Air currents are not only utilised for aspirating impurities from cereal but also for drying and exhausting machinery. Machines are exhausted for one or both of the following reasons:

– To prevent dust leaking into the atmosphere by creating a slight vacuum inside the machine.
– To remove warm, damp air, that would otherwise heat the stock and cause condensation.

In machines such as de-germinators, hammer mills and roller mills, it is essential to carry off the moist, warm air. Air currents are accordingly used for one purpose or another in almost every machine in the cereal cleaning and milling plant; bucket elevators, spouting and conveyors handling dirty maize and wheat are often exhausted as well.