Product Overview

The YUKEN CPDG Series is a range of decompression-type pilot operated check valves designed for hydraulic load holding, reverse-flow control and controlled actuator release.

The CPDG series uses a sub-plate mounting configuration and is available in valve sizes 03, 06 and 10. YUKEN’s official technical documentation specifies maximum operating pressure of 25 MPa and rated flows of approximately 40, 125 and 250 L/min respectively. Multiple cracking-pressure configurations are available.

The product family in your original title includes:

• CPDG-06-E-50-20
• CPDG-10-E-50-50
• CPDG-03-50-50
• CPDG-06-5-20
• CPDG-06
• CPDG-10

The complete type code is important because valve size, drain arrangement, cracking pressure and design number directly affect hydraulic behavior and replacement compatibility.

For replacement projects, our supplied equivalent valves can be engineered for in-place interchangeability and subjected to 100% simulated working-condition testing before shipment. This statement refers to the supplier’s manufacturing and testing capability and does not imply YUKEN original manufacture or certification.

Technical Specifications

CPDG-06-E-50-20

• Manufacturer: YUKEN
• Series: CPDG
• Valve Type: Decompression Type Pilot Operated Check Valve
• Valve Size: 06
• Mounting: Sub-plate Mounting
• Drain: External Drain
• Cracking Pressure Code: 50
• Cracking Pressure: 0.5 MPa
• Design Number: 20
• Rated Flow: 125 L/min
• Maximum Operating Pressure: 25 MPa
• Control: Hydraulic Pilot Control
• Nominal Size Class: 06 / 20 mm class
• Mass: The current YUKEN catalog lists approximately 5.4 kg for the current CPDG-06 50-design configuration; the exact mass of this legacy 20-design variant has not been independently confirmed and is therefore not presented as a definitive value.

CPDG-10-E-50-50

• Manufacturer: YUKEN
• Series: CPDG
• Valve Type: Decompression Type Pilot Operated Check Valve
• Valve Size: 10
• Mounting: Sub-plate Mounting
• Drain: External Drain
• Cracking Pressure: 0.5 MPa
• Design Number: 50
• Rated Flow: 250 L/min
• Maximum Operating Pressure: 25 MPa
• Control: Hydraulic Pilot Control
• Approx. Mass: 8.5 kg
• Mounting Interface: ISO 5781-10-13-0-00 family

CPDG-03-50-50

• Manufacturer: YUKEN
• Series: CPDG
• Valve Type: Decompression Type Pilot Operated Check Valve
• Valve Size: 03
• Mounting: Sub-plate Mounting
• Drain: Internal Drain
• Cracking Pressure: 0.5 MPa
• Design Number: 50
• Rated Flow: 40 L/min
• Maximum Operating Pressure: 25 MPa
• Approx. Mass: 3.3 kg
• Control: Hydraulic Pilot Control

CPDG-06-5-20

• Manufacturer: YUKEN
• Series: CPDG
• Valve Type: Decompression Type Pilot Operated Check Valve
• Valve Size: 06
• Mounting: Sub-plate Mounting
• Cracking Pressure Code: 5
• Design Number: 20
• Design Type: Low Cracking Pressure / 20 Design
• Maximum Operating Pressure: 25 MPa
• Rated Flow: Approximately 125 L/min
• Approx. Mass: Approximately 7 kg according to the referenced component database
• Control: Hydraulic Pilot Control

YUKEN’s official catalog specifically notes that the older 20-design low-cracking-pressure valve should not be treated as identical to the later 50-design version. The documentation identifies the 20-design low-cracking-pressure configuration as approximately 0.035 MPa, code 5, and gives a specific warning against introducing pressurized oil into the drain port of a 50-design valve.

Key Technical Advantages

1. Decompression-Type Pilot Operation

The CPD configuration represents a decompression-type pilot operated check valve. Instead of simply acting as a passive one-way check valve, the design uses hydraulic pilot control to release reverse flow in a controlled manner.

