Pressure Control to Dump Excess Fluid
Unload When Critical Pressure Has Been Reached
Relief Unloading Valves are pressure-control devices that are used to dump excess fluid when the line pressure reaches a pre-set value. A typical application is for the Helicopter In-Flight Refueling System (HIFR). Once the fuel tank is full the Relief Unloading Valve will open returning additional fuel back to the sump tank.
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Relief Unloading Valves are primarily used in hydraulic circuits, accumulators where a pressure regulator is required to automatically unload the pump when the pressure reaches the pre-adjusted pressure setting of the valve. When the pressure has dropped to approximately 85% of the valve setting, the valve poppet closes, thus diverting the pump delivery to the system. |