Piston

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