... equipment 1)Large air flow 2)Low price,low noise 3)High technical,energy saving 4)Copper motor automatic poultry ... big factory workshops etc.Negative-pressure ventilating fan series are designed scientifically. Low cost, low noise, good ventilation effect, strong air flow ... style9FJ-900B1000*1000*4000.55 shutter, frame, wind set, fan blade are galvanized9FJ-1000B1100*1100*4000.759FJ-1250B1385*1385*4001 ...