HOW DOES THE ROTARY DRUM VACUUM FILTER WORK?
There are two known ways of filtering the really thick settled solids found at the bottom of tanks or drums. i.e. vacuum filtration (rotary drum vacuum filter) or pressure filtration (filter press). We use vacuum filtration. The process itself works as follows: • A rotating stainless steel drum having a screen on the outside and vacuum on the inside is first coated using diatomaceous earth to approximately 50 mm (2 inches) thick. This becomes the filter media that traps the solids while allowing the wine or juice to pass through to the inside of the drum. The layer of D.E. is held to the drum via a pressure differential between the inside of the drum (partial vacuum) and atmospheric pressure on the outside of the D.E. If the vacuum fails, the filter cake falls away from the drum – ugly! • The wine is then fed to a trough located underneath the drum, through which approximately 15% of the surface of the D.E. on the drum rotates at any one time. By way of pressure differential (i.e. high
