
• Improved start-up performance at lower temperatures
• Elimination of seasonal oil change-outs

The viscosity/temperature profile of a hydraulic fluid must be known in order to meet the in-service viscosity requirements specified by the pump OEM.  Pump manufacturers publish fluid viscosity requirements which define minimum and a maximum viscosity at peak operating and start-up temperature respectively.   For a given oil, it is critical to know the peak operating and minimum start-up temperatures where the viscosity limits are reached. The range of temperature over which the pump can operate efficiently is often referred to as the Temperature Operating Window (TOW). Hydraulic fluids meeting the MEHF performance level definition will enable the system designer to expand the TOW for any pump.

When equipment operates at standard pressures and temperatures (typically above 60 °C), MEHF fluids deliver a higher flow rate and a better overall efficiency in gear, vane and piston pumps. This translates into higher operator productivity, and significantly lowers operating costs for the equipment user due to lower fuel consumption.  Energy or fuel savings in the range up to 20% can be expected under normal operating conditions when a MEHF is used. Higher productivity gains and savings can be achieved at peak operating temperatures.

Standard monograde HM fluids, engine oils and transmission fluids can ”work,” but do they enable the operator to reduce the overall cost of operations while improving performance and productivity?  The operator must select a fluid that suits the needs of both new and old equipment from multiple OEMs.  MEHF simplifies this task.