Description
DN25 3/2 Way Air Pilot Coaxial Valve – RSG 38025
The RSG 38025 is a DN25 3/2 way externally controlled coaxial valve designed for reliable switching, diverting and exhausting of compatible liquids and gases at pressures from 0 to 64 Bar.
Available as normally closed or normally open, the valve uses a double-acting pneumatic piston with return spring, operated by a 3–8 Bar pilot air supply. Independent pneumatic actuation allows reliable switching from zero differential pressure, making the RSG 38025 suitable for high-pressure, low-pressure and vacuum applications.
The DN25 RSG 38025 provides a manufacturer-rated Kv flow coefficient of 12.2 m³/h with standard 3/4", 1" or 1¼" BSP connections, plus an optional 1½" BSP connection.
Valve Function & Operation
The RSG 38025 is available in two switching configurations.
380A25 – Normally Closed
In the normal position, the main P → A flow path is closed and the alternative flow path is selected. Applying pilot pressure switches the valve to connect the main process flow.
380B25 – Normally Open
The main P → A flow path is open in the normal position and switches to the alternative flow path when the pneumatic actuator is operated.
Because the valve is externally controlled, operation does not depend upon process pressure or require a minimum differential pressure.
DN25 Ports & Connections
Standard DN25 process connections:
✓ G3/4 BSP
✓ G1 BSP
✓ G1¼ BSP
Optional connections:
✓ G1½ BSP
✓ Special Connections
✓ Alternative R Port Orientation
The R connection can be supplied in alternative orientations to simplify installation and pipework routing within machinery and process systems.
Pressure & Performance
Operating Pressure: 0 to 64 Bar
Reverse Pressure: Up to 16 Bar
Minimum Differential: 0 Bar
Pilot Pressure: 3 to 8 Bar
Nominal Diameter: DN25
Orifice: 25mm
Kv Flow Coefficient: 12.2 m³/h
Flow paths provide:
P → A: Up to 64 Bar
A → P: Up to 16 Bar
P → R: Up to 64 Bar
R → P: Up to 16 Bar
The Series 380 is externally controlled with a 3–8 Bar pneumatic actuator and provides reverse-pressure sealing up to 16 Bar.
3/2 Way Coaxial Valve Design
The RSG 38025 incorporates three process ports and two valve seats within a single coaxial valve assembly.
This allows one valve to perform functions such as:
✓ Supply & Exhaust
✓ Pressure & Return
✓ Fluid Diversion
✓ Filling & Venting
✓ Process Changeover
✓ Pressure Release
The coaxial construction provides a high-flow process path while switching force is supplied independently by the pneumatic actuator.
Switching Performance
Opening / Closing Time: 50–1000ms
Actual switching time depends upon operating pressure, pilot pressure, pilot valve selection and any exhaust-air throttling fitted to the pneumatic control circuit.
The valve can be installed in any mounting position.
High Viscosity Fluids
The RSG 38025 is suitable for compatible fluids with viscosities up to 1000 cSt.
Typical applications can include:
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Thick Process Oils
✓ Viscous Process Fluids
✓ Cooling Fluids
✓ Compatible Industrial Liquids
Actual suitability depends upon viscosity, temperature, operating pressure and compatibility with the selected wetted materials.
Construction & Materials
Standard Body: Brass
Optional Body Materials:
✓ AISI 303 Stainless Steel
✓ AISI 316 Stainless Steel
Internals: Stainless Steel 316L
Stainless steel versions provide increased corrosion resistance where brass is unsuitable for the process medium or operating environment.
Standard Seal Construction
Standard sealing materials include:
✓ FKM Static Seals
✓ FKM / PTFE Dynamic Seals
✓ PTFE Seat Sealing
Optional:
✓ EPDM Seal Configuration
The appropriate sealing configuration should be selected according to the process medium and operating temperature.
Media Compatibility
The RSG 38025 can control liquids and gases compatible with the selected body and sealing materials.
Typical applications include:
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Process Liquids
✓ Cooling Fluids
✓ Viscous Process Media
✓ Compatible Chemicals
✓ Compatible Gases
✓ Fluids Up To 1000 cSt
For aggressive chemicals, specialist gases or unusual process fluids, compatibility should be confirmed against all wetted materials before ordering.
Water Service Seal Option
For demanding water applications, the RSG 38025 can be configured with UHMW Polyethylene sealing.
