Energy harvesting from an acoustic field is challenging given the low energy density available in most acoustic phenomena. A notable exception is in the domain of pumped, pressurized fluids, where acoustic pressure amplitudes may be on the order of 5~10% of the mean static pressure, in some applications reaching mega-pascal amplitudes, corresponding to acoustic intensities advantageous for energy harvesting. However, the static pressures that are common within pressurized systems require mechanically robustness for pressure containment, which prevents the use of common energy harvester configurations. Nonetheless, energy densities may be high enough such that non-resonant configurations are feasible; and, the fact that the acoustic pressure within pumped systems typically has a relatively narrow band spectrum means that power conditioning circuits may be optimized for power conversion. With power available from the pumped fluid itself, through what is termed a Hydraulic Pressure Energy Harvester, it then becomes possible to implement self-powered wireless sensing nodes. This paper describes a proof-of-concept HPEH implementation and demonstration of a multi-functional self-powered wireless sensor for use in a hydraulic application.