Unloading Relief Valves | Product Series

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Unloading Relief Valves

Unloading Relief Valves

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Parker’s unloading pressure control valves automatically charge and maintain a specific pressure range within accumulators by loading and unloading pump flow. Usable with fixed or variable pumps and pressure of 420 bar (6000 psi) and flow up to 1 gpm.

Technical Specifications

  • Maximum Flow Rate: 0.25, 0.53. 1 gal/min, 1, 2, 3.75 L/min
  • Pressure Control Range: N/A, 100-1000, 150-2000, 200-3000, 725-2900, 800-1200, 1000-2400, 1750-3600 psi, N/A, 6.9-69, 10.3-138, 13.8-210, 50-200, 55.2-82.7, 69-165.5, 120.7-250 bar
  • Adjustment Mechanism: Fixed, Knob, Screw, Tamper Resistant
  • Seal Material: D-Ring (Standard), Nitrile, Fluorocarbon
  • Flow Rate: 0.25, 0.53. 1 gal/min, 1, 2, 3.75 L/min
  • Maximum Operating Pressure: 3500, 3600, 6000 psi, 245, 250, 420 bar
  • Maximum Inlet Pressure Rating: 3500, 3600, 6000 psi, 245, 250, 420 bar
  • Maximum Tank Pressure: 3000, 6000 psi, 210, 420 bar
  • Standard Setting Pressure: 500, 1000, 1500, 1700, 1850, 2675 psi, 34.5, 69, 103.5, 117.2, 125, 184.4 bar
  • Maximum Pressure Setting: 1000, 1200, 2000, 2400, 2900, 3000, 3600 psi, 69, 82.7, 138, 165.5, 200, 210, 250 bar
  • Leak Rate: N/A, 10 (port 2 to 3), 60 (port 1 to 2) drops/min, 0.66 (port 2 to 3), 3 (port 1 to 2), 25 @ 1450 PSI (100 BAR), 48 @ 3000 PSI (250 BAR) cm3/min
  • Cavity Size: C10-3, C10-4
  • Actuation Type: Pressure Sensing
  • Function: Unloading Relief Valve
  • For Fluid Type: Mineral-based or synthetic hydraulic fluids
  • Maximum Kinematic Viscosity: 45-2000 SSU (6 to 420 cSt)
  • Filter Efficiency Rating: ISO 4406 18/16/13, SAE Class 4
  • Valve Material: All parts steel. All operating parts hardened steel
  • Installation Torque: 16, 37, 37-41 lb-ft, 22, 50, 50-56 Nm
  • Operating Temperature: -35 to +200, -30 to +250, -15 to +400 °F, -37 to +93, -34 to +121, -26 to +204 °C
  • Maximum Operating Temperature: +200, +250, +400 °F, +93, +121, +204 °C
  • Minimum Operating Temperature: -35, -30, -15 °F, -37, -34, -26 °C
  • Weight: 0.5 to 1 lbs, 0.23 to 0.45 kg
  • Body Material: N/A
Safety Warning

Full Product Description

Parker’s robust and reliable unloading pressure control valves provide superior accumulator charge control by automatically charging up to the maximum setting and recharging once the minimum pressure setting is reached.  These valves are capable of handling flows up to 3.75 lpm (1 gpm) and pressures as high as 420 bar (6000 psi). Internally or externally piloted options are available and are ideal for unloading pump pressure and maintaining accumulator pressure for several energy recovery or saving applications such as dynamic or parking brake circuits on mobile or industrial machinery.

Markets:
• Agriculture
• Construction
• Material Handling
• Miscellaneous Industrial
• Miscellaneous Manufacturing
• Miscellaneous Mobile

Features/Benefits:
• Low hysteresis
• Hardened working parts for maximum durability
• All external parts zinc plated

Applications:
• Accumulator circuits

Additional Technical Insight:
Parker’s RU101, RU104, and M04A4J offer design flexibility by allowing the use of hydraulic components to automatically control pump flow to one or more accumulators.  These are low flow pilot valves that can be used to control higher pump flows in fixed displacement or load sense systems.

The RU101 is externally piloted and rated for flows up to 1 GPM and pressures up to 3000 psi.  It is typically used with fixed displacement pumps and can directly unload flows up to 1 GPM or be used to pilot a logic element to unload higher pump flows.  Once the accumulators are charged to the adjustable or factory preset maximum pressure, the pump will automatically unload back to tank.  Due to the differential area design, when the pressure drops to 80% of the RU101 maximum setting, the unloading valve will direct pump flow to the accumulators for recharging.

The RU104 is externally piloted and designed to control signal pressures up to 3600 psi. It is typically used with load sense or fixed displacement pumps to control accumulator pressures. The valve responds to accumulator pressure and will connect the sense port to pressure or tank accordingly. When the accumulators are fully charged (high) the RU104 will unload and vent the sense port to tank causing a load sense pump to de-stroke and go to stand-by pressure. When accumulator pressure drops to approximately 80% of the unload pressure the RU104 will reload, connecting the sense port to pressure, raising pressures until the accumulators are fully charged causing the RU104 to repeat the unloading cycle again.

