What are Hydraulic Accumulators?

In industrial hydraulics, the hydraulic accumulator is a key component that significantly boosts the efficiency and reliability of hydraulic systems: essentially, a hydraulic accumulator is a pressure vessel. It stores and disburses energy in the form of pressurised fluid. Acting like a battery within a hydraulic system, it helps maintain steady pressure levels, absorbs shocks, and compensates for fluid leakage. 

The Functions of an Accumulator in a Hydraulic System

•  Enhancing the performance of the hydraulic pump.
• Reducing the overall energy consumption.
•  Providing an auxiliary power source during emergencies.

How Does a Hydraulic Accumulator Work?

A hydraulic accumulator consists of a few main components, each performing a critical role to maximise efficiency and reliability:

• Inert Gas (Typically Nitrogen): this gas is used inside the accumulator to create pressure. When hydraulic oil flows into the accumulator, the nitrogen gas is compressed. This compression helps maintain constant pressure within the system, even when the fluid dynamics change.
• Hydraulic Oil: this is the fluid stored within the accumulator. Its movement helps transfer power within the hydraulic system, assisting in various functions such as dampening and maintaining steady flow and pressure.
• Accumulator Shell: the physical structure that houses the gas and fluid. It can withstand high compression ratios, ensuring the system remains safe and efficient, even when pressure exceeds the pre-charge pressure.
• Pre-Charge Pressure: before using the accumulator, it is pre-charged with nitrogen gas to a minimum pressure. This pre-charge is critical for the accumulator’s operation, determining the minimum system pressure and how much fluid the accumulator can store and release.

Each component works to help store energy, absorb shocks, and ensure hydraulic systems run smoothly. By keeping the system under minimum system pressure, the accumulator allows for a longer service life of system components and ensures that fluid flows efficiently while accommodating the varying demands of the system.

Understanding Hydraulic Accumulators

At their core, a hydraulic accumulator is an energy storage device. It holds a non-compressible hydraulic fluid under pressure from an external source. This source could be a mechanical force like a spring, weight, or a compressed gas – typically nitrogen due to its inert nature.

From stabilising the operation of hydraulic valves to extending the lifespan of the cylinder and pump by mitigating pressure fluctuations, the role of an accumulator, especially a bladder type, is critical in expanding system efficiency and reliability.

Hydraulic accumulators are essential across various industries – be it manufacturing, automotive, or renewable energy – offering wide-ranging benefits critical for peak system performance.

Our comprehensive guide will take you through everything you need to know about hydraulic accumulators.

Functions of Hydraulic Accumulators

Energy Storage and Release

The accumulator (hydraulic cylinder) stores energy in the form of compressed gas when the hydraulic circuit is at high pressure. It then releases the stored energy when the system pressure drops, boosting power.

Supplementing Pump Flow

During peak demand, an accumulator in a hydraulic system is used to supplement pump flow to the hydraulic components. This clever function allows the use of a smaller, less expensive pump without sacrificing performance.

Emergency Power Supply

In the unfortunate event of a power failure, accumulators can maintain system pressure temporarily. This ensures a safe shutdown of machinery preserving integrity and minimising risk.

Shock Absorption

Hydraulic systems need protection against unforeseen shocks and pulsations that might lead to costly damage. The buffering action of accumulators achieves this.

Maintaining System Pressure

Leakages and thermal fluctuations are inevitable in any hydraulic system, but accumulators compensate for this by maintaining the desired working pressure.

Three Main Types of Hydraulic Accumulators

Bladder Accumulators

Choose a bladder accumulator if you need the system to absorb shocks while maintaining pressure. A rubber bladder separates the gas from the fluid effectively. This separation ensures that the compressed gas expands and compresses without directly interacting with the fluid preventing contamination and ensuring a consistent pressure output. Bladder accumulators come in a variety of sizes and configurations making them adaptable to a wide range of system demands and capable of achieving higher compression ratios when the pressure exceeds the pre-charge pressure. Bladder accumulators discharge rapidly so they are ideal for hydraulic circuits that need quick responses.

