Unwanted moisture is one of the biggest concerns in stored grain – a high temperature exhaust fan helps to control the internal environment by removing unwanted moisture and contamination that are present in the air inside the storage. Although having aeration systems for drying and cooling help to eliminate or improve the conditions of stored grain – exhaust fan is also equally important; together it bolsters the condition of stored grain for short or long term storage. Another major advantage using high temperature fan is that it can be integrated in a cool and heating system.
Grain stored in a bunker or silo does not have natural airflow movement to that of outdoor (air). For example, in the winter season, interior storage systems get filled with moisture due to the lack of air movement and circulation, it is then that mould develops which inevitably causes grain to deteriorate.
When Should I Use a High Temperature Fan?
When you need to remove:
- Unwanted heat
This is especially important when you have a large amount of grain stored. Because weather and temperature are unpredictable these high temperature fans will help to protect your grain harvest and maintain the highest quality.
Lack of air circulation allows breeding ground for insects and mould due to poor moisture content level. Humidity in stored grain creates undesirable moisture content making stored grain unviable. When unwanted substances are removed it allows natural air circulation to circulate freely and stabilise the internal temperature of the stored grain, this in turn eliminate possible insects breeding and infestation.
Placing an exhaust fan above the roof helps to minimise humidity and condensation in the storage/silo. Even when there is aeration equipment being used, if the grain moisture is too high, it can still cause spoilage. Once grain is in storage, even with proper moisture content; it must be monitored to keep it in the accepted range. Moisture can come from anything; leaky hatches, downspouts or bucket elevators. The exhaust fan also gives way to fresh air circulation by pulling fresh and cool air into the storage area.
In a continuous process, the exhaust fan keeps the grain drier, diluted air at the bottom of the grain moves upward through the surface grain making it less likely to experience condensation.
Types of Exhaust Fan
Most fans can be categorised into three categories:
- Axial flow fans/ propeller fans
- Centrifugal fans
- Cross-flow fans
A) Axial flow fans/ propeller fans
Axial fans usually have 4 or more long blades attached to small hubs. It normally can generate up to 5 centimetres in water pressure. It helps to exhaust air from attics, overhead spaces and general air circulation. However, these types of fan are not recommended for cooling or drying aeration.
– 2A) Sub axial fans – Tube and Vane axial
Unlike normal axial fans, sub axial fans — Tube and Vane — have opposite properties. They have larger hubs and shorter blades that help to cool the airflow and capture undesirable heat.
B) Centrifugal fans
Centrifugal fans have backward curve or backward inclined blades. The effectiveness and efficiency of these blades can generate more than 7 centimetres in water pressure. Another advantage of these fans is that they can produce more air volume for a given air volume pressure. However, improper selection on these fan types can damage the motor when operated outside certain pressure ranges. Contact Custom Fans for professional advice.
C) Cross-flow fans
Unlike axial fans, the cross-flow fan uses an impellor with forward curved blades. Its fans are long in relation to the diameter.
The advantages of these fans are the allowable length – it can be adjusted to meet the flow rate requirement, its operating noise is less when compared to axial fans while also having the ability to provide a high pressure coefficient.
Choice of Fan
The type of fans that will help optimise or maintain a quality grain supply depends upon the type of storage, aeration (cooling and drying) system and climate. Proper selection of a high temperature exhaust fan will help to preserve the quality of the grain while in storage, avoid loss and make you more money at market.