Belimo AFB24-SR-X1 Valve Actuator, 24V,Modulating., Valve Actuator, AC/DC 24 V, 2...10 V, modulating. The AF series actuators provide true spring return operation for reliable fail-safe application and positive close off on air tight dampers. The spring return system provides consistent torque to the damper with, and without, power applied to the actuator
