Energy-Saving Hydraulic Fluids

Eco-Friendly Industrial Lubricants

Energy-Saving Hydraulic Fluids

Reduced power use and longer life for hydraulic machines

Photo 1 - Japan Petroleum Institute Award for Technological Progress

Hydraulic fluid is used in a wide variety of hydraulic machinery, from construction equipment such as excavators to machine tools and other equipment in factories. Producing hydraulic pressure requires huge amounts of electricity. Meanwhile, Japan's revised Energy Saving Act, which went into effect in April 1999, mandates that all industrial factories reduce their annual energy consumption by an average of at least 1% per year.
Knowing the role that lubricants could play in this effort, we set out to develop energy-saving hydraulic fluids. Energy-saving hydraulic fluids have a high viscosity index (VI), which translates to shorter warm-up times, and their low viscosity and low friction properties help reduce friction losses. These fluids help hydraulic equipment run more efficiently, and can reduce energy use by 2% to 8%. And by eliminating the use of zinc-based additives, we were able to create a product with five times the service life of those formulated with conventional additives.
In recognition of this achievement, our company received the Japan Petroleum Institute Award for Technological Progress for FY2003 (Photo 1).

Reduced pressure loss and improved start-up performance

In hydraulic systems, much of the energy input is lost in the pumps, fluid lines, and actuators, such that only around 40% of that energy will be available to perform work (Fig. 1).
We created a hydraulic fluid with low viscosity and a high viscosity index to reduce drag in the lines and improve cold start-up performance, and improved frictional properties to reduce sliding resistance and increase machine efficiency. In a hydraulic system, pressure loss in the lines is closely linked to the kinematic viscosity of the hydraulic fluid. What this means is that even among hydraulic fluids of the same viscosity grade, ones with a higher viscosity index will have a lower viscosity at low temperatures, which will mean reduced pressure losses. Another thing to remember is that when the equipment is first started up, it must be run for a period to warm up the hydraulic fluid and get the viscosity down to a suitable level. An oil with a high viscosity index takes less time to reach the proper viscosity, which means shorter warm-up times. (Fig. 2).

Fig. 1 - Energy loss in a hydraulic system
Fig. 2 - Warm-up time vs. viscosity index

With a high-VI oil, the equipment can be run at lower temperatures, which should mean shorter warm-up times.

Development of Energy-Saving Hydraulic Fluid, SUPER HYRANDO SE

To design a hydraulic fluid with both low viscosity and a high viscosity index, we used a hydrocracked base oil with a high viscosity index. To this we added a zinc-free friction modifier and extreme pressure agent for better friction-reducing performance. This combination was key to creating a hydraulic fluid with energy-saving properties and a longer service life (Fig. 3).
Today, that energy-saving, long-life hydraulic fluid is available as SUPER HYRANDO SE. Below is a graph showing the results of friction testing in the lab and power consumption testing done with an actual vane pump (Fig. 4).
SUPER HYRANDO SE has a lower friction coefficient than conventional zinc-based hydraulic fluids and the zinc-free hydraulic fluids sold by our competitors, and reduces power use by as much as 7% compared to zinc-based hydraulic fluids.
The table below shows the energy savings observed in testing with a variety of actual equipment (Table 1). The rates were calculated by measuring the power consumed during pump operation.

Fig. 3 - How SUPER HYRANDO SE was developed
Fig. 4 - Friction coefficient and power consumption

Table 1 - Results of testing SUPER HYRANDO SE with actual equipment

Tested by: Pump type Pressure
Reference oil
Energy savings
ENEOS Vane 4-9 Zinc-based 46 7
ENEOS Gear 15 Zinc-free 46 5
PLP Gear 15 Zinc-based 46 18
TSOG Piston 30 Zinc-based 46 13
DE Piston 4.5 Zinc-free 46 3
NSIK Vane 3 Zinc-free 32 11

Although the rate varied depending on the equipment, on the whole, energy use was reduced by around 3%–10%. In one case, the energy savings was close to 20%. For details, see the product page.