Negative-pressure ventilation fan 1,industrial ccoling fan 2,CCC motor 3,CE Certification 4, low ... lower noise and strong pressure features. The TSBD Ventilation Fan is characterized by its unique shutte blades and closing ... sheetStainless steel8560galvanized sheetStainless steel5555galvanized sheetStainless steel50 Negative-pressure air fan is suitable for ventilation and temperature reduction of high ...