DBDS6K DBDS10K DBDS20K DBDS30K DBDH6 DBDH10 Rexroth Relief Valve 630 bar

Product Overview

The DBD/DBDH series direct-acting pressure relief valves are direct-acting seat valves engineered by Bosch Rexroth for industrial hydraulic systems, widely used for system pressure limitation and overload protection. Featuring poppet-type construction (up to 40 MPa) or ball-type construction (up to 63 MPa) , these valves balance system pressure directly against spring force, opening rapidly for relief when the set pressure is reached to provide precise system overload protection.

The DBD/DBDH series covers sizes from NG6 to NG30, supporting screw-in cartridge (K type), inline threaded (G type), and subplate (P type) mounting configurations. Valve bodies are manufactured from high-strength materials with hardened and precision-ground internal components, offering fast response (typical 2 ms), high pressure regulation accuracy, and essentially zero leakage. The full series supports maximum operating pressures up to 630 bar with maximum flow rates up to 350 L/min.

⚠️ Series Notes:

• DBDS = Standard direct-acting relief valve (with damping piston, pressure ratings 25–400 bar)

• DBDH = High-pressure direct-acting relief valve (ball seat design, pressure rating up to 630 bar). Select models are type-examination tested according to Pressure Equipment Directive 2014/68/EU for use as safety valves

• “DBDS6K, DBDS10K, DBDS20K, DBDS30K” indicate DBDS series with K type (screw-in cartridge) mounting, sizes 6/10/20/30

• “DBDH6, DBDH10, DBDH20, DBDH30” indicate DBDH series, sizes 6/10/20/30

⚠️ Model Code Decoding:

• DBD = Direct-Acting Pressure Relief Valve

• S / H = S = Standard with damping piston (25–400 bar); H = High-pressure ball seat design (630 bar)

• 6 / 10 / 20 / 30 = Nominal size (NG6 / NG10 / NG20 / NG30)

• K / G / P = Mounting type (K = Screw-in cartridge; G = Inline threaded; P = Subplate mounting)

• 1X = Component series (10–19 series share identical mounting dimensions)

• /315 / /200 / /100 = Set pressure (bar)

Technical Specifications 

DBDS Series General Specifications (Screw-in Cartridge K Type)

• Product Series: Bosch Rexroth DBDS series direct-acting pressure relief valve

• Product Type: Direct-acting seat valve (with damping piston)

• Brand: Rexroth

• Pressure Rating: 25 – 400 bar (poppet-type construction)

• Size Range: NG6 to NG30

• Component Series: 1X (10–19 series share identical mounting dimensions)

• Pressure Stage Options: 25, 50, 100, 200, 315, 400 bar

• Maximum Flow Rate:

  • NG6: 50 L/min

  • NG10: 120 L/min

  • NG20: 250 L/min

  • NG30: 350 L/min

• Maximum Operating Pressure: 400 bar (poppet-type); 630 bar (ball seat, NG10 only)

• Spool/Poppet Type: Poppet with damping piston (25–400 bar) or ball (630 bar)

• Internal Leakage: Extremely low (essentially zero leakage)

• Response Time: Typical 2 ms

• Seal Material: NBR (standard) / FKM (optional)

• Compatible Hydraulic Fluids: HL, HLP, HLPD, HVLP, HVLPD, HETG, HEES, HEPG, HFDU, HFDR

• Operating Temperature Range: -20°C to +80°C

• Mounting Type: Screw-in cartridge

• Adjustment Types: Hexagon sleeve with protective cap / Rotary knob / Lockable rotary knob / Hand wheel

• Weight: NG6 approx. 0.38 kg; NG10 approx. 0.505 kg

DBDH Series General Specifications (High-Pressure Type)

• Product Series: Bosch Rexroth DBDH series direct-acting pressure relief valve

• Product Type: Direct-acting seat valve (ball seat design)

• Brand: Rexroth

• Maximum Operating Pressure: 630 bar

• Size Range: NG6 to NG30

• Maximum Flow Rate: 330 L/min

• Spool/Poppet Type: Ball seat (pressure rating 630 bar)

• Response Pressure Range: 30 – 400 bar (standard); 405 – 630 bar (ball seat, NG10 only)

• Seal Material: NBR (standard) / FKM (optional)

• Compatible Hydraulic Fluids: Mineral-based hydraulic oils per DIN 51524

• Operating Temperature Range: -20°C to +80°C

• Viscosity Range: 10 – 800 mm²/s

• Mounting Type: Screw-in cartridge (K) / Inline threaded (G) / Subplate (P)

• Certification: Pressure Equipment Directive 2014/68/EU (DBDH…XC…E type)

Model Specifications Overview

• DBDS6K: NG6 screw-in cartridge, max flow 50 L/min, max pressure 400 bar

• DBDS10K: NG10 screw-in cartridge, max flow 120 L/min, max pressure 400 bar

• DBDS20K: NG20 screw-in cartridge, max flow 250 L/min, max pressure 400 bar

• DBDS30K: NG30 screw-in cartridge, max flow 350 L/min, max pressure 400 bar

• DBDH6: NG6 high-pressure type, max flow 330 L/min, max pressure 630 bar

• DBDH10: NG10 high-pressure type, max flow 330 L/min, max pressure 630 bar (ball seat)

• DBDH20: NG20 high-pressure type, max flow 330 L/min, max pressure 630 bar

• DBDH30: NG30 high-pressure type, max flow 330 L/min, max pressure 630 bar

Key Technical Advantages

1. Direct-Acting Design for Extremely Fast Response

The DBD/DBDH series features a direct-acting design where system pressure acts directly on the poppet, overcoming spring force to initiate relief. Compared to pilot-operated relief valves, the direct-acting design delivers significantly faster response (typical 2 ms)—opening for relief instantaneously upon pressure overshoot to provide the fastest possible overload protection. Additionally, the direct-acting design does not rely on pilot oil circuits, maintaining reliable opening characteristics even during severe system pressure fluctuations.

