YUKEN S-BSG series low noise type pilot operated relief valves are innovative hydraulic components integrating a low-noise pilot operated relief valve and a solenoid operated directional valve[superscript:2][superscript:6]. Designed to reduce operational noise while ensuring precise pressure control, they are widely applied in various hydraulic systems that require stable pressure regulation, low noise emission, and flexible control. The S-BSG-01, S-BSG-03, and S-BSG-06 are three core models in this series, differing mainly in valve size, flow capacity, and installation dimensions to adapt to different system scales and working conditions. Below is a detailed introduction to their general characteristics, specific specifications, key features, and application scenarios.

1. General Characteristics of S-BSG Series

All models in the S-BSG series share the same core design concept and functional advantages, making them reliable choices for hydraulic system pressure protection and regulation:

• Low Noise Design: Optimized valve port and flow channel structure effectively reduces fluid noise during operation, making them suitable for environments with strict noise requirements (such as indoor equipment and precision hydraulic systems).
• Combined Structure: Integrates a low-noise pilot operated relief valve and a solenoid operated directional valve, enabling no-load pump operation via electric signals or two/three-level pressure control when used with a remote control relief valve[superscript:2][superscript:6].
• High Pressure Resistance: Maximum operating pressure reaches 25 MPa (3630 psi), meeting the pressure requirements of most industrial and engineering hydraulic systems[superscript:3].
• Sub-plate Mounting: Adopts sub-plate mounting design (indicated by “G” in the series designation), featuring compact structure, easy installation, maintenance, and good interchangeability with conventional models[superscript:5][superscript:19].
• Wide Pressure Adjustment Range: Pressure adjustment range is 4~25 MPa (580~3630 psi), allowing flexible adaptation to different system pressure requirements.
• Durable Construction: Valve body is made of cast iron, ensuring high strength, good pressure resistance, and long service life; operating temperature range is 0~100℃, adapting to various working environments.

2. Detailed Introduction of Each Model

2.1 S-BSG-01 Low Noise Type Pilot Operated Relief Valve

As the smallest model in the three, the S-BSG-01 is designed for small hydraulic systems or auxiliary circuits with limited installation space and low to medium flow requirements. It inherits all the advantages of the S-BSG series and is characterized by its compact size and light weight.

Core Specifications

• Maximum Operating Pressure: 25 MPa (3630 psi)
• Maximum Flow Rate: Approx. 40 L/min (10.6 U.S. gpm) [matched with its small valve size]
• Pressure Adjustment Range: 4~25 MPa (580~3630 psi)
• Valve Size: 01 (nominal diameter approx. 3 mm)
• Mounting Type: Sub-plate mounting, compatible with standard sub-plate dimensions
• Approximate Mass: 0.7~0.9 kg (1.54~1.98 lbs)
• Coil Voltage: Optional AC240V, DC24V, adapting to different power supply environments.

Key Features & Applications

The S-BSG-01 features a compact structure and low noise emission (≤55 dB(A) under rated conditions), making it suitable for small hydraulic systems, precision hydraulic control circuits, and auxiliary circuits of medium-sized equipment. Typical applications include small-scale construction machinery, precision machine tools, and light-duty hydraulic equipment, where it is responsible for pressure regulation and overpressure protection of auxiliary circuits to ensure stable and quiet operation of the system.

2.2 S-BSG-03 Low Noise Type Pilot Operated Relief Valve

The S-BSG-03 is a medium-sized model in the series, with a balanced combination of flow capacity, size, and performance, making it the most widely used model in various hydraulic systems. It is compatible with standard sub-plate dimensions (ISO 6264-06-09-1-97) and has good interchangeability[superscript:18].

