There are commercially available galvanized version of square negative pressure fan structure and technical parameters are basically the same. The main models are 1380*1380*400mm1.1 kW, 1220*1220*400mm0.75 kW, 1060*1060*400mm0.55 kW, 900*900*400mm0.37 kW. The galvanized version of the square negative pressure fan rotates at 450 rpm, the motor is 4 poles at 1400 rpm, the motor protection class is IP44, and Class B insulation. Individual smaller-sized negative-pressure fans lose their significance as negative-pressure fans due to their small air volume, high noise, and low exhaust efficiency. They are not described here.

The relatively large negative pressure fan is more efficient and more energy efficient. FRP horn-shaped negative pressure fan is divided into two types: belt type and straight type. The belt type speed is 370-450 rev / min. It adopts the protection of IP55 F grade of 6 or 4 pole aluminum shell motor. The noise of the product with low speed is relatively low. The direct motor mainly has 12 poles of 440 rpm, 10 poles of 560 rpm, and 8 poles of 720 rpm. The 12 pole motor uses ##, and the high speed fan is noisy. Belt type product##Power saving, economical and durable, straight-type products are suitable for use in places where the belt type cannot work, such as oil stains and corrosive belts. FRP horn-shaped negative pressure fan blades mainly have 6 leaves, 7 leaves, 3 leaves and 5 leaves. The blades are mainly made of die-cast aluminum alloy, engineering plastics (nylon plus fiber) and glass fiber reinforced plastic.

Blades with different blade numbers, blade angles, and radians need to be properly matched with the speed and power. A single data does not indicate the fan's pumping performance.