FDCB-HAN RDFA-LCN PVFA-LAN PRFB-LAN PBFC-ABN RDHA-LAN Sun Hydraulics Relief Valve 350 bar

Product Overview

All models in this product range have been verified to belong to Sun Hydraulics brand. Sun Hydraulics is a globally leading manufacturer of screw-in hydraulic cartridge valves, renowned for high reliability, superior performance, and exceptional interchangeability.

Product type attribution is as follows:

• FDCB-HAN: Pressure-compensated flow control valve with reverse flow check, Cavity T-5A

• RDFA-LCN: Direct-acting relief valve, Cavity T-3A

• PVFA-LAN: Pilot-operated pressure reducing/relieving valve with drain to port 4, Cavity T-22A

• PRFB-LAN: Direct-acting pressure reducing/relieving valve, Cavity T-2A

• PBFC-ABN: Air-controlled, pilot-operated pressure reducing valve, Cavity T-2A

• RDHA-LAN: Direct-acting relief valve, Cavity T-16A

FDCB-HAN (Pressure-Compensated Flow Control Valve)

The FDCB-HAN is a pressure-compensated flow control valve with reverse flow check, providing precise flow control in inlet or outlet metering applications with significant pressure fluctuations. The valve offers infinite adjustment from nearly closed to maximum flow, with an integrated high-capacity check valve providing free flow from port 2 to port 1.

RDFA-LCN (Direct-Acting Relief Valve)

The RDFA-LCN is a normally closed direct-acting relief valve designed to protect hydraulic systems from pressure transients. When inlet pressure (port 1) reaches the set value, the valve opens, allowing flow from port 1 to tank (port 2), throttling flow to limit further pressure rise. The valve operates smoothly, quietly, with essentially zero leakage, and is insensitive to oil contamination and silting.

PVFA-LAN (Pilot-Operated Reducing/Relieving Valve)

The PVFA-LAN is a pilot-operated pressure reducing/relieving valve with drain to port 4. It reduces a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1, with a full-flow relief function from port 1 to tank (port 3). The external drain at port 4 makes the valve insensitive to pressure at tank (port 3) and provides a means for remote control by pilot or 2-way valves.

PRFB-LAN (Direct-Acting Reducing/Relieving Valve)

The PRFB-LAN is a direct-acting pressure reducing/relieving valve that reduces a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1, with a full-flow relief function from port 1 to tank (port 3). The direct-acting concept provides highly reliable operation in contaminated systems, especially at dead-headed conditions.

PBFC-ABN (Air-Controlled Pilot-Operated Reducing Valve)

The PBFC-ABN is an air-controlled, pilot-operated pressure reducing/relieving valve that uses compressed air over a diaphragm instead of an adjustable spring to control the setting. The valve reduces a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1, with a full-flow relief function from port 1 to tank (port 3). The pilot ratio (hydraulic:air) is 20:1. The air control feature allows explosion-proof remote control.

RDHA-LAN (Direct-Acting Relief Valve)

The RDHA-LAN is a normally closed direct-acting relief valve designed to protect hydraulic systems from pressure transients. When inlet pressure (port 1) reaches the set value, the valve opens, allowing flow from port 1 to tank (port 2), throttling flow to limit further pressure rise. The valve is quiet, smooth, leak-free, insensitive to contamination, and features very fast response time.

Our complete range of Sun Hydraulics cartridge valves strictly adheres to OEM technical standards, achieving 100% direct interchangeability with original components. Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring performance parameters are fully consistent with genuine Sun Hydraulics products. Direct replacement significantly reduces equipment downtime and maintenance costs.

