DG-02 Yuken Direct Operated Relief Valve 250 Bar

Product Overview

The YUKEN DT/DG Series includes two distinct pressure-control product groups: DT-01/DG-01 remote control relief valves and DT-02/DG-02 direct type relief valves.

This distinction is important for correct hydraulic selection.

The DT-01 and DG-01 are remote-control relief valves used to remotely control pilot-operated pressure-control valves. DT indicates a threaded connection, while DG indicates sub-plate mounting. YUKEN specifies a maximum operating pressure of 25 MPa and a maximum flow of 2 L/min for the size-01 configuration.

The DT-02 and DG-02 are genuine direct-operated relief valves intended for maximum pressure adjustment and over-pressure protection in small-capacity hydraulic circuits. YUKEN specifies a maximum operating pressure of 21 MPa and a maximum flow of 16 L/min.

For replacement applications, engineers should verify the complete model code, mounting arrangement, pressure-adjustment range, design number, hydraulic connections and sealing configuration rather than selecting a valve solely by the DT/DG family name.

Replacement units can also undergo 100% simulated working-condition testing to verify pressure response, leakage performance, adjustment repeatability and functional stability.

Technical Specifications

DG-01

• Model: DG-01
• Manufacturer: YUKEN
• Valve Type: Remote Control Relief Valve
• Mounting: Sub-plate mounting
• Nominal Size: 01
• Maximum Operating Pressure: 25 MPa (3630 psi)
• Maximum Flow: 2 L/min
• Approximate Valve Weight: 1.4 kg
• Design Number: 22
• Actuation / Adjustment: Handwheel
• Primary Function: Remote pressure control of pilot-operated pressure-control valves
• Associated Sub-plate: DGM-02-20
• Sub-plate Connection: Rc 1/4
• Sub-plate Reference Weight: approx. 0.7 kg.

DT-01

• Model: DT-01
• Manufacturer: YUKEN
• Valve Type: Remote Control Relief Valve
• Mounting: Threaded connection
• Nominal Size: 01
• Maximum Operating Pressure: 25 MPa (3630 psi)
• Maximum Flow: 2 L/min
• Approximate Weight: 1.6 kg
• Design Number: 22
• Adjustment: Handwheel
• Primary Function: Remote control of pilot-operated pressure-control valves
• Hydraulic Connection: Rc 1/4 in the documented configuration
• Tank Line: Direct connection to the reservoir is specified by YUKEN.

DG-02

• Model: DG-02
• Manufacturer: YUKEN
• Valve Type: Direct Type Relief Valve
• Mounting: Sub-plate mounting
• Nominal Size: 02
• Maximum Operating Pressure: 21 MPa (3050 psi)
• Maximum Flow: 16 L/min (4.23 US GPM)
• Approximate Weight: 1.5 kg
• Pressure Adjustment Range:
  • B: approx. 2–7 MPa, subject to minimum-adjustment characteristics
  • C: 3.5–14 MPa
  • H: 7–21 MPa
• Design Number: 22
• Associated Sub-plate: DGM-02-20
• Sub-plate Connection: Rc 1/4
• Mounting Bolts: M5 × 45 L, 4 pcs for the specified standard
• Primary Function: Maximum pressure adjustment and over-pressure protection for small-flow hydraulic circuits.

DT-02

• Model: DT-02
• Manufacturer: YUKEN
• Valve Type: Direct Type Relief Valve
• Mounting: Threaded connection
• Nominal Size: 02
• Maximum Operating Pressure: 21 MPa (3050 psi)
• Maximum Flow: 16 L/min (4.23 US GPM)
• Approximate Weight: 1.5 kg
• Pressure Adjustment Range:
  • B: approx. 2–7 MPa, subject to minimum-adjustment characteristics
  • C: 3.5–14 MPa
  • H: 7–21 MPa
• Design Number: 22
• Hydraulic Connection: Rc 1/4
• Primary Function: Direct pressure limiting for small-capacity hydraulic circuits.

