Antifoam is injected continuously at many units, and the current conventional solution filtration systems (precoat filter) are inefficient.
In reality the precoat filter, unless it's opened, cleaned, and a new filter aid added, will be saturated within few days and lose its functionality in removing dirt and suspended solids from the system.
The most significant feature of the precoat filter turbidity pattern is the consistent trend of decreasing product water turbidity that is a result of a constant build-up in filter cake thickness providing a progressively increasing flow path.
Diatomaceous earth filters may be more generally classified as precoat filters, defined by the method of using the powder-like filter media applied as a precoat to woven cloth covered septa.
By using the correct filteraid on a rotary vacuum precoat filter and adhering to sound filtration principles, it is possible to obtain flow rates of 0.2 to 2.0 [gal/ft.sub.22/minute] for difficult-to-filter grape juices containing high blinding, compressible suspended solids (lees).
Large volumes of grape juices may be readily clarified for winemaking on rotary vacuum precoat filters using coarse grade filteraids.
The eighth filter in the system is a precoat filter
, which has been designed to remove all solids down to one-half micron from 66 SSU oil at a flow up to 150 gpm.
When New Hampshire Ball Bearings Inc, Peterborough, NH, replaced their filter paper and cartridges with an automatic central precoat filter
system, they realized a 78 percent return on investment in their first year of operation.
It competes with traditional cross flow filtration, centrifuges and equipment that uses precoat filters
, such as rotary vacuum drum and plate and frame filters.