Drift Eliminator in Cooling Tower

As a by-product of the cooling tower having promoted the most intimate contact between water and air in the fill, water droplets become entrained in the leaving air stream. Collectively, these solid water droplets are called drift. Please note these are not to be confused with the pure water vapor.

Drift eliminators remove entrained water from the discharge air by causing it to make sudden changes in direction. The resulting centrifugal force separates the drops of water from air, depositing them on the eliminator surface from which they flow back into the tower. Although cooling tower manufacturers strive to avoid excess pressure losses in the movement of air through the eliminators, a certain amount of pressure differential is beneficial because it assists in promoting uniform air flow through the tower fill. 

Drift eliminators are classified by the number of directional changes or passes with an increase in the number of passes usually accompanied by an increase in pressure drop.

Source: PDF (Cooling Tower Fundamentals)