Why are cartridge filters sometimes described as “edge” filters in clarification service?
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ABecause the disks have very sharp machined edges
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BBecause solids never deposit at the disk edge
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CBecause most solids are intercepted along the cartridge edges/periphery (depth and edge effect)
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DNone of these
Answer
Correct Answer: Because most solids are intercepted along the cartridge edges/periphery (depth and edge effect)
Explanation
Introduction / Context:Cartridge filters employ wound fiber or pleated media to provide a tortuous path with a large surface area. Their retention arises from both surface sieving and depth capture, often described using “edge” terminology.
Concept / Approach:The geometry of pleats or wound layers presents many “edges” where flow converges and fine particles are trapped. The bulk of solids removal occurs along these peripheral paths rather than a single flat face, hence the term “edge” filter. The term does not imply razor-sharp metal edges; it describes the interception mechanism.
Step-by-Step Solution:Recognize cartridge morphology: pleated/wound depth media.Understand capture: edges and depth passages collect solids throughout the media.Therefore the “edge” label refers to periphery-dominant capture.
Final Answer:Because most solids are intercepted along the cartridge edges/periphery (depth and edge effect)