Meta Filter:
Principle:
Mechanism is surface filtration.
In this, metal rings contain semicircular projections, which are arranged as a nest to form channels on the edges.
This channel offers resistance (strainer) to the flow of solids (coarse particles).
The clear liquid is collected into the receiver from the top.
Construction:
Metafilter consists of a series of metal rings.
These are threaded so that a channel is formed on the edges.
It contains a grooved drainage column on which a series of metal rings are packed.
These rings are usually made up of stainless steel and have dimensions of about 15.0 mm internal diameter and 22.0 mm external diameter.
Each metal ring has a number of semicircular projections (0.8 mm in thickness) on one side of the surface.
The projections are arranged as a nest to form channels on the edges.
These rings are tightened on the drainage column with a nut.
Meta Filters are also known as edge filters.
Working:
Filters are placed in a vessel
Slurry is pumped under pressure or occasionally by applying reduced pressure to the outlet side
Slurry passes through the channels formed on the edges between the rings
The clear liquid rises up and collected from the outlet into receiver
For separation of fine particles, a bed of suitable materials such as kieselguhr is first built up.
The pack of rings serves essentially as a base on which the true filter medium is supported.
Advantages of filter leaf:
Can be used under high pressures, without any danger of bursting the filter medium.
Running cost is low, as separate filter medium is not used.
Can be constructed from a material that can provide excellent resistance to corrosion and avoid contamination of sensitive products.
It is an extremely versatile filter because fine as well as large both types of particles can be separated.
Removal of cake can be carried out by simply back- flushing with water.
Change over from one batch to another or one product to another is easy.
Sterile products can be handled.
Disadvantages of meta filter:
It is not a continuous process.
It is used where the proportion of solid in the liquid to be filtered is about 5% or less.
Uses:
Meta Filters are usually used for-
Clarification of syrups.
Filtration of injection solutions.
Clarification of insulin liquors.
Filtration of viscous liquids can be achieved by applying pressure.