Description
DN50 2/2 Way Coaxial Air Pilot Valve – RSG 28050
The RSG 28050 is a DN50 2/2 way externally controlled coaxial air pilot valve designed for high-flow shut-off and control of liquids, gases, vacuum and compatible industrial process media at pressures from 0 to 64 Bar.
Independent pneumatic actuation allows reliable operation from zero differential pressure, without relying upon the process medium to generate the switching force. The valve uses a double-acting piston with return spring, controlled by a 3–8 Bar pilot air supply through G1/4 pilot connections with a NAMUR interface.
The DN50 version combines a 50mm nominal diameter, 2" BSP connection and substantial Kv 47.2 m³/h flow capacity, making it suitable for larger high-pressure industrial process systems.
Valve Function & Operation
The RSG 28050 is an externally controlled 2/2 way coaxial valve available in normally closed or normally open configurations.
280A50 – Normally Closed
The valve remains closed in its normal unactuated position and opens when the pneumatic pilot actuator is operated.
280B50 – Normally Open
The normally open version provides the opposite fail-state, remaining open until the pneumatic actuator is operated.
Because the switching force is supplied independently by the pneumatic pilot system, the valve does not require process pressure or a minimum differential pressure to operate.
DN50 Ports & Connections
The standard DN50 RSG 28050 connection is:
✓ G2 BSP
Alternative connection options include:
✓ NPT Threads
✓ Flanged Connections
✓ Special Connections
Flanged configurations are available where threaded connections are unsuitable or the installation requires a flanged process connection.
Pressure & Performance
Operating Pressure: 0 to 64 Bar
Reverse Pressure: Up to 16 Bar
Pilot Pressure: 3 to 8 Bar
Nominal Diameter: DN50
Orifice: 50mm
Kv Flow Coefficient: 47.2 m³/h
Weight – Brass Version: 11.7kg
Flow direction:
P → A: Up to 64 Bar
A → P: Up to 16 Bar
The combination of high flow capacity, zero-differential operation and 64 Bar working pressure makes the RSG 28050 particularly suitable for demanding large-bore process applications.
Flow Capacity
The DN50 RSG 28050 provides a substantial Kv flow coefficient of 47.2 m³/h.
This is the highest-flow threaded model within the RSG 280 Series and provides a large process flow path while retaining the full 0–64 Bar operating-pressure capability.
The DN50 configuration is particularly useful where conventional pilot-assisted valves may introduce unwanted pressure restrictions or cannot operate reliably at zero differential pressure.
Externally Controlled Coaxial Design
The RSG 280 Series combines a coaxial process-valve construction with an externally controlled pneumatic actuator.
The actuator consists of a double-acting piston with return spring, operated by a 3–8 Bar pneumatic pilot supply.
Pilot connections are G1/4 and the NAMUR interface allows a suitable 5/2 way pilot solenoid valve to be mounted directly to the actuator.
This arrangement is particularly useful for:
✓ High-Pressure Applications
✓ High-Flow Process Systems
✓ Frequent Switching
✓ Industrial Process Control
✓ High Viscosity Fluids
✓ Oils & Lubricants
✓ Industrial Gases
✓ Vacuum Systems
Switching Performance
Opening and closing times are approximately 50–1000 milliseconds, depending upon operating pressure, pilot pressure, pilot valve selection and optional exhaust-air throttles.
Optional exhaust throttles allow the pneumatic switching characteristics to be adjusted where controlled opening or closing is required.
High Viscosity Fluids
The RSG 28050 is suitable for compatible thick and glutinous fluids with viscosities up to 1000 cSt.
Typical applications can include:
✓ Thick Oils
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Viscous Process Fluids
✓ Glutinous Industrial Liquids
Media compatibility should always be confirmed against the selected body and sealing materials.
Construction & Materials
Body materials are available in:
✓ Brass
✓ AISI 303 Stainless Steel
✓ AISI 316 Stainless Steel
Internal Components: Stainless Steel
Stainless steel versions provide an alternative for applications requiring greater corrosion resistance or compatibility with more demanding process media.
Standard Seal Construction
Standard sealing materials include:
✓ FKM Static Seals
✓ FKM & PTFE Dynamic Seals
✓ PTFE Seat Seal
Optional seal configurations include:
✓ NBR
✓ EPDM
The appropriate sealing configuration can be selected according to the process medium, operating temperature and application requirements.
