Alternative Circuit for Power Supply
Power Supply with Accumulator and Fixed Displacement Pump

Graphical
Representation:

Circuit Application:

Most hydraulic accumulators are used in one of four types of circuits mentioned below:

1. Supplement pump flow in circuits with medium to long delays between cycles.
2. Hold pressure in a cylinder while the pump is unloading or stopped.
3. Have a ready supply of pressurized fluid in case of power failure.
4. Reduce shock in high velocity flow lines or at the outlet of pulsating piston pumps.

Cost Notes:

1. The cost of the accumulators usually offset savings on these smaller components, but down sizing saves on operating costs.
2. This accumulator circuit maintains pressure in the cylinder while unloading the pump. It also conserves energy while using an inexpensive fixed volume pump.

Safety Notes:

1. Another feature of the accumulator-relief-unload-dump valve is, stored oil in the accumulator discharges to tank when the pump stops. This makes the circuit safe to work on shortly after locking and tagging off out the pump.
2. For a safe accumulator circuit, a means to discharge stored energy at shut down is necessary.
3. When using an accumulator, there must be a way to discharge stored oil before safely working on the circuit.
4. Even when using the accumulator for Emergency Power Supply, install a MANUAL DRAIN VALVE for safe operation.
5. A manual drain valve with a gauge near is a best way to insure a safe operation.
6. Mark the manual drain valve and place warning signs at all hydraulic components locations indicating there is an accumulator in the circuit.
7. The warning signs should indicate there is an accumulator in the circuit and to open the manual drain before performing maintenance.
8. CAUTION! ALWAYS CHECK AN ACCUMULATOR CIRCUIT FOR PRESSURE BEFORE WORKING ON IT. NEVER ASSUME THE AUTOMATIC UNLOADING WORKED!!!!

Note: for more information see [Reference].