Description
DN20 2/2 Way Coaxial Air Pilot Valve – RSG 28020
The RSG 28020 is a DN20 2/2 way externally controlled coaxial air pilot valve designed for reliable shut-off and control of liquids, gases, vacuum and compatible industrial process media from 0 to 64 Bar.
Unlike pressure-assisted process valves, the RSG 28020 uses an independent pneumatic pilot supply to actuate the valve, allowing reliable operation from zero differential pressure. The actuator uses a double-acting piston with return spring and requires a 3–8 Bar pilot air supply through G1/4 control connections with a NAMUR interface.
The DN20 version provides a Kv flow coefficient of 9.4 m³/h. Standard connections are 1/2", 3/4" and 1" BSP, with an optional 1¼" BSP connection available.
Valve Function & Operation
The RSG 28020 is an externally controlled 2/2 way coaxial valve available in either normally closed or normally open configurations.
280A20 – Normally Closed
The valve remains closed in its normal unactuated position and opens when the pneumatic pilot actuator is operated.
280B20 – Normally Open
The alternative normally open configuration provides the opposite fail-state for applications requiring the process line to remain open until pneumatically actuated.
The independent pneumatic actuator allows switching without relying upon process pressure or a minimum differential pressure.
DN20 Ports & Connections
The standard DN20 RSG 28020 is available with:
✓ G1/2 BSP
✓ G3/4 BSP
✓ G1 BSP
Optional connections include:
✓ G1¼ BSP
✓ NPT Threads
✓ Flanged Connections
✓ Special Connections
Pressure & Performance
Operating Pressure: 0 to 64 Bar
Reverse Pressure: Up to 16 Bar
Pilot Pressure: 3 to 8 Bar
Nominal Diameter: DN20
Orifice: 20mm
Kv Flow Coefficient: 9.4 m³/h
Weight – Brass Version: 4.0kg
Flow direction:
P → A: Up to 64 Bar
A → P: Up to 16 Bar
The manufacturer specifies the complete RSG 280 Series at 0–64 Bar, with reverse-pressure leak-tightness up to 16 Bar.
Flow Capacity
The DN20 RSG 28020 provides a Kv flow coefficient of 9.4 m³/h, giving substantially greater flow capacity than the smaller DN10 and DN15 models while retaining the full 0–64 Bar pressure range.
The combination of a 20mm nominal flow path, independent pneumatic actuation and zero-differential operation makes the RSG 28020 particularly suitable for demanding high-flow industrial process applications.
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 actuator incorporates a NAMUR interface, allowing a suitable 5/2 way pilot solenoid valve to be mounted directly to the actuator.
This arrangement is particularly useful for:
✓ High-Pressure Applications
✓ Frequent Switching
✓ Industrial Process Control
✓ High Viscosity Fluids
✓ Oils & Lubricants
✓ Industrial Gases
✓ Vacuum Systems
✓ Automated Process Equipment
Switching Performance
Opening and closing times are approximately 50–1000 milliseconds, depending upon pilot pressure, pilot valve selection and optional exhaust-air throttles.
Optional exhaust throttles can therefore be used where the application requires greater control over valve opening or closing characteristics.
High Viscosity Fluids
The RSG 28020 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
For applicable flanged configurations, galvanised steel, nickel-plated steel and stainless steel body options are also available.
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, 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 1000 cSt
For aggressive chemicals 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
Ceramic Slip / Ceramic Paste Option
A specially customised RSG 280 Series valve is available for ceramic slip, ceramic paste and other suitable abrasive ceramic process media.
Standard valve sealing should not be assumed suitable for ceramic slip applications. RSG specifically recommends a customised valve configuration incorporating a special sealing and lubrication system for this demanding service.
The ceramic slip version can include:
✓ Special PU / Polyethylene Seals
✓ Special Seat Sealing
✓ Additional Scraper Ring
✓ Grease Packing System
✓ Lubrication Nipple
✓ Supplied Grease Filled
✓ Grease Overload Leak Hole
✓ AISI 304 Stainless Steel Body
The additional scraper ring helps remove ceramic material from the moving valve components during operation, reducing the amount of abrasive material reaching the primary sealing area.
The grease-packed sealing arrangement provides additional lubrication and protection, with an external lubrication fitting allowing grease to be replenished during service.
A dedicated leak hole is provided to relieve or indicate excess grease during filling.
The AISI 304 stainless steel body provides a robust process connection for ceramic manufacturing and handling equipment.
Important – Specify Ceramic Slip When Ordering
Ceramic slip or ceramic paste applications must be declared when ordering.
These applications require the specially configured valve and should not be supplied as a standard RSG 280 Series valve.
RSG confirmed this directly when reviewing an application for a ceramic manufacturer, advising that ceramic slip requires a customised sealing package, scraper ring and grease-filling arrangement.
Typical Ceramic Applications
✓ Ceramic Slip Control
✓ Ceramic Paste Control
✓ Ceramic Manufacturing
✓ Pressure Casting Machines
✓ Sanitaryware Production
✓ Ceramic Process Equipment
✓ Automated Ceramic Machinery
Different body materials and sealing arrangements can be selected according to the application and required media compatibility.
The manufacturer's type coding specifically includes vacuum, oil and grease-free, mounting bracket and special-connection configurations.
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 special sharp-edged shape of the dynamic seal creates a stripping action against the piston/plunger, 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 valve actuation is provided independently by the pneumatic pilot circuit, operation does not depend upon pressure within the process line. This makes the RSG 28020 particularly useful for 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
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/service unit is recommended to help extend the operating life of the pneumatic actuator.
NAMUR Pilot Valve Option
Optional 5/2 way NAMUR pilot solenoid valves can be mounted directly to the actuator to provide electrical control of the pneumatic pilot system.
Available pilot solenoid voltages include:
✓ 24VDC
✓ 230VAC 50Hz
Pilot valves are available with either lateral or top-facing connections.
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
The manufacturer's accessory range includes mounting brackets, exhaust throttles, silencers and directly mounted 5/2 way NAMUR pilot valves.
Position Indication
Optional inductive or magnetic position sensors can provide electrical confirmation of the valve's open and/or closed position.
These can be used to provide valve-position feedback to PLCs, machinery controls and process automation systems.
Standard M12 and intrinsically safe ATEX sensor configurations are available within the RSG accessory range.
ATEX Options
The RSG 280 Series can be configured with explosion-protected electrical accessories for hazardous-area applications.
Available manufacturer options include an explosion-protected pilot solenoid and an intrinsically safe magnetic field position sensor.
The manufacturer notes that operating pressure is reduced by approximately 20% with the Ex pilot-solenoid specification, so the required operating pressure should be confirmed when specifying an ATEX configuration.
Typical Applications
✓ 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
✓ Automated Process Systems
✓ Modular Manifold Systems
Why Choose an Air Pilot Coaxial Valve?
An air pilot coaxial valve combines the robust process 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 at zero differential pressure and makes the design particularly useful for vacuum, high-viscosity and demanding high-pressure applications.
The RSG 28020 combines this operating principle with 0–64 Bar pressure capability, a 20mm nominal flow path and a substantial Kv 9.4 m³/h flow coefficient.
Available Versions
280A20 – Normally Closed
280B20 – Normally Open
Standard DN20 connections:
✓ 1/2" BSP
✓ 3/4" BSP
✓ 1" BSP
Optional:
✓ 1¼" BSP
✓ 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
The higher-pressure RSG 281 and 282 ranges extend the same externally controlled coaxial design to process pressures of up to 120 and 160 Bar respectively.
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