Technical Specifications 

FDCB-HAN (Pressure-Compensated Flow Control Valve)

• Product Series: Sun Hydraulics FDCB series pressure-compensated flow control valve

• Model Code: FDCB-HAN

• Brand: Sun Hydraulics

• Product Type: Pressure-compensated flow control valve with reverse flow check

• Cavity: T-5A

• Series: 2

• Maximum Flow Capacity: 45 L/min (12 gpm)

• Maximum Operating Pressure: 350 bar (5000 psi)

• Adjustment – Turns from Closed to Open: 5 CCW turns

• Valve Hex Size: 28.6 mm (1 1/8 in)

• Valve Installation Torque: 61 – 68 Nm

• Adjustment Screw Internal Hex Size: 4 mm

• Locknut Hex Size: 15 mm

• Locknut Torque: 9 – 10 Nm

• Weight: Approx. 0.28 kg

• Seal Material: Buna-N (standard) / EPDM / Viton (optional)

• Seal Kit – Cartridge: Buna: 990203007; EPDM: 990203014; Viton: 990203006

RDFA-LCN (Direct-Acting Relief Valve)

• Product Series: Sun Hydraulics RDFA series direct-acting relief valve

• Model Code: RDFA-LCN

• Brand: Sun Hydraulics

• Product Type: Direct-acting relief valve

• Cavity: T-3A

• Series: 2

• Maximum Flow Capacity: 200 L/min (50 gpm)

• Maximum Operating Pressure: 350 bar (5000 psi)

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

• Maximum Leakage at Reseat: 10 drops/min

• Response Time – Typical: 2 ms

• Reseat: ≥ 90% of cracking pressure

• Operating Temperature: Up to +110°C

• Installation Torque: 61 – 68 Nm

PVFA-LAN (Pilot-Operated Reducing/Relieving Valve)

• Product Series: Sun Hydraulics PVFA series pilot-operated reducing/relieving valve

• Model Code: PVFA-LAN

• Brand: Sun Hydraulics

• Product Type: Pilot-operated pressure reducing/relieving valve with drain to port 4

• Cavity: T-22A

• Series: 2

• Maximum Flow Capacity: 80 L/min (20 gpm)

• Maximum Operating Pressure: 350 bar (5000 psi)

• Valve Hex Size: 28.6 mm (1 1/8 in)

• Valve Installation Torque: 61 – 68 Nm (45 – 50 lbf ft)

• Adjustment Screw Internal Hex Size: 4 mm

• Locknut Hex Size: 15 mm

• Locknut Torque: 9 – 10 Nm

• Control Pilot Flow: 0.16 – 0.25 L/min

• Weight: Approx. 0.34 kg

PRFB-LAN (Direct-Acting Reducing/Relieving Valve)

• Product Series: Sun Hydraulics PRFB series direct-acting reducing/relieving valve

• Model Code: PRFB-LAN

• Brand: Sun Hydraulics

• Product Type: Direct-acting pressure reducing/relieving valve

• Cavity: T-2A

• Series: 2

• Maximum Flow Capacity: 80 L/min (20 gpm)

• Maximum Operating Pressure: 350 bar (5000 psi)

• Maximum Leakage at 110 SUS (24 cSt) : 50 cc/min

• Valve Hex Size: 28.6 mm (1 1/8 in)

• Valve Installation Torque: 61 – 68 Nm (45 – 50 lbf ft)

• Adjustment Screw Internal Hex Size: 4 mm

• Locknut Hex Size: 15 mm

• Locknut Torque: 9 – 10 Nm

• Weight: Approx. 0.36 kg

PBFC-ABN (Air-Controlled Pilot-Operated Reducing Valve)

• Product Series: Sun Hydraulics PBFC series air-controlled pilot-operated reducing valve

• Model Code: PBFC-ABN

• Brand: Sun Hydraulics

• Product Type: Air-controlled, pilot-operated pressure reducing/relieving valve

• Cavity: T-2A

• Series: 2

• Maximum Flow Capacity: 80 L/min (20 gpm)

• Maximum Operating Pressure: 140 bar (2000 psi)

• Pilot Ratio (Hydraulic:Air) : 20:1

• Maximum Air Pressure: 10.5 bar (150 psi)

• Valve Hex Size: 28.6 mm (1 1/8 in)

• Valve Installation Torque: 61 – 68 Nm (45 – 50 lbf ft)

• Adjustment Screw Internal Hex Size: 4 mm

• Locknut Hex Size: 15 mm

• Locknut Torque: 9 – 10 Nm

• Control Pilot Flow: 0.16 – 0.25 L/min

• Weight: Approx. 0.26 kg

RDHA-LAN (Direct-Acting Relief Valve)

