The filter screen shall be replaced in time for the use of fresh air fan
The primary filter screen of the fresh air fan can filter more than 10 μ m of air pollution particles; the filter materials of the medium and high efficiency filter screens are significantly denser and tighter than the primary filter screen of the first layer, and can filter PM2.5 and smaller nanometer ultra-fine particles, the pore diameter of which is very small, playing a precise and fine filtering role in the whole air duct.