Required Pressure for Hydraulic Systems

Hydraulic system pressure. Standard hydraulic oil compresses at about 1/2% per 1000 psi. measure or calculate the volume of the pressurized part of the system. things that cannot be calculated are the expansion of the hoses. We know they expand because as the hose is pressured it grows slightly shorter. So add a fudge factor for this. Also as the system goes up in pressure internal leakage increases and actual volume to pressurize decreases! If internal leakage is great enough then you may not even achieve the pressure required! I work on numerous systems that cannot achieve the required pressure. (mainly worn seals or valves, pumps or broken components--but difficult to diagnose)

On a related note if the system is pressurized then it maybe required to depressurize the system before switching valves to "open". Typically decompression circuits are required for presses of 75 tons F or more. Note this does not differentiate by pressure!