An agitator is composed of a drive device i.e. motor, gear reducer, belts etc., guiding system of the shaft (lantern fitted with bearings), a shaft and impellers. If the operating conditions are under high pressure or high temperature, the agitator must be equipped with a sealing system to keep tightened the inside of the tank when the shaft is crossing it. If the shaft is long (> 10m), it can be guided by a bearing located in the bottom of the tank (bottom bearing).