Key Technical Advantages

Direct-Acting Pressure Protection

The DT-02 and DG-02 use a direct-operated pressure-relief architecture in which hydraulic pressure acts directly on the valve’s pressure-control mechanism. This makes the design suitable for small-flow circuits requiring maximum pressure limitation and over-pressure protection.

Multiple Pressure-Adjustment Ranges

The B, C and H configurations provide different pressure-adjustment ranges, allowing engineers to match the valve setting class to the hydraulic circuit rather than using one pressure spring across all applications.

Threaded or Sub-Plate Mounting

The DT configuration uses a threaded connection, while the DG configuration is designed for sub-plate installation. This allows the same pressure-control concept to be integrated into either piping-based or manifold-based hydraulic architectures.

Remote Pressure Control Capability

The DT-01 and DG-01 provide a separate engineering solution for remote adjustment of pilot-operated pressure-control valves. They should therefore be selected according to the pilot-control architecture rather than treated as the same product function as DT-02/DG-02.

Standardized Installation

YUKEN provides installation drawings, structural drawings and CAD data for the DT/DG product family, supporting controlled replacement and hydraulic-manifold integration.

Mechanical Field Adjustment

The pressure setting is adjusted through a mechanical handwheel. YUKEN instructs operators to loosen the locknut, turn the handle gradually clockwise for increasing pressure or counterclockwise for decreasing pressure, and retighten the locknut after adjustment.

Application Areas

DT-01 / DG-01

• Pilot-operated relief-valve remote control
• Hydraulic power units
• Industrial hydraulic pressure-control systems
• Press machinery
• Machine tools
• Remote pressure-adjustment panels
• Central hydraulic control systems

DT-02 / DG-02

• Small hydraulic power units
• Hydraulic presses
• Machine tools
• Clamping systems
• Industrial automation equipment
• Low-flow hydraulic circuits
• Pressure-limiting and safety circuits

YUKEN specifically identifies the direct-type DT-02/DG-02 as suitable for maximum pressure adjustment and over-pressure protection in small-capacity hydraulic circuits.

Expert Maintenance Tips

Verify the Valve Function Before Replacement

Do not replace a DT-01/DG-01 remote-control valve with a DT-02/DG-02 direct relief valve merely because the external configuration appears similar. The hydraulic function is fundamentally different.

Verify DT Versus DG Mounting

• DT: Threaded connection
• DG: Sub-plate mounting

The complete installation interface should be verified before purchasing a replacement.

Adjust Pressure Gradually

Follow YUKEN’s adjustment procedure: loosen the locknut, turn the adjustment handle slowly, then retighten the locknut after setting the required pressure.

Connect the Tank Line Correctly

YUKEN specifically instructs that the tank line should be routed directly to the reservoir rather than connected into the tank line of another valve. This becomes particularly important where several pressure-control valves share the same hydraulic circuit.

Maintain the Mounting Surface

For DG sub-plate-mounted configurations, proper machining of the mounting surface is important when the specified sub-plate arrangement is not used. Correct surface condition supports reliable sealing and installation stability.

Inspect O-Rings During Service

YUKEN’s DT-01 and DG-01 structural documentation specifies dedicated NBR O-rings for the documented design. Seal replacement should therefore be based on the complete valve configuration rather than on the basic DT/DG designation alone.

Select According to Actual Flow

DT-02/DG-02 are rated for a maximum flow of 16 L/min. If the hydraulic circuit continuously exceeds this level, the correct engineering solution is to reassess valve size and pressure-control architecture rather than simply increasing the pressure setting.

Validate Replacement Units Under Simulated Working Conditions

For replacement products, recommended factory validation includes pressure-setting accuracy, flow-pressure response, internal/external leakage, repeated pressure cycling and adjustment repeatability. This supports a reliable 100% simulated working-condition testing program for industrial hydraulic applications.