This architecture is well suited to:

• Hydraulic cylinder locking
• Vertical load holding
• Press clamping circuits
• Lifting mechanisms
• Position-holding systems

2. 25 MPa High-Pressure Capability

YUKEN specifies a 25 MPa maximum operating pressure for the CPDG/CPG family.

For industrial hydraulic design, the final application should still be checked against actual pressure peaks, flow rate, temperature, pressure drop and pilot-control conditions rather than treating maximum operating pressure as a universal continuous operating point.

3. Multiple Cracking-Pressure Options

The official YUKEN coding system provides:

• 04 = 0.04 MPa
• 20 = 0.2 MPa
• 35 = 0.35 MPa
• 50 = 0.5 MPa

This allows engineers to match valve opening behavior to actuator load, circuit pressure and reverse-flow requirements.

For CPDG-06-E-50-20, the 50 identifies the 0.5 MPa cracking-pressure setting, while 20 identifies the design number.

4. Internal and External Drain Configurations

The CPDG family supports both internal and external drain arrangements.

YUKEN explicitly states that when back pressure is applied to the outlet side during reversed free flow, the external drain type should be used.

Therefore, the E in CPDG-06-E-50-20 has direct hydraulic-system significance and should not be treated as an optional cosmetic suffix.

5. Standardized Sub-Plate Mounting

The CPDG family uses standardized sub-plate interfaces. YUKEN documentation lists:

• Size 03: ISO 5781-06-07-0-00
• Size 06: ISO 5781-08-10-0-00
• Size 10: ISO 5781-10-13-0-00

This makes the series suitable for hydraulic manifolds, power units and modular industrial hydraulic circuits.

6. Engineering Replacement Compatibility

For equipment retrofit and spare-parts replacement, engineers should verify the complete code:

CPDG + Valve Size + Drain Type + Cracking Pressure + Design Number

A generic CPDG-06 or CPDG-10 designation is insufficient to establish complete interchangeability. This is especially important when replacing an older 20-design valve with a 50-design valve.

Application Areas

The YUKEN CPDG series can be applied to:

• Hydraulic Presses
• Injection Molding Machines
• Construction Machinery
• Lifting Platforms
• Material Handling Equipment
• Clamping Systems
• Machine Tools
• Steel Processing Machinery
• Industrial Hydraulic Power Units
• Hydraulic Cylinder Circuits
• Vertical Load-Holding Systems
• Mobile Hydraulic Equipment

The valve is particularly useful in circuits where hydraulic actuators must remain locked during shutdown and then be released through a controlled pilot signal.

Expert Maintenance Tips

1. Check the Drain Circuit Carefully

For E-type external drain configurations, the external drain line must be connected correctly.

YUKEN specifies that external drain should be used when outlet-side back pressure exists during reverse free flow.

2. Do Not Treat 20 and 50 Designs as Identical

This is one of the most important engineering points for this product family.

YUKEN warns that:

• 20-design and 50-design low-cracking-pressure structures differ;
• pressurized oil must not be introduced into the drain port of a 50-design valve;
• incorrect drain-port pressurization can act in the valve-opening direction.

Always confirm the complete valve nameplate before replacement.

3. Maintain Hydraulic Cleanliness

Pilot-operated valves rely on clean hydraulic fluid for reliable spool, poppet and seal movement.

During service:

• Clean the manifold mounting face.
• Replace damaged or contaminated O-rings.
• Prevent machining debris from entering pilot passages.
• Flush contaminated hydraulic lines.
• Verify the hydraulic filtration system before commissioning.

YUKEN’s technical documentation also identifies O-ring specifications for the CP＊G configurations, which can be used when preparing maintenance kits.

4. Verify the Mounting Surface

Because CPDG is a sub-plate-mounted valve, installation-surface quality directly influences sealing performance.

When no standard sub-plate is used, YUKEN requires a properly machined mounting surface. For persistent leakage, inspect:

mounting-surface condition + O-rings + bolt installation + manifold cleanliness

rather than immediately assuming internal valve failure.