Description
DN40 3/2 Way Coaxial Solenoid Valve – RSG 37040
The RSG 37040 is a high-flow DN40 direct acting 3/2 way coaxial solenoid valve designed for reliable directional control of liquids, gases, vacuum and compatible industrial process media from 0 to 16 Bar.
Unlike conventional pilot-operated valves, the RSG 370 Series operates directly from zero pressure without requiring a minimum differential pressure. Its coaxial construction provides positive switching between the P, A and R ports, making it particularly suitable for pressurising, venting, diverting and switching high-flow applications.
The DN40 version provides a substantial Kv flow coefficient of 34.0 m³/h, equivalent to approximately 567 L/min water flow at a 1 Bar pressure differential, with a standard 1½" BSP connection.
Valve Function & Operation
The RSG 37040 is a direct acting 3/2 way coaxial valve available in either normally closed or normally open configurations.
370A40 – Normally Closed
In the de-energised position, pressure supply P is closed while the working port A is connected to return/exhaust R.
When energised, P connects to A and the return connection R is closed.
370B40 – Normally Open
The alternative normally open configuration reverses the switching function.
This 3-port arrangement allows a single coaxial valve to control both pressure supply and exhaust/return functions.
DN40 Ports & Connections
The standard DN40 RSG 37040 is supplied with:
✓ G1½ BSP
Special connections can be supplied according to application requirements.
Pressure & Performance
Operating Pressure: 0 to 16 Bar
Reverse Pressure: Up to 16 Bar
Nominal Diameter: DN40
Kv Flow Coefficient: 34.0 m³/h
Water Flow: Approx. 567 L/min @ 1 Bar ΔP
Weight – Brass Version: 18.7kg
Flow pressure capability:
P → A: Up to 16 Bar
A → P: Up to 16 Bar
P → R: Up to 16 Bar
R → P: Up to 16 Bar
The direct acting construction allows reliable operation from 0 Bar, making the valve suitable for applications where a minimum pressure differential cannot be guaranteed.
Flow Capacity
The DN40 RSG 37040 has a Kv flow coefficient of 34.0 m³/h, equivalent to approximately 567 L/min water flow at a 1 Bar pressure differential.
The RSG 370 range provides:
DN10 – Kv 2.5 m³/h
DN15 – Kv 4.5 m³/h
DN20 – Kv 6.8 m³/h
DN25 – Kv 11.5 m³/h
DN32 – Kv 17.9 m³/h
DN40 – Kv 34.0 m³/h
DN50 – Kv 42.0 m³/h
The DN40 provides almost twice the Kv capacity of the DN32 version and is designed for higher-flow applications operating up to 16 Bar.
3/2 Way Coaxial Valve Design
The RSG 370 Series uses a direct acting coaxial construction with three fluid connections:
✓ P – Pressure / Supply
✓ A – Working / Outlet
✓ R – Return / Exhaust
The actuator operates directly along the fluid flow axis, allowing the valve to switch without relying upon pilot pressure.
This construction provides fast, positive switching and is particularly useful for:
✓ Pressure & Exhaust Control
✓ High-Flow Applications
✓ Industrial Gases
✓ Viscous Fluids
✓ Oils & Lubricants
✓ Vacuum Systems
✓ Test & Process Equipment
High Viscosity Fluids
The RSG 37040 is suitable for compatible fluids with viscosities up to 1000 cSt.
Typical applications can include:
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Viscous Process Fluids
✓ Industrial Liquids
✓ Compatible Thick Fluids
Media compatibility should always be confirmed against the selected body, seat and dynamic sealing materials.
Construction & Materials
Threaded body materials are available in:
✓ Brass
✓ AISI 303 Stainless Steel
✓ AISI 316 Stainless Steel
The choice of body material allows the valve to be configured for a wide range of industrial fluid, gas and process applications.
Standard Seal Construction
Static Seal: FKM
Dynamic Seal: PTFE
Valve Seat: FKM
Optional seal configurations include:
✓ NBR
✓ EPDM
✓ PTFE Seat Option
The appropriate sealing materials can be selected according to media, temperature and application requirements.
Media Compatibility
Typical applications include:
✓ Water
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Compressed Air
✓ Industrial Gases
✓ Process Liquids
✓ Cooling Fluids
✓ Compatible Chemicals
✓ Viscous Fluids Up To 500 cSt
For aggressive chemicals or unusual process fluids, compatibility should be confirmed against all wetted materials before ordering.
Special Service Options
The RSG 370 Series can be configured for specialist media and process requirements in addition to standard industrial fluid applications.
