The fan housing impeller uses an advanced forward-tilted multi-blade impeller and a low-noise external rotor motor. The motor is directly coupled to the impeller, resulting in lower fan noise compared to belt-driven fan housings. The fan installation types include horizontal (W) and vertical (L). The BF fan housing features impellers and casings made of high-quality galvanized steel plates, all produced through mold-based manufacturing. It employs riveting and bonding techniques, ensuring a clean and flat surface without welding deformation. The BF fan housing with noise-reduction box body uses a framework and assembled panel structure. The framework is formed by a cold bending machine in one stretch (aluminum alloy profiles can also be used upon customer request). The outer layer of the panels is a coated steel plate, clean and aesthetically pleasing with strong corrosion resistance. The inner layer is a galvanized noise-reduction micro-perforated plate, with an intermediate layer of ultra-fine glass wool to further reduce noise. The product is designed for disassembly and on-site installation.