RPEC-KEN RPGC-KEN RPIC-KEN CBCA-LIN Sun Hydraulic Cartridge Valve 350 bar

Product Overview

This SUN series screw-in cartridge valve portfolio covers four core models: RPEC-KEN, RPGC-KEN, RPIC-KEN, and CBCA-LIN (including EFV variant CBCA-LIN-EFV). These products span three major functional categories — pressure control, directional control, and load holding — delivering comprehensive cartridge valve solutions for hydraulic systems.

• RPEC-KEN: Pilot-operated, balanced piston relief valve for precise pressure regulation and system overpressure protection.

• RPGC-KEN: High-flow pilot-operated, balanced piston relief valve with 200 L/min capacity for large-volume hydraulic system pressure control.

• RPIC-KEN: Pilot-to-open check valve for load-holding and zero-leakage locking applications.

• CBCA-LIN: 3:1 pilot ratio, standard capacity counterbalance valve for smooth control of overrunning loads and load-holding.

All models feature screw-in cartridge construction for direct installation into standardized SUN cavities, offering convenient assembly and low maintenance costs.

As a high-performance alternative to genuine Sun Hydraulics series products, this portfolio delivers full performance parity with Sun original specifications, featuring 100% form-fit-function interchangeability — cavity dimensions, installation torque specifications, and performance parameters are identical to the original, enabling direct replacement without manifold modifications. Every unit undergoes 100% simulated in-service testing prior to shipment, ensuring proven reliability under real-world operating conditions.

Technical Specifications 

RPEC-KEN — Pilot-Operated, Balanced Piston Relief Valve

• Product Type: Pilot-operated, balanced piston relief valve

• Cavity: T-10A

• Series: Series 1

• Maximum Flow: 25 gpm (95 L/min)

• Maximum Operating Pressure: 5000 psi (350 bar)

• Factory Pressure Setting Established at: 4 gpm (15 L/min)

• Maximum Leakage at 110 SUS (24 cSt): 2 in³/min

• Typical Response Time: 10 ms

• Main Stage Orifice Protection: 150-micron stainless steel screen

• Body Material: Steel (external stainless steel / zinc-nickel plated options available)

• Seal Material Options: Buna-N (NBR) / EPDM / Viton (FKM)

• Hydraulic Fluid: Mineral oil (EPDM seals for phosphate ester fluids)

• Temperature Range: -20℃ to +80℃

• Weight: 0.50 lb (0.23 kg)

RPGC-KEN — High-Flow Pilot-Operated, Balanced Piston Relief Valve

• Product Type: Pilot-operated, balanced piston relief valve

• Cavity: T-3A

• Series: Series 2

• Maximum Flow: 50 gpm (200 L/min)

• Maximum Operating Pressure: 5000 psi (350 bar)

• Factory Pressure Setting Established at: 4 gpm (15 L/min)

• Maximum Leakage at 110 SUS (24 cSt): 3 in³/min @ 1000 psi (50 cc/min @ 70 bar)

• Typical Response Time: 10 ms

• Adjustment Turns (Min to Max): 5 turns

• Valve Hex Size: 1 1/8 in (28.6 mm)

• Valve Installation Torque: 45 – 50 lbf·ft (61 – 68 N·m)

• Adjustment Screw Hex Size: 5/32 in (4 mm)

• Locknut Hex Size: 9/16 in (15 mm)

• Locknut Torque: 80 – 90 lbf·in (9 – 10 N·m)

• Main Stage Orifice Protection: 150-micron stainless steel screen

• Body Material: Steel (external stainless steel / zinc-nickel plated options available)

• Seal Material Options: Buna-N (NBR) / EPDM / Polyurethane / Viton (FKM)

• Hydraulic Fluid: Mineral oil (EPDM seals for phosphate ester fluids)

• Temperature Range: -20℃ to +80℃

• Weight: 0.50 – 0.57 lb (0.23 – 0.26 kg)

RPIC-KEN — Pilot-to-Open Check Valve

• Product Type: Pilot-to-open check valve

• Cavity: T-11A

• Series: Series 1

• Maximum Flow: 15 gpm (60 L/min)

• Maximum Operating Pressure: 2500 psi (175 bar)

• Pilot Ratio: 3:1

• Maximum Leakage at 110 SUS (24 cSt): 1 drop/min (0.07 cc/min)

• Valve Hex Size: 7/8 in (22.2 mm)

• Valve Installation Torque: 30 – 35 lbf·ft (41 – 47 N·m)

• Seat Material: Delrin

• Pilot Type: Sealed pilot

• Body Material: Steel

• Seal Material Options: Buna-N (NBR) / Polyurethane / Viton (FKM)

• Hydraulic Fluid: Mineral oil

• Temperature Range: -20℃ to +80℃

• Weight: 0.28 lb (0.13 kg)

CBCA-LIN — 3:1 Pilot Ratio, Standard Capacity Counterbalance Valve

• Product Type: 3:1 pilot ratio, standard capacity counterbalance valve

• Cavity: T-11A

• Series: Series 1

• Maximum Flow: 15 gpm (60 L/min)

• Maximum Operating Pressure: 5000 psi (350 bar)

• Pilot Ratio: 3:1

• Maximum Recommended Load Pressure at Maximum Setting: 3075 psi (215 bar)

