Induction fan is a ductless jet induced ventilation system part, it and the air blower, exhaust fan, exhaust fan composed the whole system. No pipe jet induced ventilation system is used, can save design, manufacture, installation of the wind pipe and other ancillary works costs, this part of the cost of induced fan unit much more expensive than and the whole level is a ventilating duct, send fan, exhaust fan to pressure ratio, using the pipeline is much smaller, so that you can choose large wind volume and low pressure of fan, so that the required power is reduced, greatly reducing the investment cost and operation cost. When the air supply and exhaust fan stops running, the induction fan can still operate, and plays the role of local ventilation and ventilation. Has been widely used in the parking lot, stadium, workshops, warehouses, shopping malls, supermarkets, entertainment and other large areas of ventilation.