Question

Screen effectiveness is defined as the ratio of

• A. Actual separation achieved to the ideal separation
• B. Oversize to undersize
• C. Feed rate to product rate
• D. Screen area to particle size

Hint:

Logic Tip: Efficiency/Effectiveness in almost all engineering contexts equals (What you actually got) divided by (What you ideally wanted to get). Only Option A fits this universal engineering definition.

Answer 1

The Correct Option is A

Concept:
In chemical engineering, the term "effectiveness" or "efficiency" of any separation equipment is a performance metric that compares real-world results against a theoretical state of perfection.

Step 1: An "ideal" screen would operate flawlessly: 100% of the particles smaller than the mesh would fall through (undersize), and 100% of the particles larger than the mesh would stay on top (oversize), with zero mixing.

Step 2: In industrial reality, screens are never perfectly efficient. Some fine dust always gets trapped in the coarse pile, and some borderline coarse particles might squeeze through due to orientation or screen blinding.

Step 3: To evaluate how well the machine is actually working, engineers calculate the recovery of the desired material.

Step 4: Screen effectiveness is mathematically defined as the ratio of the amount of material that was actually separated into the correct fraction divided by the amount of material that should have been separated in a mathematically perfect, ideal scenario.