• Maximum Setting: 4000 psi (280 bar)

• Check Cracking Pressure: 25 psi (1.7 bar)

• Reseat: >85% of setting

• Maximum Leakage at Reseat (110 SUS/24 cSt): 5 drops/min (0.3 cc/min)

• Adjustment Turns (Min to Max): 3.75 turns

• Valve Installation Torque: 30 – 35 lbf·ft (45 – 50 N·m)

• Body Material: Steel

• Seal Material Options: Buna-N (NBR) / EPDM / Viton (FKM)

• Hydraulic Fluid: Mineral oil (EPDM seals for phosphate ester fluids)

• Temperature Range: -20℃ to +80℃

• Weight: 0.35 lb (0.16 kg)

Key Technical Advantages

1. Sun Floating-Style Construction — Low Sensitivity to Installation Torque

The most distinctive technical advantage of Sun cartridge valves is the floating-style construction — the working assembly floats within the valve body, significantly reducing sensitivity to installation torque and preventing internal binding caused by excessive torque or cavity machining variations. This design dramatically improves field installation success rates and long-term operational reliability.

2. Standardized Cavity Design — 100% Interchangeability

• RPEC-KEN (T-10A)

• RPGC-KEN (T-3A)

• RPIC-KEN (T-11A)

• CBCA-LIN (T-11A)

All models utilize Sun-standard threaded cartridge cavities and are fully interchangeable with genuine Sun products, enabling seamless replacement without manifold modifications — substantially reducing system retrofit and maintenance costs.

3. High-Performance Sealing with Ultra-Low Leakage

• RPIC-KEN: Delrin seat design delivers leakage as low as 0.07 cc/min at 175 bar

• RPGC-KEN: Relief valve leakage of only 50 cc/min @ 70 bar

• CBCA-LIN: Reseat leakage of only 0.3 cc/min

Multiple seal material options (Buna-N, EPDM, Viton, Polyurethane) accommodate diverse hydraulic fluids and operating conditions.

4. Precise Pressure and Flow Control Performance

• RPEC-KEN / RPGC-KEN: Accurate pressure regulation with low pressure rise vs. flow characteristics; smooth, quiet operation with 10 ms response time

• CBCA-LIN: Reseat pressure exceeding 85% of set pressure ensures precise and reliable load control

• RPIC-KEN: 3:1 pilot ratio provides precise pilot control

5. Multi-Function Integration for Diverse Applications

• RPEC-KEN / RPGC-KEN: 2-port relief cartridges accept maximum pressure at port 2; suitable for cross-port relief circuits

• RPIC-KEN: Provides hose break protection and load-holding functionality

• CBCA-LIN: Integrates counterbalance, load-holding, and motion control valve functions in a single cartridge, with an integrated check valve for free forward flow

Application Areas

RPEC-KEN / RPGC-KEN — Pilot-Operated Relief Valves

• Overpressure protection for main hydraulic system pressure circuits

• Precision pressure control applications requiring low pressure rise vs. flow characteristics

• Cross-port relief circuits

RPIC-KEN — Pilot-to-Open Check Valve

• Cylinder position holding and load-holding

• Load drop protection against hose burst failure

• Zero-leakage actuator positioning applications

CBCA-LIN — Counterbalance Valve

• Smooth controlled lowering of overrunning loads (booms, arms, etc.)

• Cylinder position holding and load-locking

• Load control for cranes, lifts, presses, and similar equipment

Target Equipment: Injection molding machines, die-casting machines, construction equipment (excavators, loaders), lifting equipment, scissor lifts, machine tool hydraulic systems, test benches, and more.

Expert Maintenance Tips

1. Precise Installation Torque Control

Although Sun cartridge valves feature floating-style construction to reduce torque sensitivity, installation torque specifications must still be strictly followed:

• RPGC-KEN (T-3A): 45 – 50 lbf·ft (61 – 68 N·m)

• RPIC-KEN / CBCA-LIN (T-11A): 30 – 35 lbf·ft (41 – 47 N·m)

Ensure threads are centered during installation and use a torque wrench for proper tightening.

2. Cavity and Mounting Surface Cleaning

Thoroughly clean the cavity interior and mounting surface prior to installation to remove chips, burrs, and contaminants. The shoulder stop at the bottom of the cavity supports the floating portion of the valve — ensure it is free from damage.

3. Seal Selection and Replacement

• Standard mineral oil systems: Buna-N (NBR) seals

• Phosphate ester fluid systems: EPDM seals are mandatory

• High-temperature applications: Viton (FKM) seals
  Replace all cartridge seals after every disassembly.

4. Fluid Cleanliness Management

Maintain system fluid cleanliness at ISO 4406 Class 18/16/13 or higher. The RPEC/RPGC series features a 150-micron stainless steel screen protecting the main stage orifice — however, installation of a ≤10μm return line filter is still recommended for long-term reliability.

5. Periodic Functional Testing

• RPEC-KEN / RPGC-KEN: Periodically calibrate relief pressure settings and check for abnormal leakage

• RPIC-KEN: Regularly verify load-holding reliability — check for cylinder drift or actuator creep. If load drifts due to the valve, the seat has probably been damaged by contamination

• CBCA-LIN: Counterbalance valve setting should be at least 1.3 times the maximum load induced pressure. Periodically verify smooth load lowering and check for abnormal vibration or shock