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• 1). Multiply the accumulator's system efficiency, which is usually 95 percent, by its pre-charge pressure in PSI by its rated liquid volume in cubed inches. This information can be found in your accumulator's owner's manual. As an example, multiplying a hydrostatic accumulator's efficiency of 95 percent by its pre-charge pressure of 4,000 PSI and its rated gas volume of 100 cubic inches equals 380,000.

• 2). Divide the result from Step 1 by the system's pressure after the fluid has been discharged from the accumulator. Again, this will be listed in the accumulator's manual. In the example, the system has a pressure of 6,000 PSI after the fluid has been expelled. Dividing 380,000 by 6,000 equals approximately 63.33.

• 3). Divide the result from Step 1 by the system's maximum pressure when the accumulator is at its maximum pressure; this value will be listed in the owner's manual. If a system has a maximum pressure of 8,000 PSI, then dividing 380,000 by 8,000 equals 47.5.

• 4). Subtract the result in Step 3 from the result in Step 4 to calculate the volume of fluid discharge in cubic inches. In the example, subtracting 47.5 from 63.33 equals 15.83. The hydrostatic pressure accumulator discharges 15.83 cubic inches of gas.

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