Model T35-11, BT35, F35 axial-flow ventilator can replace for 30K4 product. Through the analysis and comparison to T40 and other same kind overseas products, T35 confirms the fan vane and cylindrical paddle-wheel structure through the model experiment and research. It has implemented the rectified design for the motor. It reduces the flow loss in aspect of the structure , therefore the fan efficiency is 89.5% higher than before than before. The noise is 3.6dB lower than A noise level. It also increases the intensity of the blade root and avoids the vane breaking circumstances. This series fan is applicable for conveying the non-flammable, explosive, non-corrosive gas with no obvious powder-dust. The gas temperature does not exceed 60℃. It is widely applicable for the ventilation, air-exchange, warm air radiation reinforcement purposes in the ordinary factory, warehouse, office, residence and so on. It can implement the interval series connection installation in the long exhaust pipelines in order to enhance the pressure inside the pipe-line BT35-11 is an anti-explosion type axial-flow ventilator. It can be used as ventilation and air-exchanged for the flammable, explosive volatilizing gas etc. FT35-11 is and anti-corrosive axial-flow ventilator. It can be used to convey the corrosive gas. Its performances and parameters are the same as T35-11