As we look at using fans for drying and storage of grain, it's important to know what performance those fans are giving and what performance is needed in-order to select an appropriate fan for a drying or storage bin. This grain module is brought to you by the Iowa Grain Quality Initiative and was produced by the former Crop Adviser Institute.

Click here to access the Fan Performance Module

Learning objective: Understand the fan performance provided to cool grain and learn the requirements for fan selection.

Airflow Rate Requirements: For high temperature bin drying, anywhere from 2 to 6 cubic feet of air per minute per bushel (cfm/bu) is needed. In natural air drying 1 to 3 cfm/bu is used. For aeration of stored grain, 0.1 to 0.5 cfm/bu is needed.

Equipment: Typically a fan is used to push air up through the grain, creating a positive pressure system. The fan pressurizes the flow beneath the grain. The amount of static pressure (resistance) needed to achieve a certain airflow rate depends on the type of grain, the grain depth, and the airflow rate.

Fan Types: There are several types of fans. The two most commonly used fans are vane axial fans and centrifugal fans. Vane axial fans are less expensive, create higher airflows at lower pressure, and are loud. Centrifugal fans are quiet in nature, and are usually more efficient above 4 inches of static pressure.

Fan Selection: The number of bushels in the bin and the desired airflow rate determine fan selection.