For Second year B.Pharm program as per PCI syllabus under Pharmaceutical Engineering

1. Ms. Mandakini Sampat Holkar
(M. Pharm.)
For Second Year B. Pharm. Program as
per PCI syllabus, New Delhi
Size Separation

2. Size Separation
Syllabus
Objectives, applications & mechanism of size
separation, official standards of powders, sieves, size
separation Principles, construction, working, uses,
merits and demerits of Sieve shaker, cyclone separator,
Air separator, Bag filter & elutriation tank.

3. Size separation is a unit operation that involves the
separation of a mixture of various sizes of particles in to two
or more portions by means of screening surfaces.
Size reduction process is also termed as sieving, sifting,
classifying or screening.
Size separation process used for
1.As a method to determine particle size and size distribution
used for production of tablets and capsules.
2.As a quality control tool for the analysis of raw material

4. Size separation process used for
3. To test the efficiency of a size reduction equipment or
process.
4. To optimise the process condition such method of agitation,
time of screening, feed rate.
5. To ensure good flow ability of course granules with fine
powder.

5. Mechanical
sieving
Agitation
Oscillation Vibration Gyration
Brushing
Wet Sieving
Centrifugal
method
mechanism
sedimentation
Elutriation
Mechanism of Size Separation

6. Sieve Shaker Machine

7. Principal-
Powdered drug is separated according to its particle size using
a number of sieves nested by different type of agitation.
Construction-
Standard sieve with different sieve numbers are arranged in a
machine known as mechanical sieve shaker or gyratory sieve
shaker.
Arrangement of sieve is such that the coarsest sieve is at the
top and finest at the bottom.

8. Working-
This oldest, most reliable and most commonly used method for analysis
of particle size distribution.
Sieves are arranged as shown and known weight of powdered sample is
placed on the top of first sieve.
The sieve are fixed properly with a receiving pan the bottom of sieve set
and lid to cover the top sieve.
Machine is operated by setting the timer.
After this time machine stops, weight of powder retained on each sieve is
noted.

9. Advantages-
Simple machine
Rapid and reproducible result
Compared with other inexpensive
Disadvantages-
If powder is not dried properly the pores of the sieve might get clogged
causing improver sieving
During process of shaking lot of friction and attrition. This can cause size
reduction of soft particle and lead errors in estimation.

10. Cyclone Separator

11. Cyclone Separator
Principle-A high speed rotating air flow is established within a
cylindrical or Conical container called a cyclone.
Centrifugal force is used to separate the solid from fluid.
Separation depends upon the particle size and density of the
particle.
Construction-
It consist of vertical, cylindrical vessel having conical base.
Upper part of vessel has a provision for the tangential inlet for
feed.
Outlet for separated solids is at the bottom.
Fluid moved out of vessel through an outlet provided from
centre of top portion.

12. Construction-
Arrangement is such as to prevent the short circuiting of the
air from inlet portion to fluid outlet.
Working-
Solid to separated are suspended in the stream of air which is
introduced in to the vessel tangentially at a fairly high speed.
This result in rotary movement of the particles within the
vessel
Centrifugal force makes a vortex movement throwing the
heavier solid towards walls.
Larger particles in the rotating stream have too inertia to
follow the tight curve of the stream, and strike the wall,then
fall to the bottom of the cyclone where they can be removed.

13. Working-
In a conical system as the rotating flow moves towards
narrow end of cyclone.

14. Uses-
Used to separate heavier solid particles from lighter particles.
It can be used to remove dust particles suspended in air.
It is also used to separate solids suspended in water where
the separator is known as liquid or wet cyclone.
Cyclone are also used in oil refineries to separate oils and
gases.
Advantages-Fast
Efficient
Very fine particles can be separated easily.
Disadvantages-
Special equipment is required. Fluid and energy requirement
are high

15. Air separator

16. Air separator
Principle-It works on the principle similar to cyclone separator
with the only difference that here current of air, combined
with centrifugal force, is used.
It involves mechanical force for movement of air.
Rotating disc and vanes develop rotatory movement of air.
By controlling speed of rotation it is possible to separate
particles of definite size.

17. Air separator
Construction- It consist of Cylindrical vessel with a conical
base.
In the upper part of separator the vessel is fitted with feed
inlet ,at the base there are two outlets, one for fine
particles and other for coarse particles.
The rotating plate and blades are attached to the central
shaft to produce air movement.

18. Air separator
Working-
Sample powder is passed through the feed inlet, which falls
on the rotating plate.
The rotating blades are attached to the same shaft.
These produce a current of air as shown by the arrows.
The fine particle picked up an are carried in to space, where
air velocity is sufficiently reduced.the fine particles are
dropped and ultimately collected at an outlet meant for fine
particles.
The heavy particles which downward are removed at an
outlet meant for coarse particles.

19. Air separator
Uses-is attached to ball mill or hammer mill to separate
return oversized particles for further size reduction.

20. Principle: Separation is done in two steps.
In one step in reduced powder is first passed through a bag
filter by applying the suction on the opposite side of need
entry. This helps in separation of fines.
In the second step pressure is applied to shake the filter
bags as to loosen powder adhered to the bags. The material
falls off which is collected from conical base.
Construction-
It consist of number of filter bags made of cloth (Cotton or
woollen fabric) these are suspended in a sheet metal
container. hopper is arranged at the bottom of the filter to
obtain the feed.
Bag Filter

21. At the top of the metal container there is a exhaust and
adjacent to this bell crank lever arrangement is made to
bring the filters to normal atmospheric conditions.
Bag Filter

22. Sieve
Sieves made made from wire mesh, woven from the wires
of brass, bronze, stainless steel or any other inert suitable
material.
Type of sieves-
1.Woven wire sieves-
a. Plain weave
b.Twilled weave
c. Dutch weave
2.Bolting cloth
3.Screen or closed packed bars
4.Perforated plated seiveaa or punched plates

23. 2.Bolting cloth

24. Sieve
Standards of sieves-
•Tyler standard sieve
•US standard sieve
•British Standard sieves
•German dutsche standard sieves
•IP standard sieve
•International test sieve series.

25. Standard for powder
Sr.NO Grade of Powder Sieve through
which all
particles must
pass
Sieve through
which not
more than
40%
particles pass
1 Coarse 10 44
2 Moderately Coarse 22 60
3 Moderately Fine 44 85
4 Fine 85 Not specified
5 Very Fine 120 Not specified