2. Ultra-High Pressure Rating – 630 bar Industry Benchmark

The DBDH series supports maximum operating pressures up to 630 bar. NG10 models with ball seat construction can withstand 630 bar extreme pressures. This pressure rating positions the DBDH series among the highest-rated direct-acting relief valves available, making it particularly suitable for ultra-high-pressure hydraulic systems, heavy machinery, and extreme-duty applications.

3. Ball/Poppet Seat Design – Essentially Zero Leakage

The ball or cone poppet hard-sealing design delivers extremely low internal leakage (essentially zero leakage) in the closed position. Compared to spool-type designs, the ball/poppet configuration maintains excellent sealing performance even after extended service, making it particularly suitable for applications requiring long-term pressure holding (such as accumulator circuits and clamping circuits).

4. Three Mounting Options for Flexible System Integration

The DBD/DBDH series supports three mounting types: screw-in cartridge (K), inline threaded (G), and subplate (P) . Screw-in cartridge valves can be installed directly into manifold blocks, saving valuable installation space; inline types feature G1/4″ to G1″ thread connections; subplate types conform to standard mounting interfaces. These three options cover all application scenarios from compact manifold blocks to traditional piping systems.

5. PED-Compliant Design for Safety Valve Applications (DBDH Series)

DBDH…XC…E valves are type-examination tested according to Pressure Equipment Directive 2014/68/EU and are approved for use not only as conventional relief valves but also as safety valves. This certification makes them particularly suitable for pressure vessels, boilers, power generation equipment, and other applications with strict regulatory safety requirements.

6. 100% Direct Interchangeability and Simulated Condition Testing

The DBD/DBDH series strictly adheres to Rexroth original mounting dimensions and interface standards. Cartridge valves of the same size and mounting type are physically and functionally interchangeable across brands, enabling 100% direct interchangeability without manifold modification or system adjustment. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring consistent, stable performance at rated pressure and flow.

Application Areas

• Ultra-High-Pressure Hydraulic Systems: Overload protection for presses and hydraulic tools

• Heavy Construction Machinery: Pressure limitation for excavators, large wheel loaders, mining equipment

• Pressure Vessels and Boilers: Regulatory-compliant overpressure protection as safety valves (DBDH…XC…E type)

• Accumulator Circuits: Long-term pressure holding with essentially zero leakage

• Hydraulic Clamping Systems: Clamping force protection for machine tools and workholding fixtures

• Machine Tool Hydraulic Systems: Pump port safety relief valves for maximum pressure limitation

• Metallurgical Equipment: Overload protection for rolling mills and continuous casting equipment

• Test Equipment: Pressure limitation and safety protection for hydraulic test benches

Expert Maintenance Tips

1. Verify Model and System Compatibility Prior to Installation

The DBD/DBDH series offers multiple sizes (NG6/10/20/30), mounting types (K/G/P), and pressure ratings. Confirm prior to installation:

• Size meets system flow requirements (NG6=50 L/min, NG10=120 L/min, NG20=250 L/min, NG30=350 L/min)

• Mounting type matches the manifold (K=screw-in cartridge/G=inline threaded/P=subplate)

• Pressure rating covers system operating pressure (DBDS up to 400 bar; DBDH up to 630 bar)

2. Screw-in Cartridge (K Type) Installation Precautions

For screw-in cartridge types, ensure the cavity is clean, free of burrs, and free of metal debris prior to installation. Use proper tools for installation and torque to the values specified in Rexroth technical manuals. Never use impact or hammering methods during installation, as this may damage internal poppet components or springs.

3. Inline Threaded (G Type) Installation Precautions

Inline types feature threaded connections (G1/4″ to G1″). Use appropriate sealing materials (PTFE tape or thread sealant)—apply sparingly to prevent sealant material from entering the valve body and affecting poppet movement. Tighten to torque values specified in Rexroth technical manuals.

4. Pressure Setting and Commissioning

DBD/DBDH series relief valves have adjuster screw seals exposed to system pressure—system pressure must be relieved before making adjustments. Correct procedure: check current setting → relieve system pressure → adjust valve → re-pressurize and verify new setting. During commissioning, start from low pressure and gradually increase to the set value. For optimal repeatability, select a spring range where the desired relief setting falls in the mid-to-high range of the spring’s capabilities.

5. Back Pressure Effects

Back pressure at the tank port of DBD/DBDH series relief valves directly adds to the valve setting at a 1:1 ratio. Ensure tank line back pressure is as low as possible, or account for it during setting.

6. System Cleanliness Management

The DBD/DBDH series features tight poppet clearances and demands adequate oil cleanliness. Recommended system cleanliness: ISO 4406 Class 19/17/14 or higher. Thoroughly flush system piping prior to installation to prevent hard particles from becoming trapped between the poppet and sleeve, which could cause spool sticking and pressure control failure.

7. Periodic Functional Checks and Safety Valve Certification

If the valve is used as a safety valve (DBDH…XC…E type), periodic functional verification is required in accordance with Pressure Equipment Directive 2014/68/EU and applicable national regulations. Perform opening pressure verification and seal integrity testing every 12 months or as required by regulations. If set pressure drift, abnormal leakage, or sluggish response is observed, arrange for servicing or replacement.