Question

Which among the following equipment separate the material based on specific gravity?
A. Specific gravity separator
B. Inclined draper
C. Stone separator
D. Screen cleaner
E. Indented cylinder
Choose the correct answer from the options given below:

• A. A only
• B. A and C only
• C. B and D only
• D. C and E only

Hint:

Remember the physical properties used for separation:
- Specific Gravity Separator & Destoner \(\rightarrow\) Density (Specific Gravity).
- Screen Cleaner \(\rightarrow\) Size (Width/Thickness).
- Indented Cylinder \(\rightarrow\) Length.
- Inclined Draper \(\rightarrow\) Shape and Surface Texture.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Cleaning and sorting of agricultural grains are performed using different machines that exploit variations in the physical properties of the materials, such as size, shape, surface texture, and specific gravity (density).

Step 2: Detailed Explanation:
Let us analyze the separation principles of each machine:
- A. Specific gravity separator: This machine separates particles of the same size but with different densities. It uses a vibrating, inclined deck with air blowing upward through it. The lighter particles float and slide down the slope, while the heavier particles sink and climb the deck, achieving separation based on specific gravity.
- B. Inclined draper: This device separates seeds based on differences in their shape and surface texture. Round or smooth seeds roll down the inclined belt, while flat or rough seeds stick to the belt and are carried upward.
- C. Stone separator (Destoner): This is used to remove stones and soil clods from grains. Since stones are much denser than grains, they settle to the bottom and are separated using air fluidization and vibration, based on specific gravity.
- D. Screen cleaner: This separates materials based on differences in their width or thickness (size) using perforated screens.
- E. Indented cylinder: This separates grains based on differences in their length using a rotating cylinder with internal pockets that lift shorter grains while leaving longer grains behind.
Therefore, only the Specific gravity separator (A) and the Stone separator (C) operate based on specific gravity.

Step 3: Final Answer:
The correct option is (B).