SUN Hydraulics PRDB-LEN Relief Valve | 991034 Cartridge Valve | PRDB Series

LIC Hydraulic offers the SUN Hydraulics PRDB Series, a high-performance, pilot-operated, 3-way proportional reducing/relieving cartridge valve. The PRDB-LEN (Part No: 991034) is the precision choice for hydraulic systems requiring dynamic and accurate pressure control. It functions by reducing high primary pressure at Port 2 to a consistent, adjustable pressure at Port 1. Furthermore, it incorporates a relieving function, allowing oil to escape to Port 3 if Port 1 pressure exceeds the set point due to external forces. Featuring SUN’s world-renowned Floating Architecture, this valve guarantees operational reliability even under high installation torque and harsh thermal cycles.

Technical Specifications (Bulleted List)

• Series: PRDB (Proportional, Pilot-Operated, Reducing/Relieving)

• Model Code: PRDB-LEN

• Part Number: 991034

• Max Operating Pressure: $350\text{ bar}$ ($5000\text{ PSI}$)

• Control Logic: 3-Way (Port 1: Reduced Pressure, Port 2: Inlet, Port 3: Tank/Relief)

• Design: Screw-in Cartridge Valve with Floating Style construction.

• Compatibility: Fits T-11A cavities.

Key Technical Advantages

• Floating Style Design: SUN’s proprietary design prevents internal parts from binding due to excessive installation torque or manifold cavity distortion. This ensures consistent performance and reduces the risk of valve sticking.

• Dual Functionality: Combines a pressure reducer and a relief valve in a single cartridge. It actively manages load-induced pressure spikes at the reduced pressure port, protecting downstream components.

• Superior Proportional Control: Engineered for low hysteresis and high repeatability, the PRDB series provides smooth, linear pressure transitions when paired with a proportional amplifier.

• High Power Density: The compact cartridge design allows for high flow capacities relative to its small footprint, making it ideal for manifold integration where space is at a premium.

Application Areas

• Industrial Automation: Controlling clamping pressure in CNC machining centers and holding pressures in injection molding machines.

• Mobile Equipment: Pilot pressure supply for large directional valves and brake control systems in heavy-duty loaders.

• Energy & Marine: Precise pressure regulation in winch systems and offshore hydraulic power units.

Expert Maintenance Tips

• Monitor Tank Port Backpressure: Port 3 is the tank/drain port. Ensure it is connected to a low-pressure return line. Any backpressure on Port 3 will directly increase the set pressure at Port 1, leading to system inaccuracies.

• Filtration Management: Because proportional valves have tight internal clearances, maintaining oil cleanliness is critical. We recommend a minimum filtration of 10 microns to prevent pilot-stage clogging.

• Installation Caution: While the floating design is robust, always use a calibrated torque wrench. Proper installation ensures the internal seals maintain their integrity over millions of cycles.