The flow of air through most factory assembled cooling towers is provided by one or more mechanically driven fans. The fan may be axial or centrifugal, each type having its own distinct advantages. Axial fan units require approximately half the fan motor horsepower of comparably sized centrifugal fan units, offering significant energy savings.
Centrifugal fan units are capable of overcoming reasonable amounts of external static pressure (≤ 0.5″ or 12.7mm of H2O), making them suitable for both indoor and outdoor installations. Centrifugal fans are also inherently quieter than axial fans, although the difference is minimal and can often be overcome through the application of optional low sound fans and/or sound attenuation on axial fan units.
The axial fans of induced draft equipment are mounted in the top deck of the unit, minimizing the impact of fan noise on nearby neighbors and providing maximum protection from fan icing with units operating in sub-freezing conditions. The use of corrosion resistant materials ensures long life and minimizes maintenance requirements for the air handling components.
The fans are located on the air inlet face at the base of forced draft towers, facilitating easy access for routine maintenance and service. Additionally, the location of these components in the dry entering air stream extends component life by isolating them from the saturated discharge air.