• Product Series: Sun Hydraulics RDHA series direct-acting relief valve

• Model Code: RDHA-LAN

• Brand: Sun Hydraulics

• Product Type: Direct-acting relief valve

• Cavity: T-16A

• Series: 3

• Maximum Flow Capacity: 380 L/min (100 gpm)

• Maximum Operating Pressure: 350 bar (5000 psi)

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

• Maximum Leakage at Reseat: 10 drops/min (0.7 cc/min)

• Response Time – Typical: 2 ms

• Reseat: ≥ 90% of cracking pressure

Key Technical Advantages

1. Sun Hydraulics Standardized Cavity Design for 100% Interchangeability

All models utilize Sun Hydraulics standard cavity designs—FDCB-HAN uses T-5A cavity, RDFA-LCN uses T-3A cavity, PVFA-LAN uses T-22A cavity, PRFB-LAN and PBFC-ABN use T-2A cavity, and RDHA-LAN uses T-16A cavity. All cartridge valves within the same cavity size are physically and functionally interchangeable. This standardization ensures 100% direct interchangeability without any manifold modification or system adjustment.

2. Sun Floating Style Construction – Reduced Binding Risk

All products incorporate Sun Hydraulics’ patented floating style construction. This design significantly reduces the risk of internal parts binding due to excessive installation torque or cavity/cartridge machining variations, enhancing installation reliability and service life.

3. Direct-Acting Relief Valves – Fast Response & Essentially Zero Leakage (RDFA-LCN / RDHA-LAN)

RDFA-LCN and RDHA-LAN are direct-acting relief valves with normally closed design, featuring typical response time of only 2 ms. These valves operate smoothly, quietly, with essentially zero leakage, with leakage at reseat not exceeding 10 drops/min. The spool/poppet is manufactured from hardened, precision ground steel for long-term wear resistance.

4. Direct-Acting Reducing/Relieving Valve – Superior Contamination Resistance (PRFB-LAN)

PRFB-LAN is a direct-acting reducing/relieving valve that provides highly reliable operation in contaminated systems, especially at dead-headed conditions. Compared to pilot-operated versions, the direct-acting valve offers superior dynamic response. The valve is particularly suitable for accumulator circuits, as the absence of pilot control flow results in reduced secondary circuit leakage.

5. Pilot-Operated Reducing/Relieving Valve – Excellent Pressure/Flow Characteristics (PVFA-LAN)

PVFA-LAN is a pilot-operated reducing/relieving valve featuring exceptionally flat pressure/flow characteristics, very stable operation, and low hysteresis. The external drain at port 4 makes the valve insensitive to pressure at tank (port 3) and provides a means for remote control by pilot or 2-way valves.

6. Air-Controlled Pilot-Operated Reducing Valve – Explosion-Proof Remote Control (PBFC-ABN)

PBFC-ABN is an air-controlled pilot-operated reducing valve that uses compressed air instead of an adjustable spring to control the setting. The pilot ratio (hydraulic:air) is 20:1. The air control feature allows explosion-proof remote control, making it particularly suitable for hazardous environments with flammable gases where electrical control is not permitted.

7. Pressure-Compensated Flow Control Valve – Precise Flow Control (FDCB-HAN)

FDCB-HAN is a pressure-compensated flow control valve with reverse flow check that provides precise flow control in inlet or outlet metering applications with significant pressure fluctuations. The valve offers infinite adjustment from nearly closed to maximum flow. The sharp-edged orifice design minimizes the effects of viscosity variation on flow. The balanced adjustment structure ensures easy adjustment even under high pressure.

8. 100% Simulated Operating Condition Testing

Every unit undergoes 100% simulated operating condition bench testing prior to shipment, ensuring consistent, stable performance at rated pressure and flow.

