... torsion: CE, ISO9001,RoHS Damper Actuator(Fan Actuator, Actuator, Driver, Fan Damper Actuator)TA/TD Series Damper Actuatos ... are the special design for control fan in HVAC system. The product supplies 2-40 ... Nm torsion, and couldbe installed to the fan flow, ventilation window, VAV and other equipments directly, ... is necessary, it could be operated by manual through buttons.