The M04A4J is internally piloted and is rated for flows up to .53 GPM and pressures as high as 6000 psi.  It is typically used with load sense pumps to control accumulator charging.  When the accumulators are charged to the unload pressure, the pump’s load sense port is directed to tank allowing the pump to go to its standby pressure.  Once the accumulator pressure falls to the M04A4J reload pressure, the pump’s load sense port is fed the accumulator pressure and the pump comes on stroke to charge the accumulator back up to the unload pressure.  Controlling only the pump load sense signal allows a small cartridge valve to control a wide range of flows from small to larger displacement load sense pumps.

Parker’s unloading pressure control valves offer design flexibility by allowing in-line mounting with standard line bodies, or integration into more complex custom manifolds.  They can also be combined with K04G3 shuttles for use in critical applications that require redundant accumulators such as braking and steering.  By hydraulically controlling pump unloading for accumulator charging, there may be no need for solenoid valves, pressure sensors, electronic controls, and the associated wiring.  Combining the features of the RU101, RU104, or M04A4J with the many other products offered by Parker’s Hydraulic Cartridge Division allows for application specific solutions for some of the most demanding applications, including: Construction, Mining, Industrial Power Units, Oil and Gas, Marine, Material Handling.

Related Documents

Literature and Reference Materials
HVS Global Cartridge Valve Catalog MSG15-3504
MSG15-3504 Pressure Control Valves Catalog Pages - All
Pressure Control Valves Technical Tips
Selector Guides
Competitive Crossover Tool
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Products Maximum Flow Rate Pressure Control Range Adjustment Mechanism Seal Material
RU101F10C 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Fixed Nitrile
RU101F10CV 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Fixed Fluorocarbon
RU101F20C 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Fixed Nitrile
RU101F20CV 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Fixed Fluorocarbon
RU101F30C 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Fixed Nitrile
RU101F30CV 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Fixed Fluorocarbon
RU101K10C 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Knob Nitrile
RU101K10CV 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Knob Fluorocarbon
RU101K20C 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Knob Nitrile
RU101K20CV 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Knob Fluorocarbon
RU101K30C 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Knob Nitrile
RU101K30CV 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Knob Fluorocarbon
RU101S10C 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Screw Nitrile
RU101S10CV 1 GAL/MIN, 3.75 L/MIN 100-1000 PSI, 6.9-69 BAR Screw Fluorocarbon
RU101S20C 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Screw Nitrile
RU101S20CV 1 GAL/MIN, 3.75 L/MIN 150-2000 PSI, 10.3-138 BAR Screw Fluorocarbon
RU101S30C 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Screw Nitrile
RU101S30CV 1 GAL/MIN, 3.75 L/MIN 200-3000 PSI, 13.8-210 BAR Screw Fluorocarbon
M04A4JZN 0.53 GAL/MIN, 2 L/MIN 725-2900 PSI, 50-200 BAR Screw Nitrile
M04A4JZV 0.53 GAL/MIN, 2 L/MIN 725-2900 PSI, 50-200 BAR Screw Fluorocarbon
M04A4JTN 0.53 GAL/MIN, 2 L/MIN 725-2900 PSI, 50-200 BAR Tamper Resistant Nitrile
M04A4JTV 0.53 GAL/MIN, 2 L/MIN 725-2900 PSI, 50-200 BAR Tamper Resistant Fluorocarbon
RU104S12B 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Screw D-Ring (Standard)
RU104S12BN 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Screw Nitrile
RU104S12BV 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Screw Fluorocarbon
RU104S24B 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Screw D-Ring (Standard)
RU104S24BN 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Screw Nitrile
RU104S24BV 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Screw Fluorocarbon
RU104S36B 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Screw D-Ring (Standard)
RU104S36BN 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Screw Nitrile
RU104S36BV 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Screw Fluorocarbon
RU104T12B 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Tamper Resistant D-Ring (Standard)
RU104T12BN 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Tamper Resistant Nitrile
RU104T12BV 0.25 GAL/MIN, 1 L/MIN 800-1200 PSI, 55.2-82.7 BAR Tamper Resistant Fluorocarbon
RU104T24B 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Tamper Resistant D-Ring (Standard)
RU104T24BN 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Tamper Resistant Nitrile
RU104T24BV 0.25 GAL/MIN, 1 L/MIN 1000-2400 PSI, 68.9-165.5 BAR Tamper Resistant Fluorocarbon
RU104T36B 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Tamper Resistant D-Ring (Standard)
RU104T36BN 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Tamper Resistant Nitrile
RU104T36BV 0.25 GAL/MIN, 1 L/MIN 1750-3600 PSI, 120.7-250 BAR Tamper Resistant Fluorocarbon

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