* Model-4-8 centrifugal fan is applicable for the Indoor ventilation and air-exchange In the ordinary factories and large-size architectures, It can be used for both the input gas and output gas. It should be air which dose not exceed 810℃and other non一hypergoic gas which is not harmful to human body and not corrosive to the steel and iron materiats. It allows no adhesve substances also.Its containing dust and hard particle hard particle should not be larger than 150mg/m³.