... 45K,Blade Dia is 710 mm Poultry Exhaust Fan-Huge air volume, Low noise, Good energy saving, Little fault ... matter how high the original temperature is. -keep the air change 80-90 times per hour - Wall or window ... because of negative pressure, and fresh and filtered air will be pumped into through pad to make the ... temperature in less than 28 Degree and make air change 80--90 times per hour,no matter ...