YF-L Series Electromagnetic Relief Valve | YF-L20H YF-L32H | Solenoid Pressure Regulating Valve

Chengyuan Hydraulic presents the YF-L Series electromagnetic relief valves (e.g., YF-L20H4-S, YF-L32H4-S), a sophisticated pressure control solution integrating pilot-operated relief logic with solenoid unloading. These valves are essential for achieving stepless pressure regulation, multi-stage pressure switching, and remote system unloading via electrical signals, providing critical protection for pumps and actuators. Our YF-L series is engineered for 100% Drop-in Interchangeability with standard industrial valve specifications. Supported by Chengyuan’s rigorous 100% Simulation Load Testing, every valve is verified for response time and stability under rated pressure, ensuring reliable performance in heavy-duty machine tools, metallurgical equipment, and mobile machinery.

Technical Specifications 

• Model Range: YF-L20H1/2/3/4-S, YF-L32H1/2/3/4-S

• Nominal Sizes: 20mm (L20) / 32mm (L32)

• Pressure Grade (H): Rated pressure up to 31.5 MPa (315 Bar)

• Flow Capacity: 160-200 L/min (L20) / 315-400 L/min (L32)

• Pressure Adjustment Ranges: Stage 1 (0.5-7MPa); Stage 2 (1-17.5MPa); Stage 3 (1-21MPa); Stage 4 (1-31.5MPa)

• Control Logic: Solenoid pilot unloading/regulation (-S denotes solenoid included)

• Solenoid Voltage: DC 24V / AC 220V optional

• Mounting Type: Threaded connection or subplate mounting

Key Technical Advantages:

• Triple-Stage Pilot Structure: The YF-L series features an optimized pilot design that ensures excellent force balance on the main spool. This design allows for smooth manual adjustment even at 31.5 MPa and minimizes pressure overshoot, drastically reducing system vibration.

• Rapid Solenoid Unloading: The integrated directional solenoid valve undergoes precision dynamic testing to ensure millisecond-level response times. During system standby, it enables near-zero pressure unloading, significantly lowering energy consumption and heat generation.

• High-Hardness Wear-Resistant Spool: The main spool and pilot cone are crafted from high-strength alloy steel with vacuum quenching (HRC 58-62). This ensures long-term sealing integrity and prevents pressure “creep” during high-frequency loading/unloading cycles.

• Anti-Vibration Damping Orifices: Internal flow paths are optimized to absorb hydraulic shockwaves. This ensures a smooth pressure transition curve even under heavy-duty instantaneous switching conditions.

Application Areas:

• Construction Machinery: Safety protection for high-pressure systems in drilling rigs and road rollers.

• Metallurgical Equipment: Pressure regulation and safety unloading for continuous casters and presses.

• Industrial Machine Tools: Multi-stage pressure control for large shears and press brakes.

• Hydraulic Power Units (HPU): Remote unloading and pressure setting in complex hydraulic circuits.

Expert Maintenance Tips:

• Pressure Setting Protocol: Never force the adjustment handle without loosening the lock nut. Adjust the pressure slowly while monitoring the gauge, then lock it firmly once the desired value is reached.

• Solenoid Health Check: Periodically listen to the solenoid’s actuation. A dull buzzing sound usually indicates low voltage or slight contamination of the pilot spool, necessitating a clean-out of the pilot stage.

• Fluid Cleanliness: Relief valves are highly sensitive to contamination. We recommend using 10μm return-line filters to maintain a system cleanliness of NAS Grade 9 or better, preserving the life of the pilot cone.