Hydraulic Accumulator Sizing Calculator

How to use it

Enter the oil volume the circuit must receive between minimum and maximum pressure, the minimum pressure at which the load still works, and the maximum system pressure. Set the precharge as a percentage of minimum pressure; 90 percent is a common starting point for bladder types. Choose the gas process: use 1.0 when the cycle is slow enough for heat to leave the gas, and 1.4 for sub-minute discharge such as emergency stroking of a cylinder. The chart shows how the shell grows if precharge falls too low.

• Precharge with dry nitrogen only, never oxygen or air
• Set precharge with the oil side at zero pressure
• Correct precharge for temperature if the unit runs hot
• Check that P2 to P0 ratio stays within the maker limit

Worked example

A circuit needs 2.5 gallons between 1800 and 3000 psig with a fast adiabatic discharge. At 90 percent precharge, P0 is 1620 psig. The calculation returns a shell near 14 gallons with only about 18 percent of the volume delivered per cycle. That low usable share is normal for a wide pressure window, so the usual way to shrink the vessel is to narrow the pressure range, not to raise precharge to the point where the bladder touches the poppet valve.