The E stirrers are used to mix the acids, and are fastened directly to the tank. The tightness of the mixer at the top is provided by a fixed ceramic part connected to a V-shaped cuff and a ring seal in the area of the solid propeller. Series E 600-800 mm long can be used for cylindrical barrels up to max. 400 l; series E 1000-1200 mm long - for cylindrical barrels with max. 3000 l.