Core Specifications

• Maximum Operating Pressure: 25 MPa (3630 psi)
• Maximum Flow Rate: 100 L/min (26.4 U.S. gpm) [at rated pressure][superscript:19]
• Pressure Adjustment Range: 4~25 MPa (580~3630 psi)
• Valve Size: 03 (nominal diameter approx. 3 mm)
• Mounting Type: Sub-plate mounting
• Approximate Mass: 5.5~6.5 kg (12.1~14.3 lbs) [varies by configuration: single solenoid, double solenoid, or with vent restrictor]
• Coil Voltage: Optional AC240V, DC24V
• Mounting Surface Dimensions: Conforms to ISO 6264-06-09-1-97, with standard mounting hole layout and thread specifications[superscript:18]

Key Features & Applications

With excellent noise reduction performance and stable pressure control, the S-BSG-03 is suitable for medium-sized hydraulic systems and main circuits of general engineering machinery. It supports optional vent restrictor (applicable to vent types 2B3A and 2B3B), which can reduce the impact on the main circuit during pressure conversion from set pressure to unloading[superscript:4]. Typical applications include construction machinery (such as cranes), metallurgical equipment, plastic machinery, and hydraulic stations, where it plays a key role in pressure regulation and system protection.

2.3 S-BSG-06 Low Noise Type Pilot Operated Relief Valve

As the largest model in the three, the S-BSG-06 is designed for large hydraulic systems or main circuits that require high flow, high pressure, and low noise. It adopts an optimized flow channel design to ensure stable operation even under high-flow conditions, and is compatible with standard sub-plate dimensions (ISO 6264-08-13-1-97)[superscript:18].

Core Specifications

• Maximum Operating Pressure: 25 MPa (3630 psi)
• Maximum Flow Rate: 200 L/min (52.8 U.S. gpm) [at rated pressure][superscript:19]
• Pressure Adjustment Range: 4~25 MPa (580~3630 psi)
• Valve Size: 06 (nominal diameter approx. 6 mm)
• Mounting Type: Sub-plate mounting
• Approximate Mass: 6.4~7.4 kg (14.1~16.3 lbs) [varies by configuration: single solenoid, double solenoid, or with vent restrictor]
• Coil Voltage: Optional AC240V, DC24V
• Mounting Surface Dimensions: Conforms to ISO 6264-08-13-1-97, with larger mounting surface compared to S-BSG-01 and S-BSG-03[superscript:18]

Key Features & Applications

The S-BSG-06 has the largest flow capacity among the three models, with low noise emission and high reliability even under harsh working conditions. It also supports optional vent restrictor and high venting pressure feature (to reduce response time from unloading to on-loading)[superscript:5]. Typical applications include large-tonnage cranes, hydraulic presses, heavy-duty engineering machinery, and large-scale hydraulic stations, where it is responsible for pressure regulation and overpressure protection of the main hydraulic circuit, ensuring stable and efficient operation of the entire system.

3. Installation and Operation Notes

• Mounting: The valve adopts sub-plate mounting; ensure the mounting surface has a good machined finish (surface roughness ≤1.6 μm) to avoid oil leakage. The sub-plate model should be selected according to the valve size and mounting standard[superscript:18].
• Pressure Adjustment: Loosen the lock nut and rotate the pressure adjustment handle clockwise to increase pressure or counterclockwise to decrease pressure; tighten the lock nut after adjustment to prevent pressure deviation.
• Vent Circuit: If a remote control relief valve is used in the vent circuit, ensure the pipeline volume is minimized to avoid jitter. The tank pipeline should be directly connected to the oil tank and not connected to the tank pipeline of other valves.
• Flow Requirement: When the flow rate is too low (less than 5 L/min for S-BSG-03 and S-BSG-06), the set pressure may be unstable; ensure the system flow meets the minimum flow requirement of the valve.
• Maintenance: Regularly inspect and clean the valve core and valve seat to avoid blockage caused by oil impurities, which may affect pressure control accuracy and noise performance. The product design may be modified without prior notice; refer to the latest product manual for detailed parameters.
• Interchangeability: The S-BSG series (design 53) is interchangeable with the old design (design 52) of conventional BSG series valves, facilitating maintenance and replacement.