Product Overview

The NACHI OCY-G01-W-X-20 is a Flow Regulator Modular Valve with an integrated check valve, designed for hydraulic actuator speed control.

NACHI’s official modular-valve documentation identifies the OCY family as flow regulator valves with check-valve functionality. The OCY architecture allows adjustable flow regulation in one direction while providing check-valve flow in the opposite direction. (n​achi-fujikoshi.co.jp)

For the primary model OCY-G01-W-X-20, NACHI documentation confirms:

• G01 modular size
• 1/8 nominal port
• 25 MPa maximum operating pressure
• 50 L/min maximum flow
• 0.08 MPa check cracking pressure
• W control configuration for A and B ports
• X meter-in control
• Design number 20
• Approximately 1.3 kg mass (n​achi-fujikoshi.co.jp)

The resulting function is:

Meter-In Flow Regulation + Reverse Check Function

Technical Specifications

OCY-G01-W-X-20

• Manufacturer: NACHI / Nachi-Fujikoshi
• Product Family: G01 Modular Valve Series
• Product Type: Flow Regulator Modular Valve
• Series: OCY
• Function: Flow regulation with check valve
• Mounting: Gasket / modular stacking
• Nominal Size: G01
• Nominal Port: 1/8
• Maximum Operating Pressure: 25 MPa / 250 bar
• Maximum Flow: 50 L/min
• Check Cracking Pressure: 0.08 MPa / 0.8 bar
• Control Port: W — A and B ports
• Control Function: X — Meter-In
• Adjustment: Manual
• Design Number: 20
• Approximate Weight: 1.3 kg
• Pump Displacement: Not applicable
• Pump Rated Pressure: Not applicable
• Pump Peak Pressure: Not applicable
• Maximum Pump Speed: Not applicable
• Control Method: Mechanical hydraulic flow regulation
• Primary Application: Hydraulic actuator speed control (n​achi-fujikoshi.co.jp)

Related Models

OCY-G01-W-Y-20

• Maximum operating pressure: 25 MPa
• Maximum flow: 50 L/min
• Check cracking pressure: 0.08 MPa
• Control port: W / A & B
• Control function: Y — Meter-Out
• Design: 20
• Approximate weight: 1.3 kg

NACHI documentation distinguishes X meter-in from Y meter-out configurations. (n​achi-fujikoshi.co.jp)

OCY-G03-A-X-J51

• Nominal Size: G03
• Nominal Port: 3/8
• Maximum Operating Pressure: 25 MPa / 250 bar
• Maximum Flow: 100 L/min
• Check Cracking Pressure: 0.1 MPa / 1.0 bar
• Control Port: A
• Control Function: X — Meter-In
• Mounting: Gasket type
• Design Number: J51
• Mounting Bolts: M6
• Approximate Weight: 3.0 kg (wheretobuy.nachiamerica.com)

OCY-G03-W-Y-51 / OCY-G03-W-Y-J51

• Nominal Size: G03
• Nominal Port: 3/8
• Maximum Operating Pressure: 25 MPa / 250 bar
• Maximum Flow: 100 L/min
• Control Port: W — A and B
• Control Function: Y — Meter-Out
• Mounting: Gasket type
• J51 Configuration: M6 mounting-bolt design
• Approximate Weight: 3.1 kg
• Interface: D05 / NG10 modular interface

NACHI America identifies OCY-G03-W-Y-51 as a 100 L/min, 25 MPa meter-out flow regulator modular valve. (sun-source.com)

NACHI’s official CAD database lists the corresponding configuration using the J51 notation. (n​achi-fujikoshi.co.jp)

Model-Code Interpretation

OCY

Flow regulator modular valve with check valve.

G01 / G03

Modular valve size:

• G01 → 50 L/min
• G03 → 100 L/min

(n​achi-fujikoshi.co.jp)

W / A / B

Control-port configuration:

• W → A and B
• A → A port
• B → B port

NACHI America product data confirms this coding structure for specific G03 configurations. (wheretobuy.nachiamerica.com)

X / Y

• X → Meter-In
• Y → Meter-Out

NACHI’s official CAD and catalog materials explicitly distinguish the two control modes. (n​achi-fujikoshi.co.jp)

Operating Principle

The OCY combines:

Adjustable Flow Restriction + Check Valve

Meter-In

With X configuration, the inlet flow to the actuator is regulated:

Inlet Flow → Throttle → Actuator

Reducing the throttle opening reduces flow and therefore actuator speed under suitable operating conditions.

Reverse Flow

The integrated check function provides a lower-resistance reverse-flow path.

This allows the actuator circuit to combine controlled flow in one direction with free check-valve flow in the other.

Key Technical Advantages

1. Integrated Check Function

OCY combines flow regulation and one-way check operation into one modular valve.

This reduces the need for a separate external check valve in suitable circuits.

2. Direct Actuator Speed Control

NACHI identifies OCY as a flow regulator used for actuator speed control. (n​achi-fujikoshi.co.jp)

For a hydraulic cylinder:

v = Q / A

Therefore, regulating flow provides a direct way to control cylinder speed when the hydraulic operating conditions remain suitable.

