Propeller fans, capacity

The propeller fan is used in heating, ventilating, cooling, drying, etc., rarely for pressures exceeding 1 in. of water Their rated capacities are given in the accompanying table. 

Fans are made either with axial propellers or with a variety of radial vanes. The merits of different directions of curvature of the vanes are stated in Figure 7.24 where the effect of flow rate of pressure, power, and efficiency also are illustrated. Backward curved vanes are preferable in most respects. The kinds of controls used have a marked effect on fan performance as Figure 7.23 shows. Table 7.4 shows capacity ranges and other characteristics of various kinds of... 

Power dusters use a powered fan or blower to propel the dust to the target. They include knapsack or backpack types, units mounted on or pnUed by tractors, and specialized eqnipment for treating seeds. Their capacity in area treated per hour compares favorably with some sprayers. 

---