v4-72 centrifugal fan can be used as indoor ventilator in general factories and large buildings, it deliver air and other gas which is harmless, non-spontaneous and non-corrosion. it is harmless to human body and it has no steel non-corrosive gases. B4-72 type ventilation fan can be used for ventilation of the flammable volatile gas.Viscous material is not allowed in the gas.the dust and hard particles contained can not be more than 150 mg/m3. Gas temperature shall not exceed 80℃. In order to facilitate users to install and use the fan, we adopt the latest design for 2.8 A - 6 A fan which use the overall frame structure, that means blower and motor are connected into whole.