Silverson mixer (Emulsifier) – Pharmaceutical Engineering B. Pharm Third Semester PDF Notes

mixer -Emulsifier


• It produces intense shearing forces and turbulence by use
of high speed rotors

• Circulation of material takes place through the head by
the suction produced in the inlet at the bottom of the head

• Circulation of the material ensures rapid breakdown of the
dispersed liquid into smaller globules

• It consists of long supporting columns and a central
portion. Central portion consists of a shaft which is connected to motor at one
end and other to the head

• Head carries turbine blades

• Blades are surrounded by a mesh, which is further enclosed
by a cover having openings


It consists of a emulsifier head which is covered with the
fine meshed stainless steel sieve

The emulsifier head consist of a number of blades which
rotates at high speed in order to produce a powerful shearing action

The blades are rotated by using the electric motor fitted at
the top.


•The emulsifier head is placed in the vessel containing
immiscible liquids, in such a way that it should get dipped into it

•When the motor is started, the liquids are sucked through
the fine holed and the oil is reduced into the globules due to the the rotation
of the blades

•The precision machined Silverson work head generates
exceptionally high shear rates in a four stage mixing/homogenizing process:

Stage 1

The high-speed rotation of the rotor blades within the
precision machined mixing work head exerts a powerful suction, drawing liquid
and solid materials upwards from the bottom of the vessel and into the center
of the workhead

Stage 2

Centrifugal force then drives the materials to the periphery
of the workhead and subjects them to mechanical shear

Stage 3

This is followed by intense hydraulic shear and circulated
back into the mix as the product is forced through the stator screen at high

Fresh material is continually drawn into the workhead,
progressively reducing globule or particle size and quickly resulting in a
homogeneous, uniform product

Stage 4

The materials expelled from the head are projected radially at
high speed towards the sides of the mixing vessel. At the same time, fresh
material is continually drawn into the workhead maintaining the mixing cycle


• Used for the preparation of emulsions and creams of fine
particle size


• Silver son mixer is available in different sizes to handle
the liquids ranging from a few milli liters to several thousand liters

• Can be used for batch operations as well as for continuous
operations by incorporating into a pipeline, through which the immiscible liquids


• Occasionally, there is a chance of clogging of pores of
the mesh

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