Diaphragm Accumulators

Choose a diaphragm accumulator for your hydraulic system when system demands call for efficient, space-saving solutions in low-volume applications. The main advantage of using a diaphragm as the separator medium lies in its ability to maintain pressure and enable fluid to flow smoothly, ensuring operational efficiency. Diaphragm accumulators are available in various sizes and are suitable for applications where space is at a premium. They do not compromise performance. Their design allows for rapid response to pressure changes making them ideal for systems requiring precise pressure control and shock absorption.

Piston Accumulators

Choose a piston accumulator for high-pressure situations because it can handle substantial fluid volumes. The robust piston seal ensures a reliable separation between the gas and fluid segments. This is vital for maintaining system efficiency and preventing leakage. Piston accumulators come in various capacities and offer versatility when handling larger volumes and pressures. The piston accumulator is, therefore, an ideal choice for applications demanding precise hydraulic control and durability.

Benefits of Using Hydraulic Accumulators

System Efficiency

An immediately available energy reserve means quicker response times and an overall uptick in the operational efficiency of hydraulic systems.

Reduced Wear and Tear

Accumulators act as shock absorbers by extending the lifespan of components within the hydraulic system translating to fewer replacements and repairs.

Hydraulic Energy Savings

A hydraulic accumulator works to ease off the demands made on pumps during peak periods. This equals tangible energy reductions and cost savings.

Environmental Benefits

Less energy usage is good news for our planet – preventing unnecessary power use aligns with sustainable practices.

Safety and Reliability

Hydraulic accumulators are also critical because they have a failsafe role when power supplies falter.

Maintenance and Safety Considerations

Regular maintenance and inspections are imperative for trouble-free accumulator operation. Handling these high-pressure vessels requires caution, the right know-how, and safety measures. For example, knowing how to use nitrogen gas safely to pre-charge and pressurise accumulators is essential.

Choosing the Correct Accumulator

Opt for a new accumulator that suits your system’s pressure range and volume of fluid needed. Tailoring your choice to a specific hydraulic power application ensures performance and avoids over- or undersizing. Consult Control Gear and our hydraulic specialists can guide you toward the ideal selection.

Understanding the technical parameters:

• Evaluate system parameters such as maximum operating pressure, temperature range, and fluid compatibility.
• Assess the intended application to determine the appropriate size and type of accumulator.
• Consider the pre-charged pressure – critical for the correct functioning of the accumulator.
•  Review the construction materials, especially the seals and diaphragm or bladder inside the accumulator, to ensure compatibility with the hydraulic fluid.
• Understand the certification and compliance standards that accumulators must adhere to, such as Pressure Systems Safety Regulations 2000 (PSSR) (S.I. 2000 No. 128), which cover most gas-loaded accumulators.

It is always best to incorporate these technical considerations before adding an accumulator into your system for optimal results.

Control Gear’s Hydraulic Accumulator Services

We are proud to be among the top UK suppliers and service providers for hydraulic accumulators. Our services include:

• Supply of new bladder and piston accumulators.
• Accredited workshop facilities.
•  Repair and recertification services (PSSR S.I. 2000 No. 128).
• Same-day removal, recertification, and refit.
• Certified engineers.
• System design and build services.

For more information or case studies on our hydraulic accumulator expertise, contact us or visit our service page for insights.

Key Takeaways

The bottom line is that hydraulic accumulators are vital in modern hydraulic systems. Their abilities to boost efficiency, enact safety measures, and contribute to system reliability are just a few reasons why a quality accumulator, and its upkeep, should be viewed as vital investments in your business.

Are you looking to leverage the full potential of hydraulic accumulators for your operations? Contact Control Gear today, and our team of specialists will help you with accumulator selection and 

system design, and answer any questions you may have.