Full definition
A hydraulic accumulator is a crucial component in hydraulic systems, functioning as a pressure vessel that stores hydraulic energy. It employs compressed nitrogen gas as a pre-charge medium, allowing it to absorb excess pressure and release energy when needed. The primary functions of hydraulic accumulators include dampening pressure pulsations, compensating for internal leakage, and supplying peak flow rates that can be 10-20 times the normal pump flow for short durations. Additionally, these devices play a significant role in water-hammer dampening, which is essential for protecting piping and components from shock loads caused by sudden changes in flow velocity.
There are several types of hydraulic accumulators, each suited for specific applications. Bladder accumulators are known for their rapid response times, making them ideal for applications requiring quick energy release. Piston accumulators can handle larger volumes of hydraulic fluid, capable of storing up to 500 liters, and are suitable for systems with high energy demands. Diaphragm accumulators are typically used for smaller volumes and are advantageous in applications where space is limited.
The nitrogen pre-charge in a hydraulic accumulator is critical, generally set between 60-90% of the minimum circuit pressure. This range ensures optimal performance, providing a balance between energy storage and release capabilities. The choice of accumulator type and pre-charge level must consider the specific operational requirements of the hydraulic system to avoid issues such as cavitation or inadequate energy supply. Compliance with regulations such as the Pressure Equipment Directive (PED) 2014/68/EU and ASME Section VIII is essential for ensuring safety and reliability in hydraulic applications.