This example shows a testrig for a spring-loaded accumulator. The accumulator is charged by the pressure source while the orifice is closed, held at its charged pressure by the check valve, and discharged as the orifice opens.
The plots below show two cycles of charging and discharging the accumulator. While the orifice is closed, the supply pressure is increased, charging the accumulator. The check valve holds the pressure in the accumulator as the supply pressure is dropped. The orifice opens, allowing the accumulator to discharge. Once the accumulator is empty, the flow rate through the orifice stays steady at a lower value due to the lower supply pressure. The orifice closes, and the cycle repeats.