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Renin Angiotensin Mechanism.

Bag Filter.

 Bag Filter.

Principle:

  • Particle Size and density of particles.

  • In a bag filter, size separation of fines (or dust) from the milled powder is achieved in two steps.

    •  In the first step, the milled powder is passed through a bag (made from cloth) by applying suction on the opposite side of the feed entry. This facilitates the separation. 

    • In the next step, pressure is applied in order to shake the bags so that powder adhering to the bag falls off, which is collected from the conical base.

Construction:

  • It consists of a number of bags made of cotton or wool fabric. 

  • These are suspended in a metal container. 

  • A hopper is arranged at the bottom of the filter to receive the feed. 

  • At the top of the metal container, a provision is made for vacuum fans and exhaust through a discharge manifold. 

  • At the top of the vessel a bell-crank lever arrangement is made to change the action from filtering to shaking.

Working:

  • (a)Filtering period: 

    • During this period the vacuum fan produces a pressure lower than the atmospheric pressure within the vessel. 

    • Gas to be filtered enters the hopper, passes through the bags, and out of the top of the apparatus. 

    • The particles are retained within the bags.

  • (b)Shaking period: 

    • During this period the bell-crank lever first closes the discharge manifold and air enters through the top so the vacuum is broken. 

    • At the same time it gives a violent jerking action to the bags so that they are freed from the dust. 

    • The fine particles are collected at the conical base.

Uses:

  1. Bag filters are used along with other size separation equipment, e.g. a cyclone separator.

  2. They are used on the top of a fluidized bed dryer for drying to separate the dusts.

  3. They are used to clean the air of a room.

  4. Household vacuum cleaner is a simple version of a bag filter.

Commonly Asked Questions.

  1. With a well labelled diagram describe construction and working of “Bag Filter”.

  2. Write a short note on “Big Filter”.
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