Mixed-flow design with conical twisted blades, built-in high-temperature resistant motor, dedicated cooling system, and internal guide vanes;higher airflow than centrifugal fans and higher static pressure than HTF-l axial fans of the same size; dual function for standard ventilation and high-temperature fire smoke extraction. General ventilation and emergency fire smoke exhaust for high-rise buildings, underground garages,tunnels, underground shopping malls, and industrial enterprises.Compliant with GA211-2009; continuous operation at 280℃ for ≥60 minutes,or at 10o℃c for 20 hours per session without damage.