If the hydraulic capacitance is known as a function of the capacitive pressure (difference), volume changes in the container can be calculated.

hydraulic capacitance, (general) capacitance-content relation,

If the capacitance is constant, the change of volume can be calculated simply from

     delta_V = C_V*(p_2 – p_1)

Beziehung zwischen hydraulischer Kapazität und Druck