Table of Contents
Definition
A hydraulic accumulator is a pressure vessel used to store hydraulic energy and on demand make the energy available again to the system.
Function of accumulator
An accumulator is a pressure vessel that holds hydraulic fluid and a compressible gas, typically nitrogen. The housing or shell is made of materials like steel, stainless steel, aluminum, titanium and fiber-reinforced composites. Inside, a moveable or flexible barrier—usually a piston or rubber bladder—separates the oil from the gas.
- To meet peak demand of power
When excessive power is available during lower capacity, there will be loss of power if pump run continuously, hence during the slack period, some of the fluid energy is used to charge an accumulator. Then it is used
- To smooth out pressure surge/shocks
When fluid flow is suddenly changed pressure surges are developed, moving fluid may cause fluid hammer and shock waves. Accumulator will absorb the pressure shocks and ripples and reduce vibrations and pressure surges.
- To provide emergency power source
The fluid energy stored in an accumulator may be sufficient to give an emergency supply in case of power failure causing the pumps to stop.
- Holding high pressure
Accumulator give fluid energy back up for longer periods without keeping the pump running.
Type of Accumulator
- Dead weight type – A dead weight type hydraulic accumulator is a type of hydraulic energy storage device that uses a weight to create hydraulic pressure. It is a relatively simple and old-fashioned design that has been used in various applications, especially in the past.
- Spring loaded type – A spring-loaded hydraulic accumulator is a type of hydraulic energy storage device used in hydraulic systems. It consists of a cylindrical chamber with a moveable piston or diaphragm inside and a spring mechanism that provides a pre-defined force against the piston or diaphragm. The primary purpose of this device is to store and release hydraulic energy, helping to maintain system pressure, dampen shocks, and compensate for variations in fluid volume.
- Gas charged type – A gas-charged hydraulic accumulator is a device used in hydraulic systems to store energy in the form of pressurized gas. It is often used to maintain pressure in a hydraulic system, dampen hydraulic pressure spikes, and provide a source of stored energy for various hydraulic applications. Gas-charged accumulators are commonly used in industrial and mobile hydraulic systems.
Application
1) Large hydraulic presses
2) Farm machinery, diesel engine starters
3) Aeroplan landing mechanism
4) Lift trucks etc.
Advatages and Disadvantages of hydraulic accumulator
Hydraulic accumulators are devices used in hydraulic systems to store and release hydraulic energy. They offer several advantages and disadvantages:
Advantages
Energy Storage: Hydraulic accumulators store hydraulic energy, which can be released when needed. This allows for temporary energy storage, which can be used to supplement the hydraulic system during peak demands or power outages.
Pressure Stability: They help maintain consistent pressure levels in hydraulic systems, which is critical for ensuring the proper functioning of hydraulic machinery. This stability can improve the overall efficiency and performance of the system.
Reduced Pump Cycling: Hydraulic accumulators can reduce the frequency of pump operation. This results in less wear and tear on pumps and motors, extending their lifespan and reducing maintenance costs.
Shock Absorption: Accumulators can absorb and dampen hydraulic shocks and pulsations. This is especially important in applications like heavy machinery, where sudden changes in pressure can damage components.
Emergency Power: Hydraulic accumulators can provide a source of emergency power in case of a power failure. They can be used to safely lower or stop equipment in critical situations.
Improved Efficiency: By storing excess energy during periods of low demand and releasing it when needed, hydraulic accumulators can improve the overall energy efficiency of a hydraulic system.
Disadvantages
Initial Cost: Hydraulic accumulators can be expensive to purchase and install, which can be a barrier for some applications, particularly in smaller systems.
Maintenance: Accumulators require regular maintenance to ensure they function correctly. This includes inspections, seal replacement, and recharging. Neglecting maintenance can lead to system failures.
Space and Weight: Accumulators can be bulky and heavy, which may not be suitable for all applications, especially those with space constraints or where weight is a critical factor.
Complexity: Integrating accumulators into a hydraulic system can be complex. Proper design and installation are crucial to ensure the system functions as intended, and this may require the expertise of hydraulic engineers.
Energy Loss: Hydraulic accumulators can experience some energy losses over time due to factors like fluid leakage and thermal effects. This can reduce their efficiency.
Limited Storage Capacity: Accumulators have a finite storage capacity, which means they are not suitable for applications requiring continuous high-energy storage. For such cases, other energy storage solutions may be more appropriate.
FAQ
What is accumulator and its function?
Accumulator is a pressure vessel for storing hydraulic pressure in it utilizing compressible and decompressible nature of nitrogen gas.
What are the four functions of an accumulator?
Hydraulic accumulators are able to provide a handful of functions: Energy storage, leakage compensation, and vibration and shock reduction.
Which system an accumulator is used?
Hydraulic system
An accumulator enables a hydraulic system to cope with extremes of demand using a less powerful pump, to respond more quickly to a temporary demand, and to smooth out pulsations. It is a type of energy storage device.
How do you calculate accumulator precharge pressure?
PT = testing pressure of the accumulator (relative to the atmospheric pressure, namely the “relative pressure”). Usually PT = PS x 1.43. ∆P = is the difference between the maximum and minimum working pres- sure (P2-P1).
What are the three types of accumulator?
- Dead weight accumulator
- Spring loaded accumulator
- Gas charged accumulator
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