Available configurations include:
✓ Water Service Seal Options
✓ Gas Service Seal Options
✓ Oxygen Service Options
✓ Vacuum Service Option
✓ High Leak-Tightness Version
✓ Oil & Grease-Free Construction
Different body materials, seat seals and valve configurations can be selected according to the application and required media compatibility.
For oxygen, vacuum, gas or applications requiring particularly low leakage rates, the required service should be specified when ordering to ensure the correct valve configuration is supplied.
Water Service Seal Option
For demanding water applications, UHMW Polyethylene seals are available with a maximum service temperature of +80°C.
UHMW Polyethylene provides excellent wear resistance and low friction. The dynamic sealing arrangement helps strip limescale and debris from the sealing surface during operation.
This can improve service life in water applications where deposits or contamination could affect conventional sealing arrangements.
Gas Service Seal Option
For demanding gaseous applications, Fluoroloy® A21 seals are available with a maximum service temperature of +80°C.
Fluoroloy A21 provides low friction, excellent wear characteristics and broad chemical compatibility, making it suitable for appropriately specified industrial gas applications.
Increased Leak-Tightness Version
An increased leak-tightness configuration to 10⁻⁵ mbar·L/sec is available for demanding gas and vacuum applications.
This specialist configuration includes:
✓ Oil & Grease-Free Cleaning
✓ Special Valve Seat Treatment
✓ Special Seal Components
✓ Helium Leak-Tightness Testing
Vacuum Service
A dedicated vacuum configuration is available for the RSG 370 Series.
Combined with its direct acting zero-differential design, this makes the RSG 37040 suitable for high-flow vacuum equipment requiring controlled switching between pressure, working and return connections.
Oxygen & Clean Service
Oil and grease-free construction is available for specialist clean-service applications, including appropriately specified oxygen-service configurations.
Valves for oxygen service can be supplied degreased and prepared for the application. The required oxygen service, pressure, materials and cleaning specification should be confirmed when ordering.
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
Coil & Electrical Specification
Electrical Duty: 100% ED
Protection: IP65 with connector fitted
Connection: DIN 43650A
Mounting Position: Any Position
DN40 manufacturer power specification:
24VDC – 73 Watts
230VAC 50Hz – 90 Watts
Voltage Options
Available voltage configurations include:
✓ 12VDC
✓ 24VDC
✓ 24VAC
✓ 110VAC
✓ 230VAC
✓ Other Voltages On Request
AC versions use an appropriate rectified electrical configuration.
Optional Features & Accessories
The RSG 370 Series can be configured with:
✓ Manual Override
✓ Open Position Feedback
✓ Closed Position Feedback
✓ Volt-Free Feedback Switches
✓ LED DIN Connector
✓ Aluminium Terminal Box
✓ Mounting Brackets
✓ Vacuum Configuration
✓ Oil & Grease-Free Construction
✓ Special Connections
Position Indication
Optional volt-free position feedback switches can provide electrical confirmation of the valve's open and/or closed position.
This allows valve status to be incorporated into PLC systems, industrial automation, safety monitoring and process-control equipment.
Typical Applications
✓ Pressure & Exhaust Control
✓ High-Flow Liquid Systems
✓ Compressed Air Systems
✓ Industrial Gas Systems
✓ Vacuum Systems
✓ Hydraulic Systems
✓ Lubrication Systems
✓ Viscous Process Fluids
✓ Process Engineering
✓ Chemical Processing Equipment
✓ Water Treatment Equipment
✓ Pressure Testing Equipment
✓ Test Rigs & Process Skids
✓ Industrial Automation
✓ OEM Machinery
✓ Manifold Systems
✓ Oxygen-Compatible Systems
Why Choose a 3/2 Way Coaxial Valve?
A 3/2 way valve combines pressure supply, working and return/exhaust functions within a single valve.
The RSG 37040 combines this functionality with direct acting coaxial technology, allowing reliable switching from 0 Bar without relying upon pilot pressure or minimum differential pressure.
With a substantial Kv 34.0 m³/h flow capacity, approximately 567 L/min water flow at 1 Bar ΔP, and operation up to 16 Bar, the DN40 is particularly suitable for larger industrial fluid, gas, hydraulic and process-control systems.
Available Versions
370A40 – Normally Closed
370B40 – Normally Open
Standard DN40 connection:
✓ 1½" BSP
Standard and optional voltages:
✓ 12VDC
✓ 24VDC
✓ 24VAC
✓ 110VAC
✓ 230VAC
RSG 3/2 Way Coaxial Valve Ranges
RSG 370 Series – DN10-DN32 up to 40 Bar
RSG 370 Series – DN40-DN50 up to 16 Bar
RSG 371 Series – DN10-DN32 up to 64 Bar
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