In the UK, net energy consumption stood at 128.1 million tonnes of oil equivalent in 2024, with the industrial sector accounting for 19.5 mtoe – the lowest level in over 50 years – as efficiency measures and structural changes reduced energy use in industry. Even so, hydraulics remain a major power consumer in infrastructure and industrial equipment, and every inefficiency translates directly into wasted energy and operating cost.
Why every watt counts in hydraulic engineering?
When engineers focus on eliminating mechanical energy losses in fluid power, rather than adding complexity, measurable gains in efficiency and operating life can be realised. In this article, we look at where energy is physically lost within hydraulic systems and how engineering decisions can reclaim that loss without relying on digital intervention.
Cutting loss where it starts: reducing pressure drop through better flow paths
What is the biggest source of energy loss in any fluid power system? Pressure drop. In a commercial or industrial system, a high pressure drop means the pump must deliver more power to maintain performance, with the excess turning into heat. In construction plant and infrastructure applications, long runs of small-bore hose or poorly planned routing are common contributors to elevated pressure loss.
Specifying hydraulic hoses with larger internal diameters and designing flow paths that minimise abrupt directional changes will reduce frictional losses. Engineering models such as the Darcy–Weisbach relationship show that head loss decreases rapidly as diameter increases, which is why industry best practices emphasise selecting an adequate internal diameter to minimise pressure loss and the associated energy waste. In environments where the total system run length can reach hundreds of metres, smart design choices can clock up significant energy savings over years of service.
When valves become barriers: how component geometry affects flow efficiency?
Hydraulic valves are essential for motion and load control, but they can also be major contributors to wasted energy if their internal flow passages are not sized or shaped appropriately. Directional control, pressure relief and flow control valves all introduce resistance, and the resulting pressure drop across valves converts useful hydraulic power into waste heat. However, valves can also be used to create intentional restrictions within the system, safely dissipating excess energy as fluid passes through its internal passages.
The magnitude of this loss depends on your valve type, the internal geometry, and operating position. Valves operating continuously in throttling or partially open conditions dissipate more energy than those used primarily for on/off control. In construction equipment such as access platforms, lifting systems, or stabilisation circuits, sustained valve-related pressure losses are a common source of inefficiency.
To minimise unintentional energy losses caused by hydraulic valves, the key is to treat valves as engineered flow elements, and not just control devices. It’s a combination of the correct sizing, the correct selection, and the correct operating mode. Select your valves using manufacturer pressure –flow characteristics so that the required flow can pass with minimal pressure loss, avoiding continuous throttling wherever possible, and ensuring each valve type is used only for its intended function.
Valves should be sized and applied so they operate within their optimal flow range, with internal leakage kept within acceptable limits for the duty cycle. Your valve placements and circuit layout should shield the components from exposure to unnecessary differential pressures when control is not required.
Couplings, connections, and flow disturbance
Hydraulic couplings and fittings are often treated as secondary components in design engineering, but their influence on flow quality can be significant. Sharp edges or misalignments at connection points can disrupt flow and create localised turbulence. This turbulence increases resistance and contributes to pressure loss at each interface. In systems with multiple connections (common in mobile plant) these losses can accumulate. Selecting couplings with smooth internal profiles and maintaining the correct alignment during installation will help maintain a consistent flow profile and reduces unnecessary energy dissipation.
Heat as the consequence of inefficiency
All hydraulic energy losses ultimately appear as heat within the fluid, with a range of potentially damaging effects. Whenever pressure is lost through friction, throttling, leakage, or turbulence, the energy supplied by the pump is converted into thermal energy rather than useful mechanical work. This waste heat raises fluid temperature locally and, if sustained, across the entire system.
Elevated oil temperature has several compounding mechanical effects. For instance, as the temperature increases, fluid viscosity decreases, reducing the thickness and strength of the lubricating film between moving surfaces. This increases metal-to-metal contact within pumps, valves, and actuators, accelerating wear. At the same time, higher temperatures accelerate the chemical degradation of hydraulic fluid additives, reducing their ability to control oxidation, corrosion, and foaming. Seals and hoses may also be affected, as prolonged exposure to elevated temperatures hardens elastomers, reduces elasticity, and shortens service life.
In many industrial applications, hydraulic systems operate in confined spaces where airflow is limited and additional cooling capacity is impractical or undesirable. Under these conditions, managing heat after it has been generated becomes difficult and often inefficient. Larger oil reservoirs, heat exchangers, or forced cooling systems add complexity, cost, and additional failure points without usually addressing the underlying cause of the problem.
Minimising heat generation at source – by design – is therefore an important engineering objective. As we have seen, by reducing pressure losses, limiting internal and external leakage, and maintaining smooth, well-sized flow paths, you can directly reduce the amount of energy converted into heat within the system. This creates more stable operating temperatures, improves fluid condition, and reduces thermal stress on components.
What next?
In practice, careful mechanical design is often the most effective form of energy management in hydraulic systems. To find out more or for advice specifying the best components for your application, please contact the team at Hydrastar today by clicking here, or call us directly on 01353 721704.
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