LF24-3-S US | Belimo | Damper ActuatorLF24 3 S US Damper Actuator, On Off, floating point, 24V, spring return (fail safe), built in auxiliary switch For modulation or On Off, fail safe control of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturers specifications. The actuator is mounted directly to a damper shaft from 3 8 up to 1 2 in diameter by means of its universal clamp, 1 2 shaft centered at delivery. For shafts up to 3 4 use K6 1