Screen standards and mesh numbering: The rule “higher mesh number → smaller aperture” applies to which screen standards?
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ABritish Standard screens
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BGerman DIN 1171 screens
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CAmerican (ASTM or Tyler) screens
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DAll of the above standards
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ENone of these
Answer
Correct Answer: All of the above standards
Explanation
Introduction / Context:“Mesh” denotes the number of openings per linear inch in a screen. Across common standards, a larger mesh number indicates more openings per inch and therefore smaller apertures. While the exact aperture for a given mesh can vary slightly among standards (due to different wire diameters and series), the inverse relationship between mesh number and opening size remains consistent.
Given Data / Assumptions:
- Comparison among British, German (DIN), and American (ASTM/Tyler) standards.
- General trend, not the exact numeric aperture values, is under discussion.
Concept / Approach:With more openings counted per inch, each opening must be smaller to fit within the same linear measure. Therefore, a 200-mesh screen has much smaller openings than a 20-mesh screen regardless of standard. Differences among standards affect the precise mapping of mesh number to aperture size (and whether the series is based on rational or square-root-of-two progressions), but not the qualitative trend.
Step-by-Step Solution:
Define mesh: openings per inch.Infer inverse relation between count and opening size.Recognise that all listed standards follow this rule.Verification / Alternative check:Published tables for ASTM E11, Tyler equivalent, BS, and DIN show decreasing opening sizes as the mesh count increases.
Why Other Options Are Wrong:
- Selecting only one standard ignores that the relationship is universal across the listed systems.
- “None”: contradicts basic definition.
Common Pitfalls:Confusing “mesh” with “micron grade”; always consult the specific standard for exact conversion, especially when wire diameter matters.
Final Answer:All of the above standards