Piston Accumulator

A hydro-pneumatic piston accumulator is a device used
specifically for storage of liquid under pressure. As liquids,
for all practical purposes, are incompressible, this objective
is achieved by utilizing the compressibility of gases.
A floating piston is fitted into the accumulator tube.
An inert gas - nitrogen - is filled into the gas side through a
pressure valve to a pressure P . The piston moves to the 0
bottom end, filling the entire volume V of the accumulator. 0
When the system pressure P is higher than the gas 1
precharge pressure P , the liquid enters the accumulator 0
and the piston is moved towards the gas side compressing
and reducing the gas volume to V .1
Should the liquid pressure rise to P , the volume of gas 2
reduces to V with an attendant rise in pressure, thus 2
balancing the Liquid pressure.