Sun Hydraulics RPIC-LBN 1000PSI Pressure Relieving Cartridge Valve

The Sun Hydraulics RPIC-LBN is a pilot-operated, balanced-piston relief cartridge valve designed for precise pressure regulation in hydraulic systems. In normal operation it remains closed and opens to the tank port (port 2) as inlet pressure (port 1) reaches the set value, throttling flow to maintain the desired pressure. It handles up to 5000 psi (350 bar) with a maximum flow capacity of 100 gpm (380 L/min) and a typical response time of about 10 ms. The cartridge integrates a 150-micron stainless steel screen over the main stage orifice and uses EPDM seals compatible with phosphate ester fluids (not suitable for petroleum-based fluids). Sun's floating-style construction reduces binding from installation torque or machining variations. Weighing around 1.20 lb (0.55 kg) and requiring 150–160 lbf-ft (203–217 Nm) installation torque, the RPIC-LBN supports corrosion-resistant variants designated by AP (external stainless) or LH (zinc-nickel plated) suffixes. Back pressure on the tank port is directly additive to the valve setting (1:1), and while two-port relief cartridges are generally interchangeable within a given cavity, designers should account for spool leakage in cross-port relief configurations and avoid load-holding service with this type of valve.