The initial layer of filteraid applied to the septum of the filter is known as the precoat. The precoat can vary in thickness depending on whether pressure or vacuum filtration is used. A precoat of filteraid helps to protect and extend the life of the filtercloth in the filter. A precoat also allows for easier cake discharge once the filtration cycle is complete.
The following calculation is used to determine the amount of filteraid required to apply a precoat:
Mass of filteraid required (kg) =
Precoat thickness (m) X Area of filter (m2) X PCD (kg/m3)