Media Compatibility
Typical applications include:
✓ Water
✓ Hydraulic Oils
✓ Lubricating Oils
✓ Thick Process Fluids
✓ Compressed Air
✓ Industrial Gases
✓ Process Liquids
✓ Cooling Fluids
✓ Compatible Chemicals
✓ Viscous Fluids Up To 500 cSt
For aggressive chemicals, specialist gases or unusual process fluids, compatibility should be confirmed against all wetted materials before ordering.
Special Service Options
The RSG 280 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
✓ Vacuum Service Option
✓ Oil & Grease-Free Construction
✓ Special Connections
Different body materials and sealing arrangements can be selected according to the application and required media compatibility.
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 and abrasion resistance together with very good lubricity in water-based media.
The sharp-edged dynamic seal creates a stripping action against the moving valve component, helping remove limescale and debris during operation.
This makes the configuration particularly useful 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 excellent wear resistance, low friction and broad chemical compatibility, together with high sealing performance for appropriately specified gaseous media.
Vacuum Service
A dedicated vacuum configuration is available for the RSG 280 Series.
Because actuation is provided independently by the pneumatic pilot circuit, operation does not depend upon pressure within the process line. This makes the DN50 RSG 28050 particularly useful for large-bore vacuum and zero-pressure applications.
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
The appropriate sealing arrangement should be selected according to the process medium and required operating temperature.
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 pneumatic actuator service life.
NAMUR Pilot Valve Option
Optional 5/2 way NAMUR pilot solenoid valves can be mounted directly to the actuator, providing electrical control of the pneumatic pilot system.
Available pilot solenoid voltages include:
✓ 24VDC
✓ 230VAC 50Hz
Pilot valves can be supplied with lateral or top-facing connections according to installation requirements.
Optional Features & Accessories
The RSG 280 Series can be configured with:
✓ Mounting Brackets
✓ Exhaust Air Throttles
✓ Sintered Bronze Silencers
✓ NAMUR Pilot Solenoid Valves
✓ Open Position Indication
✓ Closed Position Indication
✓ M12 Position Sensors
✓ ATEX Position Sensors
✓ Vacuum Configuration
✓ Oil & Grease-Free Construction
✓ Modular Manifold Systems
✓ Special Connections
✓ Flanged Connections
Position Indication
Optional inductive or magnetic position sensors can provide electrical confirmation of the valve's open and/or closed position.
These can provide valve-position feedback to PLCs, machinery controls and automated process systems.
Standard M12 and intrinsically safe ATEX sensor configurations are available according to the installation requirements.
ATEX Options
The RSG 280 Series can be configured with explosion-protected electrical accessories for hazardous-area applications.
Available options include an explosion-protected pilot solenoid and intrinsically safe position sensing.
Where the Ex pilot-solenoid configuration is selected, permissible valve operating pressure is reduced by approximately 20%, so the required pressure should be confirmed when specifying an ATEX version.
Typical Applications
✓ High-Flow Process Systems
✓ High-Pressure Fluid Control
✓ Hydraulic Systems
✓ Industrial Gas Systems
✓ Compressed Air Systems
✓ Vacuum Systems
✓ Lubrication Systems
✓ Thick & Glutinous Fluids
✓ Viscous Process Fluids
✓ Chemical Processing Equipment
✓ Pressure Testing Equipment
✓ Test Rigs & Process Skids
✓ Industrial Automation
✓ OEM Machinery
✓ Modular Manifold Systems
Why Choose an Air Pilot Coaxial Valve?
An air pilot coaxial valve combines the robust flow path of a coaxial valve with an independent pneumatic actuator.
Because switching force comes from the 3–8 Bar external pilot supply, operation is independent of process pressure. This provides reliable switching from zero differential pressure and makes the design particularly useful for vacuum, viscous fluids and demanding high-pressure applications.
As the largest threaded model in the RSG 280 range, the RSG 28050 combines a DN50 flow path, 2" BSP connection, 0–64 Bar pressure capability and Kv 47.2 m³/h flow capacity.
Available Versions
280A50 – Normally Closed
280B50 – Normally Open
Standard DN50 connection:
✓ 2" BSP
Optional:
✓ NPT
✓ Flanged Connections
RSG Air Pilot Coaxial Valve Ranges
RSG 280 Series – DN10-DN50 up to 64 Bar
RSG 281 Series – Up to 120 Bar
RSG 282 Series – Up to 160 Bar
For applications requiring greater pressure capability, the RSG 281 Series extends the externally controlled coaxial design to higher process pressures, with DN40 and DN50 versions available on request up to 100 Bar.
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