Hydac SK Piston Accumulator

Fluids are practically incompressible and cannot therefore store pressure energy.
The compressibility of a gas (nitrogen) is utilized in hydraulic accumulators for storing fluids. HYDAC piston accumulators are based on this principle.
A piston accumulator consists of a fluid section and a gas section with the piston acting as a gas-proof separation element. The gas section is pre-charged with nitrogen.
The fluid section is connected to the hydraulic circuit so that the piston accumulator draws in fluid when the pressure increases and the gas is compressed.
When the pressure drops, the compressed gas expands and forces the stored fluid into the circuit.