An air manifold and supply lines distribute air between the fan and the aeration ducts. Air velocities up to 3,000 ft/min are used. Pipe diameter or cross-sectional area for the designed airflow rate can be determined from Table 3 or by the equation A = cfm / v.
Slide values should be installed between the manifold and supply line. This allows air to be directed to specific ducts during filling or when hot spots are detected.
In some instances, individual fans are attached to a single duct and manifold pipes are not needed. This design uses multiple small fans rather than a single large fan with manifold pipes. The advantages of a single duct fan system include energy reduction, higher efficiency fans, less conveyance losses and lower electrical service requirements.