Qingzhou Yongsheng Machinery Co.,Ltd is one of the professional China non power roof fan manufacturers and suppliers,Website:://.qzys-exhaustfan.com, welcome to wholesale low price non power roof fan from our factory.Working Theory: convection between ;natural wind ;and air to accelerate and transform any parallel airflow into vertical so as to improve the indoor ventilation. The hot air rises and ;Cold Air ;falls, which makes the fan rotate. So the ;indoor heat, stink and dust are exhausted effectively. It also can effectively remove indoor soot, smoke, odor, moisture, heat, decorative harmful gas, dust, human metabolism and other dirty volatile mixed-doped odor as well as viruses and bacteria invasion.  Working Result: it improves the working environment, protects workers' health and enhances the working efficiency.Application Areas: warehouse, toilet, factory, workshop, stadium, tennis hall, assembly hall, garage, ;paper Mill, galvanization factory and coating factory. ◆Need no energy: Nature wind drives,operating in 24hs the whole day   ◆High efficient air