... supermaket, chemical plants, big factory workshops etc.Negative-pressure ventilating fan series are designed scientifically. Low cost, low noise, good ... ventilation effect, strong air flow, energy saving, long lasting and high efficiency. The stainless ... -900B1000*1000*4000.55 shutter, frame, wind set, fan blade are galvanized9FJ-1000B1100*1100*4000.759FJ-1250B1385*1385*4001 ...