... to mining factory, hotel, hospital and others big building. 4-72 Centrifugal Fan can be served as ventilation and air exchange ... -hypergolic, non-harm for man, non-corrosive for steel. B4-72 Fan can be used ventilate and exchange the combustible & evaporable ... than 150mg/m3, gas temperature must not exceed 80oC. 4-72 Centrifugal Ventilation Fan