Belimo spring return, and electronic fail-safe actuators, are designed to fail open or closed when power is interrupted. Power loss unwinds the spring in the spring return series, and discharges stored energy from the super capacitors to drive the actuator to the fail-safe position (adjustable) in the electronic fail-safe series. Belimo non-spring return actuators remain in their last commanded position when power is interrupted.
Belimo offers fail-safe actuators for use in a wide variety of HVAC control damper, fire and smoke damper, and valve applications. Control damper applications include: air handlers, economizer units, VAV terminal units, fan coil units, fan shutters and unit ventilators.
For more information on spring return and electronic fail-safe damper actuators click here
For more information on fire and smoke damper actuators click here