3. 50–100 L/min Capacity Range

The modular family provides:

G01 → 50 L/min

G03 → 100 L/min

This covers a broad range of industrial actuator applications. (n​achi-fujikoshi.co.jp)

4. 25 MPa Operating Pressure

The G01 and G03 OCY configurations are rated for up to:

25 MPa / 250 bar

making them suitable for industrial hydraulic circuits. (n​achi-fujikoshi.co.jp)

5. Modular Stacking Design

The gasket-type architecture permits integration with other NACHI modular valves.

Typical combinations can include:

Pressure Relief + Flow Control + Check + Directional Control

within a compact valve stack.

6. Meter-In and Meter-Out Options

The X/Y configuration provides flexibility:

X = Meter-In

Y = Meter-Out

The correct choice depends on actuator load characteristics and the desired motion-control architecture.

7. Do Not Confuse OCY With Pressure-Compensated Flow Control

Standard OCY is a flow regulator modular valve with check functionality. It should not automatically be marketed as a pressure- or temperature-compensated constant-flow valve.

NACHI catalogs separately identify OCY and other compensated flow-control families. (n​achi-fujikoshi.co.jp)

OF-G01-P20-20 — Separate Product Family

The original search term also contains OF-G01-P20-20.

This should be treated separately:

• Product: Flow Control Modular Valve
• Check Valve: No
• Nominal Size: G01
• Nominal Port: 1/8
• Maximum Pressure: 21 MPa
• Maximum Control Flow: 20 L/min
• Control Port: P
• Design Number: 20
• Approximate Weight: 1.2 kg

NACHI America describes OF-G01-P20-20 as a flow-control modular valve with pressure compensation for stable control flow under pressure and oil-temperature changes. (wheretobuy.nachiamerica.com)

Therefore:

OF-G01-P20-20 ≠ OCY-G01-W-X-20

Engineering Materials and Manufacturing

NACHI’s public OCY documentation does not provide complete internal material-grade, heat-treatment or hardness specifications.

These should therefore not be invented.

For an OCY replacement valve, the most important manufacturing controls are:

Flow-Control Element Precision

Spool/piston geometry and clearance influence flow repeatability and leakage.

Check Seat Geometry

The integrated check element determines reverse leakage and cracking characteristics.

Adjustment Mechanism

Manual adjustment must provide repeatable flow-setting behavior.

Mounting Surface Accuracy

Gasket-type modular installation requires accurate sealing surfaces and correct O-ring positioning.

The most important replacement-quality parameters are:

Dimensional Accuracy + Flow Characteristics + Check Performance + Seal Integrity

Application Areas

Typical applications include:

• Machine tools
• Hydraulic power units
• Hydraulic presses
• Clamping systems
• Automated machinery
• Material-handling systems
• Industrial production equipment
• Cylinder feed control
• Hydraulic positioning mechanisms
• Construction equipment auxiliary circuits
• Agricultural machinery

Expert Maintenance Tips

Confirm X or Y Before Replacement

X = Meter-In

Y = Meter-Out

Do not assume mechanical interchangeability means identical actuator behavior.

Confirm G01 or G03 Capacity

• G01 → 50 L/min
• G03 → 100 L/min

Using a smaller flow-control size beyond its intended capacity can increase pressure drop and restrict actuator speed. (n​achi-fujikoshi.co.jp)

Verify Check Cracking Pressure

For:

OCY-G01-W-X-20 → 0.08 MPa

For the G03 J51 family:

0.1 MPa

These values should not be mixed across sizes. (n​achi-fujikoshi.co.jp)

Inspect the Modular Interface

Before installation, inspect:

• Mounting surface
• O-rings
• Port passages
• Bolt holes
• Stack alignment
• Contamination

Avoid Excessive Mounting Torque

Over-tightening a gasket-type modular valve can cause:

• Body distortion
• Seal deformation
• Increased friction
• Internal leakage

Use the mounting specification applicable to the specific NACHI valve stack.

Verify the Adjustment Screw

Unexpected actuator-speed changes may result from:

• Adjustment movement
• Locknut loosening
• Wear
• Contamination
• Changing system flow demand

Maintain Hydraulic Cleanliness

Inspect the upstream filtration system and clean the modular-valve passages during replacement service.

Contamination may cause:

• Check-element sticking
• Unstable flow
• Increased leakage
• Incorrect cracking behavior

Recommended Replacement Validation

For an aftermarket OCY-G01-W-X-20 replacement, use:

Model Verification
→ G01 Interface Verification
→ Port Configuration Check
→ Seal Inspection
→ Cracking Pressure Test
→ Meter-In Flow Test
→ Reverse Free-Flow Test
→ Leakage Test
→ Actuator Speed Test
→ System-Level Functional Test
→ 100% Simulated Working-Condition Test

This supports a professional replacement proposition based on:

In-Place Interchangeability + 100% Simulated Working-Condition Testing

rather than dimensional matching alone.