Application Areas

• FDCB-HAN (Pressure-Compensated Flow Control Valve) :

  • Inlet or outlet metering circuits

  • Applications requiring pressure-compensated flow control

  • Actuator speed control circuits

• RDFA-LCN / RDHA-LAN (Direct-Acting Relief Valves) :

  • Hydraulic system overload protection and pressure limiting

  • Cross-port relief circuits

  • Load holding applications

• PVFA-LAN (Pilot-Operated Reducing/Relieving Valve) :

  • Reducing circuits requiring remote control

  • Hydraulic systems requiring constant secondary pressure

  • Applications sensitive to tank back pressure

• PRFB-LAN (Direct-Acting Reducing/Relieving Valve) :

  • Accumulator charging circuits

  • Reducing applications requiring fast dynamic response

  • Hydraulic systems with significant contamination

• PBFC-ABN (Air-Controlled Pilot-Operated Reducing Valve) :

  • Explosion-proof environments (hazardous areas with flammable gases)

  • Reducing circuits requiring remote pneumatic control

  • Mining equipment, petrochemical equipment

Expert Maintenance Tips

1. Verify Model and Cavity Compatibility Prior to Installation

All models are screw-in cartridge valves. Confirm that the manifold cavity matches the valve:

• FDCB-HAN requires T-5A cavity

• RDFA-LCN requires T-3A cavity

• PVFA-LAN requires T-22A cavity

• PRFB-LAN requires T-2A cavity

• PBFC-ABN requires T-2A cavity

• RDHA-LAN requires T-16A cavity

Different cavity sizes are not interchangeable.

2. Correct Installation Torque

Recommended installation torque for each model:

• FDCB-HAN: 61 – 68 Nm

• RDFA-LCN: 61 – 68 Nm

• PVFA-LAN: 61 – 68 Nm (45 – 50 lbf ft)

• PRFB-LAN: 61 – 68 Nm (45 – 50 lbf ft)

• PBFC-ABN: 61 – 68 Nm (45 – 50 lbf ft)

• RDHA-LAN: 200 – 215 Nm

Use a torque wrench for precise torque control—never exceed the specified value. While Sun’s floating style construction reduces binding risk, over-torquing can still cause body distortion or seal failure.

3. Seal Material Selection

• Buna-N (Nitrile) : Standard configuration, suitable for mineral-based hydraulic oils

• Viton (Fluorocarbon) : Suitable for high temperatures and various hydraulic fluids

• EPDM: For phosphate ester fluids only—exposure to petroleum-based hydraulic oils or lubricating greases will damage the seals

4. Pressure Setting Precautions (RDFA-LCN / RDHA-LAN)

RDFA-LCN and RDHA-LAN relief valves have adjuster screw seals exposed to system pressure—system pressure must be relieved before making adjustments. Correct procedure: check current setting → relieve system pressure → adjust valve → re-pressurize and verify new setting. For optimal repeatability, select a spring range where the desired relief setting falls in the mid-to-high range of the spring’s capabilities.

5. Back Pressure Effects

Back pressure at the tank port (port 2) of RDFA-LCN and RDHA-LAN relief valves directly adds to the valve setting at a 1:1 ratio. Ensure tank line back pressure is as low as possible, or account for it during setting.

6. Pneumatic Circuit Precautions (PBFC-ABN)

PBFC-ABN is an air-controlled pilot-operated reducing valve—maximum air pressure must not exceed 10.5 bar (150 psi) . The pilot ratio (hydraulic:air) is 20:1. The air supply should be dry, clean, and oil-free to prevent diaphragm contamination or degraded control accuracy. The air control feature allows explosion-proof remote control.

7. System Cleanliness Management

Although Sun Hydraulics products offer excellent contamination tolerance, recommended system cleanliness is ISO 4406 Code 18/16/13 or better. PVFA-LAN pilot-operated valves and PBFC-ABN air-controlled valves have tighter internal clearances and require higher cleanliness levels.

8. Periodic Functional Checks

Perform functional checks every 2,000 operating hours or annually:

• FDCB-HAN: Verify flow control accuracy and pressure compensation function

• RDFA-LCN / RDHA-LAN: Verify cracking pressure accuracy and leakage within specification

• PVFA-LAN / PRFB-LAN: Verify reduced pressure stability and relief function

• PBFC-ABN: Verify air control response sensitivity and reducing pressure accuracy

If abnormalities are observed, arrange for servicing or replacement.