Filter press fundamentals: which description best characterizes a plate-and-frame filter press?

Introduction / Context:
Plate-and-frame filter presses are ubiquitous for solid–liquid separation when high-solids cakes are desired. Understanding their operating mode, strengths, and limitations helps in selecting between press, vacuum drum, or continuous pressure filters.

Given Data / Assumptions:

• Classical recessed or plate-and-frame press.
• Cycles include fill, filter, wash (optional), blow/dry (optional), and cake discharge.

Concept / Approach:
Filter presses operate in discrete cycles; therefore, they are batch filters. They can handle a wide range of slurries, especially those forming rigid cakes. Whether the liquid or the solid is the main product depends on economics and washing needs; presses can deliver clear filtrate as the main product if cycle time and labor are acceptable.

Step-by-Step Solution:
Identify mode: cycle-based → batch.Evaluate other claims: maintenance and applicability depend on design and duty; blanket statements are inaccurate.Therefore, the correct characterization is "a batch filter."

Verification / Alternative check:
Vendor literature presents cycle times and cake yields per batch; continuous duties typically use rotary drums, belt filters, or continuous pressure filters.

Why Other Options Are Wrong:
Not suitable if liquid is main product: incorrect; many plants use presses to obtain very clear filtrate.Prohibitively high maintenance: varies; not an inherent trait.Not suitable for wide ranges: presses are versatile with proper fabric and operating pressure.

Common Pitfalls:
Ignoring cycle time and labor in cost estimates; presses deliver quality but require batching logistics.

Final Answer:
a batch filter.