The structure and technical parameters of the square negative pressure fan for galvanized steel plate are basically the same. The main models have 1380*1380*400mm1.1-kilowatt, 1220*1220*400mm0.75-kilowatt, 1060*1060*400mm0.55-kilowatt, 900*900*400mm0.37-kilowatt four models. All the zinc square negative pressure fan's rotational speed is 450 rpm, motor is 4 pole 1400 rpm, motor protection grade IP44, Grade B insulation. Individual smaller size of the negative pressure fan due to the small amount of wind, noise, exhaust efficiency and low loss as a negative pressure blower, here do not describe. Relatively large negative pressure fan ventilation efficiency is higher, more energy-saving. FRP horn-shaped negative pressure fan is divided into two types: belt type and straight knot from different transmission structure. Belt type rotational speed in 370-450 rpm, adopt six pole or four pole aluminum shell motor Protection grade IP55 F class insulation, low speed product noise is relatively low. The direct motor mainly has 12 pole 440 rpm, 10 extremely 560 rpm/min, 8 Pole 720 turn/minute three kinds, 12 pole motor uses most, the high speed fan noise is big. Belt-type products in the most energy-saving, economic durability, straight-knot products suitable for belt-type can not work if there is oil, the belt corrosion of the site use. FRP horn-type negative pressure fan blades are mainly 6 leaves, 7 leaves, 3 leaves, 5 leaves, the main materials are die-casting aluminum alloy, engineering plastics (nylon plus fiber), glass fiber reinforced plastic three. The wind vane with different blade number, wind-leaf angle and radian needs to match the speed and power reasonably, and the single data can not explain the fan's exhaust performance. , for a long time to the curtain of the people will feel cold and unbearable.