CKCB.XCN Sun Hydraulics Pilot to Open Check Valve 15GPM 5000PSI

Product Overview

The Sun Hydraulics CKCB.XCN (CKCBXCN) is a pilot-to-open check valve with standard pilot from the Series 1 cartridge directional control range. It allows free flow from the valve (port 2) to the load (port 1) and blocks reverse flow. Pressure at the pilot port (port 3) opens the valve from port 1 to port 2. Pilot pressure required is directly proportional to load pressure at port 1 (3:1 pilot ratio), while pressure at port 2 directly opposes pilot pressure. Featuring a non-sealed pilot, steel seat and non-vented design, it provides hose-break protection, prevents load drift and positively locks pressurized loads. Compatible with listed CXFA.XEN and CXDA.XBN free-flow nose-to-side check valves. All models offer 100% drop-in interchangeability with genuine Sun Hydraulics products and are validated under simulated operating conditions for reliable high-pressure performance.

Technical Specifications 

• Model: CKCB.XCN / CKCBXCN (X = Standard Pilot; C = 30 psi / 2 bar cracking pressure; N = Buna-N)
• Series: Series 1
• Cavity: T-11A
• Capacity: 60 L/min (15 gpm)
• Maximum Operating Pressure: 350 bar (5000 psi)
• Pilot Ratio: 3:1
• Maximum Valve Leakage at 110 SUS (24 cSt): ≤0.07 cc/min (1 drop/min)
• Control: X = Standard Pilot (optional L Manual Load Release)
• Cracking Pressure Options: C = 2 bar (30 psi); also A = 0.3 bar, B = 1 bar, D = 3.5 bar, E = 5 bar etc.
• Valve Hex Size: 22.2 mm (7/8 in)
• Valve Installation Torque: 41-47 Nm (30-35 lbf·ft)
• Model Weight: approx. 0.10-0.28 lb (0.10-0.13 kg)
• Seal Kits: Buna 990011007; EPDM 990011014; Viton 990011006 etc.
• Related CXFA.XEN: Free-flow nose-to-side check valve, Series 2, cavity T-5A, capacity 160 L/min (40 gpm), max pressure 350 bar, E = 5 bar cracking
• Related CXDA.XBN: Free-flow nose-to-side check valve, Series 1, cavity T-13A, capacity 80 L/min (20 gpm), max pressure 350 bar, B = 1 bar cracking

Key Technical Advantages

• 3:1 pilot ratio with non-sealed pilot design enables proportional pilot pressure to load, allows trapped air purge from the pilot line, and delivers reliable load locking plus hose-break protection.
• Extremely low-leakage steel seat (maximum 1 drop/min) ensures positive locking of pressurized loads and prevents drift in precision holding applications.
• Sun floating-style construction compensates for excessive installation torque and cavity/cartridge machining variations, minimizing internal binding risk and guaranteeing interchangeability.
• Physical interchangeability with same-size 3-port counterbalance valves (identical cavities and flow paths) simplifies system upgrades or replacements.
• Corrosion-resistant options (/LH zinc-nickel or /AP stainless passivated) and seal choices (including EPDM for phosphate-ester fluids) suit demanding environments.

Application Areas

Mobile construction equipment (excavator and crane boom load holding), industrial cylinder locking circuits, agricultural machinery, marine and offshore systems, injection molding and machine-tool hydraulics, high-pressure unidirectional control requiring hose-break protection and positive locking, plus combined free-flow directional control with CXFA/CXDA series valves.

Expert Maintenance Tips

Thoroughly clean the T-11A cavity before installation. Tighten evenly to the recommended 41-47 Nm torque. Maintain system fluid cleanliness (ISO 4406 18/15 or better preferred) to protect the steel seat. Use genuine Sun seal kits and verify fluid compatibility (Buna-N for petroleum-based oils; EPDM only for phosphate-ester fluids). The non-sealed pilot allows air purge—confirm opening direction at low pressure during commissioning. For the optional L (manual load release) control, turn clockwise to release the load. When interchanging with counterbalance valves, note that cartridge extension dimensions from the mounting surface may differ. Verify pilot ratio and load pressure match before full system pressure testing.