Description
DN40–DN100 WRAS Motorised Butterfly Valve with Failsafe
The CNX/S-Butterfly-FS is a heavy-duty WRAS approved motor actuated butterfly valve with Power Open/Close control and automatic failsafe return on power loss, designed for water systems requiring reliable electrical isolation and a defined safe valve position.
Available from DN40 to DN100 in the standard listed combinations, the range uses WRAS approved EPDM-lined wafer butterfly valves with CNX20, CNX20S, CNX50S or CNX80S electric actuators selected according to valve size and required torque.
The valve is rated from 0 to 16 Bar and is suitable for wafer mounting between BS10 Table D/E, PN6, PN10, PN16 and ANSI Class 150 flanges. WRAS approval 2211362 covers the EPDM-lined butterfly valve for water applications.
Power Open / Close + Automatic Failsafe
During normal operation, the actuator provides electrical Power Open / Power Close control.
If the electrical supply is completely lost, energy stored within the actuator's failsafe system automatically drives the valve to its predetermined safe position.
This provides automatic valve positioning during:
✓ Mains Power Failure
✓ Control Power Failure
✓ Emergency Shutdown
✓ BMS / Plant Failure
✓ Pump or Process Shutdown
The failsafe system uses stored electrical energy rather than a conventional mechanical spring.
After a failsafe operation, approximately 1–2 minutes of electrical supply is required to recharge the failsafe capacitor before another failsafe cycle is available.
Valve Sizes & CNX Actuators
DN40 / 1½"
Standard: CNX20 20Nm
Smart Option: CNX20S 20Nm with display
ISO5211: F05
DN50 / 2"
Standard: CNX20 20Nm
Smart Option: CNX20S 20Nm with display
ISO5211: F05
DN65 / 2½"
Actuator: CNX50S Smart 50Nm with display
ISO5211: F07
DN80 / 3"
Actuator: CNX50S Smart 50Nm with display
ISO5211: F07
DN100 / 4"
Actuator: CNX80S Smart 80Nm with display
ISO5211: F07
These are the actuator/valve combinations specified for the new range. The butterfly valve itself is also available in larger sizes up to DN150 where required.
CNX20 Standard Actuator – No Screen
The CNX20 used on DN40 and DN50 is the compact non-smart actuator and does not have an LCD/display screen.
It provides:
Running Torque: 20Nm
Breakaway Torque: 25Nm
Operation: Power Open / Power Close + Failsafe
Operating Angle: 90° ±2°
Operating Time: 10 seconds on 24VAC/DC and 95–265VAC/DC
12VDC Operating Time: 15 seconds
Protection: IP67
Manual Override: Included
Visual Position Indicator: Included
Position Feedback: Two adjustable volt-free switches
Anti-Condensation Heater: 0.6W
Service Life: 20,000 operations
Ambient Temperature: -20°C to +60°C
So although the basic CNX20 has no screen, it still retains the useful manual override, visual mechanical position indication and open/closed feedback functions.
CNX20S / CNX50S / CNX80S Smart Actuators
The smart versions incorporate the actuator display/screen and are used as follows:
CNX20S: 20Nm – DN40 & DN50
CNX50S: 50Nm – DN65 & DN80
CNX80S: 80Nm – DN100
Power ratings for the new assembly are:
CNX20 / CNX20S: 15W
CNX50S: 40W
CNX80S: 60W
Protection: IP67
Electrical Connection: 0.8m cable
12 seconds open/close operation and open/closed volt-free feedback switches rated up to 30VDC, 0.5A.
Voltage Options
CNX20 Standard
✓ 12V DC
✓ 24V AC/DC
✓ 95–265V AC/DC
The standalone CNX20 specification gives operating ranges of 10–15VDC, 18–26VAC / 22–28VDC, and 95–265VAC / 100–300VDC respectively.
Smart CNX Actuators
✓ 24V AC/DC
✓ 95–265V AC/DC
12VDC is not available with the smart actuator versions.
WRAS Approved Butterfly Valve
WRAS Certificate: 2211362
Media: Water
Pressure: 0–16 Bar
Working Temperature: -20°C to +120°C
Maximum Media Viscosity: 500 cSt
Mounting Position: Any
Valve Style: Wafer Butterfly Valve
The WRAS-approved EPDM liner makes the valve particularly suitable for potable and water-service applications requiring an electrically actuated butterfly valve.
Flange Compatibility
The wafer-pattern body is designed for installation between:
✓ BS10 Table D
✓ BS10 Table E
✓ PN6
✓ PN10
✓ PN16
✓ ANSI Class 150
This multi-standard wafer arrangement makes the valve particularly useful for replacement and OEM applications where different flange standards may be encountered.
Valve Construction
Body: Epoxy-Coated Ductile Iron
Disc: ASTM A351 CF8M Stainless Steel
Seat / Liner: WRAS Approved EPDM
Pin: SS316 Stainless Steel
Stem: SS416 Stainless Steel
Bushings: Fibre-Reinforced Plastic
O-Ring: NBR
The combination of epoxy-coated ductile iron, CF8M stainless disc and WRAS EPDM liner provides a robust valve assembly for industrial and potable-water applications.
Manual Override & Position Indication
All assemblies provide manual override and visual valve-position indication.
The CNX actuator also provides electrical open and closed position feedback using volt-free switches, allowing valve status to be monitored by compatible PLC, BMS and control systems.
Typical Applications
✓ Potable Water Systems
✓ WRAS Water Installations
✓ Building Services
✓ Water Treatment
✓ Pump Isolation
✓ Tank Isolation
✓ HVAC Water Systems
✓ BMS Controlled Systems
✓ Industrial Water Systems
✓ Process Water
✓ Automatic Shut-Off Systems
✓ Power-Loss Failsafe Systems
Why Choose the CNX WRAS Failsafe Butterfly Valve?
This assembly combines a WRAS approved high-flow butterfly valve with an electrically powered CNX actuator and automatic failsafe positioning, providing a complete ready-to-install water-control solution.
Unlike a standard Power Open/Close actuator that simply remains in its last position following power loss, the failsafe version stores sufficient electrical energy to automatically return the valve to its predetermined safe position if the electrical supply fails.
The range also allows the actuator technology to be matched sensibly to valve size: compact CNX20 non-screen actuators for DN40 and DN50, with optional CNX20S smart versions, progressing to higher-torque CNX50S and CNX80S smart actuators for the larger butterfly valves.
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