NMX24-SR-T N4 | Belimo | Damper ActuatorNMX24 SR T N4 Damper Actuator, porportional, 24V non spring return, NEMA 4 with Heat For proportional modulation of dampers in HVAC systems. Actuator sizing should be done in accordance with the damper manufacturers specifications. The actuator is mounted directly to a damper shaft up to 3 4 in diameter by means of its universal clamp. The actuator operates in response to a 2 to 10 VDC, or with the addition of a 500 ? resistor, a 4 to 20 mA control