Fluid Power Storage

In the case of hydraulic circuits where a large flow rate is required alternating with a low or no flow condition, an accumulator allows smaller pumps and motors to be used, reducing both installation and operating costs.
The operating cycle below would require a pump having a capacity Q2. If an oleo-pneumatic accumulator is used, it is possible to store oil during the time periods (t2 - t1) and (t4 - t3) when requirement is very low or zero. It can then reutilize it during t1 and (t3 - t2) when the required flow rate is higher than the pump capacity Q1.
This pump must be selected to have the volumes V1 + V2 < V3 + V4.

Emergency Energy Reserve

In the case of a sudden power loss, e.g. pipe or joint failure, the accumulator can provide sufficient energy to complete an operational cycle or to allow actuators to re-set to a "safe" position, preventing damage to equipment or product.
A typical use is the emergency supply of fuel oil to power plant burners. The example below shows that a failure at B causing a loss of energy can be offset by manually overriding the electro valve A thus utilizing the potential energy of the accumulator.

Pressure Compensator

When a constant static pressure is required for a long period, an accumulator is indispensable as it will compensate for pressure loss due to seepage through joints, seals, etc. as well as balancing pressure peaks which may occur during the operating cycle. Typical applications are found in closing systems, loading platforms, curing presses, machine tools, lubricating systems, etc.

Hydraulic Line Shock Damper

Rapid valve closure can produce shock waves (water hammer) resulting in over-pressurization of pipes, joints, valves, etc. The use of a suitable accumulator can neutralize or significantly reduce the shock. Typical applications are water, fuel and oil distribution circuits, washing equipment etc.

Hydraulic Spring

The accumulator can be used with advantage as an alternative to mechanical springs, e.g. deep drawing. The thrust can be easily controlled to great accuracy over a wide range of pressures by oil pressure control without the need for springs or support.

Pulsation Damper

By virtue of their design both piston and diaphragm pumps create pulsation or pressure peaks during operation. This is undesirable and detrimental to both the smooth operation and operational life of components.
The fitting of a bladder type accumulator adjacent to, and down stream of the pump will dampen the pulsation to an acceptable level. Typical applications are dosing pumps, pumps with a small number of pistons etc.

Volume Compensator

In a closed hydraulic circuit a rise in temperature can cause an increase in pressure due to thermal expansion.
An accumulator installed in the line will protect the valves, gaskets, pressure gauges etc. Common applications are found in refineries and pipelines.

Counter Balancing

The balancing of a force or weight can be achieved by using hydraulic pistons driven by an accumulator, thus avoiding the use of counterweights with attendant dimensional and weight savings. Typical applications are in machine tools, hoists etc.

Shock Absorber

Mechanical shocks in hydraulically driven equipment can be absorbed by accumulators. Possible applications are in drive and suspension systems for fork-lifts, mobile cranes, agricultural and civil engineering, machinery etc.

Fluid Separator (transfer barrier)

Fundamentally the accumulator separates two fluids (hydraulic applications use nitrogen and oil). The accumulator can be used when pressure has to be transferred between two incompatible fluids. The example below is a simplified diagram for a fatigue test of a vessel 'S' using water. The initial pressure pulse is generated by piston pump 'P' using oil. An equal volume and pressure is transferred to the water in the vessel by the accumulator. Similar applications are found in the petro-chemical industries.