SUN HYDRAULICS CORP
PRDNXDN712
Electro-Proportional

This electro-proportional, direct-acting reducer/reliever valve reduces a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1, with a full flow relief function from port 1 to tank (port 3). The valve is biased to the reducing mode, connecting port 2 to port 1 at a customer specified pressure setting. Increasing the current to the coil will proportionally decrease the reduced pressure at port 1. If pressure at port 1 exceeds the setting induced by the coil, pressure at port 1 is relieved to port 3. This valve is closed in the transition between reducing and relieving resulting in very low consumption of oil.

• Maximum pressure at port 3 should be limited to 3000 psi (210 bar).
• Pressure at port 3 is directly additive to the valve setting at a 1:1 ratio and should not exceed 3000 psi (210 bar).
• Leakage specified in Technical Data is out of port 3 with a supply pressure of 2000 psi (140 bar) and the valve set at mid range. This leakage is directly proportional to pressure differential and inversely proportional to viscosity expressed in centistokes.
• The transition from reducing to relieving is closed. The result is very low leakage. However, there is a transitional step increase in pressure between reducing and relieving modes. This step equals about 5% of the high end of the adjustment range, independent of the valve setting.
• For optimum performance, an amplifier with current sensing and adjustable dither should be used. Dither should be adjustable between 100 - 250 Hz.
• Coils are interchangeable with Sun's other full flow, solenoid-operated valves and can be mounted on the tube in either direction.
• With no electrical signal, the reduced pressure setting will default to the customer specified value. Increasing the command to the coil will proportionally reduce the secondary pressure value.
• Suitable for accumulator circuits since the absence of pilot control flow results in reduced secondary circuit leakage.
• Direct acting concept provides highly reliable operation in contaminated systems, especially at dead headed conditions.
• Full reverse flow from reduced pressure (port 1) to inlet (port 2) may cause the main spool to close. If reverse free flow is required in the circuit, consider adding a separate check valve to the circuit.
• All three-port pressure reducing and reducing/relieving cartridges are physically interchangeable (i.e. same flow path, same cavity for a given frame size). When considering mounting configurations, it is sometimes recommended that a full capacity return line (port 3) be used with reducing/relieving cartridges.
• Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.

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• Solenoid Coils for Switching and Proportional Valves
• Reducing and Reducing/Relieving Valves
• Electro-Proportional Cartridge Valves
• Electro-Proportional Terms and Definitions
• Cavity Information (S-171) and Tooling
• Sun's Floating Style Screw-In Cartridge
• Fluid and Temperature Recommendations
• Sun Model Code Explanation; 999-901-334
• Performance Data
• Cartridges: Materials of Construction
• Units of Measure, Settings, and Conversions