high efficiency, low noise, small size, high pressure, easy installation Model 4-72 centrifugal ventilator can convey air and other non-hypergolic gas which are not harmful to to the homan body, and will not corrode steel materials . The ashesive material are not allowed in the gas , its containing dust and hard paticles should not exceed 150mg/m³, gas temperature not exceed 80°it has sound ...