Definition(s)
Usable Fluid Volume
Usable fluid volume is defined as that fluid recoverable from an accumulator between the limits of the accumulator operating pressure and the pre-charge pressure, or the shut-off pressure, for the hydraulic operating system.
Source: API RP 64, Recommended Practice for Diverter Systems Equipment and Operations, Second Edition, November 2001 (March 1, 2007). Global Standards