Metafilter – Pharmaceutical Engineering B. Pharm Third Semester PDF Notes



• 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 receiver from the top


• Metafilter consists of a series of metal rings

• These are threaded so that a channel is formed on the

• 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 surface

• The projections are arranged as a nest to form channels on
the edges

• These rings are tightened on the drainage column with a

• Metafilters are also known as edge filters

Diagram of


For separation of fine particles, a bed of suitable
materials such kieselguhr is first built up.

The pack of rings serves essentially as a base on which the
true filter medium is supported. 


• Can be used under high pressures, without any danger of
bursting the filter medium

• Running cost are low, as separate filter medium is not

• Can  be  constructed 
from  a  material 
that  can  provide 
excellent  resistance  to 
corrosion  and  avoid contamination of sensitive products

• It is extremely versatile filter because fine as well as
large both type 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


Meta filters can be used for –      

Clarification of syrups      

Filtration of injection solutions     

Clarification of insulin liquors     

Filtration of viscous liquids can be achieved by
applying pressure

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