The UHMW Polyethylene configuration provides:
✓ Maximum Temperature +80°C
✓ High Wear Resistance
✓ Excellent Abrasion Resistance
✓ Low Friction
✓ Good Lubricity
✓ Debris-Stripping Seal Action
The dynamic sealing action helps remove limescale and small deposits from the sealing surface during operation, making this configuration particularly useful for demanding industrial water applications.
Gas Service Seal Option
For compatible gaseous media, the RSG 38025 can be configured with Fluoroloy® A21 sealing.
The Fluoroloy® A21 configuration provides:
✓ Maximum Temperature +80°C
✓ High Wear Resistance
✓ Low Friction
✓ Broad Chemical Compatibility
✓ Reliable Dynamic Sealing
The actual gas, pressure and operating temperature should be specified when ordering to ensure the correct sealing configuration is selected.
Vacuum & Clean Service
A dedicated vacuum configuration is available for the RSG 380 Series.
Because switching force is supplied independently by the pneumatic actuator, the RSG 38025 is suitable for zero-pressure and vacuum applications.
An oil and grease-free configuration is also available for clean process requirements. The manufacturer lists both vacuum and oil/grease-free configurations as Series 380 mechanical options.
Temperature
Media Temperature: -10°C to +100°C
Ambient Temperature: -10°C to +50°C
Water Seal Option: Up to +80°C
Gas Seal Option: Up to +80°C
Pneumatic Pilot Specification
Actuation: External Pneumatic Pilot
Actuator: Double-Acting Piston
Return: Spring Return
Pilot Pressure: 3–8 Bar
Pilot Connections: G1/4
Interface: NAMUR
Mounting Position: Any Position
An upstream air preparation unit is recommended to provide a clean pilot-air supply and help maximise actuator service life.
NAMUR Pilot Valve Options
The NAMUR interface allows a suitable 5/2 way pilot solenoid valve to be mounted directly onto the actuator.
Available configurations include:
✓ NAMUR Pilot – Side Connections
✓ NAMUR Pilot – Top Connections
✓ M12 Solenoid Pilot
✓ 24V DC Pilot Valve
✓ 230V 50Hz Pilot Valve
Exhaust throttles and silencers can also be fitted where required.
ATEX Pilot Option
An explosion-protected electrical pilot option is available for suitable hazardous-area applications.
ATEX Pilot Marking:
II 2G Ex m II T4
II 3D IP65 T130°C
When the Ex pilot configuration is selected, the manufacturer specifies that permissible operating pressure is reduced by approximately 20%.
Optional Features & Accessories
Available options include:
✓ Normally Closed 380A25
✓ Normally Open 380B25
✓ Stainless Steel Body
✓ Mounting Brackets
✓ Position Indication
✓ Oil & Grease-Free Version
✓ Vacuum Configuration
✓ NAMUR Pilot Solenoid Valve
✓ Alternative R Port Orientation
✓ Exhaust Air Throttles
✓ Exhaust Silencers
✓ ATEX Pilot Option
✓ Modular Valve Systems
Position Indication
Optional inductive position switches can provide electrical confirmation of the valve's open and/or closed position.
Versions with LED indication and a 2-metre cable can be supplied for connection to PLCs, machinery controls, alarms and process monitoring systems.
Typical Applications
✓ High-Pressure Fluid Control
✓ Supply & Exhaust Systems
✓ Pressure & Return Circuits
✓ Fluid Diverting Systems
✓ Hydraulic Systems
✓ High Viscosity Fluids
✓ Lubrication Systems
✓ Process Machinery
✓ Vacuum Systems
✓ Industrial Automation
✓ Process Skids
✓ OEM Equipment
✓ Compatible Gas Systems
Why Choose the RSG 380 Series?
The RSG 380 combines 3/2 way directional control with the high-flow characteristics of an externally operated coaxial process valve.
The DN25 RSG 38025 operates from zero differential pressure up to 64 Bar, provides a Kv 12.2 m³/h flow coefficient and handles compatible viscous fluids up to 1000 cSt.
With NC or NO operation, brass or stainless steel construction, specialist water and gas sealing, NAMUR pilot control and optional position feedback, the RSG 38025 provides a versatile solution for demanding three-port industrial fluid-control applications.
Available Versions
380A25 – Normally Closed
380B25 – Normally Open
Nominal Diameter: DN25
Pressure: 0–64 Bar
Reverse Pressure: Up to 16 Bar
Kv: 12.2 m³/h
Standard Connections:
✓ 3/4" BSP
✓ 1" BSP
✓ 1¼" BSP
Optional:
✓ 1½" BSP
Related Products & Categories
