Plate and frame filter press

Principle 

• Mechanism is surface filtration

• The slurry enters the frame by
pressure and flows through filter medium

• The filtrate is collected on the
plates and send to outlet

• A 
number  of  frames 
and  plates  are 
used  so  that 
surface  area  increases 
and  consequently  large volumes of slurry can be processed
simultaneously with or without washing

Construction

• The Filter press is made of two
types of units, plate and frames. 

• Usually made of aluminium alloy.

• Sometimes,  these 
are  also  lacquered 
for  protection  against 
corrosive  chemicals  and 
made suitable for steam sterilization.

Frame

It contains an open space inside
wherein the slurry reservoir is maintained for filtration and an inlet to
receive the slurry.

It is indicated by two dots in
description.     

• Frames of different thickness are
available.

• It is selected based on the thickness
of cake formed during filtration.

• Optimum thickness of frame should
be chosen.

Plate

The plate has a studded or grooved
surface to support the filter cloth and an outlet.

It is indicated by one dot in
description.

• Plate supports the filter medium,
receiving the filtrate and outlet

• The filter medium usually cloth
is interposed between plate and frame

• Plate, filter medium, frame,
filter medium and plate are arranged in sequence and clamed to a supporting
structure

• It is normally described by dots
as 1.2.1.2.1 so on

• A number of plates and frames are
employed so that the filtration area is as large as necessary.

• Number of filtration units are
operated in parallel

• Channels  for 
slurry  inlet  and 
filtrate  outlet  can 
be  arranged  by 
fitting  eyes  to 
the  plates  and frames, these join together to form a
channel

• In  some 
types  only  one 
inlet  channel  is 
formed,  while  each 
plate  is  having 
individual  outlets controlled by
valves

Assembly of plate and frame filter

Working

• Working can be divided into two
steps-

1. Filtration operation

2. Washing of cake (if
desirable) 

• Filtration operation 

Advantages

• Provide large filtration area in
relatively small floor space.  The
capacity being variable according to thickness of frames and number used

• Sturdy construction permits the
use of considerable pressure difference. 
(2000 Kilopascals normally used)

• Efficient washing of cake is
possible

• Operation and maintenance is easy

• It produce dry cake in form of
slab

Disadvantages

• It is a batch filter, so it is a
time consuming

• The filter press is an expensive
filter; the emptying time, the labour involved, and the wear and tear on the
cloths resulting in high costs

• Operation  is 
critical,  as  the 
frames  should  be 
full,  otherwise  washing 
is  inefficient  and 
the  cake  is on the cloths resulting in high costs
difficult to remove

• The filter press is used for
slurries containing less about 5 % solids

• In view of the high labour costs,
it is most suitable for expensive materials e.g. the removal of precipitated
proteins from insulin liquors.