Screen capacity is commonly reported as a mass flux per screening area. Which unit correctly expresses screen capacity?
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Atons per hour (t/h)
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Btons per square foot (t/ft^2)
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CBoth (a) and (b)
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Dtons per hour per square foot (t/h·ft^2)
Answer
Correct Answer: tons per hour per square foot (t/h·ft^2)
Explanation
Introduction / Context:To compare screens of different sizes, capacity must be normalized by area. The industry standard metric is mass throughput per unit area of screening surface.
Given Data / Assumptions:
- “Capacity” refers to the throughput rate normalized by area, not merely total feed.
Concept / Approach:Total throughput (t/h) alone does not permit fair comparison across screens of different areas. The correct unit is t/h per ft^2 (or t/h per m^2 in SI), often called unit screen capacity. This helps in sizing and vendor comparison.
Step-by-Step Solution:Define capacity basis: mass flow divided by screen area.Select the option that includes both time and area: t/h·ft^2.
Verification / Alternative check:Design charts plot unit capacity versus aperture, slope, and material factors.
Why Other Options Are Wrong:t/h or t/ft^2 alone omits the other needed dimension.
Common Pitfalls:Using overall t/h for selection can oversize or undersize the screen when area changes.
Final Answer:tons per hour per square foot (t/h·ft^2)