Pressure compensated priority flow control valve with releif valve.

• Pressure-compensated flow control valves are designed to provide a constant volume flow rate independent of the pressure drop across the valve. By contrast, non-pressure-compensated valves have a variable flow rate that changes if the pressure drop across the valve fluctuates. 

• Pressure-compensated flow control valves are useful in a variety of hydraulic applications. For example, they benefit situations where it is necessary to maintain a constant speed of operation of a hydraulic cylinder;regardless of the magnitude of the load that the cylinder is moving. This is because the speed of a hydraulic cylinder is proportional to the volume flow rate of hydraulic fluid it receives. 
• Pressure compensated flow control valves are also useful in maintaining constant rpm of a hydraulic motor independent of load on the motor. Much like the example above, changing loads on the motor will result in a fluctuating pressure drop across the valve ahead of the motor. Pressure-compensated flow control valves compensate for these fluctuations to provide a steady flow rate to the hydraulic motor, maintaining its rpm at a constant rate.

• Set the relief valve in a pressure-compensated pump circuit at 150 to 200 psi higher than the pump compensator. With relief pressure below compensator setting, pump flow goes to tank and makes heat. With relief pressure set at compensator pressure, the relief valve starts dumping when the pump starts compensating.