RPGC-LCN Sun Hydraulics Relief Valve 50GPM 5000PSI Pilot Operated

Product Overview

The Sun Hydraulics RPGC series (including RPGC-LCN, RPGC-LBN, RPGC-LWN, RPGC-LAN and related variants) is a pilot-operated, balanced-piston relief valve from the Series 2 cartridge pressure control range. When inlet pressure at port 1 reaches the valve setting, the valve opens to tank (port 2), throttling flow to accurately regulate pressure. These valves offer low pressure rise versus flow, smooth and quiet operation, and moderately fast response. Featuring Sun’s floating-style construction, they minimize internal binding risks from installation torque or cavity variations. Rated to 350 bar (5000 psi) maximum operating pressure with 100% drop-in interchangeability to genuine Sun Hydraulics models. Compatible with listed CBCA-LHN 3:1 pilot-ratio counterbalance valves for comprehensive high-pressure system protection and load control.

Technical Specifications 

• Model: RPGC-LCN (variants: LBN, LWN, LAN etc.; L = Standard Screw Adjustment; C/A/W/B etc. for adjustment ranges; N = Buna-N)
• Series: Series 2
• Cavity: T-3A
• Capacity: 200 L/min (50 gpm)
• Maximum Operating Pressure: 350 bar (5000 psi)
• Factory Pressure Settings Established at: 15 L/min (4 gpm)
• Adjustment Range Example: C range 10.5-420 bar (150-6000 psi), 70 bar (1000 psi) standard setting; other ranges available
• Maximum Valve Leakage at 110 SUS (24 cSt): 50 cc/min @70 bar (3 in³/min @1000 psi)
• Response Time – Typical: 10 ms
• Adjustment – No. of CW Turns from Min. to Max.: 5
• Control: L = Standard Screw Adjustment (options include C Tamper Resistant, K Handknob, W Hex Wrench etc.)
• Valve Hex Size: 28.6 mm (1 1/8 in)
• Valve Installation Torque: 61-68 Nm (45-50 lbf·ft)
• Model Weight: approx. 0.25-0.26 kg (0.50-0.57 lb)
• Seal Kits: Buna 990203007; EPDM 990203014; Viton 990203006 etc.
• Related CBCA-LHN: 3:1 pilot ratio standard capacity counterbalance valve, cavity T-11A, capacity 60 L/min (15 gpm), maximum setting 280 bar (4000 psi), maximum recommended load pressure 215 bar (3075 psi)

Key Technical Advantages:

• Balanced-piston pilot-operated design delivers high accuracy, low pressure rise vs. flow, smooth quiet operation and moderate response speed.
• Main-stage orifice protected by a 150-micron stainless steel screen for superior contamination resistance and long-term reliability.
• Sun floating-style construction compensates for excessive installation torque and cavity/cartridge machining variations, preventing internal binding and ensuring reliable interchangeability.
• Wide adjustable ranges with typical 10 ms response time suit cross-port relief and complex circuits from low to high pressure.
• 100% form-fit-function interchangeability with original Sun Hydraulics valves plus optional /LH zinc-nickel or /AP stainless coatings for corrosive environments; EPDM seals designed for phosphate-ester fluids.

Application Areas

Mobile construction equipment hydraulic pressure protection, industrial power units and presses, injection molding machines and machine tools, agricultural and forestry machinery, marine hydraulic systems, high-pressure cross-port relief circuits, and load-holding/over-center applications (with CBCA series) on cranes, excavator booms and similar equipment.

Expert Maintenance Tips

Thoroughly clean the T-3A cavity before installation. Tighten to the recommended 61-68 Nm torque and secure the locknut at 9-10 Nm. Maintain system fluid cleanliness (ISO 4406 18/15 or better recommended) to protect the main-stage orifice screen. Use genuine Sun seal kits and verify fluid compatibility when servicing. Note that back pressure at port 2 adds directly (1:1) to the valve setting. Not suitable for load-holding applications due to spool leakage. Turn the adjustment clockwise to increase the setting and lock the nut after adjustment. For CBCA-LHN, set the valve at least 1.3 times the maximum load-induced pressure.