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Renin Angiotensin Mechanism.

Planetary Mixer.

 

Principle:

  • It's an “Agitator  Mixer”.

  • It works on the mechanism of Shear and Convective Mixing.

  • This type of mixer employs a stationary container to hold the material and brings about mixing by means of moving  screws, paddles or blades.

  • They cause folding, kneading, tearing and mixing of the materials.

Construction:

  •  The construction of a planetary mixer is shown in the above diagram. 

  • It consists of a vertical cylindrical bowl. 

  • The bowl consists of an upper cylindrical section and a lower hemispherical section. 

  • The bowl can be moved up and down whereas the mixing head with the drive is stationary. 

  • This bowl can be removed, either by raising the blade above the bowl or lowering it beneath the blade. 

  • The eccentrically placed mixing mechanism rotates around its own axis. This axis also makes a rotating movement in the bowl. 

  • There is very little place between the blade and the wall of the container.

Working:

  • In this mixer, the mixing arm (agitator) moves around its own axis and around the central axis (like a planet), so that it reaches every spot of the vessel. 

  • The blade (beater) is shaped in such a way that there is very little clearance between the blade and the wall of the container. Therefore, it creates minimum dead space during mixing i.e. it left no material unmixed. 

  • The blade tears the mass apart. 

  • Shear is applied between the moving blade and the stationary wall. 

  • The plates in the blade are sloped. This facilitates the powder making an upward movement. This causes tumbling (convective) motion in the powder.

  • At the beginning, the blade moves slowly for premixing and after sometime at higher speed for active mixing. 

  • The bowl is emptied by scooping or by a dumping mechanism.

Uses:

  1. Semi-Solid mixing.

  2. Preparation of ointments, pastes, creams etc.

  3. Commonly used in bakeries for bread making.

Advantages:

  1. Minimum dead space during mixing.

  2. Suitable for solid-solid and semisolid mixing.

  3. Speed can be adjusted.

  4. Easy to clean and unload the material.

Disadvantages:

  1. Require high energy.

  2. Batch type only: No continuous operation.

  3. Limited size.


Commonly Asked Questions:

  1. Define Mixing. With help of a diagram describe the principle, construction and working of the Planetary Mixer..

  2. Write a short note on Planetary Mixer.
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