Grain aeration systems are simply means to deliver a flow of ambient air (forced by fans) through a mass of grain.
These systems range from a tube with perforations at one end with a fan at the other inserted a few feet into the center of a small bin that draws air to the tube with the purpose of preventing crusts.
Other systems move large volumes of air uniformly through a grain mass to achieve natural air drying (curing) with high reliability and specific outcomes.
Several decades ago a distinction was made between drying bins and storage bins. Drying bins had high airflow rates (and often heaters) whereas storage bins had very small fans meant to change temperature only. Drying bins had a full perforated floor whereas many storage bins had a small duct only — sometimes in a gutter in the concrete and sometimes just a tube laying on the concrete.
Previously storage bins had no aeration and only 'dry' grain was put in them. However many learned the hard way that even dry grain can spoil without aeration.
Most modern bins have full perforated floors supported above a concrete pad with relatively high airflow rates.
On this site we use aeration broadly to include all levels of airflow. We also attempt to provide guidance regarding the performance and expectations for different levels of airflow.
However please be mindful that management of a fan cannot increase the inherent limitation of an aeration system that is overloaded.
Harvested grain is perishable and takes on or gives up water from the surrounding air. Over time it comes into equilibrium with the air temperature and relative humidity (RH) surrounding it, settling at a predictable moisture content (MC) or equilibrium moisture content (EMC). The EMC is different for different grains at a given temperature and relative humidity combination.
Protection from the elements, birds, and rodents requires sound structures (bins). Grain also requires aeration to prevent spoilage by molds and insects. Modern bins are equipped with manually run aeration fans but operators lack the skills for satisfactory storage. Annually over 500 million bushels of moldy grain is mixed with good grain in the United States alone.
"Aeration is the most widely used and one of the safest technologies for preserving grain without the use of chemicals. However, unless the necessary knowledge is available on planning and operating grain aeration systems, this technology cannot be successfully implemented. Although aeration is widely applied, its use is often misinterpreted and the objectives of aeration are not achieved.” The Mechanics and Physics of Modern Grain Aeration Management by Shlomo Navarro, PhD, and Ronald Noyes P.E., Ph.D., 2002.
Spoilage prevention dramatically improves purity, food safeness and, in turn, health.
Additionally, temperature and moisture content control improves attributes such as palatability and reduces brittleness. It is highly advantages to utilize aeration to prevent spoilage of grain stored more than a few days or weeks. Harnessing the aeration system already in place (not all qualify) to achieve a uniform temperature and moisture content throughout the entire bin increases bin yield — a benefit available with Networked Grain Aeration.