1. Product Overview

The DUPLOMATIC RQ Series is a range of pilot-operated proportional relief valves designed for industrial hydraulic systems. These valves are mainly used for system pressure regulation, hydraulic circuit protection, accumulator circuits, and high-pressure oil flow control.

The RQ series adopts a pilot-operated structure with a cylindrical main spool and cone sealing design, providing stable pressure regulation, high flow capacity, low pressure loss, and excellent operational reliability.

The valves are designed according to ISO 6264 and CETOP standards, making them suitable for a wide range of industrial hydraulic applications.

2. Product Series Classification

RQ3-P Series

The RQ3-P series complies with ISO 6264-06 (CETOP R06) mounting standards and is suitable for medium-flow hydraulic systems with a maximum flow rate of 200 L/min.

RQ5-P Series

The RQ5-P series complies with ISO 6264-08 (CETOP R08) mounting standards and is designed for larger hydraulic systems with flow rates up to 400 L/min.

RQ7-P Series

The RQ7-P series complies with ISO 6264-10 (CETOP R10) mounting standards and is intended for heavy-duty hydraulic applications with flow rates up to 500 L/min.

3. Model Number Structure

The DUPLOMATIC product model follows a standardized naming format.

Example model:

RQ3-P5/41

Meaning of each section:

• “RQ3” indicates the pilot-operated relief valve series.
• “P5” generally represents the pressure range or interface specification.
• “/41” refers to the design version or functional configuration.

Additional suffixes may indicate special functions or options:

• “M” indicates a SICBLOC locking adjustment knob.
• “V” indicates FPM seals for HFDR fire-resistant hydraulic oil.
• “D24K1” indicates a 24V DC solenoid specification.

4. Structural Features

The RQ series uses a pilot-operated relief valve structure. The main valve adopts a cylindrical spool combined with cone sealing technology, ensuring stable pressure control and reliable sealing performance.

The internal oil passages are designed with large flow channels to reduce pressure drop and improve energy efficiency.

The X port can be used as a remote pilot control port, allowing external pressure control or remote pressure adjustment.

When system pressure approaches the preset relief value, the valve allows the full pump flow to pass through, effectively protecting the hydraulic system from overload.

5. Main Technical Features

The RQ series offers the following technical advantages:

• Pilot-operated proportional pressure control
• High-pressure capability up to 350 bar
• Large flow capacity
• Low pressure drop structure
• Stable pressure regulation performance
• Wide operating temperature range
• CETOP standard plate mounting
• Suitable for accumulator hydraulic circuits
• Optional locking adjustment mechanism
• Excellent reliability in industrial environments

6. Technical Specifications

RQ3-P Series

The RQ3-P series has a maximum working pressure of 350 bar and a maximum flow rate of 200 L/min.

The environmental temperature range is from -20°C to +50°C, while the allowable hydraulic oil temperature range is from -20°C to +80°C.

The recommended oil viscosity is 25 cSt, with an allowable viscosity range of 10 to 400 cSt.

The allowable oil contamination level complies with ISO 4406:1999 class 20/18/15.

The approximate valve weight is 3.5 kg.

RQ5-P Series

The RQ5-P series also supports a maximum working pressure of 350 bar, with a higher flow capacity of up to 400 L/min.

The operating temperature, oil viscosity range, and cleanliness requirements are consistent with the RQ3 series.

The approximate valve weight is 4.3 kg.

RQ7-P Series

The RQ7-P series is designed for heavy-duty hydraulic systems.

It supports a maximum working pressure of 350 bar and a maximum flow rate of 500 L/min.

The environmental and oil specifications are the same as the RQ3 and RQ5 series.

The approximate valve weight is 6.5 kg.

7. Hydraulic Oil Requirements

The valve is compatible with mineral hydraulic oils HL and HM that comply with ISO 6743-4 standards.

For standard mineral hydraulic oils, NBR seals are recommended.

For HFDR fire-resistant hydraulic fluids, FPM seals should be selected, identified by the “V” suffix in the model number.

When the hydraulic oil temperature exceeds 80°C, the hydraulic oil and sealing components may age rapidly, reducing service life and sealing performance.

8. Adjustment Mechanism

The RQ series can be equipped with the optional SICBLOC adjustment knob.

This mechanism requires the operator to press and rotate the knob during adjustment, effectively preventing accidental pressure changes and improving operational safety.

To order this function, add the suffix “M” to the model number.

Example:
RQ3-P5/M/41

9. Typical Applications

The DUPLOMATIC RQ series is widely used in:

• Industrial hydraulic systems
• Hydraulic power units
• Press machinery
• Injection molding machines
• Hydraulic accumulator systems
• Construction machinery
• Metallurgical equipment
• Heavy-duty hydraulic circuits

These valves are especially suitable for applications requiring stable pressure control, large flow capacity, and high-pressure system protection.

10. Common Models

Common models in the RQ series include:

• RQ3-P5/41
• RQ3-P5/M/41
• RQ3-P6/41
• RQ3-P6/M/41
• RQ5-P5/41
• RQ5-W5/41
• RQ5-P6/41
• RQ7-P5/41
• RQ7-P6/41
• RQ7-P6/M/41

11. Related DUPLOMATIC Models

Other related DUPLOMATIC hydraulic valve models include:

• RO3-P-5
• RO3-P5-41
• RO3-P5/40
• RO3-P5-M-41
• RO3-P3
• RO7-P6/M/41/V
• ROM5-P5/A/60ND24K1/CM
• ROM5-P5/A/60N-D24K1
• RO5-P5/M/41
• RO5-P6/M/41
• ROR3-P5/1/142
• ROA5-P5/1/I/M/42

12. Product Advantages

The DUPLOMATIC RQ series provides several key advantages:

• High-pressure operation up to 350 bar
• Excellent flow handling capability
• Stable proportional pressure control
• Reduced pressure loss and improved efficiency
• Wide environmental adaptability
• Standardized CETOP mounting compatibility
• Optional locking adjustment design
• Reliable operation in demanding industrial applications