Application
The type FSLF 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. Square footage of damper operated will depend
on make and model and the temperature required.
 
IMPORTANT 24VDC NOTE: The FSLF24 & -S models will not operate below
24VDC. A filtered and regulated power supply must be used.
 
Operation
 
Mounting of the actuator to the damper axle shaft or jackshaft 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.