Direct-acting, pressure reducing/relieving main stage piloted from port 4

The direct-acting reducer/reliever main section is meant to act as an interface between a low flow pressure source at port 4 and a circuit with higher flow requirements. The valve will reduce a high primary pressure at the inlet (port 2) to a reduced pressure at port 1, with a full-flow relief function from port 1 to tank (port 3). The valve incorporates a damped construction for stable operation allowing the use of high reduced pressure.

• The valve is biased to the relieving mode with a 100 psi (7 bar) spring. Pressure at port 4 is directly added to the setting of the valve once this threshold is exceeded. For example, 1000 psi (70 bar) at port 4 will result in a setting of 900 psi (63 bar) at port 1.
• Maximum pressure at port 3 should be limited to 3000 psi (210 bar).
• All spring ranges are tested for correct operation with 5000 psi (350 bar) inlet pressure.
• 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.
• Direct operated version offers superior dynamic response compared to equivalent pilot operated models.
• Pressure on the drain (port 4) is directly additive to the valve setting at a 1:1 ratio and should not exceed 5000 psi (350 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.
• Cartridges configured with EPDM seals are for use in systems with phosphate ester fluids. Exposure to petroleum based fluids, greases and lubricants will damage the seals.
• 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.
• 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.

Model CAD Files

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• U3K ISO 05: Reducer/reliever on P
• U3L ISO 05 - X&Y (Euro): Reducer/reliever on P
• U3M ISO 05 - X&Y (US): Reducer/reliever on P
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