Structure, Operating Principles, and Performance of Smoke Extraction Fans
Apr 27,2026
In terms of their main body structure, the smoke extraction dampers within smoke extraction fans are fundamentally identical to fire dampers; however, their control boxes differ slightly. Under normal conditions, the smoke extraction damper remains in a "normally closed" state. In the event of a fire, the damper can be activated either manually—by pulling a steel cable—or automatically, via a power signal transmitted from the fire control center. Upon activation, an electromagnet engages, causing its armature hook to disengage; subsequently, driven by the force of an opening spring, the damper rapidly swings open to facilitate smoke extraction.
As the damper opens, a cam mounted on the blade shaft depresses a microswitch, thereby closing a normally open contact. This action generates an output signal confirming that the damper is open, as well as an interlock control signal for integrated system operation. To reset the damper, the external reset handle on the control box is pulled in the reverse direction. Under the influence of spring tension, the internal hook on the blade shaft re-engages with the electromagnet's armature hook, locking the blade shaft in the fully closed position and allowing the microswitch to return to its original state.
The fan is designed to operate continuously and normally under conditions where the temperature of the conveyed medium does not exceed 85°C. Furthermore, the smoke extraction fan must be capable of continuous operation for a minimum of 30 minutes while conveying a medium at a temperature of 280°C; following this exposure, it must remain capable of continuous, normal operation once the medium's temperature has cooled back down to ambient levels. At the rated rotational speed and within the specified operating range, the fan's actual measured pressure curve must closely match the performance curve provided in the product specifications; specifically, at any given flow rate within this range, the deviation of the corresponding pressure value must not exceed ±5%.
The foregoing outlines the structural principles and performance requirements for the smoke extraction dampers utilized in cabinet-type smoke extraction fans. We are confident that, as our technological capabilities continue to advance, the structural design and performance of these systems will become even more refined, and their scope of application will expand even further.
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