Belimo FSNF24-S Actuator

The Belimo FSNF24-S is a specialized fire and smoke damper actuator designed for fail-safe operation in life safety applications. Engineered to deliver 70 in-lb torque, this spring-return actuator ensures positive close-off of dampers during power loss or high-temperature alarms. Operating on 24 VAC/VDC, the unit features a brushless DC motor for precise control and long-term reliability in demanding HVAC environments. This model includes two built-in SPDT auxiliary switches (fixed at 10° and 85°) for end-stop position feedback, allowing contractors to verify damper status remotely. The steel housing and rugged internal gear train are built to withstand the rigors of UL555 and UL555S testing requirements. It comes equipped with a 1-meter appliance cable for simplified field wiring. Whether performing a retrofit or a new installation, the FSNF24-S provides the high-torque performance and safety compliance necessary for modern building smoke control systems.

Key Benefits

• High Torque Output: Provides 70 in-lb of torque to ensure reliable operation of multi-blade fire and smoke dampers.
• Fail-Safe Engineering: Mechanical spring return provides 100% duty cycle safety, closing the damper automatically upon power interruption.
• Integrated Feedback: Dual SPDT auxiliary switches provide immediate mechanical confirmation of open and closed positions.
• Rapid Response: Designed to meet stringent timing requirements for smoke control sequences.
• Direct Drive Mounting: Features a universal clamp for easy attachment to various damper shaft sizes.

Common Questions

Is the Belimo FSNF24-S compatible with existing fire alarm relays?
Yes, the 24V AC/DC input is compatible with standard fire alarm control panels and smoke control relays. Ensure the transformer is sized for the hold-and-drive power requirements.

Can this actuator be used in high-ambient temperature zones?
The FSNF24-S is rated for high-temperature endurance, meeting UL requirements for operation at 350°F for a limited duration during emergency smoke evacuation.

What is the difference between the FSNF24 and the FSNF24-S?
The "-S" suffix indicates the inclusion of integrated auxiliary switches for position feedback, which are essential for monitoring damper state at the fire alarm control panel.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.