The type FSNF spring-return actuator is intended for the operation of smoke
and combination fire and smoke dampers in ventilation and air-conditioning
systems. The actuator will meet requirements of UL555 and UL555S when
tested as an assembly with the damper and will meet requirements of UBC for
15 second opening and closing at 350°F. Square footage of damper operated
will depend on make and model and the temperature required.
Mounting of the actuator to the damper axle shaft or jackshaft (3/8” to 1.05”) is
via a cold-weld clamp. Teeth in the clamp and V-bolt dig into the metal of both
solid and hollow shafts maintaining a perfect connection. The specially designed
clamp will not crush hollow shafts. The bottom end of the actuator is held by an
anti-rotation strap or by a stud provided by the damper manufacturer.
The actuator is mounted in its fail safe position with the damper blade(s) closed.
Upon applying power, the actuator drives the damper to the open position. The
internal spring is tensioned at the same time. If the power supply is interrupted,
the spring moves the damper back to its fail-safe position.