CAD multi-objective optimized design with built-in high-temperature motor and dedicated cooling system; continuous operation at 280℃ for >30 minutes, or at 1oo℃ for 20 hours per session without damage- compliant with GA211-20o9.Fire smoke extraction and ventilation for high-rise buildings, drying rooms, underground garages, subways, and tunnels.Type I (single-speed) / Type ll (dual-speed, dual-purpose for normal ventilation & fire exhaust) / Type D (low-speed); electric control cabinet available for remote automatic control; horizontal, vertical, or ceiling-mounted.Single-speed /Dual-speed /VFD stepless speed control (with VFD motor and controller); silencers of varying lengths or box-type silenced fan (HTF-X) available.Explosion-proof version available (rating:Exd I1 BT4).